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85z9dt | When exactly did the migration of free settlers to the Australian colonies begin to match or exceed the transportation of convicts? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/85z9dt/when_exactly_did_the_migration_of_free_settlers/ | {
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"The [first proper census of people in the New South Wales colony - i.e., Australia - was conducted in 1828](_URL_0_), and it counted 36,287 people. Of these, 5210 had came to Australia as free settlers, 8388 were born in the colony and the rest had been transported to Australia as convicts (though of 22,689 others, only 15,324 were currently in bondage, the rest being freed through completion of their sentences, or having been pardoned). So there were four times as many people who had been transported at this point as there were free settlers.\n\nAccording to John Dunmore Lang's *An Historical And Statistical Account Of New South Wales* (from 1852), Sir Richard Bourke, the governor of the New South Wales colony from 1831 to 1836, put forward a policy of assisting free settlers from Britain to arrive in the colony. In this period, about 12,000 settlers arrived (though only about half arrived on the scheme). Between 1828 and 1836, the population doubled in size from 36,287 to 77,096 people, however, so these 12,000 new settlers would not have overtaken the numbers of convicts transported to Australia (which peaked in the 1830s).\n\nThe point at which more settlers than convicts would almost certainly have around 1840, when transportation to the New South Wales colony ceased (though transportation to Australia as a whole did not cease until 1868.) The emigration scheme started by Bourke snowballed in the 1840s, and between 1836 and 1850, 103,378 free settlers arrived in Australia. As this is a bigger number than the amount of convicts that were sent to Australia *in total* (which was about 80,000), it's very clearly in about this period when free migration that overtook convict transportation (though I can't find specific migration statistics amongst the 1841 census to get a sense of whether the free settlers after 1836 but before 1840 would have been greater in number than the amount of convicts being transported)."
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5ox3dv | why is it so hard for doctors to make breast implants look natural? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5ox3dv/eli5_why_is_it_so_hard_for_doctors_to_make_breast/ | {
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"For starters, you're shoving non-biological material into biological material. You'll never match what was naturally grown. \n\nThat is kinda what you're going for in the first place anyway. A great reason to get implants is that your natural boobs were sagging too much. Implants never lose their shape, even when the body around them does. \n\nAlso, it's tough to tell where everything is going to land after healing. You do your best, but it takes some practice and skill to keep swelling and infections predictable. ",
"It isn't. New boob jobs are fantastic. The problem arises when women go for a size that is WAY too big for their body type, or go too big too quickly.\n\nMy wife has a boob job and it is virtually impossible to tell, unless you find the (miniscule) scar."
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694gxx | What makes transition metals the densest elements? | askscience | https://www.reddit.com/r/askscience/comments/694gxx/what_makes_transition_metals_the_densest_elements/ | {
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"Additionally to the high density, transition metals also have high melting and boiling points. From that you can already guess, it has to to with stronger bonding between the different atoms. \n\n > The IUPAC definition defines a transition metal as \"an element whose atom has a partially filled d sub-shell, or which can give rise to cations with an incomplete d sub-shell\"\n\nThis means those fancy d-orbitals play an important role in their properties. \nD-orbitals look [like this](_URL_0_), and usually the energy differences between those different orbitals are quite low.\nThis leads to the \"delocalization\" of those d-orbital electrons, meaning they are not very confined in their position, and the bond between them has no preferred orientation (or direction). \n\n**tl;dr: d-orbitals make them bond close together, so density is high (as well as boiling and melting temperature).**"
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3zo4d1 | What was the 101st Airborne's role in the Battle of Normandy? | My great grandfather served in the 101st throughout the duration of the war and finding his old Airborne patch as well as name plate has made me more interested in learning more about it. | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/3zo4d1/what_was_the_101st_airbornes_role_in_the_battle/ | {
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"The major purpose of airborne forces on D-Day was to protect the flanks of the invasion force by securing choke points, disrupting enemy forces and defending against counter attacks. [This image]( _URL_0_) shows the insertion of airborne forces, look for the blue aircraft silhouettes at either end of the invasion beaches. On the West of the map the southern-most silhouette has a line to a square with a cross in it, two Xs and the number 101. This is the map symbol for 101st Airborne Division and if you look closely the dotted line ends in three arrows to show the planned landing grounds south of the Carentan Estuary around the town of Carentan. This is an important location as it marks the boundary between the US VII Corps landing on Utah beach and US V Corps landing on Omaha beach. The corps boundary is annotated using a line intersected with XXX and you can see that it runs through the centre of the Carentan Estuary.\n\nThe Corps boundary is important as this is a potential weak spot which could be exploited by the Germans. The hierarchical nature of military organisations means that units instinctively report up their chain of command rather than across to other units. At a corps boundary this means that enemy action sighted by one corps is likely to be reported all the way up to the Army Headquarters (US First Army in this case) before it is reported down to the other corps. This delay in communication can be exploited by the enemy and German doctrine specifically encouraged commanders to look for command boundaries in order to break through and encircle enemy forces. This is what happened during the Fall of France in May 1940 when von Rundstadt’s Army Group A broke through at Sedan on the boundary between the French 2^nd and 9^th Armies. Note that the higher the boundary level (platoon < company < battalion < brigade < division < corps < army < army group) the more command levels information has to traverse and so the longer the delay. A corps boundary is therefore a serious weak point.\n\nSo what does this mean for your Grandfather? As a lightly equipped paratrooper he would have jumped into darkness shortly after midnight on 6 June 1944 aware that he had to find, hold and maintain a defensive position in enemy territory and set about disrupting enemy lines of communication until he was relieved by forces advancing from the invasion beaches. He would have been aware that if this task failed then the enemy could drive a wedge through the centre of First Army and then defeat the US Corps in detail leading to the collapse of the Western end of the Allied beachhead. The good news is that with allied air and naval superiority he could rely on overwhelming fire support.\n\nIn reality 101^st Airborne had mixed luck. Some elements arrived on time in good order, whereas others were ravaged by anti-aircraft fire or blown off course by wind. The Division’s artillery regiment lost all bar one of its guns. Successful missions including securing exit routes form Utah beach to be used by the 4^th Infantry Division; destroying the Saint-Martin-de-Varreville coastal battery; and capturing or destroying a number of bridges.\n\nWhat does this mean for you? Now that you know the unit he was in you can do your own research on what happened. The /r/AskHistorians reading list recommends *Overlord, D-Day, and the Battle for Normandy* by Max Hastings, but for the layman interested in US airborne forces in particular I would recommend *World War 2 Soldier Stories Part VIII: True Airborne Stories of the US Paratroopers* by Ryan Jenkins. *Band of Brothers* by Stephen E. Ambrose is the most famous book on the subject, thanks to the TV series, but it focuses on one company of the 101^st and so may only be representative of what your Grandfather did than a record of what he actually did. Unless of course he was in Easy Company of the 506^th Regiment in which case go and read the book now!\n\nOutside of literature you can contact the [101^st Airborne Division Association]( _URL_1_) with his service details and see what information they have from unit diaries or official histories. Once you find out what regiment/company he was in then there is a good chance you will be able to follow his activities for the remainder of the war."
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1vzpic | Why is silver anti-microbial? | askscience | http://www.reddit.com/r/askscience/comments/1vzpic/why_is_silver_antimicrobial/ | {
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"Medical Student who majored in Microbiology and Molecular Biology here:\nSilver has been known for hundreds of years as an antimicrobial. It is thought that since silver has a propensity to interact with the thiol groups, ( -SH groups), it denatures proteins by disrupting these bonds. Proteins without proper disulphide bonds don't have a normal structure and don't work normally or at all. This inhibits the growth of microbes which are dependent on these proteins to survive, grow, and replicate.\nThere are other explanations (interactions with DNA, for example), but this is a scientifically sound and well reasoned mechanism for silvers properties. Here's an address to a site from which I got some of the information:_URL_0_",
"I'm not super confident in the explaination I'm about to give as I'm a physical chemist, not a biochemist. The way silver interacts with large organic compounds is not my specalty.\n\nMost antimicrobial silvers are silver nanoparticals, sometimes called colloidal silver. These are small crystals of metallic Ag^0. Dry and isolated, they're totally innert and stable. (At higher temperatures they may coallesce and grow in size due to a phenomenon called Ostwald ripening though.)\n\nIn aqueous solutions, silver has an incredibly active surface. A measure of this is called the exchange current density, which is the rate at which a single layer of atoms is oxidized and reduced as a dynamic equilbirium. For silver this is upwards of 100mA/cm^2 or 500Hz (a fresh silver surface is exposed 500 times/second on average). This rapid exchange between Ag^+/Ag^0 maintains a high surface concentration of Ag^+ without net dissolution of the nanoparticle or dilution of Ag^+.\n\nAg^+ is the bioactive species, but this is where my knowledge is a little less reliable. Ag^+ catalyzes the reaction of oxygen with thiols (-SH groups that frequently terminate organic molecules) into disulfides (-C-S-S-C-), releasing water. Thiols are commen moieties in proteins. So the Ag^+ effectively binds proteins together preventing their often unique and specific functions.\n\nSilver is a very potent antibiotic/antimicrobial tool because of its mechanism is so basic and widely applicable. I can't forsee how an organism could develop a resistance to silver as it would require using minimal thiols in its basic chemistry.\n\nedit: wrote this as two drafts while researching a bit of the biochem side.",
"It's called the oligodynamic effect, and in short the mechanism isn't really known. Available data shows that it probably works by denaturing vital enzymes of bacteria because the ions can react with available thiol groups forming silver sulfides. \nSource: [Wikipedia](_URL_0_)",
"There's a lot of debate on this, but the evidence is not too strong that it is antimicrobial in all cases. Most often, large, silver interfaces are antimicrobial. I can add silver ions to a peptide/biomimetic oligomer/drug via FMOC chemistry and see no increase in activity, or the MIC value- minimum inhibitory value. It may be that trace ~0.1mM -5mM Ag in solution may diffuse into the water and cause proteins to function differently by allostery, but this is unclear. \n\nThe following is my opinion, but I work in the field of drug design/discovery...take it as you will. \n\nAqueous, silver interfaces are essentially polycationic (contain many positive charges). Gram-positive and Gram-negative (along with myco) bacteria are VERY anionic (negative) in their membranes. Gram-negatives are encapsulated by mostly negative lipids (lipopolysachharides); Gram-positives are generally non-motile and generally have a thick, negatively charged shell around them (NAG-NAM cellular walls, LTA, etc.), and then an additional plasma membrane rich in negative lipids too.\n\nIn the field of peptide science, the prevailing wisdom has always been that positively charged antimicrobial peptides 'seek out' bacteria by their charge- see the Nature paper from Zasloff (Here: _URL_0_) cited in almost every paper in the field. \n\nIn this case, it is likely that the polycationic (+) surface adheres and inhibits cellular function of the bacteria/microbes, which tend to be anionic (-). I'm guessing this is the major cause of antimicrobial behavior, since the same thing happens to other polycationic surfaces. \n\nExample: adhering bacteria to a poly-L-lysine interface (+) causes them to die over time, and stop a lot of interesting functions- you have to do these experiments fairly quickly! I'd assume silver surfaces work similarly. ",
"Side question; would plasters (band-aids) with silver in them actually make any difference to how well / quickly a cut heals? Because I remember those being advertised a few years back but don't think I've seen them since.",
"As a forensic scientist-DNA analyst and also a Microbiology major, I also have done independent research on the effects of Zinc and Silver nanoparticles on bacteria. The nanoparticle field is up and coming in the scientific community, basically, if you take a postcard and divide it into a billion equal pieces, that is the size of silver that i worked with. The silver nanoparticles were almost a thousand fold more toxic to cells than the zinc nanoparticles were. There have been multiple proposals that have been made about the actual pathogenesis of silver but, unfortunately a lot still remains unclear. A common theory, with nanoparticulate silver, is that the silver is able to penetrate the plasma membrane of a cell and begin to interact with the RNA and DNA in our cells. Heavy metals, like silver, tend to carry a positive charge and such will bind to the negatively charged DNA and RNA molecules. Binding of DNA and RNA molecules prevents the cell from doing its everyday duties; from replication (copying of DNA), transcription (converting DNA to RNA), and finally translation (ribosomes make proteins from mRNA). If the silver binds up DNA, DNA polymerase 2 cannot copy the molecule and if silver binds to RNA, ribosomes cannot create proteins. All of these factors add up to the eventual death of cells.\n\n*edit* Removed a typographical error.",
"Regarding silver nanoparticles, there are few hypothesis: \n\nAg nanoparticles could directly interact with the microbial cells causing degradation of the lipopolysaccharide molecules and forming \"pits\" leading to large increase in membrane permeability (boom!).\n\nAg nanoparticles may also produce secondary products (such as reactive oxygen species) that can penetrate the bacteria cell envelope and cause DNA damage and protein oxidation.\n\nLast but not least Ag ions released from the nanoparticles also contribute to the bactericidal effect by interacting with the thiol group proteins, turning the DNA into condensed form and disabling its replication ability.\n\nSource: In vitro antibacterial activity of porous TiO2-Ag composite layers against methicillin-resistant Staphylococcus aureus\n"
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w13yv | racism on 4chan | What's the reason? I'm mean really, is it a long running inside joke or what? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/w13yv/eli5_racism_on_4chan/ | {
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"The most commonly cited reason is that when \"weak\" outsiders come in to check it out, they are scared off by the offensive content. It's used to keep people not fit for 4chan away.",
"Racism is funny if not taken seriously. Besides its a taboo, something that 4chan likes to break. They are exercising their freedom in a way (retarded, very disturbing, but a way nevertheless).",
"I think isn't a good idea explain 4chan for a 5 year old. Try at /r/answers ",
"op is a faggot",
"[\"Internet Aspergers\"](_URL_0_)\n\n**TL;DR:**\"We have used the term because it seems to summarize ... cutting of connections to the outside world\"",
"13 year olds + anonymity = shitfest"
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4q0kim | how do mres work? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4q0kim/eli5how_do_mres_work/ | {
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"They use a magnesium heater. It's a small, teabag-like, pouch of magnesium in a heat-resistant plastic bag. You pour a small amount of water into the bag, and it reacts with the magnesium to create heat. Then you put the food, also in a heat resistant pouch, in the bag with the magnesium and water, and this reheats the food.\n\nThe gas from the reaction can become explosive, we used to make MRE bombs for fun in the Marines.\n\n*Edit* here's more info on the heater: _URL_0_",
"If you're asking about how they keep fresh, it's because they're vacuum sealed. There is little to no air in the packages. It's like canned food, but instead of a metal can it's a plastic pouch. \n\n"
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h95vi | What exactly is the difference between carbon fiber and fiberglass? | I realize that carbon fiber is stronger than fiberglass, but what makes it so? They appear to be almost identical on the surface.
