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3mbspq | How does refraction work if the speed of light is a constant? | I've always learned that refraction of a beam of light occurs as it travels from one medium to another because the speed of light in the medium varies. To quote Feynman:
> "The path that light seems to travel is always the path with the least time taken. To paraphrase it, imagine that you're lifeguard and there's a pretty girl drowning in the sea. Because you can run faster on the beach than you can swim in the water, it can be proven that there's only one fastest way how to get to that girl. Of course, it would be foolish to make such calculation under the circumstances, but there's one optimum spot where you should hit the water. This is analogous to the cause of bending in light when it travels from one environment to another in which the speed of distribution of light is different"
However, I also understand that the speed of light is a constant and that it doesn't matter what wavelength we're talking about - red light travels as fast as blue light, which travel as fast as microwaves etc.
So why when you shine a white light at a prism do you get a rainbow? This implies that the different wavelengths move at a different speed within the prism. In which case which colour moves at the speed of light?
I'm guessing the answer is in Feynman's use of "the speed of *distribution* of light"? | askscience | https://www.reddit.com/r/askscience/comments/3mbspq/how_does_refraction_work_if_the_speed_of_light_is/ | {
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"The speed of light is constant in a vacuum.",
"The speed of light is constant in a vacuum. Its speed is slowed by media. The speed of light in air is slightly slower. The speed of light in glass is slower than that.\n\nThe index of refraction is used to calculate how light will bend through a certain medium.\n\n_URL_1_\n\nLong story short, shorter wavelengths are more affected by this than longer wavelengths. So as you can see in this picture:\n\n_URL_0_\n\nBlue light is slowed more, so it bends more. Red light is less affected by this. As you can see, it results in diffraction.\n\nSorry if my explanation is a bit goofy, I haven't tutored physics in years.",
" > However, I also understand that the speed of light is a constant and that it doesn't matter what wavelength we're talking about - red light travels as fast as blue light, which travel as fast as microwaves etc.\n\nThis is only true when we are talking about light traveling through a vaccum. Everything else will have a [refractive index](_URL_0_) not equal to one and which does depend on waveleght.",
"Just to add to what others have said, it's a common misconception that the slowed speed of light in a medium is due to the individual photons colliding with matter and being re-emitted, when in fact the explanation of why light moves more slowly in matter is better understand in terms of a light wave, rather than a light particle.\n\nIf I recall correctly from electrodynamics, you can show that the oscillating electric and magnetic fields of a light wave stimulate the production of EM waves by the electrons in the matter such that the combination of the induced EM wave and the original EM wave has a shorter wavelength than the original. This is because the induced EM wave is somewhat out of phase with the original. \n\nThis result is actually derived by modeling the attraction of the electron to the nucleus as a classical harmonic oscillator driven by the incoming wave. This is obviously bullshit, since an electron is a quantum object, BUT it's actually not a bad approximation so long as the incoming EM-wave is not close to the resonant frequency.\n\nThe frequency of a light-wave is fixed at the source, and the frequency is responsible for the color of the light. Hence the color remains unchanged. But because the velocity at which a wave propagates is v = lambda * f where lambda is the wavelength and f is the frequency, we see that decreasing the wavelength actually decreases the velocity. "
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20tfw1 | How often did runaway slaves flee to native country?are there any notable stories or narratives from early America? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/20tfw1/how_often_did_runaway_slaves_flee_to_native/ | {
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"Lookup 'William Still, The Underground Railroad'\n\nHe was an abolitionist and a conductor of the Underground Railroad. He interviewed hundreds of runaway slaves, kept records and wrote biographies on them.\n\nedit: also, I know there were tribes in florida that took in runaway slaves. If they converted religions they were compensated for with shelter, food, work, security, etc.",
"Though you are likely referring to the African Slave Trade, and African slaves' attempts to return to their homeland, when we talk about slavery in early English colonies in North America we should not forget to focus on the Indian slave trade. \n\nThe Indian slave trade permeated life in the early U.S. colonies. Early contact along the Atlantic Coast was often initiated by traders or fisherman who, in an attempt to make a quick profit, would kidnap Amerindians living along the coast to sell as curiosities/slaves in Europe or the Caribbean. In the south, the Indian slave trade was the most important factor influencing the development of the Carolinas from 1650-1715. More Indians were exported out of Charles Town than Africans were imported during this period ([Gallay 2009](_URL_0_)). Slavery became a feature of total warfare with Indian nations, as seen in Massachusetts at the end of King Phillip's War, when the defeated remnants of the Wampanoag Confederacy were sold into slavery in Bermuda.\n\nPerhaps one of the most famous Native Americans, Squanto (or Tisquantum), was originally abducted with five other members of his Patuxet village in 1605. He managed to return to New England in 1614, only to be abducted again shortly after his return. His captor, Thomas Hunt, then sold him to clergymen in Spain. From Spain Tisquantum made his way to London, where he lived for a few years before boarding a ship to Newfoundland in 1617. He arrived in Newfoundland, but couldn't find transport down to Massachusetts, and returned to England. Finally, in 1619 he journeyed with John Smith back to his Patuxet village, finding the area depopulated from slaving raids and disease. A year later the *Mayflower* made landfall in Plymouth and Tisquantum began his role as translator/guide/ambassador between the Plymouth colonists and the Wampanoag leader Massasoit, aided by the English language skills he gained during his captivity."
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55aeh7 | what does crossing the co2 levels crossing 440ppm mean for the rest of us? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/55aeh7/eli5_what_does_crossing_the_co2_levels_crossing/ | {
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"While warming isn't an instant concern, ocean acidification is very much a concern. Many of the simpler organisms (that form the basis of food webs) in the ocean form shells by precipitating calcium from the water. Changes in pH alter their ability to do this.\n\nSource: Ph. D in environmental chemistry and employed as an ocean chemistry researcher.",
"The runaway greenhouse gas effect is real and quite unpredictable. Many scientists believe that the more CO2 that exists in the atmosphere, the more difficult to sink (or eliminate) it will be--hence the \"runaway\" aspect. The last major extinction event was the Permian Triassic extinction. There was increase in average global temperature of approximately 10 degrees C and an increase in CO2 to 2000 ppm over 1,000 to 10,000 years. Compare that with what we have today: 1 degree C temp increase and an increase in CO2 from 280 ppm to 400 ppm over 150 years and you will have a sense of where we are in terms of a possible extinction. Remember that this pace is accelerating so those increases are weighted on recent years suggesting an even more concerning situation. Now there are many things that are different from the time of the Permian-Triassic in terms of kinds of life in the ocean and on land. \n\nThe only other point that I will make is that CO2 is a major issue but only one gas that is responsible for global warming. Modern technology might be able to sink it but we are a ways off of that with energy being the primary constraint--building lots of solar panels or nuclear power reactors would take a lot of power--coal, oil and nature gas. \n\nI studied this stuff about ten years ago and there has been a lot of new information so I encourage you to do your own research. There are many theories about what caused the Permian Triassic extinction and no one knows for sure. ",
"why dont we just plant as many plants as possible? deforestation hurts a lot. Wont that help solve this?",
"150 million bangladeshis will lose their homes and land: almost the entire nation will be permanently flooded. If you feel like you are affected by immigration or refugees now, try to imagine where these desperate people will end up being resettled. \n\n400ppm makes the flooding of Bangladesh certain. The only uncertainty is timeframe. We have no current idea how to reverse sea-rise; it is probably spectacularly difficult. Bangladesh is only the most obvious problem. 1 billion people will eventually lose their current owned land to sea-rise, most of the largest cities on Earth are on the coast.",
"I always thought scientists thought less than 350 ppm was ideal a that over 400 ppm begins the \"we may not be able to reverse this\" area. \n\nBy the way, if you want to see what the level was the year of your birth, you can find it here (through 1997, anyway). It really shows you how quickly it's been increasing. That sheet was part of an awareness campaign where people got their birth year ppm tattooed as a reminder. \n\n_URL_0_ ",
"it means the rich will get richer while polluting more, and you will be stuck with the clean up bill to fix their F ups.\n\nA prime example of privatizing the gains and socializing the losses.",
"I think we should fund research groups to see who could grow genetically modified trees. The goal would be to see who could grow the best tree to absorb the most carbon out of the air. \n",
"Nothing. Your kids and grandkids can sort it out. They were talking deforestation and climate change and the ozone thirty years ago and did nothing. I advocated solar energy and was laughed at. Fuck em all now. I don't care. ",
"Realistic question. I live in a more rural state, where we have just experienced our third \"100+\" year flood since 1993. Which has not happened in the time people have kept records in this state. \n\nTornados have gotten far more frequent and more powerful in my state, including a relatively recent F5 which really screwed things up. Far more frequent than ever recorded in this state. \n\nAdditionally it is getting warmer every year that I have been alive, and as long as we have kept records in this state. \n\nWe are not currently experiencing negative population growth, but we don't grow much .5 percent most recently. \n\nIf this is -not- related to climate change, what is driving it? ",
"I have a CO2 sensor I use for work and I keep it calibrated. In the center of the city of Los Angeles it is 390ppm. This is the largest car market in the world, with the worst traffic in America. \n\nSomeone care to explain this?",
"Stop having fucking kids for atleast 15 years. Let everything catch up.\n\nIt will creat jobs. Bring down inflation. Let water and food supplies catch up.\n\nSome much of this is caused by too many fucking humans ",
"We're going to have to kill off half the human population on Earth to survive. Preferably the half that don't believe in climate change.",
"350 ppm used to be the line in the sand.\n\n\"In her speech \"The World's Tipping Point\"[1], Bianca Jagger states “the safe upper limit for atmospheric CO2 is no more than 350 ppm.\" and quotes the report \"The Economics of 350: The Benefits and Costs of Climate Stabilization\" by Stephen J. DeCanio, Eban Goodstein, Richard B. Howarth, Richard B. Norgaard and Catherine S. Norman, stressing \" the need for immediate, direct intervention\".\"\n\nThen it was 400 ppm.\n\n\"No, there’s no huge tipping point where 399 ppm would have been A-OK but now 400 is climate apocalypse. It’s not like that. Four hundred is just another number we really didn’t want to reach. Four hundred was a place that some optimistic folks thought, if we all really pulled together, we could get our carbon emissions to level off. The models where everyone immediately quit dumping any carbon into the atmosphere would have meant a net global temperature increase of “only” a couple degrees Celsius.\"\n\nNow it's something higher than that.\n\n_URL_0_",
"Eli5, what does your title mean?",
"ONE comment i want to make which i didnt read in this thread regards population control. Does anyone think making it against the law or making it prohibited to have more than two children is a bad thing... Sure us Americans like to think we can do whatever the hell we want and that should most certainly not be a law, but in this case... I don't think the world can accept an ever growing rate. Even at this population, much of the world has issues with resources. I do read that the average # of children per family in western worlds is under 2.5 and places like africa and non industrialized areas is much higher. My point still stands though",
"A lot of nice-ety answers in here. Sometimes the truth is bleaker than we'd like to admit. \nPart of being an adult is accepting our dilemmas and trying to attack it head on, applying directly to the forehead, head on, applying directly to the forehead, head on, applying directly to the forehead.",
"Is there any way that I can detect the co2 ppm at home? ",
"Ironic isn't it. There's been an end of the world predicted on many occasions by psychics or religious folks and they all get talked about.\n\nNow one comes along that scientists finally agree with, it's just about preventable *maybe*, and nobody gives enough of a shit to stop it.\n\n_URL_0_",
"I have ice in my glass. The ice melts but the water remains at the same level. Why isn't this going to be the same for the ice caps?",
"nothing because we are paying lip service and don't give a fuck. \n\npeople like to jump the gun and criticized industry and government for current state, however they are the actual cause of CO2 levels raising. a polluters with lower selling price vs a responsible manufacturer with higher selling price; time and time again we will always buy from polluter and criticized polluter for polluting and responsible manufacturer for outrageous price. we are not buying green products thus there isn't green products; what a surprise right? seriously how retarded can they be? \n\nthat's a fact of life no amount of down vote will change. ",
"From what I've read on everything but Facebook, it's quite a big deal, but it's not a major issue.\n\nIt's absolutely ridiculous the clickbait articles I'm reading on Facebook \"Say Goodbye to Planet Earth - It's Time To Panic!\" with a photo of a meteor for some reason as well.\n\nApparently 440ppm is an average for CO2? That might not be true, but people need to relax a little. The WORST case scenario would take effect in about 300 years.",
"Means absolutely fuckin nothing will change for us proles is what it means. World will continue going to shit, and no, you don't have a say in it.\n\nChoke on the garbage you consume and die, as the men in glass towers demand. Elon musk is building their escape mechanism so they don't have to live with the filth.",
"Electricity should have been the base of study as opposed to combustion. We would have never had this problem to begin with.",
"440 ppm better not happen for another 20 to 40 years because that will be entering the runaway effect. There is a NOAA CO2 monitor station on Mauna Loa and it went over 400 ppm just last year, now approaching 403 ppm. The amount of CO2 and methane being trapped at the surface is increasing rapidly now. Over the next few years, if the density increases even faster, then expect to start seeing dramatic effects around the globe. In some areas, it will seem like an improvement, vegetation growing further north with more temperate climate areas, like the north Canada forests. But the drought band around the equator is going to widen, the oceans get more acid, more conducive environments for toxic acids, fungus, amoebas. Trying to slow down chaotic global warming and chaotic climate change is like trying to brake an oil tanker going at full speed or diverting an asteroid headed for Earth. It has to be done early, no way to recover from too late.",
"That just reducing CO2 emissions is no longer sufficient.\n\nWe need to start finding ways to scrub the CO2. And fast.",
"It means we are quickly running out of time to enact the changes to carbon emissions needed to prevent more than 2 degrees C of warming since the start of the industrial revolution. This threshold is widely accepted the \"safe\" amount of warming where any benefits of a warmer planet are quickly overwhelmed by the problems. These include but are not limited to more drought, more wildfires and longer wildfire seasons, more extreme rainfall events due to increased atmospheric moisture availability, coral reef bleaching or loss, rising sea levels and coastal flooding, etc etc etc. The list of disruptions gets really long past that warming point and the poorest and the lowest lying nations are impacted disproportionately more than the rich but everyone will have real noticeable climate impacts. - On Camera Meteorologist, The Weather Channel\n\nAddition: This value is important at this time of year because it is typically the minimum point for atmospheric carbon, as the growing season ends in the northern hemisphere and the trees stop using as much carbon. The southern hemisphere is entering spring, but has significantly less land than the north and so the balance is for September to be the minimum. As we continue to emit carbon, there is no clear reason that we will ever be lower than this amount again without new technology and mitigation.\n\nEdit: Gold! Thanks Reddit person! Maybe we can set up a climate and weather AMA with a panel of experts if people have more questions about this (hopefully after Hurricane Matthew is gone)\n\nEdit 2: Obviously lots of interest here but I'm off to bed for now. Thank you so much for all the questions and the kindness so many of you showed. Remind me to get that AMA going in a couple weeks and we (me with some other poor saps from different parts of the weather and climate fields that I convince to join in) will try to tackle more of your questions, otherwise I'm around here, twitter, Facebook, tv, etc if the questions can't wait until then!",
"In the worst case scenario, we roughly have 300 years to deal with the problem.\n\nThere's a logarithmic relationship between CO2 and temperature. \n\nThe papers below predict that every doubling in CO2 will cause anywhere from a 0.3 C increase to 2.3 C increase. There's no consensus on how bad the problem is, only that CO2 causes warming. \n\n_URL_1_ \n\nUsing CO2 growth rates from the past 50 years, we can estimate a 1.4 ppm / year increase in CO2. That gives us 300 years in the worst case, which is more than enough time to convert to better energy sources than coal, or improvise solutions to reduce the atmospheric concentration.\n\n\n\n\n\nEdit: Updated with links. Please follow etiquette and don't down-vote for disagreeing.\n\n_URL_2_\n\n_URL_0_\n\n_URL_3_\n\n\n\nHere's a few papers with no consensus on how many degrees each doubling of CO2 will produce in temperature change.\n\nThe short-term influence of various concentrations of atmospheric carbon dioxide on the temperature profile in the boundary layer\n(Pure and Applied Geophysics, Volume 113, Issue 1, pp. 331-353, 1975)\n- Wilford G. Zdunkowski, Jan Paegle, Falko K. Fye\n\nClimate Sensitivity: +0.5 °C\n\nQuestions Concerning the Possible Influence of Anthropogenic CO2 on Atmospheric Temperature\n(Journal of Applied Meteorology, Volume 18, Issue 6, pp. 822-825, June 1979)\n- Reginald E. Newell, Thomas G. Dopplick\n\n* Reply to Robert G. Watts' \"Discussion of 'Questions Concerning the Possible Influence of Anthropogenic CO2 on Atmospheric Temperature'\"\n(Journal of Applied Meteorology, Volume 20, Issue 1, pp. 114–117, January 1981)\n- Reginald E. Newell, Thomas G. Dopplick\n\nClimate Sensitivity: +0.3 °C\n\nCO2-induced global warming: a skeptic's view of potential climate change\n(Climate Research, Volume 10, Number 1, pp. 69–82, April 1998)\n- Sherwood B. Idso\n\nClimate Sensitivity: +0.4 °C\n\nRevised 21st century temperature projections\n(Climate Research, Volume 23, Number 1, pp. 1–9, December 2002)\n- Patrick J. Michaels, Paul C. Knappenberger, Oliver W. Frauenfeld, Robert E. Davis\n\nClimate Sensitivity: +1.9 °C\nObservational estimate of climate sensitivity from changes in the rate of ocean heat uptake and comparison to CMIP5 models\n(Climate Dynamics, April 2013)\n- Troy Masters\n\nClimate Sensitivity: +1.98 °C\n\nA fractal climate response function can simulate global average temperature trends of the modern era and the past millennium\n(Climate Dynamics, Volume 40, Issue 11-12,pp. 2651-2670, June 2013)\n- J. H. van Hateren\n\nClimate Sensitivity: +1.7-2.3 °C\n\nAn objective Bayesian, improved approach for applying optimal fingerprint techniques to estimate climate sensitivity\n(Journal of Climate, Volume 26, Issue 19, pp. 7414-7429, October 2013)\n- Nicholas Lewis\n\nClimate Sensitivity: +1.6 °C\n\nThe Potency of Carbon Dioxide (CO2) as a Greenhouse Gas\n(Development in Earth Science, Volume 2, pp. 20-30, 2014)\n- Antero Ollila\n\nClimate Sensitivity: +0.6 °C\n\nThe role of ENSO in global ocean temperature changes during 1955–2011 simulated with a 1D climate model\n(Asia-Pacific Journal of Atmospheric Sciences, Volume 50, Issue 2, pp. 229-237, February 2014)\n- Roy W. Spencer, William D. Braswell\n\nClimate Sensitivity: +1.3 °C\n\nOtto, Alexander, et al. \"Energy budget constraints on climate response.\" Nature Geoscience 6.6 (2013): 415-416.\n\nClimate Sensitivity: +1.9 °\n\nA minimal model for estimating climate sensitivity\n(Ecological Modelling, Volume 276, pp. 80-84, March 2014)\n- Craig Loehle\n\nClimate Sensitivity: +1.99 °\n\n\n",
"I'm not sure if you meant to type 440, or if you meant 400 since that has been in the news lately. Recent reports are that average global CO2 concentrations have been over 400 ppm for the last month. This is just a mile marker on the way to more climate change.\n\nI haven't heard of anyone talking about 440 ppm CO2, but it may have come up because of recent climate change agreements with the goal of limiting global warming to less than 2.5°C over pre-industrial levels. According to the IPCC [executive summary](_URL_0_) this would require keeping CO2 concentrations between 400 and 440 ppm and global CO2 emissions would have to start decreasing before the year 2020.",
"So, it's not has horrible as many make it out to be. \n\nFirst, this is the limit at which reducing CO2 no longer is enough to prevent the climate from changing from what it is now. \n\nThere is concern that the warming climate could lead to a run away effect that could kill us all. In reality it's nearly impossible for man, with our current technology, to actually cause such an effect. [We'd need to get to 30,000ppm](_URL_0_) CO2 before that will happen. \n\nWhat will happen however, is the climate will change from *what it is now* to something *different* The problem with this is that our current society has developed to deal with the climate as it is now. For example, Florida has developed the infrastructure to deal with flooding and hurricanes. New York has the same to deal with snow and nor'easters. Imagine if they traded weather problems? How well could each community deal with that? Now imagine we rejiggered the entire planet? Bad times. \n\nAnd as far as scrubbing CO2 from the atmosphere goes. It's easy. We already know how to do it... we're very good at putting it in after all. The reverse isn't much harder. The hard part is, figuring out how to power it all. It will take about as much energy to scrub it as was created to put it there in the first place so... yea... lots of power. So if we figure out fusion and get lots of cheap, free energy? We're good to go.\n\nSo, not likely to be the end of the world. But a total pain in the ass. We have to hope tomorrows technology will save us from today's technology. ",
"One thing to remember: we're in an ice age right now. A warm cycle of an ice age, but an ice age nonetheless. When this ice age eventually ends there will be no or virtually no ice at the poles. Whether or not you believe in man-driven climate change is ultimately largely meaningless: the planet will warm and we will exit this ice age. We may cause it to happen a hell of a lot sooner than it would have naturally, but end it will.\n\n[There have been 5 major ice ages in Earth's history](_URL_0_) (in blue)\n\nAs you can see, for the vast majority of Earth's history the planet was not in an ice age.\n\nI bring this up because, as far as the planet is concerned and life overall, it will be fine regardless if we speed up the end of this ice age. Some species will die out. Likely many. Maybe even most. Eventually others will evolve and diversify to take over the empty niches. Life will go on.\n\nThe question is, will we continue on as well?\n\nMankind really started evolving technologically during a cold period of the current ice age and then flourished exponentially under the current warm spell. Whether or not humans continue warming the planet or not eventually the ice age will end entirely and the planet will return to its default state.\n\nChanges to expect as the planet warms:\n\nHigher sea levels. This will, of course, have catastrophic effects on coastal cities and countries. They will have to be abandoned whole-sale. Gradually, probably over a couple of generations, but abandoned nonetheless.\n\nChanged weather patterns. This is actually the most insidious problem. I'm not talking about extreme weather events though they will increase in frequency, I'm talking about permanent changes to local and global climates. The gulf stream, the jet stream, all current ocean currants and air patterns will change. This will reshape all ecosystems world-wide in unpredictable manners. \n\nPlaces accustom to generous rainfall may dry up and vice-versa. This will change the shape and face of agriculture and food production on a global level. In the short term it may mean mass starvation as rich, fertile farmlands dry up and blow away. New rainfall in new places will help those areas become the new bread baskets but they will not initially have the infrastructure nor land conditions conductive to feeding billions of people. It will take a LOT of work to convert these areas into productive food-generating farmland.\n\nOn the plus side, a *hell* of a lot of land will become usable. All of those cold northern/northern ends of countries: northern Canada, Greenland, Scandinavia, Siberia, Russia... They will become usable for more than just remote outposts for oil companies and small native villages. In fact, these are the most likely places for the new breadbaskets for the world. Not to mention the entire continent of Antarctica becoming human-inhabitable.\n\nPlans to settle and convert these extreme latitude, currently uninhabitable regions is where we will have to eventually focus as a species whether or not we get the human-induced climate change under control.\n\nAnd even with the best of plans there will be significant loss. \n\nEcologically, entire ecosystems will have to adapt or die. Probably mostly the later, because organisms already adept at surviving in the coming conditions will largely exist in lower latitudes and simply begin migrating and expanding into these new, now-hospitable environments. This will cause strong selective pressures to be exerted on both the native and invading species and we're likely to see diversification in the long run.\n\nEconomically, this will break nations. All of the island-states will be gone. The economic centers of the continental nations are mostly located on the coasts and will be destroyed. The cost of relocating and rebuilding cities inland will be crippling. Water, already a critical issue in many areas of the planet, will become critical globally. Many regions now depend on winter snow melt to feed into the water-supply networks. When this ice age ends there won't be any winter snow, or at the very least, significantly less. On the plus side, rainfall will probably increase overall but it is impossible to say where. \n\nThere will be scarcity-driven wars, as well as wars to control the resources being made accessible as the northern and southern poles thaw.\n\nThis is the best-case scenario for humanity. The worst case is all this still happens and we ourselves ultimately fail to adapt and a wide-spread mass-extinction event is triggered. In a few million years maybe some new critter evolves to build a stone axe and starts the process all over again. Though probably never again as successfully as us because we humans have used up all the easy-to-reach resources required to get much past the bronze age.\n\nSo, should we work as hard as we can to stave off this inevitable future? Hell yes we should. Cut carbon emissions, develop sequestering tech, invest in alternative energy. The further along we get up the human tech tree before this cataclysm really gets rolling the better for us as a species. And if our leaders were smart we'd start laying the infrastructure for these changes today (ala moving cities and populations inland, building infrastructure, advancing food production technologies, researching teraforming principles). But we won't. We'll wait until its an actual emergency.\n\nEdit: spelling corrections mostly. Also, try commenting if you disagree.\n\nEdit2: wow, thanks for golds!\n"
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"http://globalclimate.ucr.edu/images/monthlyco2large.jpg",
"https://en.wikipedia.org/wiki/Climate_sensitivity",
"http://clivebest.com/blog/?p=1169"
],
[
"https://www.ipcc.ch/pdf/assessment-report/ar4/wg3/ar4-wg3-spm.pdf"
],
[
"http://www.scientificamerican.com/article/fact-or-fiction-runaway-greenhouse/"
],
[
"https://upload.wikimedia.org/wikipedia/commons/8/85/GlaciationsinEarthExistancelicenced_annotated.jpg"
]
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||
2lwcot | why can't all connections to websites be secure https connections? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2lwcot/eli5_why_cant_all_connections_to_websites_be/ | {
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"Because for most web server connections, there's just no need. As a web server administrator, I won't enable https on pages unless there's authentication information or personally identifiable information involved.\n\nHTTPS has additional overhead per connection that's just not really worth it for most of the pages on my servers. That additional overhead isn't an issue for the end-user, because you won't miss that little bit of CPU time. But when it's on a web server, enabling SSL connections for everything means that you need a slightly bigger footprint per connection, which means fewer connections per server, which means more servers, which means more money.\n\nUnless the data, or the userbase demands it, it's not always the best solution for every page."
]
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[]
] |
||
3d7sd5 | After New Horizons passes by Pluto... are there any other objectives? Or will it just be taking pics of anything that passes by as it leaves our solar system? | What does it do next? Just fly off? | askscience | http://www.reddit.com/r/askscience/comments/3d7sd5/after_new_horizons_passes_by_pluto_are_there_any/ | {
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"text": [
"From my post in [this recent thread](_URL_2_):\n\n > First, New Horizons will be sending data back for a long period after the fly-by. It will take 16 months (!) for all the data to get sent back. You can read more [here](_URL_1_) and [here](_URL_3_) about the process for New Horizons to collect data and send it back to Earth.\n\nSecond, they are hoping to send New Horizons near one or more Kuiper belt objects. The potential objects are small (25-55 km across) and 1 billion miles beyond Pluto. [This from NASA](_URL_0_) describes this in more detail."
]
} | [] | [] | [
[
"http://science.nasa.gov/science-news/science-at-nasa/2014/16oct_kbos/",
"http://pluto.jhuapl.edu/Mission/Spacecraft/Data-Collection.php",
"https://www.reddit.com/r/askscience/comments/3cyps6/what_happens_to_the_new_horizon_after_it_passes/",
"http://www.planetary.org/blogs/emily-lakdawalla/2015/01300800-talking-to-pluto-is-hard.html?referrer=https://www.google.com/"
]
] |
|
20140n | why does my upper lip get dry and red every time i get sick? | I don't think it has to do only with the friction when I blow my nose, does it? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/20140n/eli5_why_does_my_upper_lip_get_dry_and_red_every/ | {
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"It does have quite a lot to do with that actually. The extra mucus creates a wet surface, rubbing it with tissue in such a manner as to wipe off the mucus is okay if that's a relatively rare thing. When it's a very frequent thing, the skin becomes irritated from all the friction caused by too much wiping.\n\nAnother problem, especially if you have a very stuffy nose, is breathing out of your mouth almost exclusively. This will also dry out your lips. So you have lips getting both extremes- dried out then wet then dry again. Delicate lip skin doesn't like all that. \n\nJust make sure you drink a lot of fluids, use some sort of lip stuff to help keep it most, and if your nose is running that bad, just shove a bit of tissue to plug it. "
]
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] |
|
7ufno0 | How do engines of different numbers of cylinders but the same displacement per cylinder (bore X stroke) compare? | It seems that more and more cars have .5L per cylinder and it got me to wondering-
Now, I know that most of the time V8 > V6 > I4 but I'm hoping for a more specific answer than bigger engines = moar power. If you had a naturally aspirated engine that had cylinders with a bore of 89mm and pistons with a stroke of 80 as: a 2.0L I4, a 3.0L V6 and a 4.0L V8- assuming all other relevant factors are identical, how would the power output and delivery differ between the engines?
Would the V6 have ~50% more power than the I4? Would the V8 have ~33% more than the V6 and double that of the I4? How would the losses due to internal friction vary by engine and affect that engine's output? Would they all see similar power curves and redlines to each other or would they be similar to other I4/V6/V8 engines?
I appreciate any answers and please be gentle, I'm just trying to learn! | askscience | https://www.reddit.com/r/askscience/comments/7ufno0/how_do_engines_of_different_numbers_of_cylinders/ | {
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"At the basic theory level, yes, each cylinder/piston (formally known as a \"power cell\") would add the same amount of power so a 6-cylinder would have 50% more power than a 4-cylinder with the same displacement/compression ratio per cylinder. In practice, it's much more complicated than that.\n\nWhen you increase the number of cylinders, the first thing you need is a longer crankshaft, which means more weight that the engine has to turn. The same goes for the valvetrain, since it's now working against six sets of valves vs. four. This will sap some of the power increase.\n\nFriction per cylinder would ideally be the same, but each power stroke is pushing against 6 cylinders worth of friction instead of four. This is somewhat offset by more frequent power strokes (every 120 degrees vs 180 degrees), but it is still a net increase and takes more power from the crankshaft.\n\nDifferent engine configurations produce different vibration profiles that may or may not have to be balanced out with counter-rotating shafts that will draw more power. A V-6 needs more vibration damping than an I-4 but, this is not necessarily a case of \"smaller is better\" because an I-6 is a naturally balanced engine that requires no dampening at all.\n\nYou also have greater auxiliary demands for larger engines. For example, larger engine requires more oil, which requires a larger oil pump, which takes more power from the engine.\n\nYou also have the issue that engine power is dependent on torque and speed (RPM)--the formula for power is torque times engine speed. A V-6 that produces 50% more torque (abstractly, each power cell creates torque, not power) and can achieve the same engine speed as an I-4 would produce 50% more power. But large engines generally aren't able to spin as fast as smaller engines, so the redline for a V-6 will usually be lower than an I-4, all other things being equal.\n\nSo in the end, just expanding 4-cylinders into 6 and changing nothing else will result in a less than ideal power increase (but an increase nonetheless). We're able to offset some of this by using better materials to allow higher engine speeds, for example, or choosing configurations that have more desirable properties, but it's a game of give and take as engine size increases."
]
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|
16fqvt | Excited state of a hydrogen atom?? | askscience | http://www.reddit.com/r/askscience/comments/16fqvt/excited_state_of_a_hydrogen_atom/ | {
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"You're looking at the wrong transition. The one excited by 656 nm is the n=2 to n=3 transition, not the n=1 to n=2. More detail at _URL_0_.",
"Just a tip: This isn't nuclear physics, this is atomic physics. ",
"I assume you're familiar with the [Rydberg formula](_URL_0_), which gives you the wavelength of the emitted light. \n\nMaybe you are also familiar with the Schrödinger equation, tells you that the energy levels are associated with particular eigenstates, ie. solutions to the Schrödinger equation. It is sort of like how you can only have standing waves of certain frequencies, and each harmonic has higher energy than the previous one."
]
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||
4fyna5 | why aren't there lice and bedbug epidemics everywhere? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4fyna5/eli5_why_arent_there_lice_and_bedbug_epidemics/ | {
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"It's pretty rare for a bedbug to be active during the day. They're sneaky, so they don't like to come out if there's a chance they'll be seen. They also like targets that are motionless, since even if they're not seen they can still be crushed by accident if the target is active. Finally, each individual bug only feeds about once a week; it remains dormant for the rest of the time. \n\nYou do find them in movie theaters, since they're dark rooms with easy hiding spots and stationary humans to feed on. Bedbugs in movie theaters are actually a growing problem. But restaurants and other brightly-lit areas aren't the most hospitable spots for bugs, because the risk of being seen is high and their targets are decently active. Even if a few bugs did take root in a restaurant, most people probably wouldn't notice, because it takes so long for a colony to really reach epidemic levels, and once it did it would be noticed and exterminated.",
" There used to be. The biggest difference now is that we have effective insecticides and cleanliness. So people tend to kill these insects as soon as they are detected, before they have a chance to multiply to really large numbers.",
"There is a huge bedbug problem in Denver right now. It's not wide spread across the country so it can't be called an epidemic but it is enough of a problem here that it affects your apartment hunting process. I look up the bedbug report at every place I look at. More than half the time there will be a report of former bedbug problems and I run away as fast as I can. Once they are detected somewhere, it is very hard to completely eradicate them. A few always recede in the a wall or other small place and they just wait until it's safe again. "
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3xwy3x | why has the weather been so hot in north america? | It's going to be 68 degrees Fahrenheit on Christmas Eve. Why is it so hot? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3xwy3x/eli5_why_has_the_weather_been_so_hot_in_north/ | {
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"I take it you're not from Southern California? It is FREEZING here. Sometimes it gets down to 55 degrees Freedom at night!\n\nSeriously though: On average global temps for 2015 appear to be the highest they've ever been, but really it's local influences that determine how unusual of a winter you may be having wherever you are located. El Nino on the North American West Coast, for example, has led to an unusually cold and wet winter here (relative for the region, at least).",
"So basically we have two semi rare (more irregular than rare) phenomenons happening at the same time. I'll try and keep it reaaaaaal simple. This year is a strong El Nino year which is caused when the Pacific has warmer than average water which results in warmer air. El Nino is a warm phase of the [El Nino Southern Oscillation] (_URL_0_) which cases warmer weather in the NE, MW, and NW while being colder and wetter in the SW and Mexico. On top of this we have a very strong [Arctic oscillation](_URL_1_) this year as well. Think of the Arctic oscillation as all the cold air spinning around the North pole keeping all the ice cold. When the oscillation is weaker some of this cold air seeps down into Canada and down to the USA making it colder; however, when it is stronger that air stays up there keeping the cold far north. \n\nThe combination of these two has made it a very mild winter so far for most of the US ",
"Come to Salt Lake, the past two weeks have been a winter wonderland. 16\" in my back yard and another foot expected over the course of the week."
]
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"https://en.wikipedia.org/wiki/Arctic_oscillation"
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|
atfeoy | what is a simple linear regression model? | How can it be applied in the field of Economics? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/atfeoy/eli5_what_is_a_simple_linear_regression_model/ | {
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"So to start out, a linear regression is when you take a series of data points and try to find the line of best fit (a straight line that is as close to every point as it can be). A linear regression can then be used to tell you if the data points have a tendency to go upwards (a positive slope) or if they trend downwards (a negative slope).\n\n\nSo let's abstract this, let's say I am at a shooting range and every day that I go I make 10 shots (scored either 0, 1, 2, or 3 each depending on where on the target I hit, a maximum of 30 points per day). Lets say the first day I shoot 12, the next day I shoot 13, the next day I shoot 11, then I shoot 15, then 14, then 13, then 17 and so on... It's very apparent as it sits that my shots are slowly getting better and that I am slowly shooting more accurately, and if we were to take the linear regression of this then we would see a line of best fit with a positive slope (meaning it's tending upwards)... However what if the data wasn't so clear?\n\nWhat if my scores were: 15, 13, 16, 11, 18, 15, 19, 13, 16\n\nWell it's still a positive slope but it's not as obvious that it was positive.\n\n\nNow let's take it into economics, my first thought of using a linear regression model in economics is in reference to stock.... In this if we were to look at a company that has very volatile stock (the price will quickly pick up and peak before dropping really fast and so on) you might not be able to easily tell (by looking at it) if it's on the incline or decline, so something you could do is take as many individual data points that you could from that stock and run a linear regression (given a certain timeframe, like you don't want it for all time necessarily, especially if the stock had survived a crash in the stock market like the 2008 crash).... The linear regression would tell you if the stock price is rising or falling, on a rising price you might be more inclined to buy the stock as then you could sell it for a higher price... On a decline you might be more inclined to sell the stock so you don't lose your value.\n\n\n\nThis is slightly simplified of how a linear regression works and how it is used in certain aspects of economics. ",
"First of all, stock markets use rolling 30 day averages to (kind of) do what you describe as a time-limited line of best fit.\n\nSecond of all, a simple linear regression is based certain assumptions about the data it summarizes- most notably that the data is in fact linear, and I'm pretty sure that is not a good assumption for the movement of stocks. There are analyses to determine a \"line of best fit\" when it's a curve rather than a line eg. loess regression though there are assumptions with that too.\n\nEconomics has a long history of mathematical and statistical analyses, so you are not wholly off track looking in that direction. However a simple linear regression is likely to often, if not always, be inappropriate for your data set, and way too simple to capture the complexity of the underlying data anyway.\n\nI admit I'm stronger in stats than economics, but as I understand it \"past results are no guarantee of future performance\" so even if you had a perfect regression, *tomorrow* might not follow the pattern..."
]
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3jr71k | Has there ever been a monarch who was deposed, but became King/Queen of another country? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/3jr71k/has_there_ever_been_a_monarch_who_was_deposed_but/ | {
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"text": [
"How about Puyi, last Emperor of China? Was Emperor of China, was deposed. Later became Emperor of Manchukuo, a puppet state set up by the Japanese invaders. Manchukuo was a portion of China, not all of China. So a different country. "
]
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||
4bde2s | Russian opinion on Lend-Lease equipment, tanks specifically. | Hey everyone. So I was just wondering what Russian soldiers thought of Western equipment during World War Two, specifically tanks? I've heard that they weren't overly effective but I'm not sure on that. | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/4bde2s/russian_opinion_on_lendlease_equipment_tanks/ | {
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"text": [
"There is a very interesting book related to this subject, \"Commanding the Red Army's Sherman Tanks: The World War II Memoirs of Hero of the Soviet Union Dmitriy Loza\". Very well written and well worth a read, btw. Loza, started as a lieutenant in the Red Army tank forces in a unit equipped with American M4 Shermans. He and his men liked the tanks quite a lot actually. He praises them for their reliability, build quality and the spacious cabin. \n\nI's been a while since I read this book, but I do remember once incident that Loza describes where his tank was disabled in the middle of a battle. He and the crew were completely pinned down, and couldn't retreat on foot, and the tank was burning. The only thing they could do was crawl under the tank to shield themselves from machine gun fire but they expected the tank to explode sooner or later so they resigned themselves to death. However the tank didn't explode and the entire crew lived. \n\nFrom what I remember, Loza didn't consider the Sherman to be inferior to the T-34 in any way. "
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|
6imw85 | why handmade products are more valuable than automatically made products? | Given that robots and machines are a hell of a lot more accurate, you'd have a near perfect item/product versus something that was hand made. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6imw85/eli5_why_handmade_products_are_more_valuable_than/ | {
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"Define \"valuable\"?\n\nIn terms of, slight reduction in quality for great reduction in price? Economies of scale. I can offer a widget for FAR less if I'm producing millions of them using robots and machines I already own versus hand-producing hundreds.",
"Machanical labour is cheaper than human labour. Also, poeple tend to appreciate things made by humans more because it has a sertain human touch.",
"There is supply and demand, with hand-made stuff taking longer per unit, they are more rare. They also tend to have a level of uniqueness since they aren't churned out with the exact same process. And some people simply value things knowing someone put a lot of time and effort into it.\n\nStill, it does depend on the product. If you need precision and a machine can do it better and cheaper than a person, the vast majority of customers will probably go with the machine-made product."
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nhjvm | Is charging electronics on USB 2.0 or micro USB as fast as charging using an outlet? | For example like charging a phone or something. | askscience | http://www.reddit.com/r/askscience/comments/nhjvm/is_charging_electronics_on_usb_20_or_micro_usb_as/ | {
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"You have the tools, why not do an experiment and report back?",
"The posters who are giving a Yes or No answer are forgetting half the equation: The device. Usually, it will indeed be faster on a 5W supply vs a 2.5W USB2 connection. However, some devices are designed to draw a max of 2.5W.\n\nSo, the answer boils down to iorgfeflkd's comment- Try it and find out. ",
"Usually no. Chargers short the 2 data pins which is a sign to most devices that they can draw whatever power they want (1-2A usually). Otherwise the device will usually limit itself to 500mA. \"Charge\" cables short these pins in the cable itself so sometimes you CAN get full power from a computer USB port (if the port is capable of putting out > 500mA), although the cable is useless for data transmission.\n\nApple uses different resistances on the data pins to signify how much power a device can draw which is why non apple USB chargers don't work as well with apple devices.",
"You have the tools, why not do an experiment and report back?",
"The posters who are giving a Yes or No answer are forgetting half the equation: The device. Usually, it will indeed be faster on a 5W supply vs a 2.5W USB2 connection. However, some devices are designed to draw a max of 2.5W.\n\nSo, the answer boils down to iorgfeflkd's comment- Try it and find out. ",
"Usually no. Chargers short the 2 data pins which is a sign to most devices that they can draw whatever power they want (1-2A usually). Otherwise the device will usually limit itself to 500mA. \"Charge\" cables short these pins in the cable itself so sometimes you CAN get full power from a computer USB port (if the port is capable of putting out > 500mA), although the cable is useless for data transmission.\n\nApple uses different resistances on the data pins to signify how much power a device can draw which is why non apple USB chargers don't work as well with apple devices."
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1rhs2h | gluten | I heard this word for the first time a few years ago and now it's everywhere. Gluten-free this and gluten-free that. I hear people at restaurants asking if a dish is gluten-free. And gluten allergies?! Is this a real thing or made up? If it's real, why did I never hear about it until recently and how can so many people now be afflicted with something that seemingly arose out of the blue? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1rhs2h/eli5gluten/ | {
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"It's a wheat protein. For most of us it is fine to eat. People with celiac disease are incapable of digesting it properly and thus it causes great gastric discomfort. It's become somewhat of a fad recently because a lot of people just decided if gluten is bad for some people it may be bad for them, and so they try not to eat it, despite being able to digest it.\n\nIt's only recently that we understood that gluten was causing these symptoms in people. Like autism the problem existed before we just didn't have a name for it.\n\n\nEdit: read the post under mine, he knows more than I do.",
"Gluten is a wonderful, magical protein that happens to be found in wheat (and a few other things). It is the protein that allows dough made from flour made from wheat to be all rubbery and elastic, which makes things like bread a whole lot easier.\n\nUnfortunately, some people are intolerant to gluten. This isn't an allergy, per se--allergies refer to a specific set of reactions (IIRC there are people who actually are allergic, but they are much more rare). However, these gluten intolerant individuals do have a valid medical reason why they should not eat gluten.\n\nThere are also lots of people who are always looking for the latest health trend, though. These are generally well-meaning people who are misguided. They typically have a friend of a friend who is gluten intolerant who had some great health benefits from cutting gluten out of their diet, so they figure they ought to take the \"healthy\" step and cut it out from their diet, too! This has all the logic of you getting transfusions when your friend has lost a lot of blood--getting a transfusion is a good move for them and has valid medical reasons, but it just doesn't make sense for you.\n\nYou haven't heard much about gluten intolerance because there simply hasn't been a lot of awareness until fairly recently. Suddenly people are going to their doctors with symptoms they had previously just dismissed and are getting checked out, and some of them really are intolerant. However, a good number are just hypochondriacs and still more simply misunderstand gluten. It's not some evil additive or a biological poison--it's just a part of wheat, and we've been eating it for millennia with no problem. ",
"My little brother has celiac disease. He's 14 now but I can remember him throwing his guys out several times over the years , even after he was diagnosed and my parents changed his diet. The thing is if something with gluten even touches his food he will throw up (so no dipping my chips in his dip). Some of the gluten food is healthier , but there is junk just like anything else , my older brother and I tried his food for him often before he would try it when younger and comment on how good it was no matter how bad it tasted just to make him feel normal and some what like this disease wasn't a curse. My mom has learned to cook several gluten free dishes which are good and several restauranrs like chick Fil a , moes , and Los Portales offer great gluten free menus. My mom often tells stories about how when he was age 2-3 he would throw up everything he are and quickly became malnourished with the big bell and small arms and legs and deep bags under his eyes. Took several blood test to actually figure out what it was. Lastly the fad in Hollywood has been a huge help to people with the disease , even if people think it is stupid "
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45holr | I get on a spaceship and travel at nearly the speed of light. When I come back to earth, I've aged less than you. But given that speed is relative, how does the universe "know" which one of us was moving quickly? | askscience | https://www.reddit.com/r/askscience/comments/45holr/i_get_on_a_spaceship_and_travel_at_nearly_the/ | {
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"The difference between the two of us is that you turned around, so you underwent acceleration, and I didn't. That is what distinguishes the two of us.\n",
"There's three reference frames involved. In one frame I stay still and you leave really fast and then come back really fast. In one you stay still and then I leave really fast and then you go even faster to catch up. In the third reference frame we're both moving but you're going faster, and then you stop and wait for me.\n\nThere's no reference frame where you were stopped the whole time. You may have stopped for part of it, but you were moving so fast for the rest of it that you aged less overall.",
"Acceleration is not relative - that is what distinguishes you. Until you accelerate to turn around again, both the person in the spaceship and the person on Earth seem to have aged less compared to the other person.",
"The technically correct answers so far may still leave you confused, because intuitively you realize (correctly) that regardless of whether or not one twin accelerated, if motion is truly relative, then the aging should be the same for both twins unless the aging is mediated directly by the acceleration itself (which it straightforwardly is not, in special relativity -- you can make the contribution during the acceleration arbitrarily small, by making the acceleration very high for a very short time). The confusion ultimately stems from thinking relativity is [Machian](_URL_0_); in other words the philosophy (which inspired Einstein) that in a very deep sense motion is truly relative, that for example in a universe containing a single particle, acceleration is impossible. The real world (and Relativity) turns out to *not* be Machian -- there really is something that *keeps track* of motion, or that motion is *relative to*. That *thing* is spacetime. Probably the clearest counter-example that shows relativity is *not* Machian is the existence of gravitational waves: ie waves in the fabric of spacetime. So don't be confused -- things really do move *relative* to something: space time itself. And therefore there is something to \"keep track\" of which twin really accelerated and which did not. What's \"relative\" in relativity are the laws of physics and the speed of light: the laws of physics are the same for any moving body. But movement isn't \"relative\" in the deep philosophic sense that might lead you to get confused about the twin paradox. "
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cyi0rj | How do super storms like Hurricane Dorian affect marine life as the storm travels through the area? Do they affect deep sea creatures? | Edit: Thank you, anonymous do-gooder for the gold! They say it is better to give than to receive, but this is my first gold so I gotta say this feels pretty darn good! | askscience | https://www.reddit.com/r/askscience/comments/cyi0rj/how_do_super_storms_like_hurricane_dorian_affect/ | {
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"I'm not sure on other life, but whenever a decent hurricane blows through the Florida area, lobsters migrate. Gigantic pods of them, divers call it a \"walk\" because... That's what they're doing lol. It's really quite impressive to see, they're also insanely easy to catch that way. Just dive down, find the big ones while they all back into each other to try to defend, grab and bag.",
"Large storms like Dorian with high winds cause a mixing of the nutrient-poor surface layer with slightly deeper, nutrient-rich waters, bringing nitrogen, phosphorus and trace metals to the sunlit photic zone which can cause phytoplankton blooms and subsequent zooplankton blooms, which then attract larger predators like fish. \n\nAs for deep sea creatures on the ocean bottom? They can’t feel the relatively shallow surface mixing caused by storms (disclaimer: does not apply to creatures in shallow coastal waters), the energy dissipates with depth and in any case the ocean is separated by density gradients between different layers of water that kind of act as barriers to mixing/energy transfer",
"The impact of storms can be seen in the geologic record, with layers of sediment deposited by storms up to several meters thick. For plants and animals in the near shore and shore face environments the storms are bad; eroding or churning up sediments followed by raid deposition elsewhere.\n\nFor creatures that live on the sea floor in deeper waters, below the wave base, there is still likely to be impact from increased sedimentation, though not as dramatic as in shallow waters.",
"There was a livestreaming camera on a rig during the last hurricane, 1 camera above looking at a flag that got torn to shreds and another underwater at the foundations. Where fish just idly, occasionally, lightly sway with the currents.",
"Whats also important to note is we truly will probably never know how much a hurricane affects our environment, since simulations are only so good. People may think that stopping a hurricane would be great for every living species, but it could cause an effect such as mess with the ocean currents and potentially kill off entire species.\n\nYou may want to look at the direct effect hurricanes have on life, but you also need to think about indirect effects.",
"It's a mix of good and bad.\n\nWith this storm in particular the surge is likely to do significant damage to the Archie Carr National Wildlife Refuge. This 22 mile stretch of beach running from Melbourne to Wabasso is the most productive nesting site for sea turtles in the United States and one of the most important nesting sites in the world.\n\nA lot of Green and Loggerhead nests are going to be completely destroyed and the dunes are likely to be heavily eroded as well.",
"I am writing a PhD thesis on the ocean response to tropical cyclones. Contrary to what some people have suggested here, the energy of cyclone (hurricane) winds powers ocean currents well over 100 meters below the ocean surface. This has been observed directly using autonomous ocean profilers that measure temperature, salinity and velocity at different depths:\n_URL_0_\n\nNow, the answer to your question varies according to what you consider \"deep sea.\" However, a particular process does come to mind that can reach down hundreds of meters deep and impact marine organisms: hurricanes power vertical currents that lift up water towards the surface.\n\n If a hurricane's eye moves slowly (say 1m/s), water may be sucked up from 150 meters deep all the way up to the surface ([source]{_URL_1_}). \n\nHowever, if the hurricane moves much faster, it will create a large underwater wave: deep, cold water will be carried up and down by as much as 80 m and with a regular frequency in time. These are called near-inertial internal waves (NIWs) and they are an effect of the Earth's rotation. Across the global ocean, these waves help transport energy from the ocean surface towards deeper regions and thus play a role in shaping climate.\n\nNow... These effects are mostly localized along the hurricane track, and are likely to be very weak to the sides of the track. This explains why a submarine could navigate \"below\" a hurricane and not have much trouble. However, a submarine navigating right below a hurricane eye is about to get into A LOT of trouble, as it's going to lose (to some extent) the ability to control its depth.",
"These other responses are physically correct, but the ones I read are missing a critical component. \n\nIn coastal areas, such as the Bahamas, Florida, etc. Most of the aquatic life exists within a few hundred metres of shore. Take a look at the BBC Ocean's episode \"Shallow Seas\" for a more detailed look. \n\nMost aquatic life lives in the photic zone because they survive by eating photosynthetic organisms that can only survive near the surface. They rely on coral to provide them with shelter, food and substrate for life.\n\nHurricanes devistate shallow seas. The coral can get destroyed, and takes decades to grow back. This is going to have a generational effect on the near-shore aquatic life in the Bahamas.\n\nTL;DR: most fish can swim, these will be fine. Most fish's food can't swim. These won't be fine, which means the fish won't get killed by the storm, but will soon be just as starved as the people stranded on an island with no food, water or power.",
"When a storm churns across the ocean, the warm surface waters provide additional moisture and can fuel the storm into a hurricane. As the hurricane grows larger and more potent, it can generate waves as high as 18.3 meters, tossing and mixing warmer surface waters with the colder, saltier water below. The resulting currents can extend as far as 91.5 meters below the surface, wreaking deadly havoc on marine life.\n\nIf the wild currents fail to break up coral reefs in their path, the rain-infused water they bring reduces salt levels and otherwise stresses corals. As the hurricane moves toward shore, the underwater tumult can cause shifting sands and muddy shallow waters, blocking the essential sunlight on which corals and other sea creatures rely.\n\nSlow-moving fish and turtles and shellfish beds are often decimated by the rough undercurrents and rapid changes in water temperature and salinity wrought by a hurricane. Sharks, whales, and other large animals swiftly move to calmer waters, however, and, generally speaking, are not overly affected by hurricanes.",