Every time I google carbon fiber vs fiberglass, I end up with 1x10^14 hits for custom-made carbon fiber hoods for 1989 Honda Civics. | askscience | http://www.reddit.com/r/askscience/comments/h95vi/what_exactly_is_the_difference_between_carbon/ | {
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"Try the other way of spelling fibre, you get better [results](_URL_0_). You can also do things in Google like subtract words that you don't want to see in your search. For example, searching for \"carbon fibre vs fibreglass -car\" returns much better results and a search without -car."
]
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6okt01 | how is there always a relevant xkcd? how!? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6okt01/eli5_how_is_there_always_a_relevant_xkcd_how/ | {
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"I imagine it functions along the same lines as Quantum Fetish Mechanics. By the time you think of it, it already exisists on the internet. "
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cjqrdv | ; why are tattoos such taboo in some religions? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/cjqrdv/eli5_why_are_tattoos_such_taboo_in_some_religions/ | {
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"Some religions believe your body is the physical property of God. You are just borrowing it for your time on Earth and at the end when you die he gets it back. You're not allowed to damage it because it's not yours and a tattoo is damaging the skin.",
"1 Corinthians 3: 16-17 (KJV Bible) says \"Know ye not that ye are the temple of God, and that the Spirit of God dwelleth in you? If any man defile the temple of God, him shall God destroy; for the temple of God is holy, which temple ye are”. \n\nSince our bodies are temples we should treat them with the utmost respect. Tattoos (and other things) are a disrespectful way to treat our bodies that God gave us.",
"because religion is a method of control. and therefore restricting what people can do / eat etc. helps maintain a grip on the populace. in Catholicism the act of confession was less about confessing your sins and more to do with placing the priest in a position of power by knowing the naughty things you did. giving him the power over the congregation by being able to remind them he knows there darkest thoughts.",
"For hebratic religions is was often to make it clear who was a follower of who. It my understanding that many of the non-Jewish religions used tattoos as ritual markings and branding to show that they are devoted to a specific worship. Since the Hebrew God said have no other Gods before me, and demanded no markings, then one way to stay clearly separate from the other religions was to not have tattoos or body markings. \n\nA good chunk of the Hebrew law was for this reason, and as such many scholars feel like it is not longer relevant today.",
"Tattoos have been used by some religions to mark the bearer as dedicated to a god, and in so doing request the deity's protection as a bearer of the god's markings. In that case, religions that forbid the worship of false gods (Islam, Christianity, Judaism are the most common examples), often also forbid tattooing, so as to avoid behaviors that could lead to worshiping a false god."
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2wr7dk | Why don't we wear fancy clothes as much anymore? | In the West it seems that there has been a gradual degeneration of day-to-day clothing. Even as late as the 1960s, men attended baseball games in suits an ties, and women got "dressed up" to go shopping. How is it that old people today, who lived through this change didn't object to this massively visible cultural shift? Is the degeneration (from suits to jeans and teeshirts in 50 years) of clothing for the majority of daily wear cyclical in history? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/2wr7dk/why_dont_we_wear_fancy_clothes_as_much_anymore/ | {
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"I can't speak to the cyclical nature of clothing, but I think your first question has a rather simple answer - baby boomers. The Baby Boom generation that was born in the 40s and 50s, came of age as \"hippies\" in the 60s and 70s. Suits and hats for everyday wear was what their parents wore. The movements embraced by the new western youth preached social change, something that was largely incongruent with the \"stuffed shirt,\" rat race\" running image of their parents' generation. They naturally gravitated to more casual, less socially stratified clothing (i.e. clothing not restricted to one social class or another). \n\nThe fashion designers of the 60s and 70s followed suit (no pun intended) and as the Baby Boom Generation became the dominant culture makers in western society, this casual aspect of everyday clothing became more and more ingrained in the culture. \n\nThe real change in Work Wear came about at this time as well. In the 50s and 60s, \"Aloha Fridays\" became very popular in the US due to the popularity of all things Hawaiian in the US skyrocketing in the period just before and after Hawaiian statehood, and marketing promotions by Hawaii itself. Employers around the country were encouraged to allow their employees to wear Hawaiian shirts on Fridays. This eventually morphed into \"casual Fridays\" when employees realized that this was a \"perk\" they could offer to their employees that didn't actually cost the anything. \n\nFast forward to present day. Now the children of the Baby Boomers (Gen X and Y) are the most prevalent age group in the workforce. Having been dressed by their parents in casual clothing their entire lives, they came into the workforce in the 90s and 00s expecting a casual environment and the casual clothing to go with it. \n\nIn summation, the 60s changed everything, clothing included.\n\nAs to your question of why the older generation didn't \"object\" to this casual shift, the short answer is that they did (repeatedly and vehemently) but they eventually lost the argument. \n\n*Just as an anecdotal side note, my grandfather was born in the 20s, went to Europe with Patton's army in WWII, and wore a hat every time he left the house until the day he died. My father was born in 1950, was in the Army during Vietnam (although he never went \"in country\"), and I don't think I've ever seen him in a suit. If that isn't a testament to the differences in their respective generations, I don't know what is."