"A quick Google search suggests while marine life capable of just going deeper to avoid effects do so (whales, sharks) and mammals/wildlife capable of moving also move to avoid a hurricane's effects in response to drops in air pressure etc, slower fish, crabs and other slow marine life etc can be severely affected by massive changes in salinity, reductions in dissolved oxygen (hypoxia) and of course, intense turbulence from rough seas. \n\nIf a particular area has a lot of slow moving land life as well, than an ecosystem's community structure can look very different and take a long time to recover.\n\nDeep sea life is not particularly effected as turbulence and the surface and changes in dissolved oxygen don't happen at deeper sea levels.\n\nSource of some copy-pasted comments: _URL_0_",
"Wave create currents in the ocean surface at depths about half of the wavelength of the wave (L/2). Because wavelengths of waves are typically between ~1 cm to ~10 m most of the deep sea remains relatively undisturbed by the surface processes in storms.\n\nWe don’t know a lot about deep ocean currents as the data available is very limited. What we do know generally comes from ADCP measurements and currently relies on either measurements over the ADCP deployment time in a single location, or shipboard measurements collected during shorter timescales but over wider regions. That being the case there are very few measurements of storm-related activity.\n\nThere are cases of density driven “turbidity” currents damaging subsea cables/equipment in the deep sea. Deep sea sediment flows bury entire communities of deep sea animals, a process well preserved in the fossil record. From rocks and sediments we know that a lot of sediment is transported into deep water during storm events that would affect the creatures that live there.",
"Fisherman and First Nation peoples in Australia say the coastal fish disappear well before the cyclones make landfall, so they obviously take their chances further out to sea. Incidences such as those were seen as precursors well before science gave early warnings. Coral reefs do suffer quite a lot of damage and and can take decades to recover.",
"Sea turtles can get into trouble. I used to work for a major aquarium that had a sea turtle clinic. After hurricanes we sometimes have sea turtles brought in that were found stranded, and they were always terribly battered. They actually can get bruises on their shells, deep bone bruises. I still have pics of a loggerhead that was found after Hurricane Sandy that was missing a flipper entirely (right front flipper was gone) and was covered with bruises - we think it got caught in the storm surge and was rolled against rocks. (It survived & learned to swim pretty well with 3 flippers). Another time, we happened to have a satellite tag on a sea turtle that had been heading southish in the North Atlantic and we were tracking it just before a hurricane came unusually far north through that area. The day before the hurricane, the turtle turned around and made a beeline north, for Nova Scotia, which was the closest land, and it hunkered down in the lee shore of a protected cove, where it stayed through the whole storm. A few days later it came out again and resumed its original track. We all had the impression it had felt the hurricane coming and deliberately looked for a protected spot.",
"idk if its relevant, but i live in an area that was destroyed by hurricane michael and since then, every time weve gone off shore to fish, all of our spots on our gps the structures look completely different on the sonar and many of them have just been reduced to completely flat sand and/or moved around very far even at well ofer a hundred foot depth. ill be going to dive them again for the first time in over a year soon to see if any of them are really completely gone or buried, but the fish arent where they used to be"
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1bypbw | why do alcoholics stop drinking entirely instead of drinking less? | It's something I've never quite understood. I'm sorry if this seems offensive in any way, I'm just curious. Also not sure if this is true of all alcoholics, but I know it's the approach of AA, which is what you mostly hear about. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1bypbw/eli5_why_do_alcoholics_stop_drinking_entirely/ | {
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"For some people, the best way to quit is not to think \"oh I am going to drink less\", as less is quite subjective and there is still a lot of temptation there, but instead to change your mind set entirely to \"I don't drink alcohol\". That way there is never a grey area of what to do, and it's easier to ignore because you can remind yourself that you just *don't do it*. Not that you shouldn't, but you *don't*.\n\nSome people really can cut back on their own, but for others the complete change of mindset works best.",
"Warning: typing in huge generalities.\n\nA lot of alcoholics can't \"drink less\" because it is an addiction. If they *start* there is a very reasonable fear (or behavioral pattern) that they can't/won't be able to stop again. It's easier to just eradicate the influence, lifestyle, and temptation completely. ",
"The more drunk you get, the easier it is to convince yourself that you can totally handle another drink (or anything else). And I think withdrawl is hardest to handle when it first starts.",
"In [the words of Leo McGarry](_URL_0_), \"The problem is I don't WANT a drink. I want TEN drinks.\"",
"People who are addicted are unable to stop at one, that's why they have a problem.",
"If I drank at all I'd probably be drunk every day by the end of the week.\n\n12 years sober.",
"Believe me, it's zero drinks or all of the drinks. \n\nIt's not necessarily alcoholics, though. I don't know many of those. I know a lot of people who abuse alcohol, though. You're ingesting something which ruins decision-making skills, plus feels really fun. The second one seems like a great idea, the third one feels like an AMAZING idea, and after that who even cares, keep going this is THE BESSSTTTT",
"\"Oh, I'll just have *one* cookie\" said Radiantsun before he devoured the entire box of Oreos.",
"Just to add to what everyone else said: this is a biochemical reaction inside the bodies of alcoholics. It's not a question of willpower. \n\nI quit a year ago. At my absolute lowest, if I had a drink, I couldn't stop until I drank every drop I could find. If that meant drinking the entire fifth of vodka and eight or nine beers on top of it, that's what would happen. It stops being a choice and becomes a physical need, like breathing.\n\nIn fact, people who have been alcoholic long enough actually can't quit without medical supervision, as the withdrawal can literally kill you (same as if you quit breathing).\n\nIt's not really known why some people become alcoholic and others don't, but once you cross that line, there's really no way to go back. You can be sober for twenty years, and one drink will have you downing a six pack every night within a few weeks. \n\nTL;DR it's a biochemical reaction INSIDE the body, not a \"decision\".",
"Like the others have already said. \n\nI'm on week 3 of being booze-free (high five!). I try to quit once every few months or so. Here's what usually happens: \n\nI find an excuse to drink. It can be a celebratory drink (I had a good day today, I won at poker, the weather is nice, etc.), or it can be a dispirited drink (girl troubles, bad day at work, nothing to do, etc.).\n\nWhenever I have that one drink, I just cannot stop. The beer tastes so friggin' good. After number two, I feel friggin' good. I feel sharper. I start brainstorming seemingly brilliant ideas. I'm wittier. I'm more courageous. I'm better. \n\nBeer number 3 is more or less the same, but now I am drinking faster. Beers one and two went down in about 15-20 minutes each. Beer number 3 is now gone after ten minutes. \n\nAnd that's when it's time to get loaded. \n\nAs I am drinking beers four through six, I am still feeling pretty good. I realize that I am inebriated, but I don't care. The music I'm listening to becomes epic. The girls in my proverbial blackbook are so much more attractive. I am feeling confident, but now in more of a condescending way than I was feeling back on beers one through three. I conjure up thoughts about how much better I am than other people, or how awesome it would be to sleep with so-and-so, often a friend's wife or girlfriend. I make a plan to go out and have a good time. While I am thinking these thoughts, though, my ass is usually planted on the couch. \n\nOnce I crack beer number seven, things start to deteriorate. I'm drinking more slowly now. I become very lazy. I slur my thoughts and my words. I continue to have thoughts of superiority, but there's no way in hell I'm getting off my couch. All of my great ideas from earlier are put on the back burner, only to be forgotten the next morning.\n\nAfter beer seven, I realize than I am not functional. There's no way I am going to go out. So I throw on a movie or something and continue to sip away at beer number eight. \n\nAfter beer eight is down the hatch, I run into a dilemma. I feel tired and want to go to bed, but if I do that, I'll have to get up again right away to take a piss. If I stay up, I'll have to have more beer. But if I have more beer, I'll have to piss again anyways. \n\nThis is when one of two things happen. I invariably decide to stay up a while longer. But I continue to drink. If I have beer, I drink it albeit much more slowly. If I don't have beer in the house, I break out the whiskey or other hard alcohol. Whether it's more beer or a change in alcohol, I continue to drink until I am ready to pass out. I'm rarely able to finish the movie I started. \n\nI ultimately get 8 or 9 beer's worth of alcohol inside my body before I decide it's time for bed. Surprisingly, I never just pass out on my couch. I am always about to wash up and go to bed. \n\nThe next morning comes, and I feel like crap. I do what I need to do (usually work) and head home. I would love to go to bed, but it's way too early. I feel groggy and possibly have a headache, and I don't want to spend the rest of my evening in this state. What's the best solution? Crack a beer. After that ice cold beer hits my tongue, relief and excitement permeates my body. It's time for another round on binge drinking. The cycle continues.\n\nIt's an endless cycle. Believe me, I would *love* to be a bona-fide \"social drinker\". But it's not going to happen.\n\nTL;DR: I can't drink just one. Once I start I can't stop. I reach various mental, emotional, and physical states before I pass out. I hurt the next day, and the only way to alleviate the pain is to drink again. ",
"Imagine you're trying to stop yourself from having sex. What would be easier?\n\n1) Staying away from pussy completely?\n\n2) Putting just the tip in every now and then and resisting the urge to thrust?",
"For people in AA it is a common understanding that the excessive drinking is not the disease but a symptom of the disease. I see people all the time replace their excessive drinking with excessive (fill in the blank). So I don't have a problem with alcohol I have a problem with moderation. So I don't want the reminder, I just abstain from drinking and other addictive behaviors.\n\nThat being said, there are plenty of people I know that drank a lot and often and it became a problem in their life so they either stopped drinking during the week or will stop after their 3rd beer or something like that. But I can assure you they still have a feeling of just getting shit faced which why a lot of recovering alcoholics rather just not have that reminder altogether and abstain completely."
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2huqhr | How can we see yellow when we don't have yellow color receptors in our eyes? | askscience | http://www.reddit.com/r/askscience/comments/2huqhr/how_can_we_see_yellow_when_we_dont_have_yellow/ | {
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"As you are probably already aware, people have three color cone receptors. The three cones detect different wavelengths of light and those three different wavelengths correspond to red, blue-green, and blue. Now recall your last art class when you were mixing paint. You had your primary colors: red, yellow, and blue. If you wanted to make a green, you would mix a little bit of yellow and blue together. Colors detected by your eye work in a similar way. \n\nWhen you mix red and green light together your eye sees yellow. This is called [additive color](_URL_0_). Not to confuse you further, but the reason you can't mix red and green paint together to get yellow is because those work as subtractive coloring. The link above shows cool animations of both additive and subtractive coloring. \n\nThe TL;DR for additive color and subtractive color is as follows: additive color refers to the mixing of red, blue, and green light waves to create different colors whereas subtractive color refers to the color after red, blue, or green wavelengths have been removed. For example, a yellow box would absorb all colors, but red and green. Red and green mix to produce yellow. The yellow box would then absorb (subtract) magenta and cyan (this is also how your printer prints colors! It uses subtractive color to produce your prints. Color ink cartridge usually have yellow, magenta, and cyan ink). "
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7l28rs | Can Graphene have the photoelectric effect? | If light hits a metal with a frequency higher than that of the threshold frequency of the metal then it will exhibit the photoelectric effect and release a photoelectron with kinetic energy. Knowing that graphene has some similar properties to metals such as being able to conduct electricity, I was wondering wether or not it itself could have the photoelectric effect. Perhaps when coated on plastic. | askscience | https://www.reddit.com/r/askscience/comments/7l28rs/can_graphene_have_the_photoelectric_effect/ | {
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44v43e | How realistic is the famous meeting between Hannibal and Scipio Africanus talking about the best generals in history? | [deleted] | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/44v43e/how_realistic_is_the_famous_meeting_between/ | {
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"While it may seem odd that Hannibal chose Generals all within recent memory he had good reasons to do so. Alexander the Great is a great choice for greatest general of all time because of the scope of his expansion in such a small (relatively) amount of time especially being outnumbered in almost all of his battles(Gaugamela being his most famous). Pyrrhus of Epirus is also a good choice for being pretty high on the list (though i dont think he'd be considered that high now) because of his wars in southern Italy and Sicily. He is even the namesake behind Pyrrhic victory, though i dont know it thats considered a good or bad thing. Likewise even though Hannibal chose himself he had good reason to do so. He had many notable victories under his belt (Cannae and Lake Tresimene being the biggest ones). He held together an army that spoke many different languages in enemy territory for years and won battle after battle.\n\nAlso the other generals you mentioned were pretty good but just not on the level of the other three. Leonidas' most famous battle is one in which he lost. It was a very great last stand but you just cant put him above any of the others when his whole strategy was to wedge his infantry in a bottleneck and wait. The other Generals just dont have the masterpieces that Hannibal and Alexander are known for. Alexander laid siege to city of Tyre that was an island fortress that was almost impenetrable by conventional assault. Instead of giving up or moving on, he just built a land bridge out into the sea towards the island and captured the city. The city of Tyre in Lebanon now still has no small island off the coast because the landbridge still stands. And Hannibal with his victories in Roman territory were technical masterpieces. He achieved something that had never been done before at Cannae when he completely surround a numerically superior force and destroyed them almost to the last man. 50,000 Romans were killed in a single day. That amount of bloodshed would not be matched until WWI.\n\nIt may seem odd that Hannibal chose men that lived in such close proximity to him but the reason for that is just that they were considered at the time to be better generals. While the others may have been Great Generals in their own time, the other three were great generals of all time or in some way made some unique imprint on history"
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2zhuv4 | how do large companies such as facebook make back the billions they spend to acquire "unicorn" start-ups and popular applications? | The short reply that people have always given me is "ad revenue" but is this really possible? What advertising companies are spending billions to pop up within applications and how is that beneficial to them? Do that many people click on them and buy whatever it is they're offering? I understand that I am ignorant on this topic so please refrain from the low-ball replies. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2zhuv4/eli5_how_do_large_companies_such_as_facebook_make/ | {
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"User data.\n\nAcquisitions are mostly about getting a customer base, then using them for advertising. Very few are about technology unless it is extremely difficult duplicate or is under patent, in which they buy the company for patent.\n\nIt's not just ad revenue. In this day and age, knowing someone's facebook, twitter, instagram, snapchat, reddit, etc gives a huge amount of information for analytics for advertising. It is no longer that you're 18-35 and male. Now it's your exact age, your birthday, your mentions, likes, psychological profile, picture upload choices, goetagged telemetrics, etc. Companies are bought for supplying even more data about your likes and interests. All so you will see a Buick commercial instead of a Toyota commercial. So you're sent an ad for free break fast at Dennys near your birthday. Or a Jaguar XJ23 ad since you have 20 pictures of Jaguars on your instagram.\n\nThat's why you get companies, because you tell the world what you are, and they advertise it to you so you can buy it.\n\nBelieve it or not, this isn't a bad idea. Would you rather get ads for things you're interested in or ads you aren't interested in?",
"Globally (as of 2013) internet advertising brought in about $120 billion. Getting a tiny slice of $120 billion is a great year, facebook got $6.4 billion of it.\n\nSo they make back the billions through expectating of ad revenue, ad revenue that keeps growing every year.",
"The key with advertizing is that the vast majority of it is wasted. I'm a 33 year old male watching a tampon add on television, wasted add. I don't watch football but still see Monday Night Football adds, wasted adds.\n\nWasted adds are wasted money. A better idea is to target the adds to people who they (the advertizes) have a shot at selling to. Everyone sees the same number of adds, but all the adds are relevant to the individuals who see them. No more tampon adds for men. \n\nFacebook and Google's secret sauce is all the information that they have about us. Think about it, Facebook knows my gender so it knows not to show tampon adds. Facebook knows my likes, so it knows I don't like football. Google knows my search history, knows where I live, I have an Android phone so it knows where I work and where I drive. \n\nFacebook also knows who I'm friends with. And since it got Whats app it knows who I'm actually talking to regularly. People tend to like things that their friends like, so it uses this information to better target adds. \n\nBasically, everything Facebook or Google does can be boiled down to \"they are trying to get more information to better target advertisements\".\n\nIn terms of \"can they really make that billion back on adds alone?\" I answer with this link \n_URL_0_\n\nThat's Facebook's most recent financial statements, take a look at the revenue section. Their only source of revenue is advertizements. They made 3.8 billion in 3 months, 3 months!",
"It's not all money but also shares of the buying company.\n\nLet's say that facebook buys a company then a lot of the \"aquired for Y billion dollars\" comes from facebook shares, that were never given out and thus didn't cost facebook anything. But facebook has a certain value and thus those shares have value.",
"Its bizzare but for a huge company like facebook (and apple, microsoft, google and so on) money in the bank is not a good thing, especially is there is alot of it. Of these money they need to pay taxes, and some of the money goes away. What you want is company value. They cant tax that and its hard to steal. \n\nSo when facebook buys a \"unicorn\" for 1billion $ they have not lost 1B$ in \"cash\" the value of facebook has increased with 1B$, this makes the stocks go up making facebook more money (and the entire process is started over again... go figure...). There is altso the tax side of it. Lets say that facebook pays 20% tax on gross income. On that 1B$ in \"cash\" they would have had to out 200M$ to tax. But by buying this \"unicorn\" they get to keep the full 1B$ and 0$in tax. \n\nOfcourse this cant be used on everything, buying something today for 1B$ that will be worth 5$ in a year is not good buisness and will hurt alot more than paying taxes."
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r6n5d | why some liquid medicines state a dosage such as 10mg/5ml rather than just 2mg/ml? | Am I just being overly pedantic? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/r6n5d/eli5_why_some_liquid_medicines_state_a_dosage/ | {
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"If the typical dosage is 10 mg (or multiples of that) then you have to do a lot less calculation to arrive at the correct amount. And if you have simpler or no calculation there is less risk of getting the dosage wrong.",
"As a pharmacy technician, I wondered the same thing at first. But I learned that the mL given in the strength will often be a typical dose. For example, if you're given a liquid with strength 10mg/5mL, the 5mL would be what the patient would take each day. This also saves a step or two in calculating how many days worth you are dispensing, which is important for insurance purposes.\n\nShort answer, it saves the pharmacist or tech a few steps in dispensing the medication, which helps prevent mistakes. "
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2576fh | why does it take such a long time to "trace" phone calls, but it takes me less than 2 seconds to traceroute an ip address? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2576fh/eli5_why_does_it_take_such_a_long_time_to_trace/ | {
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"Tracing a call is probably super quick these days. A screenwriter won't care, though, and will milk it for drama."
]
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4rzsb2 | why do so many people in cities smoke? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4rzsb2/eli5_why_do_so_many_people_in_cities_smoke/ | {
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"Because of the concentration, you see them. People in rural and suburbs smoke/dip, but because people are more spread out, you don't notice it as much.",
"also some confirmation bias, more people go outside to smoke in the city, so you will see more people outside smoking. "
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72e6vi | why do babies throw everything? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/72e6vi/eli5why_do_babies_throw_everything/ | {
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"If you are talking about infants it's because they have virtually zero motor control. They are learning to process and comprehend outside stimuli. That's why all of their movements are spastic looking. ",
"Not all babies do.. but often it starts out as an accident.. they hold something and start shaking their arm irradically and end up letting go of the thing. \n\nAfter a few times they start getting better muscle control and then.. they notice something cool. If they throw something their parent picks it up and gives it back to them.. so throwing things sort of becomes a game to them.",
"If you mean the \"dropping\" phase, they are figuring gravity out. Oh, look, this falls. Let's see if it falls again. It does. Repeat. IT DOES!! How cool is this!! Let's try the fork now. It also falls!!! Woah, I totally need to do this again in three minutes, to see if it still works. ",
"you ever get a new tool and wanna use it on everything? well this baby just learned how to throw and now wants to throw everything. \"what can i throw? how far can i throw it? will mommy/daddy bring it back every time i throw it? woah food spreads out when i throw it...look it went everywhere isn't that cool? does this food?\"\n\nit's all a process of discovery...babies are just now learning things we have known all our lives."
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84gk2r | How would an Indian person have been treated in Victorian England? | Hello. I apologize if this isn't an appropriate question or doesn't go here. I am working on research for a time-travel story. One of my main characters is Indian, and finds himself in England in 1848. I'm having trouble finding information on how he would be seen and treated and what sort of discrimination he would face. He's also going to be looking for a cover story, so I'm open to ideas about who he could claim to be to arouse the least suspicion possible.
Thanks in advance! | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/84gk2r/how_would_an_indian_person_have_been_treated_in/ | {
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"Hey there! This is great--it sounds like you are just getting started with the research on this part of your story, so you'll be open to the things you find in your reading. \n\n(We get a lot of people here who already have their plots set up and storm off when they find out they had an element incorrect; you don't want to be them!)\n\nSince you're working from the ground up to create your character's \"world\" in Victorian England, I recommend immersing yourself in background reading to get the details right. Catherine Hall is a *fabulous* scholar of 'daily life'-type things in 19th century England, in light of colonial/imperial concerns at home and overseas. I would definitely recommend starting with some of her books! In addition to the ones listed on her [Wikipedia page](_URL_1_), there is the volume she edited, *At Home with the Empire: Metropolitan Culture and the Imperial World* that you might find useful. \n\nYou might also find the reading recommendations supplied in [this recent thread](_URL_0_) useful.\n\nOf course, if you are more interested in directly consulting users here for our knowledge than in doing your own work, you should contact people individually so you can work out an appropriate compensation plan for the use of the experts' time.\n\nGood luck!"
]
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"https://en.wikipedia.org/wiki/Catherine_Hall"
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1r3q3y | Why was it such a big deal that Henry VIII hadn't produced a male heir even after his daughter Mary was born if England allows women to take the throne? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/1r3q3y/why_was_it_such_a_big_deal_that_henry_viii_hadnt/ | {
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"The only previous female monarch in England, Matilda, was a bad precedent. Her inheritance was challenged and there was a civil war. Most royal heiresses married a foreign prince and delivered their country and its independence to her husband's dynasty. That is what would have happened if Mary had been able to produce a child with Philip of Spain. She would have ended English independence at least for a time, made it another part of the Habsburg empire like Portugal and Flanders.",
"To add to what /u/oldspice75 commented about English independence, I feel there was the fear of the Tudor dynasty failing from within England. Henry VIII's father, Henry VII, took his crown from the Battle of Bosworth Field in 1485, and solidified his claim by marrying Elizabeth of York. Having those male heirs in place gain support and give security to the people for the very reason /u/oldspice75 mentioned."
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2p2lq0 | why does "premium" 'cat food often contain fruit and veggies is cats are obligate carnivores? | It seems that having things like apples and peas in there is just an another type of "filler," like corn. I would think that cats would be unable to properly process such foods.
edit: should be "if," not "is", in the title. This is what happens when I get up before I wake up. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2p2lq0/eli5_why_does_premium_cat_food_often_contain/ | {
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"Wild cats' prey are herbivores.\n\nCats often eat their smaller prey animals whole; so, when a cat eats a mouse, it in turn eats what the mouse has eaten - a small amount of grains, for instance.\n\n > So, for a cat, the consumption of fermented gut content from a mouse or rabbit aids in the management of the cat's own intestinal flora. The intestinal flora in turn maintains the integrity of the mucosal surface. It is likely the VFAs contribute little as an energy source to the cat, but the bacterial load is likely very beneficial.\n\n-[The Stomach Contents of Prey](_URL_0_)"
]
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wis6a | Was melee fighting really as 1 on 1 as it's portrayed as in movies? | It seems that just about in every movie with sword-fighting there's always a climatic battle between 2 main characters. I'm wondering if there was ever a time in which there was honour or something similar in battle so that allies would just watch the two fight to the death? Or, more likely, would a eager soldier see 2 generals fighting and stab the enemy in the back while he wasn't looking to gain glory? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/wis6a/was_melee_fighting_really_as_1_on_1_as_its/ | {
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"Yes, however depending on what era and what context the fight wouldn't last more than a few minutes (and this only for perhaps duels where time, endurance, terrain, and psychological impact counted.) Leaders were often targeted, however leaders also often had trained soldiers nearby to guard them. IMO Oliver Stone's Alexander did a decent job in showing ancient combat.",
"Soldiers of the Caliphate would use champions to challenge their enemies to a duel. There is evidence of duelling in the Napoleonic Wars between soldiers of the same branch (usually the horsemen). "
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2hnb73 | Was the Middle East before 1948 always a conflictual place? Why? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/2hnb73/was_the_middle_east_before_1948_always_a/ | {
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"You should probably try to specify a time before 1948, since the Middle East has a long and complicated history that can't really be summarized in a Reddit post.",
"Before I answer (I have a pretty basic understanding of Middle Eastern history), I do have a few queries to make my answer more succinct.\n\nWhat do you mean by conflictual? Anti-Western aggression? Civil wars? Violence towards non-Muslims in the region? Sunni/Shiite antagonism?\n\nI'm assuming by Middle East, you're also including places such as North Africa. Is this an accurate assessment?\n\nI guess I really just want you to clarify your question.",
"The tail end of the Qajar dynasty in Iran could be summarized as incredibly tumultuous. By the early twentieth century, the government lacked central authority over the country, giving way to the constitutional revolution in 1905. To be clear, the country was in such a dire state, it could not, among other things, actively protect its Northwestern borders in the face of spillover violence from the Armenian Genocide. Their rule ultimately came to a close with the coup and rise of Reza Shah Pahlavi (not to be confused with his son and successor, Mohammad Reza Pahlavi). In the decades to follow, leading up to 1948, the country fought against an Allied invasion and later fended off several attempts by the Soviet Union to absorb parts of Northwestern Iran.\n\nWith all that said, I'm not even really scratching the surface. There is a lot more to twentieth century Iran than my post lets on, but the general takeaway should be that-- at least in the context of modern Iran-- the region has had an incredibly rocky past."
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6bw1yl | how come hotel key cards get erased by being near cell phones, but credit cards don't? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6bw1yl/eli5how_come_hotel_key_cards_get_erased_by_being/ | {
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"I actually asked something similar a while back and was given a fair answer. What it boils down to is the strength of the equipment used to magnetize the cards. A stronger device magnetizing the card means you'd need a stronger magnet to wipe it.",
"What /u/wizer900 said. The strips are much weaker. To expand, they're weaker because they will change the codes often. My dorm in college was a remodeled hotel bought by the school so we dealt with these often. Any card could be rewritten to any door if you just used the machine. Doors and cards get their information changed frequently for security reasons. ",
"Can't they make a better way? Not like everyone has a phone in the pocket, jeez. ",
"Magnetic strips are classified by their *coercivity* (their ability to withstand an external magnetic field demagnetizing the strip). \n\nThere are two types of these strips in the card industry, often called HiCo and LoCo cards. High-coercivity cards are typically around 10-15 times stronger resisting the magnetic force than a low-coercivity card.\n\nBecause they take less energy to produce and to encode data onto, they're a cheaper card overall, and for a high-turnover application like temporary access control (be it your Metrocard or a hotel keycard), cost savings is important.",
"Hotel key cards are designed to be reused (and hence reprogrammed) every time a guest checks out and returns their card. Credit cards are designed to never be reprogrammed.\n\nHence, a much stronger magnetic encoding is used on a credit card.",
"So are hotel key cards coded to a given room's lock? If I were to check out of a hotel, and come back to the same hotel room a month later with the original key card could I still enter the room?",
"FYI the tap-ability of your credit/debit cards can be ruined by your cellphone too. I've had it happen multiple times.",
" Alright I just wrote a paper on the enhancement of magnetic fields using NORF (narrow oscillating radio frequency) so I can give you some insight. \n\n Your phone produces a magnetic field due to the flow of electricity through the device, now, it has been found that specific radio frequencies can actually enhance the magnetic field of your phone. Many devices produce electromagnetic radiation, including radio waves. These are things like phones, computers, soda machines, pretty much every electronic device.\n\n Since the hotel key card is programmed with a magnet, the magnetic field of your phone, which is now amplified by the radio waves given off by all the electronic devices in the hotel, can easily erase any data written on the key card.\n\n If you keep having this problem I recommend googling a Faraday cage sleeve for the keycard, they aren't that expensive, maybe 5-15 usd.",
"I talked to a hotel employee about the frequency of failure of Thor room key cards. They said it happens ALL the time and double it had anything to do with phones. ",
"Front desk employee at a hotel here.\nWhen i encode the card i have to set a end date too.\nSometime i don t bother looking the duration of the stay and i put 4-5 day on all card.\nAs we change days at lunch break (1pm) some cards will work at 11am and not at 2pm.\nWhen a client come and ask why it doens t work anymore i always say it is their phone so their fault (this avoid many negatives remarks and they feel stupid beeing rude for it) , but 80% of the time it is a staff mistake."
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1ywizy | Did the French Government ever apologize for the Holocaust? | I watched a documentary on Black Brazilians which said "the Brazilian Government is the only Government to publicly apologize for slavery in their country." After watching a french movie called The Roundup have a lot of questions.
~Has the French Government ever formally apologized to the victims and their families of The Holocaust?
~ Was their ever anything equal to an Underground Railroad where Jewish people could escape before or during the Roundup?
~ How are Germans treated in France today?
~ My French Teacher told us about a time he told a joke to a German friend mentioning the Gestapo and the German didn't know who or what they were. So, In Germany do they not teach about was the nazi party did to the Jewish people? I can understand that it is a touchy subject, but how is the holocaust taught in schools ?
~Were Germans and Jewish people married during the round-up? If so were they split up? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/1ywizy/did_the_french_government_ever_apologize_for_the/ | {
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"Concerning your fourth point:\n\nThe crimes of Nazi Germany, everything that led to it and WW2 as a whole are taught VERY prominently in Germany. I might be overestimating it a bit in hindsight, but History lessons felt like 1/4 Nazistuff, 3/4 for the complete rest of human history. They even sneaked lessons about Nazi Germany into other subjects like Religion/Ethics (discuss the ethics of Nazi Germany!) or German Language (read a book about Nazi Germany!). We were force-fed the topic to a degree that some kids would simply snap and refuse to discuss the topic anymore. Luckily that stance starts to fade as soon as the topic is no longer forced down your throat..\n\nThe Gestapo is absolutely included in that education."
]
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3kslgs | why is the quality of editing on internet news reports so poor? | It seems like I have to re-read each news article I see online and decipher the meaning or correct in my head the poor spelling. I can forgive English-US English translations, but a news report should be spell checked and read before being published. I've noticed that these sorts of problems are creeping into the books I read on my Kindle as well. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3kslgs/eli5why_is_the_quality_of_editing_on_internet/ | {
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"It's hard to know without an example, but I can tell you that a lot of times, the web sites for local TV news stations will have horrible spelling mistakes, because they're just putting the copy for the newscasters on the web, and those aren't often checked for spelling errors since, as long as the anchor or reporter says the word correctly, nobody knows that it was misspelled.\n\nFor such places, the online presence is an afterthought. My experience is that getting the news from the online site of print outlets, like newspapers, makes for a much better reading experience.",
"3 big things at play:\n\n1) on the internet being first is often more important than being perfect. \n\n2) because you can edit live and because of #1, some sites will throw up the content, and then edit/update it after. You see this particularly for sports, where espn will have super short articles right after a team wins and then as you refresh the article will be longer and more complete. This means you can be a bit sloppy to be first then clean things up for the archival version (not possible once print is out the door).\n\n3) the public tends to be less damning against a news source's long term reputation for typos on the web than in print, so there is less incentive to spend time and money being as meticulous, given the incentives for speed in #1 and #2."
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31l28y | surely someone must know: how do blind people use those bird chirping noises to cross the street? how do they know it's not for the kitty-corner side of the street? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/31l28y/eli5_surely_someone_must_know_how_do_blind_people/ | {
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"Bob is walking north when he approaches an intersection that he knows has an auditory signal. He wants to continue north. He presses the button and listens for the next auditory signal. There is one particular sound that's used for north-south intersections and a different sound that's used for east-west intersections. When Bob hears the north-south signals, he continues his north-bound walk."
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||
7b3wte | if i had $1billion, what "bank" would/could i deposit it all in. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/7b3wte/eli5_if_i_had_1billion_what_bank_wouldcould_i/ | {
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"It would be stupid to put it all in one bank because, for one, banks can fail, and two, it could be put to much better use. Ideally one would invest most of it in various forms of assets like stocks and bonds, real estate, etc. "
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320ys2 | I hope someone can point me in the right direction. I'm looking for information on life in the American west, circa 1870-1875. | I've found a lot of good stuff describing life and travel in the west, but haven't had much luck locating things like exact prices of goods and services, wages, or maps. I would love to find some maps of locales like Dodge City, if such a thing exists, but my google fu has so far failed me, and my local library doesn't have much. I asked in /r/history a week or so ago and never got a response. | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/320ys2/i_hope_someone_can_point_me_in_the_right/ | {
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"If you're looking for maps, one of your best bets is Sanborn Fire Insurance maps. It looks like maps existed for [Dodge City](_URL_0_) shortly after the period you're interested in. Sanborn Maps are not free, but your local library may have a subscription to an online database. Also, they were fire insurance maps so they were generally only of areas that were wealthy enough to worry about fire insurance, but they're still one of the best sources of (US city) historical maps we have.",
"[1875 Montgomery Ward Catalogue](_URL_0_) Catalogues were the major way of purchasing items in the Old West. The local general store would generally have a collections of them you would place an order at your local store and then wait about 3 months. You can find other catalogues online if you look around. \n\nAt this point in time 1870 - 1875 wages were about 10 cents/hour for blue collar workers. It came out to about $1/day or $30/month.\n\nI'm afraid I don't really have a great source for maps. "
]
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3befoe | Where did the concept of 'a captain must go down with his ship' come from and why? It seems idiotic to waste a captain like that. | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/3befoe/where_did_the_concept_of_a_captain_must_go_down/ | {
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"This thread seems to be accumulating multiple below standard posts. Remember, if you can contribute nothing more than your skills at using Google to find an article, please don't post.\n\nAsk yourself these questions:\n\n* Do I have the expertise needed to answer this question?\n\n* Have I done research on this question?\n\n* Can I cite my sources?\n\n* Can I answer follow-up questions?\n\nIf you answer \"Yes\" to all of these questions, then proceed. If you answer \"No\" to one or more of these questions, seriously reconsider what you're posting. For more clarification, see [our rules](_URL_0_).",
"As an idiom it dates back at least the beginning of the 20th century. As a concept it goes back a few decades earlier. \n\nThe concept is not that the \"Captain must go down with his ship\". It is that the Captain should be the last to be rescued. This often times results in the captain going down with the ship but that is a result of saving the lives of everyone else first. \n",
"Follow-up question: was there an increase in occurrences of a captain going down with the ship after the execution of Admiral John Byng?",
"This concept is something of a myth. Although some Captains and Masters have gone down with their ships, in some cases clearly deliberately, there has never been any sort of requirement or expectation that this should happen. In many cases Masters have remained onboard until as many passengers as possible have got away, for example. There have, of course, been many cases where Masters or Captains have been lost in the loss of a ship, but haven't elected to \"go down with their ship\" but have simply been lost in the course of the foundering or other loss of the vessel. Captain Leach of HMS Prince of Wales (along with the Force Z commander, Admiral Tom Phillips) was lost with the ship, but had attempted to abandon along with everybody else. The Captains of HMS Hood, Jervis Bay, Rawalpindi, Glowworm, Courageous and Glorious, as Royal Navy examples were all lost with their ships, but there is no suggestion that any of them chose to be. Admiral Tryon may have chosen to go down with his ship after the fatal ramming by HMS Camperdown, but there is no evidence for this, and HMS Victoria's captain, Captain Bourke was saved.\nThe only cases I can think of where a Captain or Master deliberately chose not to survive their ship's loss, as opposed to remaining onboard through particular circumstances like Captain Herndon, are the loss of the Titanic, the Laconia and the French cruiser, the Leon Gambetta. \nIn the case of the Titanic it has been assumed that Captain Smith chose not to seek to escape the sinking vessel, but there is contradictory evidence about this, with some survivors asserting that he remained in the Wheelhouse whilst others assert that he was in the water after the sinking. Rudolph Sharp, the Master of the Laconia probably did deliberately go below as she sank. He had been Master of the Lancastria when she was bombed and sunk in 1940, the worst British maritime casualty with the highest loss of life. Admiral Senes and all of the officers stayed onboard the Leon Gambetta when she was torpedoed and sunk in 1915, none of them making any attempt to escape, so it can safely assumed that in this case they certainly did choose to go down with their ship. "
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g7aao | Why do geothermal plants produce steam? | I know they boil water, but I was looking at some diagrams of several power plants and found that they include a condensation unit. Why is there still steam emitted, despite the presence of this piece of machinery? | askscience | http://www.reddit.com/r/askscience/comments/g7aao/why_do_geothermal_plants_produce_steam/ | {
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"Are you thinking of a cooling tower? All thermal power generating plants have some waste heat to dissipate (if they didn't they would be violating the laws of Thermodynamics with a 100% efficient process). Usually this excess heat is rejected through evaporative cooling via a cooling tower, which is the large cylinder ejecting clouds of 'steam' (it isn't actually steam, but steam condensing back into water droplets in the air- true steam is not visible) that you see driving by.\n\nThe condensation unit you are seeing in the plant diagram is there to collect the steam after it passes through the turbine and condense it back into water to be recycled back to the boiler to improve water use efficiency. It is basically a heat exchanger that condenses the steam back into liquid water, with a tiny bit of subcooling so it does not cavitate or flash in the condensate return pump. A separate stream of cooling water is used to absorb the steam's heat in the condensate tank, and that cooling water is what gets cooled in the cooling tower. "
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101irv | can someone explain "old man strength" and "retard strong"? is there any science behind these concepts? | To clarify, old man strength is when you are 60+ but can still lift a lot, chop wood, move furniture, etc. It seems counterintuitive knowing that muscle mass shrinks as you age. Retard strong, while politically incorrect, is about how mentally disabled people seem to be much stronger than what they appear to be. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/101irv/can_someone_explain_old_man_strength_and_retard/ | {
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"As to the idea of \"retard strength\", they are not stronger but because of their mental disability they do not inhibit themselves like we do. For example if i go to pat you on the back my brain knows to limit how hard my hand moves, but someone with a mental disability this might not happen and they slap you despite not meaning to do so. "
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69ht4c | Are the stories of "No Man's Land Deserters" in World War One true? | I heard some tales about soldiers, both German and British alike, abandoning their trenches to hide out in No Man's Land, coming out only at night to scavenge for food and resorting to cannibalism while releasing blood curdling sounds (likely from Shell Shock).
I know this all kinda sounds romanticized, and I tried looking up as much as I could with no avail. Is there any truth to this myth? Thank you! | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/69ht4c/are_the_stories_of_no_mans_land_deserters_in/ | {
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"A similar question has been asked before. You can view my own answer as well as that of /u/jonewer [here](_URL_0_)"
]
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[
"https://www.reddit.com/r/AskHistorians/comments/4m6sp6/were_there_really_multinational_communities_of/"
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6ap8vw | why are sinks that require you to hold the knob thing with one hand to pour water even made? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6ap8vw/eli5_why_are_sinks_that_require_you_to_hold_the/ | {
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"Water conservation, typically. I believe it's to prevent people from walking away & leaving the faucet on.",
"It's pretty simple. Water preservation. People won't want to stand there for hours to let the water over flow, but with the \"always on\" faucet, they can plug the drain and run. "
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4gadev | if people want to make video games as realistic as possible, why are the distances in video games over exaggerated? | For example on Sunset Overdrive or Assassin's Creed, why is 200m as long as half way across the city? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4gadev/eli5_if_people_want_to_make_video_games_as/ | {
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"Because no one wants to spend two hours just to get to an objective. It's basically just to get rid of tedium. ",
"The problem is movement, not the actual movement of the character, but the fact that if you make a character move at a \"realistic\" speed it is perceived as insanely slow, making the gamers go crazy at the slow movement.\nAlso in games cities most often aren't that big. Count the buildings and you will notice that there isn't much more than a few blocks in that \"city\". I haven't played AC so i cant say about that game, but generically that's how it is",
"Have you tried running through a city IRL? It's slow, boring and time consuming. This is why video games don't do this, because if it took hours to do everything, no one would bother. You can achieve realism without having to strictly stick to scale. ",
" > If people want to make video games as realistic as possible\n\nThey don't. They typically want to make them as fun as possible.",
"There are also games like Arma 3 that do attempt to make distance a real factor, but even they limit it by keeping you on an island in Greece. They have a few small cities on their map, and you actually have to drive 15 minutes sometimes to get to a different area you are trying to get to. If you actually followed a speed limit, it would take you much longer. At the end of the day like others said, people want to play games for fun, not usually for simulation. ",
"You should play [Desert Bus](_URL_0_), and then you will know!"
]
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5t7b51 | What is the smallest amount of matter needed to create a black hole ? Could a poppy seed become a black hole if crushed to small enough space ? | askscience | https://www.reddit.com/r/askscience/comments/5t7b51/what_is_the_smallest_amount_of_matter_needed_to/ | {
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"black holes must be significantly heavier than the Planck mass M_P, which is about 22 μg. Anything quite heavier can form a (extremely short-lived unless it is really heavy) black hole, while anything quite lighter cannot. So yes, poppy seed is good, *E. coli* bacterium doesn't work.\n\nImagine you have an object lighter than M_P and you're trying to compress it to inside its Schwarzschild radius, which is smaller than the Planck length l_P. In fact, ignoring some pesky numerical factors, you have the formula\n\n M / M_P ~ R / l_P\n\nwhere R is the Schwarzschild radius of the mass M, the radius in which you'd have to compress M to make it a black hole. Since at the length scale of l_P smooth classical spacetime stops existing to give way to a quantum foam, for R to be smaller than l_P sounds already fishy. \n\nBut you try anyway. What you find is that well before your compressing mass even reaches the Planck length, in compressing it you have already given it a lot of energy, which increases its mass (through E = Mc^(2)). In the end, it turns out you have made it into a black hole with M > > M_P and R > > l_P. ",
"It is possible that quantum [black holes can be created](_URL_0_) at for example the hadron collider in Cern. If that happens, they would evaporate in around 10^-27 seconds. ",
"After reading all the comments about how much power a black hole would produce, etc, entirely hypothetically, what if we contained a black hole with a field of influence the size of approximately a golf ball, and harnessed the electricity from said black hole from any method possible, would that even be possible, or effective?",
"Along this same vein, maybe you guys can answer something that I've kicked around a bit.\n\nSince black holes are incredibly massive *for their relative size*, but don't create additional mass, would they necessarily start \"sucking\" everything around them up?\n\nFor example, if the earth was to collapse into a black hole for some reason, would it immediately suck up the moon, or would the black hole simply continue earth's normal orbit around the sun with the moon in its normal orbit around the now much smaller, but still the same total mass, earth?",
"Any amount of matter could (theoretically) be crushed into a small enough area that it would create a black hole. However, black holes decay over time, due to a process called Hawking radiation. The less massive they are, the faster this process happens, and the more violent it becomes. \n\nYour poppy seed would need to be crushed to an incomprehensibly tiny, but still physically viable size. It would then become a black hole, whereupon it would explode \"immediately\" (meaning, after an incomprehensibly short time) in a fashion comparable to that of a nuclear weapon, equivalent to the amount of mass in the poppy seed multiplied by the square of the speed of light (**EDIT:** the total conversion of a single poppy seed would actually provide about 200 times the amount of energy *we receive* from the ordinary burning of a single gallon of gasoline, which in itself is capable of moving a several-thousand-pound vehicle at high speeds for dozens of miles; take that, multiply by 200 times, and imagine it expressed \"instantly\" as a flash of heat and light, ~~and a shockwave~~ (no shockwave out in space; would be a different story in an atmosphere, which is what I was thinking with the example)).\n\nIn comparison, the largest black hole in existence has an event horizon that's about 40 times the diameter of Pluto's orbit, and it will likely not decay for about a googol ( 10^100 ) years. That's a very large number, considering there are about 7.5 * 10^18 grains of sand on Earth, and 10^82 atoms in the observable universe.",
"If you condensed a poppy seed down to a black hole then took an open palm swat at it, what would happen? Could you move it, would it be so dense it goes through your hand? Would the mysterious forces of gravity make your hand explode?",
"If you rearrange the Schwarzchild radius formula to solve for mass, you get m = r*c^(2)/(2G), where m is the mass of an object required to form a black hole given its radius is r; c and G are the speed of light and the gravitational constant, respectively. \n\nGiven the smallest possible distance in physics is the Planck length (~1.6*10^(-35)m), let's use that as the radius. Plugging things in, we get: 1.6x10^(-35)x(300,000,000)^(2)/(2x6.67x10^(-11)) ~= 1.08x10^(-8)kg.\n\nWolfram Alpha confirms this with a result of 1.088 * 10^(-8)kg or 0.01088 milligrams (which is also, apparently, approximately the mass of 4 grains of sand).\n\nI just realised you also asked about a poppy seed. While we can assume that it is more massive than 4 grains of sand, let's calculate the Schwarzchild radius nonetheless (using Wolfram Alpha's estimate of 2.8 grams):\n\nr = 2(6.67x10^(-11)x(0.028)/(300,000,000)^(2) = 4.15x10^(-29)m, around a million Planck lengths.\n\n**TL;DR: The smallest amount of matter needed is 1.09x10^(-8)kg, or approximately 4 grains of sand, so yes, a poppy seed could become a black hole.**",
"I think it's worth mentioning that both matter and energy warp spacetime, so enough of either can warp it severely enough for all trajectories to end at the singularity.\n\nIf enough photons are gathered together in a small enough volume their combined energy will create a black hole. This is called a [Kugelblitz](_URL_0_). \n\nPhotons (the force carriers for light) do not have mass. So no mass is required for a black hole to exist.",
"is there like a 'neutral force' in the universe that every other force is compared to? it seems like for a black hole to exist it must be much denser *in relation* to some other force around it, so is there a common neutral force across the entire universe? probably a stupid question",
" > Could a poppy seed become a black hole if crushed to small enough space ?\n\nYes, but it would blow up immediately.\n\nBlack holes emit Hawking radiation. The smaller the hole, the stronger the radiation, which makes the hole even smaller, which makes the radiation even stronger... repeat until KABOOM.\n\nA poppy seed is pretty much at the size (I mean mass) where it goes kaboom in an instant. The energy equivalent of the mass of a poppy seed is a small tactical nuke. Do not try this at home.",
"There is no limit to matter in either direction. The formation of a black hole is entirely about density. There is an amount necessary to create one in a realistic situation, but it's kinda vague. AFAIK, it's about 8 times the mass of the sun, as the core of a star going SuperNova. So, the original Star needs to have at least 16 times the mass of our sun, roughly."
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"https://en.wikipedia.org/wiki/Kugelblitz_(astrophysics\\)"
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1pmajg | do any other animals eat for needs besides survival? like pleasure, or health concerns? | I know my fellow humans and I enjoy a good slice of cheesecake for no other reason except it makes me feel preeeeeetty preeeetty pretty good. Do any other animals eat things just for joy? Or even do any animals eat things for health concerns?
Pls hurry so i can go back to being fat. thanks. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1pmajg/do_any_other_animals_eat_for_needs_besides/ | {
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714b2w | How did the whole 'endangered species' thing come about? | Was it hard for people to accept? What was the catalyst? Who started it? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/714b2w/how_did_the_whole_endangered_species_thing_come/ | {
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"[This recent answer](_URL_0_) by /u/hillsonghoods partially touches on your question."
]
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"https://www.reddit.com/r/AskHistorians/comments/6ouk3t/how_much_of_a_surprise_was_it_to_contemporary/"
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2nffr5 | Why do European monarchs always have the same names with a number afterwards? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/2nffr5/why_do_european_monarchs_always_have_the_same/ | {
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"hi! there's lots of room for more on this, but you can get started on comments in this post\n\n* [Why has no other British King been named Arthur?](_URL_0_)",
"So in Searocksandtrees's post the British monarchs are discussed. I'll give some info on French Kings.\n\nIf you go back all the way to the Merovingian dynasty there has been several Clovis, several Clothaire, ...Etc they were not known by numbers in chronics of the time but by their period of rules, sometimes with a deed they may have done. \n\nHowever during their lifetime, they were not called by a number until the XIIth Century. But even at this time, they used it that way : Louis the Ninth or Louis the Eight ( in French it would be Louis le Neuvième for example ). The first monarch to have a chronic written during his lifetime and using or know numerotation was Charles the Wise where he is mentioned under the name : Charles V. This remained very rare.\n\nLouis XIV was however called several times as such and not Louis the Fourteenth. Even under his predecessor, writers barely used Louis the Thirteenth but used Louis the Just. \n\nHowever, most of the people ( I mean low class people or simply people living at the time ) would never use a numerotation to refer to the King. For example you would not say Louis XVI if you lived in 1785 but simply King Louis or Our King Louis. It's only in the XIXth Century that historians started to put a number after all the monarchs even those during the Merovingian dynasty who never saw a number used during their lives. It was certainly done to ease everything. \n\nAs to why they are so many monarchs with the same name is pretty much like in England and many other nations. In France, the names were given in function of your godfather and godmother ( both in royal and noble families but also among the people, I saw that quite often during my genealogy researches ) :\n\nFor example, Louis XV had more than a dozen of godsons and goddaughters, resulting in plenty of Louis and Louise. The godmother would often give the second name. This tradition also introduced some \" new \" names. For example, the future Louis XVIII was born Louis Stanislas Xavier de France ( Stanislas being the deposed King of Poland, his grandfather ). Then they took their ruling names. \n\nWhy so many Louis ? Well Louis derives from the name Clovis and Clovis was the \" first King of France \". That was quite prestigious but then we had Louis the Pious ( Louis Ier ) who himself was remembered as a good monarch and it started to become popular. However, Louis IX, several years after his death became a Saint of the Church. That explains why it became such a popular name among French monarchs. You were named after a Saint who also happens to be an ancestor. \n\nIn France we also had ten Charles. Some were quite catastrophic monarchs such as Charles VI or Charles IX but the first Charles was Charles the Great ( or Carolus Magnus/Charlemagne ), a glorious ancestor. \n\nWe also had four Henri. The last two, Henri III and Henri IV were murdered and it may have thrown a cold on the name. \n\nSo indeed, like in Britain and a lot of other nations, monarchs were given the names of a glorious ancestor or someone responsible for great deeds. \n\nSources : *Louis I, II, III… XIV…L’étonnante histoire de la numérotation des rois de France* Michel-André Lévy"
]
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5vb3a6 | do people with exotropia (one or both eyes facing outwards) have a wider field of vision? | I know it sounds *ridiculous* but for some reason it has always bugged me. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5vb3a6/eli5_do_people_with_exotropia_one_or_both_eyes/ | {
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"They technically see a wider field, but they can't easily interpret what they're seeing because the images don't line up anymore. It'd be like walking around cross-eyed all the time. \n\nIf a baby is born with exotropia, the developing brain can actually start to ignore the lazy eye, eventually leading to blindness in that eye. ",
"I have exotropia in my left eye.\nFirstly, I've had wonky eyes forever, one way or another, and as such my brain has decided to mostly ignore what my left eye sees.\nTo expand on that, I can still 'see' out of my left eye (I can switch between looking out of my dominant right eye, or my practically useless left eye), but the image is out of focus, regardless of glasses/contact lenses.\nAs previously stated, my left eye acts more like an extension of the peripheral vision for my dominant right eye.\nInterestingly, I've had several surgeries to straighten the eye, however, it has drifted back to the left over time. I'm told this is because the area of the brain that develops in children to focus images cannot develop as well (or at all) in adults.\nAs a result, I can't perceive distance, or see in 3D.\nAny questions, feel free to ask. "
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5s5qjl | is it possible to reverse nerve damage caused by neuropathy | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5s5qjl/eli5is_it_possible_to_reverse_nerve_damage_caused/ | {
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"Which kind of neuropathy does this relative have? Neuropathy is a description of a condition (deteriorating nerves), not an ailment in its own right.\n\nAmong peripheral neuropathies, there are some caused by vitamin deficiencies, some caused by genetic flaws, and some caused by other conditions.\n\nIf the neuropathy is caused by a vitamin deficiency, a change in diet can reverse the neuropathy to a degree.\n\nIf the neuropathy is genetic, the trick is to live as healthy a life as possible, keeping blood circulation and general cardiovascular health up, but this will only slow the onset of the neuropathy, not reverse it.\n\nThat said, there have been some recent scientific breakthroughs in nerve regrowth that are showing promise in clinical studies; in 15-20 years, there may be treatments to regrow the damaged nerves for some types of peripheral neuropathy.\n\nWikipedia actually has a decent article that goes into more depth.",
"It depends on the cause of the neuropathy and the extent of the damage. Typically the effects of neuropathy can be reduced by treating the underlying cause. Nerve damage is generally seen as permanent, however stem cell therapy seems promising. For your relative, if the neuropathy is secondary to diabetes then properly managing their blood sugar should slow down the advancement of the neurologic degeneration. **[Wikipedia Link](_URL_0_)**"
]
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4hzxao | How is Graham Hancock wrong? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/4hzxao/how_is_graham_hancock_wrong/ | {
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"Graham Hancock does a LOT of cherry-picking of evidence, displays a LOT of confirmation bias, and his research is actually really poor. He constantly sets up straw man arguments to dismiss legitimate academic conclusions. He cites \"experts\" who are actually working outside their field of expertise (like citing an astronomer as an authority on spider species, who incidentally gets his facts wrong about the spider). And that's just some of the methodological issues with his work.\n\nSomeone online did a thorough deconstruction of Fingerprints of the Gods, and I'll link you to their three part destruction of his theory.\n\n[Part 1](_URL_2_), [Part 2](_URL_1_), and [Part 3](_URL_0_)\n\nLet's go into a couple of details that they bring up. Let's start where he does, with the Piri Reis Map, which he states shows Antarctica without ice, therefore has to have been mapped 10,000 years ago. What he doesn't actually do is *look at the freaking place names on the map*. If he actually read the freaking map, he would see that what he claims is Antarctica is actually clearly labeled as Argentina. The southernmost part of the map is Puerto San Julian. And it's *labeled*. And that's just the start of his problems.\n\nAnother massive issue is his insistence that the Inca depicted Viracocha as a European. The truth is, they didn't. There is no mention of pale skin in the legends, there are in fact several South American cultures that had beards (like the Ache in Paraguay), and stories about initial lack of hostility is thought to be Spanish propaganda.\n\nIn addition, Hancock clearly knows nothing about field archaeology or stratigraphy, asserting for example that\n\n > “[r]adiocarbon was redundant in such circumstances; thermo-luminescence, too, was useless”\n\n(stated while dismissing the archaeological date of the Incan fortress of Saksawayman)\n\nSeveral things are wrong and misleading with his statement. First, there are several other ways of dating large masonry walls. Hancock cherry-picks and does not tell the readers that the buildings he is trying to say are really super old and built by a supercivilization are on top of another buried city conclusively dated by pottery and radiocarbon to 1100 CE.\n\nThese are just a couple egregious examples of what is either a stark lack of knowledge, incredibly poor research methodology, or a deliberate attempt to deceive readers by withholding information or presenting erroneous information as fact.\n\nGraham Hancock is a hack."