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akaykf | Source of metals in Antiquity | Hello! I am reading into metalworking and how it developed and where the source materials came from. But I am a bit unsure how to I have to understand it. I was reading that iron can be found at a surface level as a part of other materials. Is the amount of those sources enough to have a culture using it for daily life and warfare, or were mines necessary to get enough iron in antiquity? I am especially interested in the Roman Period, say 400BC and also ancient Greece and China/India during the same time. One could also include Alexander's Empire. Did they build mines into mountains to get it, and if, how? What where the tools they used? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/akaykf/source_of_metals_in_antiquity/ | {
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"The common sources of iron ore that are easily accessible without mining are bog iron and iron sand. Bog iron, as the name suggests, is found in bogs and similar moist environments (e.g., along streams); the deposits of ore are formed by bacteria (which will make new ore, and the bog can be reharvested after a decade or a few decades). Depending on the bog, one might have to dig for the ore, but this involves digging in a soft bog rather than mining in rock. The other easy source, iron sand, is formed by the erosion of iron ore deposits. The iron content in the sand is often low, but the iron grains can be separated from the silica sand by panning or washing.\n\nBog iron and iron sand were, in many places, used as the main sources of iron ore into quite recent times (the 18th and 19th centuries, depending on where). Old-style collection of the ore by hand is not sufficient to sustain modern industrial iron-making (the labour costs would be far too high), but mechanised collection of iron sand is still used (sand mining).\n\nHowever, the limiting natural resource for iron-making was often wood, for making charcoal, as the carbon source and energy source for smelting, and energy source for working the iron. Charcoal making could easily take more labour than collecting ore (assuming the use of bog iron or iron sand), and the lack of plentiful wood would stop the development of a major iron industry (and deforestation could bring a large-scale iron industry to an end).\n\nSome discussion about the labour costs of bog iron, iron sand, mining in rock, and charcoal making in _URL_0_ (and u/tsayper reports a quite remarkable productivity of bog iron harvesting of \"750 kg of bog ore in a day per worker\").\n\nIf there were iron ore deposits suitable for mining close to a source of wood, mining could be used to obtain ore. If the rock was soft enough to be broken by picks, iron/steel picks could be used (before iron, stone hammers, antler picks, wooden picks, etc., were used). If the rock was too hard to be easily mined by picks, fire was used to break the rock. Firewood was piled against the rock face, and lit. Once the fire had burned down, and the rock face was still hot, water was thrown onto the rock, breaking it as the surface cooled rapidly. Picks and fire were also used for mining of other metals, notably copper, tin, lead, silver, and gold. Fire-setting remained the preferred method of breaking hard rock for mining until blasting with explosives became available.\n\nThe advantage of mining large bodies of ore is that there is lots of ore in one place, and while it might take more effort to break the ore and surrounding rock, the labour cost of transport will be lower (assuming that one can smelt the ore near the mine).\n\nOther tools are important or useful for mining, such as wheeled mine-carts, pulleys, and pumps. Bulliet (2016) notes that the earliest known wheeled vehicles are mine-carts from Copper Age copper mines in the Carpathians; ore is heavy, and being able to move the ore in cramped mines makes mine-carts attractive.\n\nAll three of these sources of ore (bog iron, iron sand, and mining large bodies of ore) were used in ancient India. Bog iron and mining were used in ancient China and by the Romans. Iron sand was used in Medieval and later China, but it isn't clear when it was first used. Iron sand was not a major source of ore in Europe, seeing little use (if any) until the Industrial Revolution. Bog iron and iron sand continued in use in India and China into modern times, until the end of the traditional iron industries in India and China in the 19th and early 20th centuries.\n\nReferences:\n\nBulliet, Richard. The Wheel : Inventions and Reinventions, Columbia University Press, 2016.\n\n",
"The Romans mined extensively, and used techniques very similar to those used well into the 19th century. For instance, a gold-seeking shaft mine in 1849 California was very similar to a shaft mine in Roman Gaul. The set them into mountains, into the desert, into rivers, or anywhere else the experts thought there might be deposits. They had iron tools which were nearly identical to those of the 49ers. You can see some examples [here](_URL_0_) from the Hedemünden legionary fort. For your request of 400 BCE, there is not much evidence (or any) for Roman mining. That would be a time period for late Classical to Hellenistic Greek activity. Most Roman mining data is from the first century BCE and then into the Imperial period. I know nothing about mining in China or India.\n\nIron was (and still is) quite common, and both the Greeks and Romans had the technological know-how to extract it via mining (they did not need to rely on bog iron, and all the bog iron on the whole earth would not supply the amount of iron a Roman army consumed in a single campaign). In the ancient world, iron deposits were plentiful in Italy, including central Italy. At Noricum, up in the Alps, there was an especially-rich source which was naturally carburized. Spain was also a major source of iron.\n\nGold was extracted also from the Alps, from alluvial deposits using hydraulic methods, and on a massive scale. Spain was also a gold source, especially in the first century AD, where we find evidence of absolutely gigantic operations using hydraulic opencast mining methods for both alluvial and also hard rock deposits. Hundreds of such sites are now known from NW Spain and Portugal. The eastern deserts of Egypt were also a source of Roman gold-seeking, in simple open-pit shaft mines. At one such site, the name of which is completely escaping me, there is some pretty good evidence of ingot casting on-site. \nThis is interesting, because from shipwrecks we find ingots of iron, lead, copper, and tin, but never gold or silver. Presumably the gold ingots from the Egyptian pit mines would be shipped to the sea, or else back to the Nile overland for transport down to Alexandria and the sea. It's unclear exactly why we don't find them in shipwrecks. Some hypothesize that the Roman state, which controlled the extraction of precious metals from the imperial period onwards, would have gold and silver ingot shipped separately, and under heavy guard. That still does not explain how they prevented those shipments from falling victim to storms. Neptune did not discriminate between gold ingots and lead ingots. In shallow water, the Roman state had the resources to mount an operation to recover the lost ingots, but in the deeps those ingots would have been lost. It could also just be a weird accident of preservation of evidence.\n\nFor silver, the major and best source for the Greeks was on the Greek mainland itself, usually in smaller deposits. Famously, the Athenian discovery of a silver mine at Laureion (at the southern end of their territory) enabled that city to propel herself into greatness (by purchasing the materials to construct a powerful fleet of ships). For the Romans, Spain was the site of a veritable \"Silver Rush,\" and the amount of silver extracted, beginning in the first century BCE, from places like San Domingos and Aljustrel is absolutely staggering. \n\nFor your specifically, I would recommend the book by Robert Shepherd, *Ancient Mining* London 1993. This is a basic survey of ancient mining, techniques, technology.\n\nUnfortunately, the other quality academic studies for ancient mining are usually not in English. There are a few good English ones, though.\n\nDomergue, C. (2008). *Les mines antiques: la production des m´etaux aux ´epoques grecque et romaine.* Paris. [if you read French, this is the place to go]\n\nHirt, A. M. (2010) *Imperial Mines and Quarries in the RomanWorld: Organizational Aspects 27 BC – AD 235.* Oxford. [Roman, and late]\n\n"
]
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5c21ec | When and what marked the transition between "Old West" towns just becoming known as regular towns? | We often hear about the "Old West" however I've always wondered what the transitional period between the "Old West" and just the "West" was. When did the western "cowboy" lifestyle fade out and become more modern? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/5c21ec/when_and_what_marked_the_transition_between_old/ | {
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"The influential contemporary historian Frederick Turner famously declared that the frontier (akin to 'Old West') in 1890 whereby the Native American population, harshness of the landscape and much of the mystery and intrigue of lands to be explored had been mitigated and suppressed [1]. \n\nThis trend evidenced it can be argued by the creation of the national park system in the US commencing with Yellowstone in 1872. The symbolism of this is that its founders were attempting to recreate scenes of a 'virgin landscape' [2]. The National Parks attempted to restore a lost history and serve as a memorial to the 'frontier spirit' which was the glue which held the early United States together [3]. \n\n___\n\n\n1. Axtel J (1987) Colonial America without the Indians: Counterfactual Reflections, Journal of American History\n2. Cronon W (1995) The Trouble with Wilderness; or, Getting Back to the Wrong Nature, in Cronon W (1995) (ed) Uncommon Ground: Rethinking the Human Place in Nature \n3. Callicott JB (2008) What “Wilderness” in Frontier Ecosystems?, Environmental Ethics. "
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5andrx | what are graphics apis such as directx or vulkan and what do they do? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5andrx/eli5_what_are_graphics_apis_such_as_directx_or/ | {
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"(Technical note, DirectX actually covers a bunch of things like sound and input, we'll assume we are talking about the Direct3D portion of DirectX which is what Vulkan does)\n\nThey both provide an abstraction layer, a language or set of commands, between the graphics card and the software that wants to use it. It means that even if a card from AMD does things differently then a card from NVidia they will both respond to a DirectX command like 'draw a polygon here'. They might accomplish the task in a different way but the end result will more or less be the same. This means programmers don't have to write a different version for every brand or generation of graphics card.\n\n"
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3jrsto | why don't snakes choke when they devour large prey whole / is it ever possible for a snake to choke ? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3jrsto/eli5_why_dont_snakes_choke_when_they_devour_large/ | {
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"Yes, snakes can choke. Sometimes they start to swallow a prey, and when startled or find that it is too big, they reverse the swallowing process. It's usually not healthy for the snake to do repeatedly, and can hurt the snake.\n\nAlso, snakes have a special extendable tube trachea they push forward to the front of their jaw when swallowing a large prey. It's like a snorkel for eating."
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9uz5pj | What determines which areas of the brain are damaged during hypoxia? | When the blood and oxygen supply is cut off to the brain what determines which regions of the brain are damaged? Does the motor cortex tend to be more susceptible to damage because in states of hypoxia the body is trying to move? | askscience | https://www.reddit.com/r/askscience/comments/9uz5pj/what_determines_which_areas_of_the_brain_are/ | {
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"Generally the areas damanaged depened on two factors\n\n* metabolic demand\n* blood supply\n\nThe first factor should be obvious. Neurons that have high resting metabolic demand are going to run out of energy first. Note that the brain *depends* on aerobic energy production and can't really get by like muscles do with anaerobic respiration.\n\nThe cortex and cerebellum along with the thalamus and pons are some of the most demanding regions.\n\nBlood supply is important because areas that are served only by fine terminal branches of cerebral arteries are more likely to be deprived of oxygen if the cerebral blood flow decreases.\n\n > Does the motor cortex tend to be more susceptible to damage because in states of hypoxia the body is trying to move? \n\nNot really. The motor cortex is pretty active even when the body doesn't try to move. And in cases of anoxia, consciousness (and hence conscious movement) will be lost within 10 s in most cases.",
"According to a chapter in Magnetic Resonance of Myelination and Myelin Disorders (2005), the most sensitive structures in the brain to hypoxic-ischemic conditions are the Hippocampus, then Cerebellum, then Striatum, and then Neocortex. \n\n_URL_0_\n"
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4mprbp | why are basements (even finished ones!) still a smooth 10-15 degrees cooler than the rest of a house? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4mprbp/eli5_why_are_basements_even_finished_ones_still_a/ | {
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"Because basement floors are made of a small cement pad over dirt which is usually a good 8+ ft below grade. This is far enough down to not really be subjected to much seasonal temperature changes.",
"Part of it is that warm air rises, cold air sinks. That's also why it can get super hot upstairs.",
"The dirt surrounding the basement is cooler because of less light penetration and more moisture. It's dark and wet.",
"Underground temperature is pretty constant. Once you go so far into a cave system the temperature becomes constant. "
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7425vb | 2nd Time: Why did the Nazis appropriate so much ancient Mediterranean culture if they were trying to recreate a Germanic state? | If they thought that "Alpine" and "Mediterranean" whites were inferior why have such a raging hard on for Rome and Greece? Wouldn't German and Scandinavian culture be the only appropriate template for the kind of "lost purity" they were looking for? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/7425vb/2nd_time_why_did_the_nazis_appropriate_so_much/ | {
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"Well first, Nazi beliefs were not a coherent and logical whole philosophy and aesthetic by any standard, and different Nazis believed very different things. Some of the artists the Nazis denounced as 'degenerate art' had themselves been long-time party members. Second you have the stylistic time period in which they were acting. They'd had backward-looking medieval-revival 'Germanic' art within the_Jugendstil_ movement (~1890-1920). The [Völkerschlachtdenkmal](_URL_5_) is a good example of something supposedly 'medieval' and 'Germanic' (although it's neither). By the time the Nazis were gaining power, it was thoroughly out of fashion though, and with it the backward-looking styles. \n\nThings had moved on into two broad directions. One was completely unadorned, minimalist modernism, the foremost representative in Germany and perhaps the world being the [Bauhaus School](_URL_4_). But Bauhaus was considered too modern, too progressive, and possibly communist by the Nazis, who wasted no time in shutting it down once they were in power. \n\nThat leaves the other option, which is neoclassicism, represented elsewhere as Art Deco, and in Germany with the Nazi version of it. This was not as backward-looking as it seemed, as it wasn't trying to outright imitate or 'appropriate' the Romans or Greeks. Rather, it was looking forward but drawing on what they perceived as a _universal_ tradition. \n\nPerhaps most important, as usual with Nazi stuff, is what Hitler himself thought. And Hitler was a thorough neo-classicist. He had less respect for southern Europeans as people, but did not seem to mind their art at all. In the famous [picture in Paris](_URL_0_) he was flanked by his 'fellow' neoclassical artists - architect Albert Speer on the left, sculptor Arno Breker on the right. Neoclassicism had been back in all of Europe for a good 200 years by that time, and wasn't really regarded so much as specifically Greco-Roman anymore, but something more universally European.\n\nSo with his monumental art Hitler was trying to create something universal, idealistic, new and yet referencing the past. And in that it wasn't very different from the contemporary Soviet neoclassicism of the Stalin era. Hitler was both a revolutionary and a romantic. He did not want to preserve the historic Berlin but [completely reshape it](_URL_6_) and some other cities. With radical new monumental buildings, that were nevertheless neoclassical. In a way they had to be, as history left no ancient Germanic monumental buildings to draw inspiration from anyhow. To build a giant 'germanic' monument they'd have to make it all up, and this inherent 'fakeness' was part of the reason it'd gone out of style.\n\nIt's speculative but Hitler probably didn't want to hark back to a style dominant during the German Empire either. He wanted to abolish the old German Empire institutions and create some new amalgam of racial theories, worship of the medieval German society and other 'ancient' stuff, and yet forward-looking on the military, technology and such.\n\nAnother tiny example is that Hitler actually loathed German [Fraktur](_URL_2_) cursive writing, and insisted that all official publications in the future would use a Roman font. Which is a bit funny considering how Fraktur has later been given so many 'Nazi' associations due to being the more common font in Germany during that period.\n\nThe fascists in Italy, naturally loved neoclassicism too, imagining themselves to be the new Rome. But _unlike_ the Nazis (and more like the Soviets in the 1920s) they had some appreciation of (or at least tolerance for) modernist art,\n and specifically [futurist](_URL_1_) art for the italians. [This striking, daunting art for the fascists 1934 referendum](_URL_3_) for instance, - definitely not neoclassical.\n\nSo in short: They viewed neoclassical styles are more 'universal European' than specifically Greek or Roman, and art policy among the Nazis and Fascists were heavily influenced by their respective leader's personal tastes."
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1ka71d | why can't you get prosecuted for posting videos/picture of yourself doing drugs while you can for posting a murder you've committed? | I know murder is far worse than smoking a joint but I've always wondered what stops law enforcement, for example, from prosecuting people showing their illegal grows and smoking on camera. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1ka71d/why_cant_you_get_prosecuted_for_posting/ | {
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"Typically the picture is a starting point for an investigation. \n\nIf you post a picture of you doing drugs, they interview you and you say \"fifth amendment\" or \"it wasn't drugs. It was something that looks like but isn't drugs,\" that's where the investigation ends. \n\nIf you post a picture/video of you killing someone, they open an investigation and comb the scene for evidence corroborating what you've said, look for a body, etc. ",
"You can be \"prosecuted\" for anything, you won't be found guilty of it though. If you just have a picture of a dead body but no one is known to be missing then you aren't going to go to jail. A picture doesn't mean you committed a crime.\n\nif they see it though they'll definitely look to see if that person can be identified and if they are alive or not. If they aren't then that's more then just a picture of evidence and they'll pursue it.\n\nFor drugs there isn't likely any other evidence, and it's not really as serious of a crime.",
"It's easy to say it wasn't really drugs, (they make it look very real in the movies) it is hard to say it wasn't really murder...",
"Doing drugs isn't illegal, but the possession of drugs is.",
"Mommy and Daddy aren't going to waste all their rest time after their busy day to find out who ate the cookie that was left on the table. However, if it was something more serious, like leaving a trail of muddy prints all over the white carpet, you're going to get a beating.",
"Proving you had drugs yesterday is a lot harder than proving you murdered someone yesterday. photos or no photos. ",
"Usually, a picture of what appears to be a dead body, coupled with the subsequent discovery of a dead body, is pretty strong evidence of criminal culpability (when combined with other factors) for which no statute of limitations exists. A picture of apparent drug use, on the other hand, is just that: apparent drug use that cannot be easily confirmed. "
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2jcos2 | the effectiveness of "traditional" advertising? | At this point in my life, I can't help but feel instantly turned off when I see advertisements for items in places like TV commercials, radio ads, advertisement boxes on websites, billboards, etc. In fact, personally, I feel as if I'm less likely to buy a product if I have to experience its advertising through those traditional avenues, and I'm sure there are many others out there who feel the same way.
At this point in time, how effective is traditional advertising, and how are people not completely averse to those advertising methods by now? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2jcos2/eli5_the_effectiveness_of_traditional_advertising/ | {
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"Companies have often wondered the same, and several have tried cutting the ad budget over the years. Usually they see sales drop by more than the budget is worth. So yeah, it makes a difference. \n\nAsk yourself this - you need to get some random product you don't buy much and have no sense of where to get good ones or what a good one even consists of. Where do you go first? Usually I pick a company name semi-randomly from among the ones I've heard advertisements from, and I don't bother comparison shopping unless it's a big ticket item. That's how advertisements work. "
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7vygh9 | why do things sound significantly different when you listen to them with one ear vs both ears? for example when only using one out of a pair of headphones, even when listening to things recorded in mono. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/7vygh9/eli5_why_do_things_sound_significantly_different/ | {
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"text": [
"For the same reason things look different when you look at them with one eye versus with two eyes (or at least, they should!). Just like we humans have binocular (bi-n-ocular, two eyes) vision, we have binaural (bi-n-aural, two ears) hearing. When you see something with just one eye, you lose a whole lot of information compared to seeing it with both eyes, such as the ability to tell how far away from you it is (depth perception). It's the same when you hear something with just one ear - you lose the same kind of information, and things sound much \"flatter\" and less vibrant. Plus there's the influence of whatever the other ear is hearing - maybe silence, maybe room noise, etc. The brain kind of mixes both channels to get a sense of the environment, and so it can have an impact on how you hear what goes into the other ear. "
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49p76h | What was the highest rank awarded to a U.S. black soldier/officer in WW2? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/49p76h/what_was_the_highest_rank_awarded_to_a_us_black/ | {
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"**EDIT**- I misconstrued the title and saw it as rank/award...which is why I chimed in with what I wrote below. While not directly answering the question, I'm sure followup questions would have asked this. \n\n\nWell, First Lieutenant Vernon Baker's actions in early '45 would earn him a Bronze Star, which was upgraded to the MoH in 1997, 52 years after the fact. The dude was involved in an attack on a German castle that sat on a very high bluff, and basically single-handedly solo'd the whole trip, destroying a machine gun position, phone lines, a pair of bunkers and two machine gun posts. That is pretty impressive. \n\nTwo other black first lieutenants were also posthumously awarded the MoH for similarly-brave actions, also awarded decades after the fact. \n\nThe only black soldier to be awarded the Medal of Honor actually *during* the war was Private George Watson. The transport he was on in the Pacific near New Guinea was hit by Japanese bombers , and as the ship went down he spent time in the water towing/rescuing men who couldn't swim. He spent too long in the water, was exhausted, and the suction of the sinking ship dragged him down. The MoH was awarded posthumously, of course. \n\nIn total, 7 black soldiers of various ranks would wind up winning the award. Watson right after his death, and the other 6 in a ceremony led by President Clinton. ",
"The highest ranking black man during the war itself was Benjamin Davis Sr, who reached the rank of Brigadier General in the US Army in 1940. "
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1hx419 | genetically modified organisms | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1hx419/eli5_genetically_modified_organisms/ | {
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"Every organism has within it a set of instructions for how that organism is made and what it does. This is DNA.\n\nDNA is like an alphabet with only four letters. By spelling out different 'words' using these 'letters', we get the 'instructions' that describe the organism. \n\nA genetically modified organism is made when a scientist intentionally rewrites part of the DNA to make an organism do something different than it used to.\n\nOften, they'll copy a 'word' from a different organism and add it to the one being modified. For example, the reason daffodils are yellow is because of a yellow nutrient that happens to be healthy for people to eat - but we don't like eating daffodils. So what some scientists did was copy the word for that yellow nutrient and add it to the instructions for rice. This genetically modified rice is now yellow and can be eaten for people to get that nutrient. This example is called \"golden rice\"."
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1avzye | Prior to gunpowder what was the most effective military deployment? | Two armies deployed in an open plain what what be the most effective deployment from the stone age until the age of gunpowder? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/1avzye/prior_to_gunpowder_what_was_the_most_effective/ | {
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"text": [
"I think you must mean 'development.' \"What was the most effective military development?\""
]
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346xej | How did the stereotype of African Americans being lazy come about? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/346xej/how_did_the_stereotype_of_african_americans_being/ | {
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"Ooh I question I might be able to answer since some of my research is dealing with this. Unfortunately I'm on my phone so this will have to be a bit brief before I can come back and edit it. \n\nA lot of it has do with how slaves were portrayed in plantation novels(many of them were responses to Uncle Toms Cabin). Those played up the Sambo/Uncle Remus image of slaves as jovial, childish, happy go lucky, jokesters, etc"
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bcy83q | Can marine animals taste salt? Would they know if the concentration changes? | Would the marine animals such as fishes and whales know the saltiness of the sea water? Would they try to swim away from a "more salty" place to a "less salty" place? Will the change in concentration affect them? | askscience | https://www.reddit.com/r/askscience/comments/bcy83q/can_marine_animals_taste_salt_would_they_know_if/ | {
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"As far as \"taste\" I'm unsure, as for concentration their bodies certainly can tell! Salt (NaCl) is incredibly important in animal bodies, it helps power many of the important cellular processes of the body. But too much salt can also be detrimental to the body. \n\nThe gills of a fish are important not only for respiration, but also as a way to maintain the correct salinity. It's a complicated process but to answer VERY simply, excess salt is lost through the gills, skin, and kidneys of a fish. If the fish is healthy it should be able to do this in most environments. \n\nTo answer about moving to an area of lower concentration I'm going to have to make an educated guess, I know more about anatomy and physiology than ocean salinity! I would assume that most ocean habitats aren't going to vary that much in regards to a population of fish. That is to say, a species of clown fish is most likely going to experience similar levels of salinity all it's life and therefore won't really need to move to a different location"
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|
46vdgc | What did the Family of Queen Victoria do for entertainment? | Also what did other families do for entertainment in the time Queen Victoria reigned the UK?