]
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"https://badarchaeology.wordpress.com/2014/02/05/hancocks-fingerprints-of-the-gods-part-iii-plumed-serpent-central-america-part-one/",
"https://badarchaeology.wordpress.com/2014/01/05/hancocks-fingerprints-of-the-gods-part-ii-foam-of-the-sea-peru-and-bolivia/",
"https://badarchaeology.wordpress.com/2014/01/02/hancocks-fingerprints-of-the-gods-part-i-misunderstanding-early-modern-cartography/"
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||
27xmk8 | Is there any mention of Jesus traveling in his younger years? | Apparently my girlfriend, a newly minted yoga teacher, encountered a supposition that in the time before biblical mention, Jesus travelled and perhaps learned from wizened teachers outside of his native culture.
I'm only interested in whether there is mention or implication; I don't expect consensus :) | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/27xmk8/is_there_any_mention_of_jesus_traveling_in_his/ | {
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"There's no historical support that I've ever seen, but Osho for one claims Jesus went to Kashmir (his support is mostly the French historian Bernier's observation that Kashmiris looked Jewish afaik)",
"No, there's no mention or implication that Jesus ever travelled beyond Galilee and Judea. "
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2cltw3 | Can you recommend any books on the history of technology and innovation? | I'm thinking more to do with the development and spread of ideas, rather than particular technologies (eg, computers or weapons).
I'm reading Matt Ridley's *The Rational Optimist* and the first few chapters have provided an interesting overview of the history of innovation over the past 100,000 years or so. I want to find out more about how ideas in technology and innovation developed and spread. | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/2cltw3/can_you_recommend_any_books_on_the_history_of/ | {
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"These are a little obvious, but if you haven't read them, you're definitely missing out:\n\n[Connections by James Burke](_URL_0_)\n\n[A Short History of Nearly Everything by Bill Bryson](_URL_1_)\n\nNot really original, but great fun, great stories and exactly what you seem to be looking for.",
"Thomas Hughes, *American Genesis.* \n\nSteve Usselman, *Regulating Railroad Innovation.*\n\nLou Galambos, *Networks of Innovation.*\n\nThere are hundreds of other very good title out there, but these three are, IMO, foundational to your question. Start with Galambos, then Hughes. If you're really into it, go for the dry-ish but hugely informative Usselman.\n\nIs this sort of stuff is of serious interest to you, look into the [Society for the History of Technology.](_URL_0_) Their journal, *Technology and Culture,* is fantastic. "
]
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"http://smile.amazon.com/Connections-James-Burke/dp/0743299558/ref=sr_1_2?ie=UTF8&qid=1407178222&sr=8-2&keywords=connections",
"http://smile.amazon.com/Short-History-Nearly-Everything-ebook/dp/B004CFAWES/ref=sr_1_1?s=books&ie=UTF8&qid=1407178286&sr=1-1&keywords=a+short+history+of+nearly+everything"
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d498m3 | how can we see magenta if it doesn’t technically exist on the visible spectrum of light? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/d498m3/eli5_how_can_we_see_magenta_if_it_doesnt/ | {
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"Because it's our name for a color that consists of a *blend* of two existing colors.\n\nHow can we eat a strawberry rhubarb pie, if there is no strawberry rhubarb plant? :-)",
"Our eyes have colour receptors that correspond to red, green and blue. But they actually each detect a range of light wavelengths, with the response peaking at red, green and blue. When we detect light inbetween those colours, both sets of receptors get activated. E.g. we see yellow light because it activates both the red and green receptors about equally.\n\nThis means we have no way to tell the difference between actual yellow light, and a mix of red and green light. Another consequence of this is that if we see a mix of red and blue light, we perceive it as a different colour (magenta), even though there is no single wavelength of light which looks the same."
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1hsu3b | How did the Greek hoplites use spears? | i was watching this video and the guy thinks that they were used under arm and has a few good points. I've always been told they used over there head. where they used multiple ways?
_URL_0_ | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/1hsu3b/how_did_the_greek_hoplites_use_spears/ | {
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"Honestly, we don't know. Artwork shows both styles, and their art is more symbolic than representative. Each form has its own strengths and weaknesses. It doesn't help that we don't exactly know how phalanxes fought either. The basic idea of a hoplite phalanx was around for ~500 years, so they had plenty of time to experiment with both. I think it was probable that they would switch between overhanded and underhanded as the situation dictated.\n\nSome reference images:\nAmphora from ~560 showing overhanded :[here](_URL_1_)\n\nAmphora from ~500 BC showing underhanded:[here](_URL_2_)\n\nNot sure on where/when this is from, but shows both styles:[here](_URL_0_)\n\nFor what it's worth, it's harder to find examples of underhanded grips, although that isn't indicative of much. From a usability standpoint, an overhand grip shortens your stab quite a bit, and allows less power, but is much easier to put on target, along with being more versatile and maneuverable. An underhand grip allows you to strike from further and with more power, but you will be striking into a shield most of the time when fighting an opponent carrying something like an aspis or thureos.\n",
"This is a very debated topic, but what u/stylepoints99 says about our lack of knowledge isn't really true. Snodgrass discusses this in his works, and also discusses how much we can trust the depictions of vase paintings in deciding on military matters as well. I'm not going to go too far into it, because frankly it's best if you just read Snodgrass yourself. Summary of what he says usually comes out pretty dry and boring, but the short version is that hoplites of the Archaic Period and Classical Period almost certainly used their spears overhand when in the battle line. Underhand thrusts, Snodgrass notes, are in vase paintings predominantly reserved for single combatants and heroes. Heroes, of course, can be discarded, but single combatants are interesting because almost all depictions of them are during the pursuit (such as in u/stylepoints99's second link). However, it seems rather likely that as the battle began to grow more chaotic (in the final phases, Xenophon tells us) and the lines became more untidy more troops used whatever method would protect themselves best. We find a poetic reference, for example, to the aged hoplite clutching in his hands his testicles, which have just been stabbed--which many scholars take as an indication that the underhand thrust must have been used in this particular instance, since it's easier to stab up under the shield if you're going for the groin. Epaminondas may have had at least some of his troops utilize the underhand position, rather than the overhand, since he also increased the distance between soldiers in the battle line. However, it's very important to note that every depiction we have of troops actually *in a phalanx* shows them using their spears overhand, which Snodgrass points to as an important thing to notice."
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bywwah | The ancient history of kink. | Fetish and kink fascinate me endlessly, and while there is a vast ocean of books and knowledge out there about kink from this century, I'm now more interested in the ancient history of kink. I'm talking the 17th century and backwards. If you know of any books about this I'd be so grateful if you gave me the title.
The human psyche is as intricate as it is crafty, and I'm sure kink has played a part of history as long as there has been a desire for sexual relationships. How did ancient civilizations or even more "modern" societies deal with this phenomenon? I assume most of our sexual history is blanketed by strict religion and societal rules and norms but has this always been the case? Has there ever been a place in time where sexuality and then kink didn't have to stay secret?
Has fetish/kink essentially been divided by class until later times? I assume aristocracy in all parts of the world would have more resources and time to explore themselves and others, plus have an easier time dodging the religious rules of the common folk?
Another question: (and forgive me if this is obvious or stupid) have kinks and fetishes closely followed societal trends and taboos throughout history? As an example, would foot/ankle worship be statistically more significant in an era where showing some ankle would be seen as scandalous? Is there any written evidence of fetishes that are now lost to time?
Thank you for your time! | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/bywwah/the_ancient_history_of_kink/ | {
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"You might want to check out /u/AnnalsPornographie's answer and follow-ups to this question from a few months ago: [Is there any documentation of various sexual “kinks” in ancient civilizations?](_URL_0_)"
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9aoqsy | how does strict nat and upnp affect online connectivity while gaming? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/9aoqsy/eli5_how_does_strict_nat_and_upnp_affect_online/ | {
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"NAT or Network Address Translation is basically a way for your router to handle translating private/local IP addresses (192.168.x.x/172.16.x.x/10.x.x.x) to public addresses. Without it, each device on a local network would either need a public IP address, or would not be able to communicate with devices outside its own subnet without some other comparable wizardry going on.\n\nUPNP or Universal Plug N Play is a way for a device (almost always consumer) to automatically configure itself and other devices on the network (sometimes routers) for purposes of application-specific communication.\n\nThere really isn't a \"strict\" NAT or UPNP. Modern online gaming really doesn't require any special configuration, as you're typically establishing an outbound connection between yourself and a server (which bypasses any inbound firewall restrictions), as well as any other players and the server handles the client to client communications. NAT still exists but it's seamless from the user's perspective and UPNP isn't extensively used anymore.\n\nBack in the day, you might directly communicate with other players in online games and thus port forwarding would have been required on your router (Both due to NAT and inbound firewall rules, which are basically \"Deny anything I've not explicitly told it to accept\") to forward traffic on the appropriate port to your computer, assuming this wasn't handled by UPNP if the application and router both supported it."
]
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33uely | why do eyes adapt to dark spaces but not dark glasses or tint? | When we go inside our eye adapts to less light than outside and we see objects equally bright, but when we wear sunglasses or ride in a car with tint our vision is darker than usually. Why is that the case?
P.S. Sorry if it's a dumb question. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/33uely/eli5why_do_eyes_adapt_to_dark_spaces_but_not_dark/ | {
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"Not a dumb question at all. Our eyes are sensitive enough to see at night with just starlight up to a completely sunny day. However, it takes time for our eyes to adapt to the lighting conditions and even when adapted, we only can see a limited range above and below that adapted value.\n\nOur eyes are very similar to how a digital camera works. A digital camera measures the amount of light in the scene and sets a light level. Anything above that light level will appear completely white. Everything below will be black.\n\nHave you ever tried taking a picture of someone inside a house next to a window looking outside? The large difference in outdoor vs indoor light intensity makes the camera set the light level too high, making everything inside look too dark. \n\nThis is what is happening when you wear sunglasses (that do not cover a large portion of your vision) or ride in a tinted car. Your eyes and brain are setting a high light level based on the bright stray light that gets through so that everything else looks dim.\n\nIn addition, it takes our eyes about 5-10 minutes to adapt to light and dark conditions (dark takes longer). When you initially put on sunglasses, everything appears dark. However, as you wear them for a few minutes, things will seem to brighten up. If you remove the sunglasses while still outside, everything will appear too bright because your eyes were adapted to the darkened vision."
]
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3qf2i3 | Why can protein structures not be predicted by computers? Why is crystallography necessary? | I thought it could be done as scientists probably know the amino acid sequence, and because the chemical properties of the different amino acids are known. | askscience | https://www.reddit.com/r/askscience/comments/3qf2i3/why_can_protein_structures_not_be_predicted_by/ | {
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"The problem is a result of two factors: 1) we only know the chemical properties of functional groups on proteins to a reasonably high level, and 2) this is compounded by the fact that proteins are massive molecules that aren't that restricted in their base chain conformation because of free rotation about the nitrogen and alpha carbon.\n\nWhat I mean when I say the chemical properties aren't known is-- given a particular functional group and the flexibility of the chain, and different environmental conditions (pH and salt concentrations of the solvent the protein is in), the way that functional group reacts with other groups can vary dramatically. Added on top of this, small variations in structure at one point on the protein can result in huge variations elsewhere. ",
"The average protein has 1000 amino acids. That means 999 connections between those amino acids. Although those connections can rotate, they tend to be close to one of three rotation angles based on how the atoms line up. \n\nSo even being restrictive and assuming only those three orientations are possible (in reality there is some wiggle room), that is 3^999 possible conformations, or about 4*10^476. The fastest computer in the world is 33.86 petaflops, or about 3*10^16 floating-point operations a second. So even if checking each conformation took one floating point operation (in reality it takes a lot), that would still require about 10^460 seconds, or hundreds of orders of magnitude after the last star and black hole die.",
"Good answers in this thread, the folding space is many orders of magnitude too large to search exhaustively.\n\nTwo additional comments:\n\n* Computers *can* predict protein structures rather well today. However this mostly works based on alignments and homology modelling with closely related proteins (of known structure), as opposed to *ab initio* (from scratch) quantumchemical or MD calculations. The more structures (and unique new folds) are solved, the better this gets. David Baker for example does amazing work in this field.\n\n* Crystallography is not the only method available, structures can also be determined by NMR and more and more by cryo electron microscopy.\n\nEdit: typo."
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4a68gl | can penicillin be made from cheese you buy? if so, how would you make it? | Never know if the end of civilization is coming, might have to make some! | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4a68gl/eli5_can_penicillin_be_made_from_cheese_you_buy/ | {
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"You don't \"make\" penicillin exactly (well nowadays it's probably synthesized but that wasn't the case of its discovery). It's a common mold, meaning there's all sorts of mold and fungi spores floating around in the air. Yeah if you leave some bread/cheese out it might start growing penicillin mold on it, but it'll probably be growing a lot of other molds/fungi too that could be very toxic. Unless you have the bio/chem know how to identify and extract only the mold you want, I wouldn't recommend it."
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1lih49 | patent trolls | For some reason this isn't clicking with me, who's the good guy and who's the bad guy in a situation like this? is there even a good and bad guy? The picture that keeps coming to mind is that guy who has that really general patent on console controllers. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1lih49/eli5_patent_trolls/ | {
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"From what I understand they're small companies (who usually make little to no products) who file bazillions of patents on the off chance a big company makes a product which infringes upon any number of those patents, after which point they sue for ridiculous amounts of money. \nMostly the \"bad guy\" is the patent troll, taking up the innovating company's time and resources via litigation instead of allowing them to continue to innovate. ",
"First off there never is a bad guy or a good guy only people. And in this case people abusing a legal system, and people getting screwed over by the former.\n\nSo a patent is a contract between a person/company and society. You keep inventing cool stuff and we promise not to copy you unfairly without paying you.\n\nThis is essential in the pharmaceutical industry where a new drug will take years and millions even possibly BILLIONS of dollars to make.\n\nSo a company Pfizer invents a new drug, now for a period of time (seven years / ten years?) only they can make sell that drug. During that time they have to make back the money that they spent on inventing the drug. After that time anyone can make that drug without paying Pfizer, so the price of drugs suddenly goes down.\n\nSo patent laws are good to make sure that companies have incentive to make new cool stuff. And patent wearing off is also important so eventually everyone can afford these new cool stuff that was invented. If patent laws were too strong and never wore off, then Pfizer could make one drug and sell it for a very high price and make loads of money and not bother to ever make any other drugs.\n\nNow a patent troll is someone who buys a company that owns a patent that may be too broad or badly worded. E.g. if someone in the early fifties patented the idea of two computers communicating with each other (it doesn't matter the type of computer or what language they computers are using two computers talking to each other), at the time it seemed reasonable it was a new and innovative idea and the inventor needs credit for it, but some ends up with this patent and that company goes out of business and a patent troll buys that company.\n\nNow the patent troll can sue basically anyone who invents pretty much any piece of software. They won't sue someone who is playing in their basement because they won't get money out of them, and they won't sue Sony or Microsoft because they won't win the court case. But they will sue start up companies and small businesses, the real innovators of the industry.\n\nThis is especially bad in the software industry because:\n\nA) It is changing so fast that something innovative today is standard practice next year.\n\nB) Patent lawyers know the law and don't know much about computers and software and programming languages.\n\nC) Often a general process gets a patent like \"computers talking to each other\" or \"a device that controls a computer\" instead of the specific software and hardware that has actually been invented.\n\nD) More than 50% of patents are software patents.\n\nPatent law is essential for some industries, but it only stagnates and prevents innovation in the computer industry. And that it is why it should be reformed or abolished.",
"One other thing that I didn't see mentioned yet, those that are operating as \"patent trolls\" are smart in at least one way. They know that going to court over one of these cases is very expensive, especially for the company being sued that would need to bring in not only lawyers, but other experts to show how their product shouldn't be covered under the patent. But it would also be quite expensive for the patent holder. So usually they are approaching companies and demanding a licensing fee. The reason why patent trolls/ trolling works is that many or most companies will do the math and decide it is cheaper to pay them off than fight in court and/or face delays in releasing their products.",
"A bad guy will patent a bunch of different things that could be important in the future. Then a good guy company will have to buy the patent from the bad guy before they can make, sell, or even research the product that was patented. Sometimes the bad guy is greedy and wants more money, hurting everyone in the long run because society isn't getting advancements. ",
"The term comes from the old stories about trolls who lived under bridges and charged a fee to cross the bridge. By buying patents without really inventing anything, they are the trolls who charge a fee for the use of technology",
"Let's say there are two companies here - A and B. Company A has a great idea for a product and gets a patent for it. They don't have to bring the product to the market. They don't have to develop, produce, or market the product, they just have the patent. Company A can do this many times over for different products and/or ideas without ever having to make anything.\n\nAlong comes Company B. They have a great idea that they plan to produce and sell on the open market. Company B has invested in the development, production, marketing and distribution of the product. Let's say this product is wildly successful.\n\nCompany A hears about this wildly successful product and find they have the patent on it. By having the patent, they can legally go after Company B for a percentage of past and future sales. Remember, Company A didnt have to invest all that money into the product like Company B did, but they own the patent and can go after any company that infringes on their ideas.\n\nThere are a few companies like Company A that do not produce anything, only have great ideas that are patented. And because of those patents, they can \"troll\" the market to find things that infringe to make money via the legal system when they sue companies that produce similar ideas to theirs.\n\nEDIT: Formatting",
"Or, in my case, I came up with something that was my graduate thesis 30 years ago. I patented it, a few years ago and shortly afterwards I got an e-mail from some idiot that said that he invented it 15 years ago and was going to sue me for patent infringement. Since I happened to have a copy of my graduate thesis, I was never worried. Patent trolls are strictly in it to get some type of money settlement without having to put much work or investment into it. ",
"The polite term for a patent troll is \"an NPE\" (Non-Practicing Entity).\n\nThe name makes their (highly profitable) business model clear. \n\nThey are firms which acquire thousands of patents (often from companies going into bankruptcy) for the express purpose of using them to sue people who actually build things. Sometimes they claim to be a \"brokerage\" that will look for companies that they can sell or license these patents to in order to help the original inventor make money. In practice, this is pretty much never the case. Most of these firms have made no effort to market and sell these patents to interested parties.\n\nThe original motivation for patents is: I have a guitar company, you have a guitar company. I think of a cool way to make a guitar and patent it so that **I** can make and sell something that **you** can't for a certain number of years. After that period expires, my cool guitar invention goes into the public domain.\n\nWhat NPEs do is they have no intention of ever making cool guitars for you. They just wait until **someone else** gets funding, builds a guitar production line, and starts selling these cool guitars. Then they sue them and try to get a piece of the profits without actually providing anything of value to the consumers.\n\nIn this sense, they are a \"tax\" or \"drag\" on companies that actually make things, while putting none of their own capital at risk in the difficult business of actually making useful products.\n\nTheir counter-argument is that they help \"the little guy\" who had a great idea but can't get the funding to put it into a business himself by buying his patent from him. As I said before, in practice this is rarely the case.\n\nPeople dislike NPEs because over the past 15 years, their lawsuits have become an enormous part of \"the cost of doing business\" for small to medium sized companies. There are many cases of medium sized companies that must spend more on defending these lawsuits than on product development.\n\n"
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19zfgx | why do people get flakes in their hair? | Ive tired all types of methods but still everyday I brush my hair and flakey flakey :( any input Is more than welcome | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/19zfgx/why_do_people_get_flakes_in_their_hair/ | {
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"text": [
"Its bits of dead skin from your scalp. I used to have dandruff too it went away after I STOPPED using head and shoulders. "
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|
3gan57 | Why didn't Ottoman pirates join in with the plundering of gold from the new world? | As far as I read, the Ottoman state was not interested in joining the colonization race, since they already controlled the trade routes to the far east.
But why were individual Ottoman pirates not intercepting gold hauling ships of colonizing nations?
They appear to be ruling the Mediterranean in the 16th century. The news of gold from the new world must have surely reached them.
Were they afraid of sailing out of the Mediterranean for some reason? Did they lack some technology? Was it due to some policy?
| AskHistorians | http://www.reddit.com/r/AskHistorians/comments/3gan57/why_didnt_ottoman_pirates_join_in_with_the/ | {
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"Your assertion that the Ottomans \"controlled the trade routes to the far east\" is an oversimplification of the situation in the 16th century. They controlled part of a route that was a bottleneck for trade between Europe and large parts of Asia, but they did not control the entire trade route. \n\nYour other assertion that they were \"ruling the Mediterranean in the 16th century\" is also misleading. \nWhile piracy and slavery in the Mediterranean were serious problems up until the 18th century, the Ottoman simply did not ever dominate the entire Mediterranean. They were checked both in the Siege of Malta, and the Battle of Lepanto, both in the 16th century. \n\nFurther on sailing out of the Mediterranean, beyond not having control of the western Mediterranean, you may want to read several recent posts:\n\n* [this post on Mediterranean versus Atlantic naval warfare in that era](_URL_1_). \n\n* [on the limits of Ottoman power in western Mediterranean](_URL_0_).\n\n* [whether the Ottomans were interested in the new world](_URL_2_).\n\nThe conflict over Mediterranean waters was covered in several books, including:\n\n* Roger Crowley, \"Empires of the Sea,\" ISBN 978-1-58836-733-4, 2008.\n* Adrian Tinniswood, \"Pirates of Barbary: Corsairs, Conquests and Captivity in the Seventeenth-Century Mediterranean,\" ISBN-13: 978-1594485442, 2011.\n* Angus Konstam, \"Sovereigns of the Sea,\" ISBN 978-0-470-11667-8, 2007.",
"Sometimes so-called \"Turkish\" pirates will show up in what seem to be the most unlikely of places. An example would be in 1631, a Basque vessel was attacked by a ship bearing a three-crescent flag, in the stretch of water between Newfoundland and Cape Breton.\n\nWhat follows is an account of the incident, quoted in Ruth Holmes Whitehead's *Nova Scotia: The Protohistoric Period 1500-1630.*\n\n > On the eighteenth they sighted land at Cape Ray; and shortly afterwards they perceived a vessel, which they took for a Turkish one, coming down upon them with the wind. This made them get under way and prepare for defence; but the Turk, perceiving a considerable number of men on the deck, drew off and bore down on a Basque vessel at which it fired some cannon-shots and then drew alongside. The grappling was not well done, however, and the vessels separated; and, as they separated, a Basque sailor who\nwas in the stem of his vessel grasped the flag that was in the stem of the Turk, and pulled it to himself. At once the Basque vessel began to make off ... so that it escaped and carried off the said flag, on which were depicted three crescents. \n\nWhitehead argues that the pirate vessel likely originated from one of the Barbaray Coast States in North Africa. So while probably not Ottoman per se, it is an example of similar pirate operating outside of what would ordinarily be considered traditional territory."
]
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"https://www.reddit.com/r/AskHistorians/comments/37mpi4/how_did_naval_warfare_look_like_in_the_high_and/croaz5e",
"https://www.reddit.com/r/AskHistorians/comments/3et5p9/why_didnt_ottoman_empire_or_north_african_barbary/"
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230bct | What is the oldest law that is still in force? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/230bct/what_is_the_oldest_law_that_is_still_in_force/ | {
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"My best guess is The Fairs Act of Ireland from 1204 CE. Page 12 of this pdf [warning] of the [Irish Statute Book](_URL_0_), under the Schedule titled \"Statutes Retained\" indicates that it's the oldest law still in effect in Ireland. I assumed maybe Iceland or Japan might have something older, but I don't know of anything and couldn't find anything on any my databases. \n\nI'm an attorney rather than an historian, but most of my journal work related to really old (most copyright) laws in Europe. "
]
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||
3f7u6v | why do emergency vehicles have to turn off their sirens while passing cemeteries? | I work at a mortuary with a cemetery out back. Some nights I work as the gatekeeper. Ive noticed that, night or day, most emergency vehicles will turn off their sirens while passing by the cemetery.