| AskHistorians | https://www.reddit.com/r/AskHistorians/comments/46vdgc/what_did_the_family_of_queen_victoria_do_for/ | {
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"Let's use family in this context to mean immediate family, as in her husband and children. \n\nAs a child, heir to the throne Prince Edward really did not have too much of a childhood. He was caged inside an intensive education system which did not leave much time for traditional childhood play. However as an adult, he enjoyed shooting, hosting and attending parties, riding, traveling, hunting, and of course dining. He was also very fond of horses and horse racing. He gambled frequently and also bet money on horse races. \n\nNotably, Princess Louise, Victoria and Albert's sixth child and fourth daughter, was an accomplished sculptor and artist. She created the marble statue of Victoria that can be seen today in London's Kensington Gardens Park. \n\nVicky, Princess Royal, was was a prolific letter writer. As Empress Frederick, she took an interest in the Berlin Observatory and added to the growth of the German Society for Ethical Culture. \n\nAlbert, Prince Consort, loved art and with Victoria, amassed a collection ranging from sculptures to paintings, etchings to family portraits. He was a musician and excelled in sports especially fencing and riding.\n\nVictoria herself was an excellent artist. She went so far as to design her own wedding gown and the dresses of her bridesmaids. Victoria drew and painted all the way into her 60s. Windsor has a collection of paper dolls Victoria created as a young girl. She also kept detailed diaries throughout her life. \n\nSources:\n\n[Princess Victoria's Paper Dolls](_URL_0_)\n\n[The Sport of Kings, Shooting and the Court of Edward VII] (_URL_2_)\n\n[Death of an artist: Princess Louise, Duchess of Argyll](_URL_3_)\n\n[Victoria & Albert: Art & Love](_URL_1_)\n\n\n"
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"https://www.royalcollection.org.uk/exhibitions/princess-victorias-paper-dolls-c-1830",
"https://www.royalcollection.org.uk/victoria-albert-art-love",
"http://www.maneyonline.com/doi/pdfplus/10.1179/cou.2013.18.2.004",
"http://royalcentral.co.uk/blogs/death-of-an-artist-princess-louise-duchess-of-argyll-39623"
]
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|
62xg3y | How is the power of nuclear weapons increased? | askscience | https://www.reddit.com/r/askscience/comments/62xg3y/how_is_the_power_of_nuclear_weapons_increased/ | {
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"So most nuclear warheads in the current stockpile are of the Teller-Ulam design. You have a small(ish) fission primary, which initiates the whole thing. This creates the conditions necessary for fusion in the secondary. The neutrons produced in the secondary, in turn, cause fission in the natural uranium casing that surrounds the whole device. In most thermonuclear designs that have been fielded, the yield is about 50:50 from fusion and fission.\n\nBased on what is in the open literature, and what we've seen in the history of testing, the Teller-Ulam design can be scaled arbitrarily large by adding more and more stages. So if you wanted a stupidly large warhead, you could \"just\" keep adding more fusion stages.\n\nAn example of this is the Tsar Bomba that was built and tested by the Soviets. While not a practical weapon (it was built in the grand tradition of various other oversized Russian things, like the bell and the cannon), it is the largest device ever detonated, yielding 50 Megatons. To reduce the fallout from it, they omitted the Uranium casing, so 97% of its power was derived from fusion. With the Uranium casing, it probably would have yielded 100 Megatons.\n\nNow, one of the things that you have to understand, is that larger weapons aren't always better. You're far better off sending in multiple smaller warheads rather than one big one. It's bad enough that to get a 10 fold increase in blast radius, you need a 1000fold increase in warhead power. See [here](_URL_0_) for an interesting article on this concept. The other reason why you'd want to deploy multiple smaller warheads is it's harder to defend against a bunch of small ones, and they're easier to build and deliver than a big one.",
"Nuclear weapons work by releasing energy from nuclear fission reactions, and often nuclear fusion reactions.\n\nIncreasing nuclear fission bombs is a matter of making sure more material undergoes fissioning before the explosion of the bomb decomposes itself. This can range from increasing the efficiency of the reaction to just increasing the amount of fuel (which has to be done carefully so that the bomb can't go off prematurely). The largest pure-fission bomb, the Ivy King test, used a _lot_ of enriched uranium in a very efficient arrangement and got half a megaton's worth of energy out of it.\n\nOther ways to increase inefficiency involve things like having tiny amounts of fusion reactions, which produce neutrons that cause more fissioning. \n\nFor thermonuclear weapons, a fission bomb's energy is used to compress and ignite fusion reactions, which in turn can produce neutrons to ignite more fission reactions, even in otherwise \"inert\" depleted uranium.\n\nMaking a big thermonuclear bomb is just a matter of increasing the amount of fusioning and fissioning you do. It is not hard to scale up the explosive power. For thermonuclear weapons, there is literally no real limit to the practical explosive power of the bomb — it just becomes heavier and heavier, and thus harder to \"deliver\" to a target. The largest weapon design I have seen seriously studied by US weapon designers had a projected yield of 10,000 megatons. That's a single bomb with 500,000 times the power of the Nagasaki bomb. It was never built.\n\nMore difficult, and more useful from a \"delivery\" standpoint, is scaling down the volume and mass, while still getting a respectable amount of explosive power (increasing the efficiency). There are several apparent tricks that are used by weapons designers to do this, so you can fit [10 human-sized warheads onto one missile base](_URL_1_), but they all come down to engineering tweaks (e.g., using a spherical fusion component surrounded by highly-enriched uranium, for an extra boom with only a minimal volume). [This is more or less what the more advanced thermonuclear warheads look like today](_URL_0_), if you had them in cross-section. They are just very efficient in terms of the yield-to-weight ratio and their mass/volume; this level of nuclear weapon technology was more or less achieved by the USA in the 1970s (with some very small optimizations in the 1980s). Each of those warheads has an explosive yield of \"only\" 475 kilotons (24X the Nagasaki bomb), but they are present in such numbers (and on highly-accurate missile platforms) that destruction of a target is still easily accomplished. "
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||
p6vlp | Why am i supposed to skip a dosage of my daily
medication if I'm too late to take it by a few hours? | This isn't for a medical advice, I'm not on medication anymore. But I don't understand why I was sometimes told to skip a dose for certain medication if I remembered to take the pill too late. | askscience | http://www.reddit.com/r/askscience/comments/p6vlp/why_am_i_supposed_to_skip_a_dosage_of_my_daily/ | {
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"AFAIK, you're *supposed* to take a missed dose, so long as it's not too close to your *next* dose. For example, if you're on a \"twice daily\" medication (12 hours-ish apart from each other) and you forgot one by a few hours, there's still plenty of time before your next dose.",
"The body can only tolerate fairly low concentrations of some drugs. If you take two doses too close together, the first may not have been fully metabolised yet and so the concentration of the drug in your body may exceed the safe guidelines",
"In practice it depends on the drug. Different drugs have different pharmacokinetics (PK), that is the disposition of the drug within the body (e.g., absorption into blood, distribution to tissues, metabolism, filtration into urine) that affect it's plasma concentration (Cp) vs time (t) profile: a tool commonly used in PK.\n\n[Here is an example](_URL_0_) of a multiple oral dose Cp vs t profile.\n\nDrugs also have different therapeutic windows, that is the concentration range of drug in blood plasma between its minimum effective concentration (MEC) and minimum toxic concentration (MTC), it is the aim of therapy to keep the drug concentrations within this window. So for a drug that has a narrow therapeutic window, you can see that if you take a dose too soon after another one your Cp may end up to high and you could experience toxicity. Of course for drugs with wide therapeutic windows this is less of an issue: returning to the correct regimen will bring the concentrations back down to the intended \"steady-state\" concentration with time.\n\nDo also note that the concept of the therapeutic window is not hard and fast for any particular drug, and is not an absolute rule. Take phenytoin, a drug for seizure control: phenytoin has a therapeutic window in the region of 10-20 micrograms per millilitre.\n\nHowever dosing of phenytoin is frequently monitored because its PK and pharmacodynamics (dose-response relationship) exhibits wide inter-patient variability. That is to say, there is no Cp of phenytoin within a given patient population where incidences of sub-therapeutic response and toxicity aren't high."
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n422h | why do some people still think that homosexuals shouldn't be allowed to serve in the military? | After watching the Rick Perry video that is gracing the front page, I was surprised to see that some people still hold this view. Why is it that this view is actually held in a 21st Century society? Is it because they don't trust them being in enclosed situations with the military's future, or is that a naive thought on my part? I'm from the UK and can only think of a recent time of this being raised as an actual issue in a satirical way in an episode of The Office.
Is it just the military or do they believe that homosexuals shouldn't be in the police force and other occupations?
Also, how is it that politicians can openly share such oppresive arguments in what is self-proclaimed 'The Land of the Free'? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/n422h/eli5_why_do_some_people_still_think_that/ | {
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"Not really LY5 but here goes:\n\nSome straight men project their own sexual appetite onto gays and then make predictions about the behavior of gays in an overwhelmingly male environment.\n\nSome believe that the military is among the 'most manly' and 'most honorable/virtuous' institutions. Some also believe that homosexuals exhibit behavior that is un-manly and dishonorable. As a result, they feel the open acceptance of gays in the military will diminish the reputation of the institution.\n\nOthers feel that even if gays conduct themselves professionally, the perceived objectification of their hetero comrades will be a constant worry/distraction, affecting the performance of the unit.",
"I'm going to try and portray this issue without bias. You asked for the reasons why people are against homosexuals in the military, so here they are:\n\nSome feel that homosexuals should not be able to serve on the frontlines for the same reasons that women are currently not allowed to serve on the frontlines - it could lead to risky irrational decisions that could jeopardize the safety of others.\n\nFor example, women are not allowed to serve in active frontline combat because some feel that men would subconsciously base their decisions around protecting the female rather than doing their duties. If a female soldier is shot in combat and is not in a reachable position, for example, a male soldier might take an unnecessary risk out of instinct. This might not happen if the shot solider was another male.\n\nIf you replace the female soldier in this scenario with a male solider, and the other male solider with a homosexual male solider, then the argument still stands. The homosexual solider might take a risk a heterosexual might not have if the homosexual felt a personal attraction towards the other solider, which could jeopardize the his own life and the lives of the other soldiers without him even realizing it.\n\nPlus, some would argue that the logistics of having gay soldiers in with heterosexual soldiers would be way too complicated. A squad gets very personal with each other during combat - sharing cramped quarters without any privacy in a life-threatening environment day in and day out for months is complicated as it is without adding in another variable. \n\nPlus, keeping gay soldiers out of active combat protects them - it takes one homophobic and irrational soldier to fuck things up. The homosexual soldier may be subject to intense hazing because of his sexuality, which could destroy his mental (and possibly physical) health, and could lead him to do something he might not otherwise do.\n\nI've only listed the pro-\"Don't Ask, Don't Tell\" arguments - I'm personally on the fence on the issue. The issue is exponentially more complicated than the \"pro-gay vs homophobes\" argument some people see it as. \n\n---\n\nIn response to your other questions:\n\nMost people do not see a problem with homosexuals in the police force. The issue with homosexuals in the military primarily deals with dealing with enclosed spaces for months at a time, along with intense squad-based combat logistics. There are openly gay police officers, firefighters, etc. around America, and most people are OK with it (those who aren't usually aren't OK with homosexuality in general).\n\nFree speech is only free if it's given to everyone, regardless of their views. It's not free speech if you're not allowed to voice your opinion, regardless of how radical it is. Politicians are still citizens under the Constitution, and are granted the same level of freedom of speech as everyone else. Silencing those for simply speaking their minds would be a greater injustice than letting them state their views, no matter how oppressive they can be.\n\n----\n\nSource: I've been around the military my whole life - with my father a former Marine and my mother a civilian working for the Navy, both my grandfathers being multi-war vets, and various friends and family members actively serving, along with growing up near one of the largest submarine bases in the world, I've definitely heard both sides of the issues facing the military. \n\nApologies for the long-winded response, but I hope I answered your questions and showed you another side to a very complicated and controversial issue in American military politics. Also, sorry for any grammar or spelling mistakes, since apparently making a grammar mistake is heresy on Reddit.\n",
"Not really LY5 but here goes:\n\nSome straight men project their own sexual appetite onto gays and then make predictions about the behavior of gays in an overwhelmingly male environment.\n\nSome believe that the military is among the 'most manly' and 'most honorable/virtuous' institutions. Some also believe that homosexuals exhibit behavior that is un-manly and dishonorable. As a result, they feel the open acceptance of gays in the military will diminish the reputation of the institution.\n\nOthers feel that even if gays conduct themselves professionally, the perceived objectification of their hetero comrades will be a constant worry/distraction, affecting the performance of the unit.",
"I'm going to try and portray this issue without bias. You asked for the reasons why people are against homosexuals in the military, so here they are:\n\nSome feel that homosexuals should not be able to serve on the frontlines for the same reasons that women are currently not allowed to serve on the frontlines - it could lead to risky irrational decisions that could jeopardize the safety of others.\n\nFor example, women are not allowed to serve in active frontline combat because some feel that men would subconsciously base their decisions around protecting the female rather than doing their duties. If a female soldier is shot in combat and is not in a reachable position, for example, a male soldier might take an unnecessary risk out of instinct. This might not happen if the shot solider was another male.\n\nIf you replace the female soldier in this scenario with a male solider, and the other male solider with a homosexual male solider, then the argument still stands. The homosexual solider might take a risk a heterosexual might not have if the homosexual felt a personal attraction towards the other solider, which could jeopardize the his own life and the lives of the other soldiers without him even realizing it.\n\nPlus, some would argue that the logistics of having gay soldiers in with heterosexual soldiers would be way too complicated. A squad gets very personal with each other during combat - sharing cramped quarters without any privacy in a life-threatening environment day in and day out for months is complicated as it is without adding in another variable. \n\nPlus, keeping gay soldiers out of active combat protects them - it takes one homophobic and irrational soldier to fuck things up. The homosexual soldier may be subject to intense hazing because of his sexuality, which could destroy his mental (and possibly physical) health, and could lead him to do something he might not otherwise do.\n\nI've only listed the pro-\"Don't Ask, Don't Tell\" arguments - I'm personally on the fence on the issue. The issue is exponentially more complicated than the \"pro-gay vs homophobes\" argument some people see it as. \n\n---\n\nIn response to your other questions:\n\nMost people do not see a problem with homosexuals in the police force. The issue with homosexuals in the military primarily deals with dealing with enclosed spaces for months at a time, along with intense squad-based combat logistics. There are openly gay police officers, firefighters, etc. around America, and most people are OK with it (those who aren't usually aren't OK with homosexuality in general).\n\nFree speech is only free if it's given to everyone, regardless of their views. It's not free speech if you're not allowed to voice your opinion, regardless of how radical it is. Politicians are still citizens under the Constitution, and are granted the same level of freedom of speech as everyone else. Silencing those for simply speaking their minds would be a greater injustice than letting them state their views, no matter how oppressive they can be.\n\n----\n\nSource: I've been around the military my whole life - with my father a former Marine and my mother a civilian working for the Navy, both my grandfathers being multi-war vets, and various friends and family members actively serving, along with growing up near one of the largest submarine bases in the world, I've definitely heard both sides of the issues facing the military. \n\nApologies for the long-winded response, but I hope I answered your questions and showed you another side to a very complicated and controversial issue in American military politics. Also, sorry for any grammar or spelling mistakes, since apparently making a grammar mistake is heresy on Reddit.\n"
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7svehy | how does the reusable gel heating pads work? | You know, the ones with a clicky metal thing inside? I'm sick with flu and cooking my pads, and I need some answers. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/7svehy/eli5_how_does_the_reusable_gel_heating_pads_work/ | {
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"text": [
"There is a chemical mixture inside, that when excited (by the metallic disk being clicked) produces a self-sustaining exothermic reaction. What this means in layman speak is that the reaction, once started, will continue on its own until it runs out of material, and that the reaction releases heat.\n\nWhen you heat the pads afterwards, you are using heat to cause an endothermic reaction; ie. a reaction that requires heat. You can think of it as melting the stuff back to liquid (or gel) so you can re-use it."
]
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[]
] |
|
3fxjy2 | If you cover one eye, how does your brain know to somewhat prioritise what the uncovered eye is seeing? | To clarify, I would like to know why (I assume its the same for all humans) its physically difficult to try to see the blackness that your other eye is seeing when covered. | askscience | http://www.reddit.com/r/askscience/comments/3fxjy2/if_you_cover_one_eye_how_does_your_brain_know_to/ | {
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"text": [
"the simple answer is that what you see is a nonlinear sum of the inputs from the two eyes - in terms of apparent contrasts (brightnesses and darknesses), what you see is approximately equal to the square root of the sum of the squares of the physical contrast (change in retinal illuminance over space) in both eyes. [here is a classic paper] (_URL_0_) that demonstrates this. sorry about the paywall, i can't find a free pdf online.\n\nit suffices to say that, if each eye is getting contrast 1.0, then what you see is C = sqrt(1^2 + 1^2) = 1.414. if you close one eye, this is setting one of those contrasts to zero, so you will see C = sqrt(1^2 + 0) = 1. so, contrast will appear slightly reduced, but closer to the binocular case than to nothing at all.\n\nin other words, simple rules of binocular combination ensure that, with one eye closed, you will see something rather than nothing.\n\nit's actually tons more complicated than this (image structure is taken into account, so you get stuff like binocular rivalry; contrast adaptation normalizes apparent contrast over short and long time scales, so the value 'C' above is not just determined by its inputs; also, with one eye covered for a long time, on the order of minutes, you will get periodic fading of the uncovered eye's image, for complicated reasons). but the above explanation is roughly accurate.\n\n*edit*\n\ni wanted to add one thing, a point of mystery on this topic that no one really talks about. in the extreme left and right periphery of your visual field, there are two regions called the 'monocular crescents'. these are regions of the visual field that are seen by only one eye. if you close one eye, you'll see a peripheral part of the scene disappear (the right part if you close the right eye, and vice versa) - these are the crescents.\n\nwhen you close one eye, there's no binocular combination to prop up your visual experience in the monocular crescent, but you don't see blankness. you see... nothing. the visual field in that region just stops existing. why? what is the process that underlies this? it's a completely unexplored question..."
]
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[
"http://www.sciencedirect.com/science/article/pii/0042698984900646"
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2qh3ut | What are the origins of modern day Balkland peoples? E.g Albanian, Serbs, Croats etc... | I have quite the gap of knowledge between the ancient peoples of the region such as the Dacians and Thracians and the groups that now inhabit the area. Where did they originate from? Was it a similar story to Hungary and the Magyar nomads? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/2qh3ut/what_are_the_origins_of_modern_day_balkland/ | {
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"text": [
"For Albanians the most accepted theory is either illyrian origin or thracian-dacian origin. All 3 were native balkan people. For slavs like the croats serbs etc most likely extended out from lands near belarus and north ukraine"
]
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[]
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|
4a7olb | if we know so much about the human body, why is there so much conflicting information on topics like weight loss and muscle gain? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4a7olb/eli5_if_we_know_so_much_about_the_human_body_why/ | {
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"text": [
"Basically, because the weight loss and fitness industries are huge, and people want to make money. Really the basics always boil down to \"eat less calories, exercise more\", but plenty of folks like to dress that up in order to turn a profit.",
"Because the studies are often small, which means it is difficult to observe an effect. You can use math to pool them (meta-analysis) but those have their own criticisms.\n\nWhen the effect is small and accurate measurement is difficult, as in muscle growth (hypertrophy) differences between two protocols in only 6 weeks, it will be difficult to tell whether there is a difference.\n\nThere is also a large amount of inter-subject variability in responses. It is very likely you and I would grow different amounts of muscle doing the same workout, just because we are genetically different.\n\nIn terms of resistance training, we know a lot about how the average, young, untrained white man responds."
]
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||
2r5t9x | Why did eukaryotes develop linear chromosomes if it gives us problems with telomeres? Wouldn't it have been evolutionarily advantageous for all organisms to keep circular chromosomes? | I ask this because having linear chromosomes entails the problem of telomere reduction/degradation whereas that doesn't seem to be a problem in circular chromosomes. | askscience | http://www.reddit.com/r/askscience/comments/2r5t9x/why_did_eukaryotes_develop_linear_chromosomes_if/ | {
"a_id": [
"cndby5l",
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8,
8
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"text": [
"There is greater genetic availability with linear duplex chromosomes due to cross over. Also, there is less problem with frameshift reading killing the organism with linear vs. circular chromosomes...",
"I fully agree with Catrobbins, but It's also worth mentioning that telemere degradation is not necessarily a bad thing. It's a limiting factor on replication, which helps prevents cells being cancerous, this isn't an issue in prokaryotes with circular chromosomes however.\n\nExcess growth and replication is often a bad thing in multicellular organisms, and limiting it can be beneficial to the organism. "
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fo33o | I have a science degree but I'm not yet prepared to study some areas of physics. What math should I review, and what math should I study to understand the meaning behind quantum equations? | I've taken engineering math in college, however I didn't end up using it in any of my senior classes. I've taken three semesters of calculus and even differential equations, but I've forgotten nearly everything since I haven't used it. I want to review, starting even with basic calculus, then try to learn differential equations, but I'm not sure where to start and what sections to study more on.
I'm afraid that if I don't improve my math, I'll ruin some opportunities, and I also would enjoy reading up on advanced topics that I can actually understand.
I think I want to start with KahnAcadamy, but I feel overwhelmed at all of the lessons I either haven't taken or have completely forgotten. | askscience | http://www.reddit.com/r/askscience/comments/fo33o/i_have_a_science_degree_but_im_not_yet_prepared/ | {
"a_id": [
"c1hcrxk"
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"text": [
"What areas of physics are you interested in?\n\nFor undergrad physics (until special relativity and quantum mechanics), linear algebra and differential equations are everywhere. You should also know at least the cool results from multivariable analysis (gauss, stokes, etc), and the theory to solve laplace's and poisson equation."
]
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[]
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|
1mfydz | Is it a coincidence that most of the major powers of the world are in the northern hemisphere? | Just wondering if weather or some other geographic feature has made it easier for countries in the northern hemisphere to succeed seemingly more than countries in the southern hemisphere. | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/1mfydz/is_it_a_coincidence_that_most_of_the_major_powers/ | {
"a_id": [
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"text": [
"Well, 67% of the land and 90% of the human population is in the northern hemisphere. A quick look at geography shows that a significant proportion of this southern land is desert. The hemispheres didn't really have a level playing field to start with."
]
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6wzotu | how did french, german and italian speaking (and some other) people decide to become switzerland together, instead of the germans becoming german, the french becoming french, etc. ? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6wzotu/eli5_how_did_french_german_and_italian_speaking/ | {
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"Switzerland was formed when a group of Principalities decided to band together and form a loose confederation in 1291. The various 'states', called Cantons, were allowed to maintain their own language. Other states joined later and the Swiss army also took land (at one time they held Milan Italy). in the 1500's they were beaten back by a French and Venetian alliance. They gave up expansion and chose neutrality which allowed them to form a more uniform, while still diffused, nation.\n\nThere is a lot more but the TL;DR is that a bunch of little states took advantage of different power vacuums and chose to work together while remaining individual. They have been highly successful at this so why mess with success?",
"Switzerland formed before the concept of a \"nation state\" was a popular thing. So people who spoke French didn't necessrily feel like they had to be part of the same country as other French speaking people. Germany and Italy weren't even unified countries by that point.\n\nBy the time nationalist movements gained momentum in the 19th Century, when Germany and Italy became unified countries, Switzerland had already been around a long time as a stable and prosperous country. So most people there were happy to consider themselves Swiss and didn't have a strong desire to join with the other Germans and Italians. They probably didn't see other German/Italian/French speaking people as *their* people, just some other people who happen to speak the same (or similar) language. Kind of like how Americans don't consider themselves English just because they speak English.",
"It began life in the 13th century, when the modern concept of a nation state simply didn't exist. That idea didn't really come into existence until the signing of a treaty called the Peace of Westphalia, about 400 years later, which introduced the then revolutionary idea that sovereign states with definite borders could be created, that they shouldn't interfere in each other's affairs, and that they could be held in check by a balance of power.\n\nThat was still centuries away when a couple of cantons -- essentially microstates -- within the Holy Roman Empire decided to cooperate in ensuring that in the mountains of the central Alps, trade could be allowed to take place in peace.\n\nAt the time, the Holy Roman Empire was a complicated patchwork of tiny states, constantly changing as local ruling dynasties intermarried, died out, split, waged war on each other and so on.\n\nBut these central Alpine communities decided instead to work together, to look out for each other, help each other in times of war and settle local disputes among themselves.\n\nMore and more cantons joined this confederacy, and it's important to remember that at the time, it didn't occur to people to draw national boundaries where there happened to be linguistic boundaries. The language you spoke didn't really have any bearing on who you owed your allegience to.\n\nThis confederacy grew, and partly by conquest: in this first \"heroic\" stage of Swiss history, they would often take territories by force, deposing the local rulers. That phase ended with the Battle of Marignano in 1515, which the Swiss lost; this was the point at which Switzerland pretty much stopped growing.\n\nAfter that, the Reformation came to Switzerland, dividing it into Protestant and Catholic parts. This caused a civil war, but the confederacy survived. When the Thirty Years War raged throughout the Holy Roman Empire, the Swiss -- still split between Protestant and Catholic but still cooperating with each other -- couldn't pick a side and so kept out of it. And that's one reason they were granted their status of sovereign state at the Peace of Westphalia, completely independent of the Holy Roman Empire.\n\nIn the 18th century Switzerland was invaded by France (Napoleon wanted control of the Alpine passes), which imposed on the country a central government subservient to France, reducing the cantons to mere administrative divisions. This was very unpopular, and the Swiss refused to fight alongside the French when Austria and Russia also invaded Switzerland. Eventually, Napoleon agreed to restore some of Switzerland's autonomy and the cantons. A few years later, the Congress of Vienna, which had convened to sort out the mess left by the Napoleonic Wars, officially gave Switzerland back its independence; also, all the other European countries agreed to recognise Swiss neutrality for ever after.\n\nSince then, Switzerland has been quietly getting on with the business of making chocolate and cheese, and staying well out of international conflicts.\n\nTL;DR: Switzerland was created at a time before our concept of the nation state existed, and since then the Swiss have been proudly not taking orders from anyone else."