It could be that they are doing this because of the mortuary, because they are on the same plot of land, however I find that harder to believe. I've asked some of my coworkers and even the ones that have worked there for decades only noticed it when I brought it to their attention.
Does anyone know why this is?
P.S.- I've noticed it's mostly fire trucks, paramedics from the fire station, etc. Ambulances from hospitals will do it, too, and so will police cars, but they are less careful about it it seems. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/3f7u6v/eli5_why_do_emergency_vehicles_have_to_turn_off/ | {
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"text": [
"It's because at night, and during the early morning, we try to only use the sirens and horns when we actually need them.\n\nWe are public servants, so it would be quite shitty to wake our citizens up if they don't want to be."
]
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5vtwu4 | why is freshly popped toast crunchy but toast that has been sitting out for awhile chewy? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5vtwu4/eli5_why_is_freshly_popped_toast_crunchy_but/ | {
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"text": [
"Toast that is freshly made has had most of the water cooked out of it. That makes it crunchy. Toast that has sat around for a while has absorbed water from the air and become more chewy. "
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||
1qataz | why do people wear helmets in autocross? | When doing driving exercises, like autocross, why do tracks or clubs require people to wear helmets? Obviously, the helmet would be to protect your head, but with cars being loaded with airbags (steering wheel, side curtain, etc) and also being held in by a 3 point or 5 point seatbelt, what would the helmet provide that isn't already accounted for? Also, I'd imagine an airbag hitting you in the face with a full face helmet on might do more bad than good. Plus a full face helmet would obstruct your view. This is something I've been genuinely curious about for a long time | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1qataz/eli5_why_do_people_wear_helmets_in_autocross/ | {
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"Have you ever seen a rollover crash? How the top of the car, even with a roll cage, crumples in. If someone weren't wearing a helmet the top could cut your head open. ALSO you can bang your head on the side door and get knocked out.",
"Because banging your head against the side of the door or window at 50 mph does a grand job at hurting your brain. Even the helmet isn't always going to help, just look at what happened to Dale Earnhardt. ",
"I ride motorbikes (in the UK so compulsory helmets) and would argue the same reasons for 4 wheeled motorsports as I would for 2 wheeled. A good, properly fitting and quality helmet will protect your head massively more than nothing at all. \n\nThe seatbelts are very good at what they do but they don't hold your head still and you can still have your head move at some pretty extreme speeds when crashing which could result in a head injury or, more likely, a neck injury where a neckbrace would also help (look at modern Dakar bike riders for the freedom of movement your head still has with these). In a high quality helmet you'll have a multiple layers under the hard exterior, the 2 softer inner layers probably do a majority of the work in cars, being the foamy material actually in contact with your head and the inner layer of polystyrene which is softer and has some ability to compact to cushion your head. Also, as I understand it, an airbag deploying has been described to me as someone hitting you in the face with a big exercise ball with absolutely no warning, a properly fitting helmet would take the brunt of this.\n\nMy current helmet has a 120 degree field of vision so in a car I can still see both mirrors just moving my eyes and the vertical space doesn't hinder my vision out the windscreen at all (actually tested when I got the helmet and wore it home in the car :D)"
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34qm6t | how come the internet archive project (_url_0_) has so much space to store the entire web history? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/34qm6t/eli5_how_come_the_internet_archive_project/ | {
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"For a start, it does not store the entire history of the web. It stores a lot of snapshots of a lot of sites, but nowhere near all sites, nor even everything that is on a site they have stored.",
"Storage space is incredibly cheap and website are usually very small in size. The biggest-sized items on the web are high-resolution images, video, and applets (Flash, Java, Shockwave, Silverlight, etc.)\n\nFor websites that don't have any of those things, it's almost all text files and small images. The reddit front page, for example, is less than 1 megabyte of data (and I just checked in the console to be sure). In fact, most of the elements loaded were on the order of a only few kilobytes.\n\nA 1 Terabyte hard drive can be picked up for $50. One terabyte is enough to hold a million or more 1 MB web pages (exactly how much more is muddied by the [inconsistencies in various usage of binary prefixes](_URL_0_), but I digress)\n\nThere's a lot of data on the internet, but most of it isn't in the web pages you visit. The vast majority is in sites like YouTube and Netflix."
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5s2tvf | what would change if all 50 us states became independent countries? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5s2tvf/eli5_what_would_change_if_all_50_us_states_became/ | {
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"I read a great thread years ago (I think 2011-2012) where someone asked what would happen if all 50 states declared war on another. It was very cool. Talked about coalitions that would form naturally. For example, New England states which produce food would ally with New York (which had industry and a port). States that have population, military resources, and natural resources would draw in surrounding states and mini-nations would form. "
]
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[]
] |
||
nrimn | How is barometric pressure used to predict a coming storm or a change in weather? | askscience | http://www.reddit.com/r/askscience/comments/nrimn/how_is_barometric_pressure_used_to_predict_a/ | {
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"Very, very roughly:\n\n* No change in pressure, similar weather.\n* Drop in pressure - worsening weather.\n* Increase in pressure - improving weather.\n\n[wikipedia](_URL_0_)",
"You would want to look at changes in barometric prressure over time. A rapid drop in pressure could indicate an approaching low pressure system or frontal zone, which are typically associated with precipitation. An increase in pressure would indicate a high pressure system and fair weather. Low pressure indicates rising air, and upward motion is necessary for condensation and finally precipitation. ",
"Very, very roughly:\n\n* No change in pressure, similar weather.\n* Drop in pressure - worsening weather.\n* Increase in pressure - improving weather.\n\n[wikipedia](_URL_0_)",
"You would want to look at changes in barometric prressure over time. A rapid drop in pressure could indicate an approaching low pressure system or frontal zone, which are typically associated with precipitation. An increase in pressure would indicate a high pressure system and fair weather. Low pressure indicates rising air, and upward motion is necessary for condensation and finally precipitation. "
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1n3i0q | Why did the seafarers from Borneo colonize Madagascar and not places closer to their origins? | I think it's a huge mindfuck that they were able to cross thousands of miles in their outrigger canoes and settled successfully in an island that's geographically VERY remote from where they originally were. Were the first settlers able to maintain ties with their origins for a long time? Why couldn't they settle in places closer? Like the Polynesian islands in the east or the various islands in the Malay/Indonesian archipelago? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/1n3i0q/why_did_the_seafarers_from_borneo_colonize/ | {
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"They did. The [Polynesian expansion](_URL_0_) moved both east and west. Madagascar and Easter Island represent the farthest extent of their settlement, and were also settled latest. The Polynesians would jump from island to island, and when those islands got too crowded or political, groups would head for their outriggers and look for the next one. \n\n(Don't be fooled, by the way, into thinking those canoes were primitive just because they were built out of renewable materials. Every aspect of their construction was carefully considered and tested for centuries under brutal conditions. They were remarkably seaworthy and survivable craft. They were provisioned with ingenious care. They were navigated by men trained in every nuance of the art. They knew the stars. They could interpret wind and waves, the movement of fish and clouds. You don't colonize a quarter of the globe unless you know what you're doing and you do it damn well.)\n\nMadagascar does seem like an outlier, at first - until you take a look at [this map of ocean currents](_URL_1_). Compare that to the first map. You can see that the Polynesians basically followed the ocean currents out from Taiwan into the Pacific, and then west to Madagascar. Those same currents explain why no craft from Africa made the much shorter trip before the Polynesians arrived - currents pushed you north or south away from the island if you started from the continent. It also explains why the Polynesians didn't keep going to South America. Going east from Easter Island spins you into the Humboldt Gyre and you just get kicked back west. "
]
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"http://www.transpacificproject.com/wp-content/uploads/2011/06/austronesian-expansion.jpg",
"http://marinebio.org/i/currents/Ocean_currents_1943.jpg"
]
] |
|
67a8lt | How is it that the concept of an Electromagnetic Field avoids the problems caused by the concept of a "Luminiferous aether" with regards to relativity? | When people talk about a "field that permeates all of space" I picture something either like a 3 dimensional grid, or like a liquid that fills up the universe. However, it seems that something like that would create a universal frame of reference with regards to the propagation of light, which the theory of relativity states does not exist. What's a better way to conceptualize a field to avoid this problem?
(I apologize if this question makes no sense, I don't really understand this stuff at all) | askscience | https://www.reddit.com/r/askscience/comments/67a8lt/how_is_it_that_the_concept_of_an_electromagnetic/ | {
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"The first postulate of special relativity can be formulated as such: \n\n > The laws of physics are invariant (i.e. identical) in all inertial systems (non-accelerating frames of reference)\n\nWhich implies that as far as the laws of physics goes, there is no special frame of reference. It doesn't explicitly say anything about universal frames of reference, but you can infer that when it comes to the laws of physics, it doesn't matter which frame of reference you're in. So you can't point out any one frame as being in any sense 'better' or more 'true' than any other. However, there are still frames of reference that are more usuful than others. See [this](_URL_1_) answer on stackexchange.\n\n\nAs for your question, I think the answer is that the field - or the grid, if you will - isn't universal in the sense that it looks different depending on which frame of reference you're in. It's fine to view it as a field - recommended, even - but you have to keep in mind that a different observer may or may not agree with you on how that fields looks. You can find some good illustrations, with explanations, on [wikipedia](_URL_0_) and in the [Feynman Lectures](_URL_2_).",
"The Electromagnetic Field is a \"thing\" that fills all of space that light can propagate in. In this sense it is basically the same as a \"luminiferous aether.\" The key difference is that it is a *relativistic* aether, which means that unlike ordinary material stuff like air or water that for example sound can propagate in, it doesn't have a rest frame. The word \"aether\" is usually just reserved for \"material stuff like air or water that has a rest frame\", from before people realized there were such things as relativistic fields that could not have a rest frame, like the electromagnetic field. "
]
} | [] | [] | [
[
"https://en.wikipedia.org/wiki/Classical_electromagnetism_and_special_relativity",
"https://physics.stackexchange.com/questions/25928/is-the-cmb-rest-frame-special-where-does-it-come-from",
"http://www.feynmanlectures.caltech.edu/II_26.html"
],
[]
] |
|
6v4b6s | what is the significance of maggots in the decay of corpses? | Hello ELI5 community. I haven't seen any posts similar enough to my question, but if you know of any that have already been answered, I'd be grateful for the redirect. So here's my question: can the body naturally decompose without the help of organisms such as maggots? It's well known how bodies can be preserved when frozen or in extremely cold temperatures-they're typically kept in freezers/cold morgues right? And it's also known that cold temperatures can prevent maggot eggs from hatching. So I was wondering if the low temperatures actually had an effect on the physical body which prevents them from decomposing, or if the real reason it's slowed is because it prevents the hatching of maggots and thus there's nothing to eat the dead flesh. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6v4b6s/eli5_what_is_the_significance_of_maggots_in_the/ | {
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"Decay is caused by microorganism, freezing the body freezes them. So yes, freezing the microorganism is the only reason the decomposition stops.",
"Maggots help speed the process along but bacteria alone can decompose a corpse. In warmer temperatures bacteria thrive as well as maggots. "
]
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[],
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] |
|
89yx4p | why/how could one get a heart attack after being angry? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/89yx4p/eli5_whyhow_could_one_get_a_heart_attack_after/ | {
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"I've heard that it works like this (but someone please correct me if I've been misinformed): The heart is a muscle and when you get angry one of the body's reactions is to increase heart rate, blood flow, etc. If the heart is asked to do more than it's capable of doing (i.e., you're out of shape, older, etc) the heart simply isn't able to keep up with the signals to beat (kinda like the drums on slave galleys) and just sort of falls over. \n\nLike I said, that's how it was once explained to me, but I can't independently verify it."
]
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||
pwwpq | Why is the fertile life of human sperm so short? | Since there's a huge amount of selective pressure to impregnate successfully, why do human sperm [die so soon](_URL_0_) after coitus? Other species have sperm that can last [years](_URL_1_), so there must be some evolutionary benefit for human sperm to have such a short shelf life. What is this benefit? | askscience | http://www.reddit.com/r/askscience/comments/pwwpq/why_is_the_fertile_life_of_human_sperm_so_short/ | {
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"It is more energetically costly to have stronger, more long-lived sperm. That is why women only produce a few eggs that last for the majority of a lifetime, while men produce countless sperm that last for a short period of time. Women are also more selective with mates and have to provide more resources once fertilization occurs, so this is why they put more energy into a few gametes. Sperm is supposed to be spread to as many eggs as possible, and once fertilization occurs no more energy is needed for the growth of the sperm. ",
"Somewhat outside of my tag, but I have some college background and lots of reading on evolutionary subjects like this.\n\nTo add to AlloLay's great answer, another reason why humans don't need to have the sperm longevity that other organisms have is that we have a LOT of sex. It's ridiculous how many intercourse sessions we have per pregnancy. Also, human females are fertile every month rather than every year and our social groups tend to favor kin-selection. Our genetic diversity is pretty low and traditionally a group of humans are related enough that sperm competitions isn't a priority. Even if a man helped to raise a child that wasn't really his, many of his genes would still be present in the kid because of the relatedness of a typical hunter-gatherer band of humans. (read up on classic selfish gene theory for more)",
"They're entirely self contained, and thus, don't have much energy to keep them going. The lifespan of a sperm isn't that different from yours, given the size difference, if you were to totally stop taking in any form of water or nutrition."
]
} | [] | [
"http://www2.oakland.edu/biology/lindemann/spermfacts.htm",
"http://en.wikipedia.org/wiki/Ant#Development_and_reproduction"
] | [
[],
[],
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|
397cht | Why does water evaporate so much quicker than oil? | I keep noticing that water stains on clothes evaporate in a matter of minutes, but oil never seems to evaporate at all. The stain of sauce I made during lunch last week would still be sitting happily on my shorts hadn't they been washed. What is happening here? Why doesn't the oil evaporate like water does? | askscience | http://www.reddit.com/r/askscience/comments/397cht/why_does_water_evaporate_so_much_quicker_than_oil/ | {
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"For one thing, although oil is non-polar and only exhibits relatively weak inter-molecular forces (forces that act to bind neighboring molecules together (cohesion/adhesion)), when compared to the hydrogen bonding that water exhibits. This would seemingly make oil evaporate more quickly than water, however, these weak forces increase in strength with increasing number of electrons in the molecule. Oil has a much greater mass than water, and thus has many more electrons than water does. I am sure others will elaborate. ",
"All other things being equal, smaller molecules are more readily vaporized than larger ones.\n\nThe water molecule (H2O) approximately 50x smaller than your average oil molecule (soybean triglyceride used as reference)."
]
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[],
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|
6t2mxj | How did Trireme fleets navigate the Aegean? | The way I understand it, the large galley ships of Antiquity usually couldn't carry enough supplies on board to sustain the crew for more than a day or so, and so they tended to stay within sight of the coast.
How would this work logistically for voyages across the Aegean? Say if I'm in Miletus, and someone in Corinth looked at me funny, and I wanted to give them a piece of my mind with 200 triremes, how would I get from A to B?
Would I have to go up along the coast of Asia Minor, across the Hellespont, along the Thracian coast, then south off of Greece proper?
Would there be enough islands 'bridging' the Aegean with ports that can resupply such a large fleet that a more direct route is possible?
Could one resupply the triremes at sea from sailing vessels that can carry more cargo, and just go straight across that way? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/6t2mxj/how_did_trireme_fleets_navigate_the_aegean/ | {
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"It's not actually that difficult to keep within sight of land sailing more or less straight across the Aegean. Modern-day Greece has over a thousand islands, as many as five or six thousand by some estimates (depends what an island is). The modern Greek Tourism Bureau lists 227 inhabited islands, most of them in the Aegean. Add in the large number of islands considered part of Turkey and you've got a lot of islands--if we were big enough we could probably run through the Aegean on the islands like stepping stones through a creek. The Aegean also isn't really all that big. Stanford's Orbis tool suggests a journey from Athens to Ephesus in summer should only take 3.5 days, with average winds and travelling only by day. The route they plot stops at Delos and Ceos along the way, as well as a brief stop at Sumium before setting out on the sea proper to supply and prepare. Potentially, if one wanted to travel at a more leisurely pace, one could stop at any of the thousands of smaller islands in the Aegean. Now, larger voyages across truly open sea occurred sometimes. The Athenian fleet on its way to Syracuse had to round the Peloponnese before hopping across the Adriatic and skirting the Italian coast. The journey would not have been totally on sea the whole time of course, since Athenian fleets regularly beached in Peloponnesian territory to raid and rest more or less with impunity, but the journey from Corcyra, where the Athenians and their allies gathered before setting off, to the heel of Italy takes a good couple days, without any possibility of stopping on the way. The Athenian fleet, Thucydides says, made the journey to Corcyra as rapidly as possible, stopping at Aegina before racing to Corcyra. We must suppose that the Athenians stopped at night along the Peloponnesian coast. From there Thucydides describes the fleet as sailing across the Ionian Sea from Corcyra to Tarentum, stopping briefly at the promontory at the Italian heel. That's at least a couple days of open sailing. The cities in south Italy shut their gates to the Athenians and did not allow them to come to market, so the Athenians lived on water and presumably the grain brought by allied grain ships. The grain was carried, we must assume, to land--the idea of trying to resupply while floating at sea on a delicate trireme is horrifying. Rhegium closed her gates to the fleet, but allowed them to pitch camp outside the city and provided them with a market. After that the fleet crossed into Sicily. The point of all that is to show that there were options, even if a fleet could not enter a city and could only rest. This of course is in a fleet, which would really need to stop regularly at large harbors--a single ship or a small squadron would have fewer problems beaching on some deserted islet somewhere for the night. When there was no other option but to hoof it across open ocean for several days, as in the crossing of the Ionian Sea, fleets of warships would do so, with some apprehension (luckily it was midsummer when the Athenians set out, so sailing conditions would have been excellent), but if any other course of action presented itself it was usually preferable "
]
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|
fmsaq | What atoms last the longest in the body? | Inspired by this post:
_URL_0_
I have heard on a number of other occasions that all atoms in your body are eventually expelled and replaced. Is there any study on which parts of your body "retain" particular atoms in the longest? I would guess it would be bones and teeth, right? If so, how long are those atoms retained? Is it known?
| askscience | http://www.reddit.com/r/askscience/comments/fmsaq/what_atoms_last_the_longest_in_the_body/ | {
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"Accumulated heavy metal atoms like mercury stay with you forever (I think).",
"Almost everything that occurs naturally in your body except the DNA is renewed. Once a cell is made as long as it dies its DNA is (generally, modulo some repair systems) untouched. \n\nIn general though most of your body is continuously remodeled, including muscles, bones, etc\n\nMost neurons once formed stay with you till your life. Hence the DNA in such neurons are probably the longest lasting atoms in your body.\n\nThough the actual research here can be outdated: read here how they used this mechanism to find out that most neurons never get replaced after development: _URL_0_"
]
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3gbnoj | why the black lives matter protesters shut down bernie sanders twice? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/3gbnoj/eli5_why_the_black_lives_matter_protesters_shut/ | {
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"I'll probably be downvoted for this, but so be it.\n\nThe BLM movement is not about social justice or any other glorious left-wing ideal. It's a black nationalist movement. As black nationalists, they hate Sanders for the same reason that white nationalists would hate a Jewish candidate. Why aren't they attacking, say, Trump? Because Trump will ignore them whereas Sanders will foolishly try to win their favor.",
"Because it's undirected anger. \n\nThere's mounds of evidence for institutional discrimination against African-Americans, and the prominent shooting deaths of unarmed black kids has been a focal point for a lot of pent up anger. If this was the 60's there'd be a few well known leaders of the black community to help direct this anger to something productive (like supporting candidates or legislation, trying to get changes made in the way police train shoot/no shoot drills, etc). But there are no major leaders of the black community at the moment. \n\nSo, this is what you get, a lot of anger with no one to focus it somewhere productive. Which leads to the misdirection of that anger to someone who is probably interested in helping.",
"I think it's just the most opportune, and the short, tl;dr answer is \"right cause, wrong platform\". \n\nBernie Sanders is much, much more grassroots than the other candidates, and therefore, there's much more opportunity to jump into the foray. I couldn't imagine the protesters getting anywhere near, say, Hilary or Trump.\n\nKind of sucks, because in this race, Sanders would probably be their biggest ally.",
"From what I have read, it at least appears the recent interruption in Seattle wasn't directly tied to BLM, but to two women who started BLM Seattle and are actually part of a more extreme organization called Outside Agitators 206 who are more focused on rallying against the police. Either way, it is just misguided anger and doesn't really make sense.",
"He's certainly more progressive than his opponents, but [he's been relatively quiet on the issue of police brutality against Black Americans:](_URL_0_)\n\n > Most Black voters want the answer to one question: What is Sanders’ plan to address the police brutality crisis in the Black community?\n\nSo far, he's acknowledged that there is a police brutality problem, but has not really given us any thoughts on how he plans to actually respond to that problem.\n\nBLM want him to offer his thoughts on how to tackle the issues faced by the Black community in the present day, as a continuation and expansion upon his track record of activism."
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9vyl17 | Question about medieval weaponry used post battle | The Medieval period is full of interesting and strange weapons. Im currently doing some research for a project and I'm having trouble finding the name of a very specific weapon.
Basically as I undersand it (during the medieval period) after a battle the winning side, or the side left at the battlefield, would go around and kill those who were left alive but who were hurt beyond remedy. As I have heard people would use a sort of "narro sword" or "long spike" that they would insert into the side of the persons torso between the ribbs to pierce their heart and kill them quickly.
First of I'm not sure that this is true, it might just be a tall tale. However if anyone knows of this weapon (or a similar weapon) I would be grateful if you could name it and perhaps direct me to a source on the weapons history.
Thanks a bunch! | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/9vyl17/question_about_medieval_weaponry_used_post_battle/ | {
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"You're probably thinking of the *misericorde*, a long, narrow-bladed dagger with similarities to both the earlier rondel dagger and the later stiletto, appearing around the 13th century and carried as a sidearm. Its shape certainly lent itself to penetrating armour to deliver a *coup de grace* (the name *misericorde* derives from a French or Middle English word meaning an act of mercy) but it wouldn't have been used exclusively for that - rather, it was a general-use knife that happened to be particularly good at that.\n\nAs ever when dealing with this sort of thing, bear in mind that mediaeval weapons were no respecters of taxonomy; the same thing could be called by different names at different times and places or by different people, or different things called by the same name.\n\nThe record is patchy on details - much of what we know about mediaeval weaponry comes from \"manuals\" and treatises by people like Fiore dei Liberi and Sigmund Ringeck, most of which were written a little later (15th and early 16th century) and whose audiences were understandably more interested in how to win a fight than in the messy details of what happened afterwards. There are a few mentions in Charles Boutell's *Arms and Armour in Antiquity and the Middle Ages* (1902!) but it's fairly superficial stuff like where they were worn and what their pommels were shaped like, i.e. details gleaned from historical illustrations, not a description of actual use."
]
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|
2jf3ur | Why do I see water vapor when I open the hot water in my shower? | The boiling point for water is at around 100ºC.
I'm not sure what is the maximum temperature I can get in my shower but I don't think it is near 100ºC.
It has something to do with the difference of pressure between the pipe and the atmosphere? | askscience | http://www.reddit.com/r/askscience/comments/2jf3ur/why_do_i_see_water_vapor_when_i_open_the_hot/ | {
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"Water that is truly in the gas phase is not visible to our eyes. What we see when we describe steam or vapor is an accumulation of water molecules condensing back into the liquid phase in the form of very small droplets.\n\nWe usually think of water as existing in one of the three phases of matter depending on temperature and pressure. Under normal everyday conditions, water is a liquid, and we often think we need to heat that water to 100℃ in order to change it into a gas. This is only partially true, as it turns out that water is in a constant equilibrium between existing in the gas phase in the atmosphere and existing in the liquid phase, either in a container or perhaps flowing from your faucet to the shower floor. What this means is that water molecules are constantly escaping from a cup of liquid water into the gas phase and other gas water molecules are condensing back into the liquid, even at room temperature. However, this equilibrium is shifted far more in favor of the liquid at room temperature. As you heat the water up, the equilibrium shifts increasingly towards the gas phase.\n\nWhat happens when you turn on the hot water in your shower is that you now have a local system in which more of the water molecules pouring out of the faucet are inclined to make the transition to the gas phase. However, as those gas water molecules move beyond the locally warmed system to the relatively cooler surrounding air, they condense back to the liquid phase and accumulate as a fine mist of visible droplets (or worse, they condense onto the surface of the relatively cold mirror I will need to look into in several minutes time in order to make myself presentable!)."
]
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|
rlzqr | Does skin grow back (or does it just stretch)? | Sorry if this is a stupid/basic question.
My friend heard a lecture from a doctor who said that skin does not grow back, but rather just stretches in wound healing. In the case presented in that lecture, a dog suffered from severe wounds that caused its skin to stretch during the healing process to the point where at the final stage of healing, the dog's movements were severely restricted as a result of the stretched skin. Is this also case in humans?
Specifically, in the case of third-degree burns in humans when skin is grafted from a different part of the body, does the skin actually grow to cover the exposed areas, or do only certain layers/reparative cells close up the wound?
I understand that the topmost layers of skin grow back over time, but does it also happen for lower layers? | askscience | http://www.reddit.com/r/askscience/comments/rlzqr/does_skin_grow_back_or_does_it_just_stretch/ | {
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"[Skin grows back](_URL_0_), more or less.\n\n > The proliferative phase lasts from 2 days up to 3 weeks. During this time the wound begins to heal by building tissue, including skin and blood vessels. The proliferative phase is broken down into four sub-phases: granulation, contraction, angiogenesis, and re-epithelialization.\n\nYou can get [keloids](_URL_1_) if you have extensive loss of the epithelium, as from a deep abrasion or a burn, and these can become tight and painful over a large area. If you keep the area moist while it's healing, this probably won't happen though.\n\nI had a couple of road burns from cycling accidents that formed mildly keloid-looking scars, but then I had a bad one on the front of my calf and went to the company infirmary where I was working. The nurse there gave me a type of bandage that may have been new at the time. It was a large plastic affair, that fitted over the entire wound and kept the moisture inside. I was to leave it on quite a long time, and then replace it with a new one. That wound healed without any scar, and ever since then I've used that process for minor wounds, which also healed without scarring.",
"The stratum basale is the most basal layer of the epidermis, which makes up skin. It contains keratinocytes, which can be considered stem cells of the skin. These undergo differential maturation as they proceed to form the stratum corneum which is the visible skin you can see. So yes, skin can grow back.\n"
]
} | [] | [] | [
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"http://www.ehow.com/how-does_5408825_cut-skin-heal_.html",
"http://en.wikipedia.org/wiki/Keloid"
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|
1bjxfx | Who policed pre-Revolutionary Boston? | Who investigated crimes? How was criminal justice handled?