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1m5kd5 | The ability to curl one's tongue is a common example used to explain phenotypes and genotypes. What actually causes this phenotype when the appropriate genotype is present? | What does the genotype do that allows a person to curl their tongue? What's the physical difference between someone who can curl their tongue and someone who cannot? | askscience | http://www.reddit.com/r/askscience/comments/1m5kd5/the_ability_to_curl_ones_tongue_is_a_common/ | {
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"Hey GoonCommaThe,\n\nAs far as I recall, it's currently a myth that the ability to curl one's tongue is regulated genetically. \n\nHere's an article that can shed more light; _URL_0_\n\nIt's possible that some individuals just have better ability to control the intrinsic muscle of the tongue, but everyone still has these muscle present."
]
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[
"http://udel.edu/~mcdonald/mythtongueroll.html"
]
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|
6210g3 | Do any painkillers block the burn of spicy food? | In the lastest video of a popular web series featuring celebrities eating hot wings, the celebrity seems to be barely affected. He later admits he's wearing a fentanyl patch. Would this block the "pain" of the capsaicin?
Would any other drugs (either medical or recreational) block the effect of capsaicin?
| askscience | https://www.reddit.com/r/askscience/comments/6210g3/do_any_painkillers_block_the_burn_of_spicy_food/ | {
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"text": [
"Yes. Nociception (pain) is blocked by acting on mu- receptors in the brain or periphery (also the gut which is often the cause of opioids induced constipation). This is high in the pathway, so even though capsaicin receptors (TRPV-1's) are separate than other \"pain\" receptors, the mechanism of opioids would still help block the signals/stimuli response. \n\nThey did a study on capsaicin and fentanyl in monkeys actually;\n\n_URL_0_"
]
} | [] | [] | [
[
"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2866037/"
]
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|
22cbwk | how (in) effective is the "pull out" method as a form of birth control? | Weird conversation to be having with a 5 year old, I know. But statistically what are the odds of a "pull out" resulting in a pregnancy? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/22cbwk/eli5_how_in_effective_is_the_pull_out_method_as_a/ | {
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"Theoretically it could be < 100% if executed ideally. Consistent proper form yields rates of 1/20 couples getting pregnant per year with inconsistent form yielding 1/4 couples getting pregnant per year. The 1/20 even when done properly may be partially attributed to precum containing sperm from previous ejaculations in which case urinating would help flush the system. [source and more reading]\n\nedit: Failed with the link and don't recall the site I got the stats from but it was top google.",
"Can confirm. Have child because of this method.",
"I been doin it for 5 years... works for me. that or I'm infertile.",
"If you correctly it is something like 95% effective, however it is rarely used perfectly. ",
"Failure rate is higher than 4 % per year, typically around 22% [(wiki)](_URL_0_). This means if you use that method for one year, you have a 1/5 chance to become a parent.",
"[He is a short video on the subject, which I assume is accurate.](_URL_0_)",
"The Pearl-index is precisely what you're looking for.\n\nThe pull out method (coitus interruptus) has a Pearl-index of 4-18, which means that if 100 women were to use this method for the entirety of one year, 4-18 of them would become pregnant.\n\nA lot more and detailed information is easily available on the web.\n\nDon't they teach you these things in school?",
"For what it's worth, it worked for my girlfriend and me for about 7 years, although I've never been tested for my own fertility. She now has children with another man and my current wife is unable to bear children.",
"This is the only method that the wife and I have used for 15+ years including high school. The only children we have are the three we were trying for. ",
"I've used it for 4 years now and no kids. Girlfriend also takes the pill so I'm not a complete idiot.",
"It works well if done correctly especially since pre-ejaculate has little to no sperm in it. Of course this is assuming first time sex for that day after using the bathroom which flushes out the tubing if you know what i mean. \n\nThe problem is that doing it correctly part first you really need to be knowledgeable about these things which most who are trying it aren't. The second part second is having that mental and physical control which most people don't. Its human male nature to not want to pull out and the main reason your having sex in the first place is because it feels good. This leads to the \"just a few more thrusts\" or wait to the last possible second mentality that makes it an awful choice. That combined with the fact that people also often have sex while under the influence which further lowers your control over your body and you're absolutely playing with a loaded gun.",
"Well shit...shes on the pill, I use a condom and I pull out.."
]
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8qc4h0 | The Taliban and the USA? | A constant criticism of the US seems to be its incessant meddling in the affairs of other countries. I was talking to a friend about this and he brought up the Taliban, referring to the US backed Mujahideen as the source of it. While, it could be argued that Al-Qaeda (in particular Osama bin Laden) were linked to previous Mujahideen, the Taliban seemed to be something entirely different. So, the question I’m asking would be regarding US and it’s involvement with the Taliban. | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/8qc4h0/the_taliban_and_the_usa/ | {
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"text": [
"More of course can be said, but [this old response](_URL_0_) will likely be of interest for you."
]
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"https://www.reddit.com/r/AskHistorians/comments/2h7p0v/some_question_on_afghanistan_are_the_taleban_and/ckq97cn/"
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|
1stkhy | why do we keep discovering ancient artifacts and why are they so rare? wouldn't the world have accumulated mass amounts of stuff over 1000s of years and be common to find? | Have they all been destroyed over time? Or have we already found most of them? With so many civilizations dating all the way back it's not like they could just disappear. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1stkhy/why_do_we_keep_discovering_ancient_artifacts_and/ | {
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"Things break down and more importantly tend to be reused by descendants. While that piece of Roman armor might be precious *today*, in the ancient world it was just Grandpa Flavius' old helmet, and we really needed to make a new plow, so we'd smelt it down."
]
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55zffi | Siberia is vast. Prior to the railroad and telegraph, how did Imperial Russia govern such a large area? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/55zffi/siberia_is_vast_prior_to_the_railroad_and/ | {
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"Well, they didn't. As you intimate, it required the railroad to govern effectively. They controlled pockets all the way to the Pacific by the mid-1600s or so, but they didn't establish direct control over the majority of Siberia until the establishment of the Trans-Siberian Railroad, constructed from 1891 to 1916.\n\nIs there something more specific about the state of affairs before or after this that I can help expound upon?"
]
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||
ob30q | What is happening in your body when you are recovering from a cold? | I am of course talking about the common cold (Rhinovirus) - When you get a cold, is your body working to build immunity to that particular strain of the virus? what processes are going on that make your body more immune to it? Is it a new strain of the virus that gets you sick later on in the future (the next year, for many people) ? | askscience | http://www.reddit.com/r/askscience/comments/ob30q/what_is_happening_in_your_body_when_you_are/ | {
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"The immune system is very complicated but hopefully this should help with some of the basics:\n\nYour immune system has 2 major parts, there are the \"innate\" defences like enzymes in saliva and some cells like macrophages that destroy intruders and then there is a more specialised \"adaptive\" part which is more relevant here. The innate defences try to alert the body/stop intruders getting in, while the adaptive part is usually what fights off an established infection and is responsible for immunity.\n\nIn the adaptive system there are 2 types of cells (lymphocytes) called B-cells and T-cells. They are both similar in the sense that they have a receptor on their surfaces that binds to foreign substances. Each cell has a unique receptor on the surface that is designed to bind to one thing. It could be anything, doesn't have to have seen it, it doesn't have to exist (although it can't be part of the host body).\n\nIn short: you have trillions of B-cells and T-cells each waiting to encounter their designated intruder.\n\nWhen a lymphocyte gets presented with a substance (e.g. a bit of virus, technically known as an \"antigen\") that matches its receptor and gets the right signals it starts to divide and make copies of itself that also have receptors for that substance. Therefore you have thousands of lymphocytes ready to fight this particular invader.\n\nSome of the lymphocytes become dormant so you have an army to fight the same virus in the future. This is what creates immunity. In addition the different cells have particular roles. \n\nB-cells make antibodies that float in the blood and help clear virus etc. they have the same affinity as the receptor. There are different types of T-cells, \"helper\" T-cells help other cells like B-cells and macrophages [these are the main cell missing in HIV/AIDS so are very important] while \"killer\" T-cells can kill cells that have been infected with virus to stop the virus from replicating.\n\n > Is it a new strain? \n\nYes, probably. There are hundreds of strains so while your immunity might go down over time it's more likely that you caught a strain you didn't have immunity to. "
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|
9hpm0b | how does the anti-shoplifting system in a supermarket work? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/9hpm0b/eli5_how_does_the_antishoplifting_system_in_a/ | {
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"It’s these stuck on thing that have a slight magnetic field to them the get activated when you walk through the thing that beep. "
]
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||
251ccr | Is there a rating scale for bolts of lightning? What conditions would cause massive singular strikes of lightning instead of many smaller ones? | I just experienced the craziest bolt of lightning ever. Lit up the whole house with the shades drawn in the middle of the day-- which I would expect if it was nearby, but it was still a whole 10 seconds until the most thunderous thunder I have ever heard. Which got me thinking-- Does lightning comes in various sizes and intensities? Do we have a system for rating lightning, and why would massive bolts ever occur over smaller more frequent discharges? | askscience | http://www.reddit.com/r/askscience/comments/251ccr/is_there_a_rating_scale_for_bolts_of_lightning/ | {
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"Yes! Lightning has vastly different strengths that are typically measured in the peak electrical current of the lightning. There are few other measures such as the charge-moment change (how much electrical charge is moved by the lightning), radiated energy (how much radio waves it gives off), or optical power (how bright in the visible spectrum).\n\nThese are usually measure by either ground stations for the first three or satellites for optical measurements.\n\nNow the question of what determines the strength of lightning is not settled. There are some known factors such as the convective strength of the thunderstorm or the time since the previous lightning flash in the storm, however there is no single equation or model that describes how strong a given lightning flash will be for a particular storm.\n\nWe can look at data and make general statements like \"Oceanic thunderstorms produce fewer but stronger lightning flashes\", but these statements are almost always drawn from large statistical samples and cannot necessarily be applied to a single event.\n\n > why would massive bolts ever occur over smaller more frequent discharges?\n\nOne aspect may be the terrain underneath the thunderstorm; if there are a lot of tall pointy objects nearby (trees, churches, radio tower) it is effectively \"easier\" for lightning to attach to these points than to smooth surfaces like lakes. This leads to either more charge building up in the cloud causing the eventual flash to be stronger or more discharges in the cloud that won't necessarily be weaker or stronger.\n"
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rg9nf | When doctors get a positive result, do they automatically run the test again to rule out false-positives? | I was wondering if this is standard procedure for low-prevalence diseases, STI's etc, since, you know, base rates. For instance: I get tested for something that effects an average of say, 5 people per 100,000 and the test is 99.99% accurate. If I test positive, should I assume that I still have a 67% chance of *not* having the disease, or would they have already re-run the test before notifying me of my positive status. | askscience | http://www.reddit.com/r/askscience/comments/rg9nf/when_doctors_get_a_positive_result_do_they/ | {
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"Depends on how accurate the test is, how much it costs, how likely you're to really be afflicted, whether they can run a better test, and how dangerous the condition actually is.",
"Speaking from experience working in a state laboratory: yes and no. Our standard protocol was to run the test (herpes, hepatitis, HIV, influenza, measles, mumps, rubella) in duplicate a second time. Some tests (Rocky Mountain Spotted Fever, rabies, hantavirus) were too costly and specific enough that only one positive result was necessary. \n\nHowever, we were simple lab scientists. The physician working on the patient still had final say on diagnosing the patient regardless of what our results say. ",
"For some diseases we have screening tests and diagnostic tests. Syphilis demonstrates the difference well. We screen for syphilis with [RPR](_URL_4_) and [VDRL](_URL_2_) tests that have high [sensitivity](_URL_0_) but low [specificity](_URL_1_). So, they are meant to pick up as many people as possible but not necessarily say for sure someone has a disease. A negative VDRL or RPR means you most likely don't have syphilis. A positive VDRL or RPR doesn't necessarily mean you do since they can be tricked by several other organisms. Rerunning the test wouldn't change a false positive if it was falsely positive due to a different infection such as Lyme disease. If a screening test is positive, they could then perform a diagnostic test like [FTA-ABS](_URL_3_) which is highly specific for syphilis and can confirm the diagnosis. They could also just treat after the first test depending on the physician, risk factors, and physical exam. ",
"Short answer, not usually.\n\nLonger answer: It depends also on the pre-test probabilty. If the pre-test probability of having X disease is high, then a positive is less likely to be false, and more likely to be believable. If the pre-test probability is low, then a positive result is more likely to be spurious and to be questioned.",
"Nomograms demonstrate what we do with test results.\n[The left side](_URL_1_) shows \"pre-test probability\". This is what we gained with a history/physical/any other tests done. This probability represents why we gave you the test in the first place, there is a purpose for every test and not just a shotgun approach.\n\nIn the middle is the \"[likelihood ratio](_URL_0_)\" which is a measure based on the sensitivity and specificity of the exam.\n\nFinally when we put those together we get the \"post-test probability\". This should make it evident that if based on my clinical accumen I am reasonably confident of the diagnosis I don't gain much from a positive lab result no matter the strength of the test; and on the other hand if I am quite confident that the disease is not present and I get a positive from a strong test I am still not convinced it is the disease but I need to start again and begin re-evaluating and re-forming a differential.\n\nEvery test has a different level of \"meaning\" and realize that there are very few tests in medicine that measure an actual disease process, most are measures of your internal environment that may fall into an abnormal range indicating a disease process is active."