I'm most interested in the years just prior to the start of the war, from about 1770 to 1775.
Thanks. | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/1bjxfx/who_policed_prerevolutionary_boston/ | {
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"**The Sheriff**\n\nThe primary policing authority was Sheriff Stephen Greenleaf. He had the power to call on the militia to deal with criminals or mobs, serve writs to search buildings and ships, and to arrest suspects and place them in the gaol (a prison). \n\nIf you're interested in what gaols looked like, or who they could hold, check out this little blurb from Colonial Williamsburg about their extant [public gaol.](_URL_5_)\n\n**The Militia**\n\nThe militia could be called out in cases of emergency, and weren't usually called out to deal with a single criminal, who could generally be apprehended by Greenleaf himself and perhaps one or two of his underlings. The militia was composed of all able bodied free males of appropriate age in Boston (some northern rural communities actually allowed slaves to serve in the militia, though I am not sure if this was true of Boston), and they operated as a popular and fairly democratic body. More than once, Greenleaf or a Crown official would call on the militia to suppress a popular mob, only to find that either the mob already included the militia or the militia would dissolve to join the mob and exacerbate the problem.\n\n**The Town Watch**\n\nGreenleaf was probably the most visible sign of authority in the city, but he wasn't always on duty. During the night, the Town Watch would be given care of the city. The Town Watch was divided into four man teams that patroled designated areas of the city. One of these Watches was headed by Benjamin Burdick who held the title Constable of the Town Hall Watch. \"Town Hall\" would designate their district or jurisdiction, though there does not appear to have been a lot of wrangling over who had jurisdiction where, and I've not yet read of criminals being released for being seized by the \"wrong\" authority. This short blog post about Benjamin Burdick also provides us with a primary source guide to a [watchman's duties.](_URL_3_)\n\nThe watchmen were instructed to keep an accurate log of each night (which could be provided as evidence in court if need be). They walked through their entire neighborhood, either as a team or in pairs, and kept an eye out for any mischief. They were paradoxically instructed to both be quiet, and to call out the time and the weather. There appears to have been no curfew, except for \"Negro, Indian and Mullatoe Slaves,\" all of whom were instantly suspect. The watchmen carried lanterns and and least two of them were armed with sticks for bludgeoning if need be. The [image](_URL_1_) of the watchman was a fairly common one in all colonial and British cities, generally wearing a large overcoat and wrapped tight against the cold. They are always portrayed as carrying a stick and a lantern, and often a wooden rattle to alert the town in case of emergency. This image holds even when they are depicted as entirely [inept and sleeping on the job.](_URL_2_)\n\n**Soldiers**\n\nThe final and least effective policing during this time in Boston were the British regulars. Prior to 1768, there were no regular soldiers garrisoned in Boston. The Americans objected strongly to their presence. Despite popular belief, British soldiers were [not quartered in people's homes.](_URL_4_) British law required that soldiers be quartered in any barracks available, and could only resort to occupying available rooms in tavern, alehouses, and public buildings when the barracks were filled. This meant that of the two regiments sent to Boston in 1768, one was stationed in Castle Island, and all but permanently removed from the populace.\n\nBritish soldiers would be stationed at specific spots and usually within guard houses and [sentry boxes](_URL_0_) (this is only a scale model of a sentry box, but gives you a good idea of what they would look like). An officer would be assigned to lead guard duty at any given time of the day or night, and would lead a team of soldiers out of the guard house to the various sentry boxes and important posts, where the soldiers would be replaced with fresh guards.\n\nSoldiers \"challenged\" passerbys at night. This generally consisted of a soldier demanding the approaching party identify themselves, probably with a phrase like \"Who comes there?\" They were then supposed to repeat themselves if they received no answer, and if they felt it necessary present their musket. \n\nThe soldiers were generally ineffective in policing for legal reasons. The watchmen strongly objected to the soldiers' challenging subjects, and declared it was their legal right to challenge, and not the soldiers'. Further, British law allowed British soldiers to be tried in civilian courts if they committed a crime against subjects. Soldiers were not permitted to fire their weapons unless it could be definitively proven that they had reasonable fear for their lives. This meant soldiers generally intervened with fists, swords, and bayonets. Brawling was very common in Boston between the soldiers and the populace, and soldiers were more often than not arrested for this. Civilian courts had civilian juries, and soldiers did their best to avoid them if at all possible. In several instances soldiers broke each other out of the gaol to avoid trial, or officers intervened to have them removed. In the end, placing soldiers in Boston only inflamed the populace, and made the job of Greenleaf and the Watch even harder.\n\nEDIT: Clarity"
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"http://boston1775.blogspot.com/2007/03/benjamin-burdick-jr-constable-of-town.html",
"http://avalon.law.yale.edu/18th_century/quartering_act_165.asp",
"http://www.history.org/almanack/places/hb/hbgaol.cfm"
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ezfhj6 | How do the Teutonic Knights differ from the Knights Templar? I know that the Teutonic were Germanic but where did they differ in terms of ideology’s. Both were Christian but what made them different in there crusades, fighting styles, rules? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/ezfhj6/how_do_the_teutonic_knights_differ_from_the/ | {
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"The first Crusade started in 1096 and lasted until 1099, the causes of this are widely debated but I was taught that the Crusades were launched in response to the Seljuk victory at Manzikert which saw a large portion of Anatolia(Modern day Turkey) fall into Muslim hands. When the Emperor of the Byzantime Empire asked the Pope for help, the Pope thought this would usher in a reunification of the Catholic and Eastern Orthodoxy church, so he called for a Crusade to defeat the Muslims, and reclaim the holy city of Jersualem, which had been under Muslim control for over 400 years at this point in time. Ultimately the reunification between the Catholic and Eastern Orthodoxy never ocurred, and even Constantinople was sacked by a Crusading army in the future, but your question is about two of the many military orders that rose up in this time. \n\n In, 1119, the French knight Hugues de Payens petitioned King Baldwin of Jerusalem with the notion of creating a holy militant order to protect pilgrims making the journey from Europe. Though the city of Jersualem, Acre, and Antioch in the north all were held by Christian's and upstart Crusading Kingdoms, the lands were stricken with a bandit plague. These bandits would often make short work of peasants and other Christian Pilgrims coming in from Europe. So in order to combat this the Knights Templar were created. \n\nThe Templars were renowned warriors, feared by Muslims and praised by Christians everywhere. They grew in such power that they rivaled the Kings in Europe. Chapter houses were opened throughout the Crusader States as well as in Europe. They had a strict code that men of the order would own no castles, hold no lands, and never marry. So the order was made up primarily of second sons who wouldn't have inherited their fathers lands anyway, so striking out to make a name for themselves, they pledged their undying loyalty to God and to the Order. They opened Hospitals and they cared for Christian pilgrims everywhere. As good as they might seem, they were also brutal towards their enemies, but even they would put aside their loyalties to help the Muslims combat the later Mongol invasion of the middle east. \n\nMany other Knightly Orders rose in this time, including the Teutonic Knights who were not known for what they did in the Holy Land, but rather what they did in Lithuania and Poland. \n\nThe Teutonic Order was created in 1192, in Acre, comprised mostly of German Knights. They mostly helped build hospitals to house the German pilgrims coming to the Holy Land. Once the Holy Land was lost to the Saracens, the Teutonic Order retreated to Transylvannia, and then eventually to Northern Germany and modern day Poland. There they guarded German missionaries from Prussian pagans who would often raid and kill all Priests and Monks who tried to convert them. Overtime the Teutonic Order eventually came to start recruiting more and more Prussian converts into their ranks and began to build up more and more power. Again copying what the Templars did, the Teutons built chapter houses all over Germany, but their true house of power was Königsberg (Kaliningrad, Russia). \n\nEventually the Teutonic Knights began to become more and more power hungry and began to brutalize their new enemy, being the Lithuanian pagans. They even began to move against the Polish Kingdoms, which were Catholic, and the Novgorodian Princes who were Eastern Orthodox. Eventually the Polish and Lithuanians defeated the Knights at the Battle of Grunwald which cost them much of their power, until their Livonian Branch was defeated by Alexander Nevesky almost 100 years after Grunwald which finally ended the Orders claims over Russian lands in the North. \n\nFundamentally The Teutonic Order was based on the Templars with each member refusing land and wealth all in the service of God. The main difference between them was the fact that the Templars never recruited \"auxiliaries\" not even Turccopoles, to fight against the swifter horse archers of the Muslim and Mongol armies. While the Teutonic Order heavily relied on auxiliary troops. \n\nUltimately both ended up being too powerful for their own good and created many enemies by being so. The difference was that the Teutonic Order was much more aggressive with its neighbors, while the Chapter houses of the Templar order were mainly just that, never really lands to rule just lands to recuperate and launch another crusade against the Holy Land. \n\nAnother big difference between them is money and the banking system that the Templar order built. This banking system gave the Templar a lot more influence over the rest of Europe and much more organized that the Teutonic Order could ever have hoped to have been. The Teutonic Knights also waged war on the Catholic Kingdom of Poland over territorial disputes, which the Templar Order most likely would have just used gold to solve the issue rather than annihilate Christians. That however is just a guess and its not based upon fact, it very well could have been that the Templar order may have found itself in the exact position as the Teutonic Knights found themselves. However I do not believe that the Teutonic Order would have found the same end as the Templars due to their order being much more disorganized and not as well financed."
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38igpo | Why did the German states, and then Germany manage to industrialize so effectively in the 19th century? | Did they industrialize more per capita than other European countries? If they did what gave them the edge? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/38igpo/why_did_the_german_states_and_then_germany_manage/ | {
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"This industrial growth is both a byproduct and a necessity of Chancellor Bismarck's plans for Germany's socio-political control of the region. The general feeling in Europe since the Franco-Prussian War was that a general European War was eminent and whatever happened Bismarck wanted Germany to be in the driver's seat. ",
"One important factor for the development of a massive German steel industry after 1871 is the annexion of Lorraine with its coal mines and high quality iron ore deposits.\n\nThough, as others have already pointed out, the industrialization in Germany began much earlier.\n\nThe first railroad in what is now Germany was opened between Nuremberg and Fürth in 1835, only ten years after the opening of the world's first public railroad, the Stockton and Darlington Railway in England.\n\nIt is certainly no coincidence that the city of Nuremberg was famed for its excellent craftsmanship even in the Middle Ages. [Edit] Cf. [Peter Henlein](_URL_0_)."
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6uz2wx | what is the process of paying taxes for someone who is self-employed? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6uz2wx/eli5_what_is_the_process_of_paying_taxes_for/ | {
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"They make quarterly tax payments. You would typically fill out the 1040es, then paywhatever that says is due.\n\n_URL_0_\n\nYou are not actually turning in the form, so if you wanted to, you could just guess how much you need to pay (especially if you have done it for a few years.)\n\n",
"I'm a self-employed music teacher. I pay quarterly taxes based on my estimated income for the year and then make up the difference at the end of the year. I *always* end up owing more at the end of the year - not entirely sure why, my income estimate is rarely off by that much. "
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7v4ic1 | Why did the USSR fail to capitalize on social unrest in the 60s and 70s? Alternatively, why couldn’t the Beatles play in Moscow? | The antiwar movement, civil rights, and rock and roll all were destabilizing to the United States. Why didn’t the USSR support these movements more, considering if these were painted as communistic that would have galvanized a significant yourh population towards the east? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/7v4ic1/why_did_the_ussr_fail_to_capitalize_on_social/ | {
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"While a number of Western , largely conservative, critics of the New Left and the wider 1960s counterculture as communist, this did not mean the New Left was Marxist-Leninist in nature or that the USSR identified with them.The Soviet leadership was ambivalent about the New Left and this mirrored the generalized ambivalence the New Left's ideologues held for the USSR. Although the New Left espoused a harsh critique of American society, their ideological focus was more in line with younger communist movements and leaders like Mao, Ho Chi Minh, or Che. Brezhnev and other Soviet leaders had experience with this type of ideological independence with both Tito and Mao during the 1940s and 50s and that had led them to be leery of ideological movements that deviated from Marxist-Leninist orthodoxy. Conversely, many within the New Left perceived Moscow as being run by old men and the emerging gerontocracy under [Brezhnev](_URL_3_) did not exactly present a picture of revolutionary dynamism. The fact that the SDS did grew out of an American progressive milieu instead of the American Communist Party added a further layer of skepticism for Soviet leaders. \n\nMoreover, the New Left would also occasionally criticized Soviet actions; one of the precursors of the New Left in Britain, the Communist Party Historians Group, which included such luminaries like E. P. Thompson and Eric Hobsbawm, openly critiqued the Soviet invasion of Hungary in 1956. There were similiar sentiments over the Soviet's crushing of Prague Spring. Graffiti both at Berkeley's and Chicago's1968 protests drew explicit connections between American police actions and Czechoslovakia. While this graffiti (welcome to Czechago) was more about thumbing the eye of the anticommunism of the West, it was not a celebratory picture of the USSR, especially in contrast to how the \"Old Left\" romanticized the Soviet worker state in the 1930s. \n\nThe transgressive cultural precepts of the New Left, especially its liberal stance on sexual mores, were at odds with the social conservatism that typified Soviet leadership during the Brezhnev era. One of the odder quirks of Soviet state attitudes towards music in the late 1960s and 1970s was they felt that rock bands exemplified by the Rolling Stones, The Doors or Jimi Hendrix were a cultural plot by the capitalism to sap the revolutionary vigor of youth through an appeal to hedonistic excess. Many teachers and other Soviet cultural gatekeepers lamented that the arrival of Beatlemania in the late 1960s via the Baltics or western Ukraine, which was more open to connections with Western Europe, as pulling Soviet youth towards esoteric Indian philosophy and spirituality rather than more grounded subjects. The Soviet state was very quick to repress its own counterculture whose hippies took their cues from the global movement (long hair, sexual freedom, etc.). \n\n When faced with the rise of this movement in the West, the Soviet leadership was quite confused as to what to make of it. For example, these two Soviet cartoons [1](_URL_1_) and [2](_URL_5_) show solidarity with the war protesters as true representatives of the struggling masses that the USSR was on the side of. In contrast, this [cover \"Distinguishing Badges\"](_URL_4_) of the 1969 Soviet satirical *Krokodil* mocked the West's fashion of long hair and androgynous clothing as does this [Soviet cartoon](_URL_0_) that attacked the fashionable Soviet youth. This [cartoon](_URL_2_) mocking stylish fringes would not be so out of place in Western anti-hippie discourse such as *Mad Magazine*. \n\nWriting in 1975, the German journalist Klaus Mehnert observed:\n\n > The New Left is not one of the perennial topics that Soviet writers *have* to write about, rather it is a marginal phenomenon in Soviet writing [emphasis original]. Therefore, it is studied only by those especially interested. Seldom have I found anyone in the Soviet Union who even knew the New Left’s name. \n\nMenhert found that although the Soviet state published extensively about the New Left and student protests, the state was more interested in the fact that the New Left was protesting than what in fact the New Left was actually saying. \n\n*Sources*\n\nDworkin, Dennis L. *Cultural Marxism in Postwar Britain: History, the New Left, and the origins of cultural studies*. Duke University Press, 1997.\n\nKatsiaficas, George N. *The Imagination of the New Left: A Global Analysis of 1968*. Boston, Mass: South End Press, 1987. \n\nMehnert, Klaus. *Moscow and the New Left*. Berkeley: University of California Press, 1975. \n\nRisch, William Jay. *The Ukrainian West Culture and the Fate of Empire in Soviet Lviv*. Cambridge, Mass: Harvard University Press, 2011. "
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am277k | how the part of the human brain that controls concentration and problem solving works on concert with the part that looks for instance gratification and procrastination. | I had read an article a long time ago about how there is a part of our brain that seeks instance gratification is a type of self-defence mechanism. Now, I may not be remembering it correctly and the article may have been a theory, but I wanted to learn more about where these opposite ideas come from in the brain and why we have these (and other?) contrasting connections going on.
& #x200B;
Thank you, in advance! | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/am277k/eli5_how_the_part_of_the_human_brain_that/ | {
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"I think you might want to find the article, since the language you're using isn't very precise. There's no part of your brain that controls \"concentration and problem solving,\" and there's no part of your brain that \"looks for instant gratification and procrastination.\" These are high level, abstract concepts, and there's not a specific part of your brain responsible for any of that stuff. If you find the article, or have any more specific questions, I can address them, but I think there are problems with the premise of your question.",
"ELI5: Problem solving and concentration is associated with activity in your prefrontal cortex, which is a \"new\" part of your brain (biologically speaking). This sort of activity is concious, deliberate and requires a great deal of energy. Instant gratification and procrastination is less clear cut, but is related to reward and avoiding punishment, which is associated with structures in the \"older\" parts of your brain. This activity is more subconcious, automatic and requires less energy. These systems are interconnected and influence each other. When you crave a chocolate, the old system is trying to produce a behavior (eat chocolate), but then your new system try to stop the impulse (which requires effort and deliberate thought). Your ability to do this can be low or hampered by your state for instance (sleepy, hungry etc.), which cause impulsive behaviors. That is how you get instant gratification and procrastination. "
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3awfd5 | Is the rate at which a feather and a brick fall in a vacuum truly the same? | I hear so often that the rate of acceleration near ground level on Earth is *always* exactly the same no matter how heavy they are. However, using the gravitational equation F=(GmM)/d^2 would lead me to believe that the gravitational force on a brick is ever so slightly greater than a feather, and with F=ma with mass being a constant, if F is greater, so is acceleration. Since the Earth has such a huge amount of mass, this difference is negligible and perhaps undetectable, but is it not completely untrue to say that if a brick and a feather are dropped in a vacuum at the same time, theoretically they will land at the exact same time? And if this is untrue, why is it asserted to be truth in so many textbooks? | askscience | http://www.reddit.com/r/askscience/comments/3awfd5/is_the_rate_at_which_a_feather_and_a_brick_fall/ | {
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"If you ignore the movement of the larger body, say the Earth or moon, then the relationship is exact as \"m\" cancels out, \n\n > F = ma = GMm/r^2 \n > a = GM/r^2 \n\nSo you're right, it's a half-truth, but the difference is so unimaginably small ignoring it gives works out great. The reason it's in all the textbooks is because it's exactly the behavior you'd predict for Galileo's ideas of acceleration he developed in his book *On Motion* and not Aristotle's. Galileo used a clever thought experiment involving tying a heavier and light object together with a string. This was an important stepping stone to the formulation of Newton's laws of mechanics including gravitation.\n\nFor those who love Moon footage, here's David Scott of Apollo 15 demonstrating this with a hammer and a Falcon feather, \n_URL_0_"
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98pdez | what stops minors from buying lottery tickets from machines | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/98pdez/eli5_what_stops_minors_from_buying_lottery/ | {
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"Nothing stops you from buying them. You just won't be able to redeem them yourself, if you win. ",
"The ticket would honestly be invalidated; most of the lotto machines are on camera feeds, and the ticket sales are timestamped. For the smaller prizes they won't care, but for the bigger prizes they'll check the camera feed to ensure that the person who bought the ticket is part of the party who is redeeming it. When they notice the discrepancy, they'll think that the ticket was either stolen or that the person who bought it was a minor.\n\nEither way; no money for you, at least not from the major prizes."
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117lof | What were some of the most impactful yet unpredicted developments in history? | I was listening to Dan Carlin's common sense podcast and he was going on about how history can show you that the range of possibilities for the future is much wider than people generally think.
He mentions how before the soviet union fell, no one would have thought it possible that it would fall. Similarly, no one was really predicting 9/11 beforehand, it just wouldn't have seemed possible. But both of these events had a huge impact because of how many things changed from the fallout of these events.
What other events in history were like these: hugely important with far reaching effects on the world, but before they happened they would have been laughed off as impossibilities. | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/117lof/what_were_some_of_the_most_impactful_yet/ | {
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"Industrialisation and the Plague.",
"[The Mongol Empire](_URL_0_) expansion in the 13th century. Within 50 years they'd taken all of central Asia, Asia Minor and were expanding into Europe.",
"The Reformation - except for the Hussite Wars Catholicism was firmly in charge of Europe, and then, Martin Luther came.",
"Plastic. Not a historian, but I'd wager that was a doozie.",
"I've always found the various royal marriages in Europe to be incredible with how they could change boundaries. Louis VII of France divorcing his wife Eleanor of Aquitaine, who ends up marrying Henry II of England which gives England control over practically half of France. The Hapsburg dynasty and their acquisition of Burgundy, the Low Countries and Spain all through marriages. It's just bizarre from a modern perspective.",
"A 9/11-style attack most certainly **WAS** predicted. It's just that the specific details were not.\n\n\"Bin Ladin Public Profile May Presage Attack\" (5/3/01)\n\n\"Bin Ladin's Networks' Plans Advancing\" (5/26/01)\n\n\"Bin Ladin Attacks May Be Imminent\" (6/23/01)\n\n\"Bin Ladin and Associates Making Near-Term Threats\" (6/25/01)\n\n\"Bin Ladin Planning High-Profile Attacks\" (6/30/01)\n\n\"Planning for Bin Ladin Attacks Continues, Despite Delays\" (7/02/01)\n\n- subject lines of Richard Clarke emails to Bush Administration prior to 9/11/01\n\n\"You know, Dick Clarke. Dick Clarke, who was the head of the counterterrorism program in the run-up to 9/11. He obviously missed it.\"\n\n- Dick Cheney, on Richard Clarke\n\n\"Bin Laden Determined to Strike in U.S.\"\n\n- Presidential Daily Brief, August 6, 2001\n\n\"All right, you've covered your ass now.\"\n\n- George W. Bush, to the CIA briefer who warned him about an imminent bin Laden strike, August 6, 2001\n\nAs for using aircraft as weapons....\n\n\"The Joint Inquiry of 2002 confirmed that the Intelligence Community had received at least twelve reports over a seven-year period suggesting that terrorists might use planes as weapons. After briefly discussing each of them, it says that \"The CIA disseminated several of these reports to the FBI and to agencies responsible for preventive actions. They included the FAA... \" ([citation](_URL_1_))\n\nThere were also of course REAL WORLD warnings like Air France Flight 8969, where the hijackers were going to fly the plane into the Eiffel Tower or blow it up over Paris with a maximum fuel load.\n\nThere's that plane that hit the White House in 1994. (A few years before 9/11, Tom Clancy had a best seller, \"Debt of Honor\" that ended with a 747 crashing into the US Capitol building during a State of the Union address and killing the President and most of congress. A few days after it was released a small plane hit the White House, killing the pilot, destroying the plane, and doing almost no damage whatsoever to the White House.)\n\nThere's the \"Bojinka plot\" in 1995: \"A report from the Philippines to the United States on January 20, 1995 stated, \"What the subject has in his mind is that he will board any American commercial aircraft pretending to be an ordinary passenger. Then he will hijack said aircraft, control its cockpit and dive it at the CIA headquarters.\" [...] \"Murad had been trained as a pilot in North Carolina, and was slated to be a suicide pilot.\" ([citation](_URL_0_))\n\nIn April 2001 NORAD ran a war game in which the Pentagon was to become incapacitated; a NORAD planner proposed the simulated crash of a hijacked foreign commercial airliner into the Pentagon.\n\nAt the July 2001 G8 summit in Genoa, anti-aircraft missile batteries were installed following a report that terrorists would try to crash a plane to kill George Bush and other world leaders.\n\nSo yeah, there were plenty of predictions.\n",
" > before the soviet union fell, no one would have thought it possible that it would fall. \n\nExcept of course for all the people who predicted it, and some who helped arrange it.\n\nIn the early 80's I had friends in high school who emigrated from the Soviet Union. They told me about how during each harvest, because of the lack of tractors and other farm equipment, the universities sent their students to work in the fields to work alongside the army, harvesting grain. The grain would then sit in huge piles, rotting, because of a lack of transport to take it to the rail lines.\n\nA couple years later during the famine in Ethiopia there was a scandal when ships full of food and grain had to wait for Soviet ships to offload tanks for the Ethiopian army. What wasn't understood at the time was that it HAD to be done in that order: The tanks had to be unloaded to make room for the food and grain, which was payment for the tanks, and was shipped to the Soviet Union. Remember the food riots in the southern USSR around that time, with the accusations that chemical weapons were used to break up one riot? Live Aid prevented a famine - just not where planned.\n\nSo why didn't the Soviets have the tractors and combines, or the transport needed to take their grain to the rail lines?\n\nA huge percentage of the Soviet Union's transport production, trucks, tanks, etc, was shipped at huge expense to Vietnam and destroyed by the USAF.\n\nIn 1973 the US at a cost of 663 US casualties aided ARVN in repulsing a 150,000 troop invasion - fewer than 40,000 ever got back home - bringing with it more tanks than the Wehrmacht had at Kursk and more trucks than Patton ever had - none of which ever got home. AC-130 gunships destroyed another 10000 trucks.\n\nAll those tanks, trucks and other materials were replaced by the Soviets. When North Viet Nam invaded the South in 1975, again they had more armor than the Wehrmacht had at Kursk, and more trucks than Patton ever had in the Red Ball Express. Add to that all the Soviets fighter planes, countless surface-to-air missiles and medical supplies, arms, tanks, planes, helicopters and artillery, all dumped into Vietnam.\n\nThink of what that does to the economies of both the U.S. and the Soviet Union:\n\nWhen the U.S. builds 50,000 vehicles, sends them to Vietnam and loses them, it's bad. But this provided jobs for tens of thousands of people. They pay income tax, and spend the rest, paying sales tax. This creates jobs for people selling them goods, who pay more taxes, etc. When the Soviet Union builds 50,000 vehicles to Vietnam and loses them, it's bad, period. The workers had to be given jobs regardless, and they don't pay taxes. In a war of attrition, the U.S. had the upper hand.\n\n**Vietnam took the USSR - a country that could put the first satellite into orbit, the first man into orbit, etc. - and converted it into Bulgaria with missiles.** They neglected their own infrastructure to send materiel to Vietnam for the U.S. to destroy.\n\nThe punch line is that Soviet Union believed all the analysis and propaganda that they had won in Vietnam and that they could project power... and they marched right into Afghanistan.\n\nA big part of Reagan's military build-up - not just the super-secret-yet-somehow-highly-publicized Star Wars and stealth programs - is that the Soviets with their already wobbly economy would bankrupt themselves trying to counter it. And they did.\n",
"Standardized shipping containers.\n\nThanks to standardized shipping containers, many cities are getting their waterfronts back. Rail lines within cities, with spur lines running to countless warehouse loading docks - are disappearing. Out in the country, here in Manitoba for example, something like half our rail lines have been torn up in ther last 20 years.\n\nNow goods don't have to be loaded on a truck, then unloaded and reloaded at the rail yard, then unloaded and reloaded at a port, then unloaded and reloaded at the destination port, etc., etc, etc. The goods are loaded into a container ONCE, and that container gets moved from truck to rail to ship to rail.\n",
"Consider the rapid change brought on by the miniaturization of computers! There was a point in time when they really didn't think that they would get smaller than fridge-sized and from the introduction of the personal computer in the seventies to now, forty years later, when everyone has a powerful computerized communication tool about as big as half a deck of cards in their pocket. Completely changing the way we communicate and the speed at which we communicate vast reams of information around the world.\n\nI'm relatively young and I can remember the time before the internet when even making a long distance call in my own country was, if not exactly difficult, expensive and a rare occassion. Now I can communicate with a person I do not know in a country on the far side of the world in moments, every day, as much as I like. That is just the internet, a piece of what the advance of computing has done in less than a decade, and that's happened in the last TWENTY years!",
"Honestly, every historical event, no matter how minor, was likely impactful in a way. Without any of them, the world would be different, sometimes very much so. Even the most minuscule of actions or people have their place in the world.\n\nSo to try and attribute just a handful of events as being particularly impactful is a useless gesture at best. Everything has it's importance in history, and everything has played an equal part in shaping our world today.",
"The rigid horse collar. It largely ended slavery in Europe, four or five hundred years before it restarted in the Americas. At one time there were as many slaves in Europe as free men.\n\nIt used to be that a horse could do four times as much work as a man. But a horse **ate** four times as much as a man, so the versatility of human slaves won out.\n\nWith the rigid horse collar, the horse not being strangled as it pulled, now a horse could do 10 times as much work. But it still only ate four times as much. And so now the horse won out.\n"
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50kmqc | How did the HRE become the mess that it did? | [deleted] | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/50kmqc/how_did_the_hre_become_the_mess_that_it_did/ | {
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"Can you clarify what you mean by 'the mess that it did'?"
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406fxg | Quantum fluctuations after big bang? | I was just wondering what the actual mechanism of these "quantum fluctuations" that ive read about are. As i am understood they are some how responsible for fluctuations in particle density in the very early universe which caused stars, galaxies etc. to form, and i was just curious what they actually are. Thank you. | askscience | https://www.reddit.com/r/askscience/comments/406fxg/quantum_fluctuations_after_big_bang/ | {
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"This is rooted in the context of inflation. In inflationary models you typically have a period of extremely rapid exponential expansion of the Universe due to a particular scalar field, the inflaton, being in an excited state. A field in an almost uniformly excited state acts exactly like dark energy, but immensely faster.\n\nWhen inflation ends, the inflaton decays to its ground state releasing energy in the form of particles. The Universe enters the radiation-dominated era, which is better understood.\n\nThe point is that the inflaton, being a quantum field, has quantum fluctuations in space. These small fluctuations have a very specific spectrum. As the inflation itself scales the Universe to some e^60 times its original size these minuscule fluctuations become massive in size.\n\nThe energy density will therefore have very minute variations over very large scales. These variations are preserved until gravitational collapse of dark matter and therefore structure formation occurs. They act as \"seeds\" for the collapse.\n\nSo the large-scale structure of the Universe (I mean cluster, supercluster and above scale) should have been directed by these primordial fluctuations. Fair enough, the statistical properties of the spectrum of the matter distribution in the Universe are compatible with coming from the characteristic fluctuations of a quantum field.",
"Have you heard of the Heisenberg uncertainty principle? This is the idea that, on extremely small scales, smaller even than atoms, you can't measure things like distance and velocity with exact precision. Actually, the statement is you can't measure *both* of those precisely - the more accurately you measure some particle's position, the less accurately you know how fast it was moving, and vice versa.\n\nYou'll usually hear this phrased in terms of position and velocity, but it's a much more general principle of *quantum mechanics*. In quantum mechanics, all sorts of things are subject to uncertainty. When we talk about quantum fluctuations, we're referring to the randomness inherent in that.\n\nIn the case of quantum fluctuations after the Big Bang, we mean fluctuations in the *density* of the Universe. In particular, we mean in the density of a type of matter called the \"inflaton\" which dominated the Universe shortly after the Big Bang, during cosmic inflation. \"Density\" here means the energy density, how much energy inflatons have in some region of space. It turns out that energy has an uncertainty relation with time. That sounds a bit weird, but it means that the less time you use to make a measurement, the more uncertainty you'll have in your measurement of the energy.\n\nThe thing about cosmic inflation is that back then, the Universe was expanding on steroids. The expansion rate was *accelerating*, so that very small things quickly blew up to enormous sizes. Scales which were ruled by the strange laws of quantum mechanics became larger than the observable Universe in an instant.\n\nSo let's take some small region of space during inflation. After a very short period of time, it's suddenly of a cosmic size. The density of the patch of Universe contained in that cosmic size depends on the density of the inflaton when it blew up. But because this blow-up happened so quickly, the uncertainty principle tells us that there's uncertainty in what that density was. The actual value that nature picks is then up to random chance.\n\nWhat you're left with, as you can imagine, is a bunch of regions of the Universe all with different values of the density. Inflation pushes these regions apart faster than light can reach them, so they lose contact. But after inflation ends (still only a fraction of a second after the Big Bang), they slow down and start to come back into contact with each other.\n\nAfter a while, the observable Universe is made up mostly of gas, and contains a whole bunch of these regions, all with (slightly) differing densities. Eventually, in the denser regions, the gas is pulled together by gravity until it starts to collapse on itself, forming stars and galaxies. This is how quantum uncertainty in the very early Universe is thought to have lead to the cosmic structure we see today."
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1c1a38 | What factors led the decline of Londinium and how did this change and allow London to develop? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/1c1a38/what_factors_led_the_decline_of_londinium_and_how/ | {
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"London is essentially a port city. Even if it isn't literally a port, it is a good \"hub point\" for much of the British island to connect to the Thames, and thus essentially controls much of the trade into and out of Britain (Bristol is probably the biggest exception). Therefore, its fortunes are heavily dependent on the general commercial health of the isle. The collapse of Rome in the west led to a collapse in commerce, which gutted London, but when the immediate post Roman turmoil gave way to the rise of the Anglo Saxon kingdoms, Lundenwic developed."
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v5axo | Is it possible to mentally stimulate the release of adrenaline? | Physically unstimulated; imagine the person is sitting in an armchair at home, eyes closed. | askscience | http://www.reddit.com/r/askscience/comments/v5axo/is_it_possible_to_mentally_stimulate_the_release/ | {
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"Depending on what you mean by physically unstimulated, i.e if you have been in a scary/dangerous situation before then by thinking about it or thinking of possible consequences could easily cause a reaction. On the other hand, if you have had a relatively calm life it would be very difficult to invent a situation in your head in order to cause the release of adrenaline.",
"Sure. Ever think really hard about something, maybe the outcome of a certain decision, and suddenly feel your heart racing when you contemplate a bad outcome? The heart racing is due to your brain stimulating your sympathetic nervous system; when the adrenal glands receive sympathetic stimulation, it causes a release of epinephrine(adrenaline) and some other interesting chemicals.\n\nEver wake up from a bad dream, sweating, heart racing? You just mentally stimulated your adrenal glands to release more epinephrine!\n\nYou probably mentally stimulate a release of adrenaline all the time!"
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f08cco | What is actually happening when an image is out of focus and how do lenses focus them? | I have a strip of film which I was trying to project onto a wall using a torch. I noticed the image was out of focus, but I don't understand why. | askscience | https://www.reddit.com/r/askscience/comments/f08cco/what_is_actually_happening_when_an_image_is_out/ | {
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"The basis of a lens is the refraction index (n) (I studied it in Spanish so idk if the terms I'm gonna use are the correct terms in English too) each material has it's own n. Vacuum's n is 1 and air's is a bit more. When light changes from a material to another one with a different n, it \"bends\" (that's what happens to water for example).\n\nA light source emits light in all directions, a (convex) lens converges all its light rays into a single point (due to it's shape and having a different n), the image point. In case of cameras that point must be in the sensor to be on focus. If it isn't, a single light source will \"activate\" more than one point in the sensor, and thus, become blurred.\n\nYou can't focus the whole scene because objects are at different distances, so the image point is at different distances too. When you focus you change the distance between the lense and sensor. In your case you'd have to move the torch closer or further. (I'm not entirely sure about this last one).",
"Every lens has a focal point. A focal point is where the light rays will converge if they strike the lens from very far away (meaning that they are parallel when they reach the lens).That focal point determines how far away an object needs to be in order to be focused. \n\nYour film strip had a lens when it was created. So to project it onto a screen you would need to send the image created by the torch through another lens and adjust the distance frogm the strip to the lens until the image is in focus. \n\nIn other words, a lens bends a light ray when it passes through. The amount of bending determines what becomes focused in the image. With no lens, the light rays are going in various directions when they hit the screen so the image is blurry.\n\nEdit: OPs best option might be a pinhole camera (see my explanation below), but the torch might not be bright enough.",
"To give you a rough idea...\n\nTake a look at [this photo](_URL_1_). It is an example of *ray tracing*, for a double-convex lens. It shows the paths for all the light rays emitting from a single point. Ignore the eyeballs. \n\nThe three important rays are 1) the incoming ray traveling parallel to the axis of the lens, which will bend to pass through the rear focal point, 2) the incoming ray passing through the front focal point, which will bend to travel parallel to the axis of the lens, and 3) the incoming ray passing through the midpoint of the lens (intersection of mid plane and horizontal axis), which travels through the lens without bending. For this image, they are the top, second-to-bottom and middle rays, respectively. These three rays will define the intersection point where the image will be focussed. All other ray paths - emitting from that same source point - will eventually end up at that same intersection. *(The exact mechanism for how/why the rays behave like this has to do with refraction and geometry, but is not overly important for discussion of focussed/unfocused images.)*\n\n**If you place your camera sensor on the vertical plane where the rays intersect, then you’ll get a sharp, focussed image. But any source/object closer or further away from the lens will have an intersection on a different plane than the sensor, and will look fuzzy and out of focus.**\n\n[Here is a busier image](_URL_0_) showing how light rays from various points on an object create an (inverted) image.\n\nProjecting an image onto something (i.e. at a movie theatre) is much the same, but instead of a camera sensor you have a wall or screen. The ray tracing is a bit different, but the physics is the same. \n\nSorry if this is clear as mud. This is a tough question to answer in just a few paragraphs, and from a phone. You could take a semester-long optics class just to answer this. Ray tracing like this - where you bend/refract the light only once in the mid plane of the lens - is only an approximation, and only for *thin* lenses. If you do actual ray tracing for each surface of the lens, accounting for index of refraction and geometry, you’ll find that the rays do not intersect so perfectly. They’ll be *close*, but not quite as tight of a point. [Here is an example of exact ray tracing](_URL_2_), where the rays do not converge to a single point.\n\nEdit: Fixed bad link",
"Imagine that the image on your film is a single tiny dot of white surrounded by black. If you shine a torch onto this film, you will not see a tiny dot on the wall behind it, but a splodge of light. The first thing to understand is that this is what the blurred image is made up of - many splodges all overlapping one another.\n\nWhy is the point turned to a splodge? Because the bright part of the torch is not tiny. If you trace a ray of light from, say, the top edge of the torch, through the white dot and onto the wall, it will land at the bottom of the splodge. A ray from the bottom edge of the torch traced in the same way will land at the top of the splodge.\n\nOne way of making the image more in focus is to use a very small, very intense light. Unfortunately it tends to be impossible to make something very small and intense.\n\nThe other way is using a lens. A lens bends rays of light coming through it by different amounts depending on where they strike the lens. You can look up a diagram to see how that works but the upshot is that if you get the right lens and place it at the right distance in front of the film, the two rays of light I described above will be bent - *focused* - so that they both land at the same point on the wall. No more splodges; no more blur.",
"If you have a perfectly small, pin-headed source of light projecting through the film, you'd get a focused projection of it.\n\nIf you notice how harsh the shadows are from an LED flashlight vs an incandescent one, you'd see the LED is a closer representation of a point source. The shadows are just a projection of a mid-point on a far-point.\n\nSince we can't natively generate a pin-point of light like this, we use a lens to \"cross the streams\". They come down to the pin-point then separate again.\n\nIf you take a magnifying glass and hover over a penny, at first it will be bigger. Keep lifting it and it's completely blurry, then upside down. The point where it's completely blurry sets the focal length of that lens.\n\n[lens](_URL_0_)",
"A lot of interesting explanations here that focus on lenses. I was an optical engineer, so I’ll try to explain things in a different way. \n\nThe image that’s captured on film is probably focused. If you use a very small-sized, but bright, light source, you could project a mostly focused image onto any wall (it doesn’t even have to be flat) without a lens. The problem is, your torch isn’t a small pin-sized light. It’s emitting light from an *area*. This means the image on the wall is the result of the *superposition*, or sum, of all the images if you had a small pin-point light at each point on your torch. That’s the blurry result that you’re seeing. \n\nWhy did I say mostly focused? Well, it turns out that the way light moves through space causes the image (or wavefront, in optics terms) to change slightly. This is called free space propagation. The way it works follows the same math as a wave propagating through water!",
"_URL_0_ has some good illustrations of the concepts in play.",
"Lenses are convex disks of glass. This means there is a cone like refraction of light. At the tip of the cone is the focal point, this is the point where the image is \"in focus\". We can adjust the position of the focal point forward and back by physically moving the camera by taking steps. We can make adjustments on the camera itself to change the position of the lenses. This stretches or squeezes the focal point. We call it zooming.\n\nA good way to see how a focal point works is to put a magnifying glass to the sun and try to burn something. When you see smoke it should pass through the cone reveal the cone of light. You could also toss some dust if you're not allowed to burn anything."
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8u02pz | why is the roman empire considered so important that we teach it to this day? | [deleted] | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/8u02pz/eli5_why_is_the_roman_empire_considered_so/ | {
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"It was one of the first actually the first of its kind. It was run politically sound with a few exceptions. It turned into a republic also which is even better. We base some of outlets government off of it as well.",
"All historical nations are \"important,\" and should be taught, but the powerful ones in particular are of note. The Roman Republic and Empire were quite powerful, and many European nations have their roots in the Empire, so they form a part of most Western history curricula.\n\nElsewhere in the world, you may find curricula which focus more on other great empires. The Han Dynasty of China existed at the same time as the Roman Republic *and* Empire and was very successful.",
"TL;DR: the Roman Empire was massive, lasted for ages, and covered much of Western Europe, so it’s no surprise it is so important to Europeans and their offshoot nations. (And I assume to many others, in North Africa, the Middle East, etc., but I can’t speak for them.)\n\nAt its height, the Roman Empire was one of the largest empires in world history. It lasted, in some form, for almost 1500 years. Within its borders it often provided a level of peace, stability and organisation that was unprecedented, and perhaps unmatched in Western Europe for another thousand years (that’s a very debatable point).\n\nIt undertook amazing feats of civil engineering, many of which are still visible and impressive today, or are even still in use (especially in the east).\n\nThe Roman Empire also produced a great deal of literature, from comedies to philosophy to engineering. Many of these were core texts until the modern era, and some are still very relevant today.\n\nIt was the birthplace of Christianity, and the empire officially adopting Christianity was a turning point for the religion. The home of the Catholic Church is, of course, still Rome, and its language Latin.\n\nAfter the fall of the empire in the West, rulers and intellectuals looked to the Roman Empire as a model to aspire to. From their fragmented, troubled kingdoms the Roman Empire was a lost giant. In many ways, this admiration has continued up to the present day, with Rome viewed, for better or worse, as *the* greatest empire.\n\n*Edit:* The Roman Empire, and its rise and fall, has also been turned into many powerful stories and lessons. Its rise, its peak and fall can be used as political and moral lessons (which may or may not reflect the actual history).",
"*All right, but apart from the sanitation, the medicine, education, wine, public order, irrigation, roads, a fresh water system, and public health, what have the Romans ever done for us?*",
"Rome is the foundation upon which civilization is built: \n\n* Many of the languages in Europe are derivatives of Latin. \n\n* The legal systems of Europe are based on Roman Law (even in Germany and England attorneys **still** use Latin terms for many legal concepts). \n\n* Catholicism is still headquartered in Rome, and spread Roman culture and institutions globally for centuries. \n\n* Most imperial units are based on Roman units of measurement. \n\n* Our calendar comes from Rome, and several months of the year in the modern calendar are directly derived Latin (September, October, November, and December are literally 7th month, 8th month, 9th month, and 10th month in Latin, the names were retained after January and February were added to the calendar). \n\n* ~~April Fools is a memorial to a Roman calendar change (shifting the new year From April 1st to January 1st).~~\n\n* Concrete and glass weren't invented in Rome, but Rome popularized them and developed many techniques we still use today (like glass blowing). ",
"The Roman Empire/Republic started in 509 BC. Rome fell in 476, but the eastern Roman empire continued on for nearly another millennium, lasting until the Fall of Constantinople in 1453.\n\nBut by then, the Holy Roman Empire had been going since 800, claiming the prestige of Rome, and it lasted until 1806. Much its ruling class, largely the Habsburgs, became prominent in the Austrian Empire and Austria-Hungary, which allied with Germany in WWI to form the Central Powers, reconstituting much for the former Holy Roman Empire, ending 1918.\n\nAnd you know how the Nazis were known as the Third Reich? Reich #1 was the Holy Roman Empire, so as late as the 1940s, nations were still trying to set themselves up as the continuation of an empire that started over almost 2500 years before.\n\nSo as you can see, the Roman Empire is kind of a big deal.\n\n",
"There are other massive, important empires that lasted a long time in history, but Rome is notable because it was very important in Europe and Christianity, both of which have had a large influence the rest of the world.\n\nLatin, the Roman language, was the only language the Bible was written and taught in for many years, and many languages in Europe are directly derived from it or, like English, have received many words from it despite belonging to a different language group. It was the Lingua Franca of Europe for all of history right up until the last couple hundred years or so. \n\nEvery who reads the Bible will get a face full of Roman-era terminology, geography, and social issues they have to grasp, so as long as Christianity is a thing, so will studying and visualizing Rome. What's more, one of the major reasons Christianity even became as major a religion as it did was because the Roman empire converted to it under Constantine. \n\nOur Democracy was based in part on the Roman (and Greek) model. The architecture of our big political buildings, with all the marble and columns and stuff, is based on Roman (and Greek) architecture. The reason not many people tried Democracy until the US and French revolutions is because they all knew how it had failed in Rome. \n\nThe Byzantine empire was essentially just the Roman empire with another name, and it was the center of culture, religion, and technology in Europe for nearly a thousand years, as well as the trigger for the Crusades. Even when it fell, Constantinople's destruction is what triggered the age of exploration and the Columbian exchange.\n\nThe Roman empire operated at a level of technology and coordination that wouldn't be matched in western Europe for a thousand years after the fall of Rome. If you travel Europe today you'll *still* see Roman roads, walls, and aqueducts. Some are even still in use. Revived interest in the classical era was what brought about the Renaissance."
]
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[],
[],
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|
sx2a5 | why are countires threatening each other with nuclear weapons? if anyone used one wouldn't they just be hurting themselves? | I keep reading about all the counties that have nuclear weapons and it's such a big deal but why would anyone use one in the first place? Isn't it just a stalemate for everyone since using one would just screw everyone over?
I know there's a lot of history here and a lot of politics but I don't really know or fully understand any of it. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/sx2a5/eli5_why_are_countires_threatening_each_other/ | {
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"Who's threatening to use them? Having nuclear weapons is essentially just a deterrent for other countries using nuclear weapons. Trying to get nuclear weapons is basically just ensuring no ther country uses it on you.",
"You are on the playground, and you and each of your classmates have a handful of rocks. No one throws because they don't want to suffer the repercussions of being thrown back at. Except little johnny decides to be be good and decides to drop his rocks. You and all of your class mates turn and throw your rocks at him.\n\nThe problem is that if technology can be built and used for evil it will be. The idea is to keep that [stalemate](_URL_1_) you mentioned so no one throws first.\n\nAlso, [some men just want to watch the world burn](_URL_0_)."
]
} | [] | [] | [
[],
[
"http://www.youtube.com/watch?v=efHCdKb5UWc",
"http://en.wikipedia.org/wiki/Mutual_assured_destruction"
]
] |
|
34d5tu | Where can I read contemporary accounts of sailors (or pirate)'s lives (from before the 20th century) | I've been reading lots about sailors, whalers and pirates lately and would love to read about their lives in their own words. [This](_URL_0_) article about a sailor's journal peaked my interest but I haven't been able to find anything else online, other then some letters of marque which aren't particularly thrilling reading.
It seems my google-fu is not up to the task of finding any more. Can our reddit historians help? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/34d5tu/where_can_i_read_contemporary_accounts_of_sailors/ | {
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"Dampier, William (Ed. John Masefield). Dampier's Voyages (London, 1906).\n\nExquemelin, A.O. Bucaniers of America (London, 1684). [Note: I've read this one. I think there's a 1920's edition available on Google e-books for free. Great resource but note that the author's surname may also be listed as: Esquemeling.]\n\n\nThe Library of Congress has great primary sources online on buccaneers, and privateers:\n_URL_0_\n\n\n",
"[Two Years Before the Mast by Richard Henry Dana](_URL_0_), which is about sailing in the 1830s.",
"The British Library now holds the massive archive of the East India Company. I believe only a portion has so far been digitised, although that it is an ongoing operation. It was more than a year ago when I last looked, at which time indexing was severely limited' but there was a search function. I was able to browse unexpurgated letters from the EIC President at Batavia, Richard Fursland, back to the Board in London, from the period 1615-1623 which I was then researching - lots of complaints of squalid conditions, drunkenness and ill-discipline, plus the high cost of red peppers (the latest culinary marvel). Sorry I can't attach a link, as I'm on my tablet."
]
} | [] | [
"http://www.dailymail.co.uk/news/article-1044940/Diary-18th-century-sailor-provides-fascinating-insight-life-decks-Nelsons-navy.html"
] | [
[
"http://www.loc.gov/exhibits/kislak/kislak-interactive.html"
],
[
"http://www.gutenberg.org/ebooks/4277"
],
[]
] |
|
6m9f9s | Why did British Prime Minister Anthony Eden reject French Prime Minister Guy Mollet's idea of an economic and political union between France and Great Britain? | I've been doing some reading surrounding the proposed Franco-British Union, and saw that British Prime Minister Anthony Eden rejected this idea. To quote Wikipedia, where I was doing the reading:
> In September 1956, due to a common foe during the Suez Crisis, an Anglo-French Task Force was created. French Prime Minister Guy Mollet proposed a union between the United Kingdom and the French Union with Elizabeth II as head of state and a common citizenship. As an alternative, Mollet proposed that France join the Commonwealth. British Prime Minister Anthony Eden rejected both proposals and France went on to join the Treaty of Rome, which established the European Economic Community and strengthened the Franco-German cooperation.
Are there a particular reasons why Eden rejected these specific proposals? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/6m9f9s/why_did_british_prime_minister_anthony_eden/ | {
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"There was significant entanglements related to the French that caused Eden to reject these proposals, most of them stemmed from sentiments from the time he was Foreign Secretary and considerations at the time also in play. \n\nThere was a few presumed and inevitable outcome that came with much closer social and political allegiances with the French. Most imperative and damning among them would be tying two very different types of colonial projects and the mannerisms in which they were treated together.\n\nFrance unlike the British had separated itself much more heavily from the influence of the United States following the second world war with the express intention of maintaining it's colonial empire and autarky to the best extent possible. Conflicts like the 1st Indochina Conflict and the Algerian conflict were just ending and starting respectively by the time of the Suez Crisis in 1956 and neither bore well for the French. Long and diplomatically isolating conflicts were what brought Guy Mollet into attempting his shotgun marriage proposal to the British. Eden was quite aware of the risks of such engagements. \n\nIn addition to those more overt diplomatic contradictions between what the French sought and the British would benefit from on the matter. Eden also was of the opinion that France needed to cooperate further with Germany and the rest of Europe rather then retreat into the Entente rationale of the 1930's, Eden had taken a very strong stance on the European Defense Committee in favor of it. And was also a strong advocate to grant recognition to West Germany as a sovereign state. In this sense Eden held the traditional Churchillian cosmopolitan view of Europe. One that would be extremely integrated but without the presence of a British state. \n\nAt the time over 50% of British commerce was contained entirely in the Sterling Area whilst only a quarter was at the same time in Western Europe. It was considered more effective to keep Britain self contained with it's primary focus being on opportunities with the United States. At least in Eden's opinion. \n\nThere was a lot of other nuanced fields like the technicality of the French state being 100% integrated between the Metropolitan areas and colonial Empire that would've involved a colossal increase in social expenses for the British, and even more logistical problems like the remaining French obligations to states like Tunisia and Morocco that would have become joint British - French obligations. \n\nI can't speak entirely to why Eden rejected French membership of the commonwealth. (Although it may have simply been the fact that France would have needed political capital to change itself to a Monarchy that Guy Mollet himself knew he couldn't bring to bear.) But the conditions and asterisks related to a full Franco - Anglo union would've been insurmountable due to their declining but still outstanding worldwide and political obligations. "
]
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[]
] |
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