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"http://en.wikipedia.org/wiki/Fluorescent_treponemal_antibody_absorption_test",
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70wd8j | why would a railgun be better than a regular cannon? | Regarding the railgun US Army just tested... It seems like a waste of money if it just fires shells a different way. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/70wd8j/eli5_why_would_a_railgun_be_better_than_a_regular/ | {
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"I mean, military development since the sling has been trying to figure out how to fire projectiles a different way. If it's a better way, that's important, whether you're talking cannons, catapults, or railguns.\n\nRailguns are capable of higher velocities, which means that the same projectile would do more damage or travel further. Long-term, there's reason to think that they'll be cheaper, and more convenient, since you wouldn't need to use explosives, which can exp....y'know. Go off.",
"It fires at a much higher velocity and is a lot simpler. There will be no powder or even a warhead, just a heavy chunk of metal blasting out of the end\n\nThe higher speed of a rail gun gives it an extremely long effective range, let's it penetrate a variety of targets extremely well, and enables a large number of rounds to hit at the same time by firing them with slightly different trajectories",
"The main advantage for a railgun would be the range. For conventional guns, you need bigger barrel to deliver more damage, but launching such weight requires more explosives, which limits the size of the shell for safety reasons.\n\nBigger shells also means more tonnage and an ammo store is one of the most vulnerable parts of a ship.\n\nWith a railgun the shells are easy to manufacture and are nonexplosives, also smaller and lighter than conventional shells and capable of delivering massive damage with the speed of the impact alone.\n\nThe only thing needed for a railgun is electricity and large ships can be fitter with nuclear reactors very easily.\n\nAs long as such ship will have its reactors functional, it could take out any number of ships from a distance well past the horizon, then cannibalize them, make more shells and repeat.\n\nIf a fleet of such ships work in conjunction with spy planes/satelites/drones, it can wreck absolute devastation onto an unprepared battlegroup.",
"A few reasons:\n\n1) muzzle velocity. The theoretical speed of a projectile is much greater, providing better range, accuracy, and penetration.\n\n2) projectile size and cost. Using EMF to launch a projectile instead of gunpowder dramatically shrinks the inventory of firing charges and shells you need to keep on a ship.\n\n3) safety. Removing most of the explosives from a ship that may itself get shot at eliminates the catastrophic secondary detonations that sank so many ships in WWII. The torpedoing merely wounds large ships, it's often the ammunition or fuel cooking off that actually destroys them."
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acp90a | Which is the history of the beginning of this sub | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/acp90a/which_is_the_history_of_the_beginning_of_this_sub/ | {
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"As it happens, one of the mods, /u/agentdcf, wrote a paper about the beginnings of the sub - [You can read it here.](_URL_1_)\n\nI'm also trying to find a post that's an interview by the Reddit admins of our subreddit's founder, /u/artrw, not long after the sub was created. The hunt continues... \n\nedit: well.. I've searched and can't find what I'm looking for, but here's one by /u/artrw from 2012, telling about the early days - [[meta] The culture of r/askhistorians](_URL_0_)"
]
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"https://www.reddit.com/r/AskHistorians/comments/sus8h/meta_the_culture_of_raskhistorians/",
"https://www.reddit.com/r/AskHistorians/comments/682ta1/friday_freeforall_april_28_2017/dgv7zhf/"
]
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||
1qo3sz | why are consoles/phones so limited at launch and sold out for a while after? these are huge companies, it seems they could supply as much as needed. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1qo3sz/eli5_why_are_consolesphones_so_limited_at_launch/ | {
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"Almost all consoles come out selling at a loss - meaning, it costs them more to make the console than they actually make back from selling it. Over time, the cost of producing the console's parts goes down (as they're relatively older), so it's more cost-effective for them to wait a little longer to meet the demand.",
"These companies enjoy market conditions in which they can act like monopolies. Without going into too much technical details over firm dynamics, it is in a monopoly's interest not to over-saturate the market with their product. This drives up demand and makes it more inelastic. Put simply, those who will buy it, will pay more. \n\nMost of these products like iPhones and Xboxes could probably be sold at $100 or $200, but because monopolies (or ones with good marketing strategies) can more or less sell with impunity, they enjoy large profits from each units sold. \n\ntl:dr The companies make more profit by under-supplying, driving up demand, and the price consumers are willing to pay. ",
"They COULD have a huge production line, but after that initial launch, those production lines are going to be half useless. The launch rush is not sustained for a long time. You build up a stockpile with what will be your regular production line and release at a strategic time."
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qq228 | why do most people need complete silence to sleep? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/qq228/why_do_most_people_need_complete_silence_to_sleep/ | {
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"Because they cannot sleep with noise.",
"It's difficult for me to sleep without a fan or another type of constant, white noise. When it's \"completely silent\", it's really not because any sudden, quiet sound becomes audible when you normally might not notice it. So unless you're just about to fall asleep you're forced to focus on it and your brain stays awake and so do you. My two cents. ",
"I have a hard time sleeping if it's completely silent.",
"Yeah, *most* people don't need complete silence to sleep. Most people live in cities, no complete silence there. I live in the woods, I fall asleep to the sound of the creek every night. I couldn't easily sleep with complete silence. ",
"noises distract me, distracting me keeps me alert,I can't go to sleep if I'm alert."
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3khd4e | why would an automaker choose an inline 6, v6, or horizontally opposed 6 cylinder engine? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3khd4e/eli5_why_would_an_automaker_choose_an_inline_6_v6/ | {
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"Sometimes it helps fit the car's design (for example, a horizontally opposed engine could be mounted lower, resulting in a lower hood. Most carmakers choose a design type and stick with it, perfecting the design to get better performance from the engine.",
"A lot of it is habit and tradition. BMW for example has always done I6s not V6s and continue to do so. American automakers do V6s in part because the first ones were made by removing two cylinders from V8s. That got them into doing V6 engines and they have stuck with that mostly. \n\nThere are some advantages and disadvantages of each that can play into it. V6 engines are really compact compared to the other types. Straight-6 engines on the other hand are balanced by design and don't require additional counterweights or other balancing mechanisms. Automakers will also take these into consideration. ",
"Packaging is probably the single biggest factor. Front wheel drive cars tend to have very crowded engine bays, with the engine, transmission, and suspension components all competing for the same space under the hood. Narrow angle V6s are a naturally compact design which makes them very popular in front wheel drive sedans.\n\nBMW uses a lot of inline sixes. The cars they make are almost exclusively rear wheel drive, and their brand identity focuses pretty heavily on handling and performance. A long narrow engine puts more weight towards the center of the car and gives the guys engineering the front suspension more space to work with. This combined with the inline six's natural smoothness makes it a good choice for a performance sedan.\n\nFlat sixes are kind of a niche design, only really used by Porsche and Subaru in modern times. Porsches are rear engined, so a short wide engine works well because the engine has a low center of gravity and doesn't have to compete for space with the front suspension bits. Subaru's signature thing is their all wheel drive system which has (AFAIK) always used a flat 4 or 6. "
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b60wdm | why do 3rd party booking sites (agoda, booking etc.) have cheaper rates than the hotel itself? and why does the hotel price match the rates on the 3rd party booking sites? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/b60wdm/eli5_why_do_3rd_party_booking_sites_agoda_booking/ | {
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"The hotel doesn’t want to insult the guests that paid full price and make them feel like they’re getting ripped off. Unrented rooms are a waste. There still going to exist whether occupied or not. As long as the revenue received is greater than the cost of operation (maids, electricity water gas etc) any money made is better than nothing. So they let the third party sites sell at a discount in hopes of filling up the rooms that would otherwise go unoccupied. \n\n\nChances are if they overbook and nobody no shows if you booked via a third party value site they’ll bump you for a full paying guest. ",
"Hotels pay those booking sites a fee to be on the site.\nThe booking sites use part of that fee to offer a lower room price.\n\nThe hotels can choose to give you a discount if you book there directly, but they won't straight up lower their rates, because it would cut their proffits.",
"In addition to the other things mentioned in this thread, there's the scam that sites like _URL_0_ run where you book a room at a hotel at a reduced price for that hotel, but when you get there the hotel says \"Oh, sorry, we overbooked and are full, we've reserved you a room at this far less nice hotel around the corner.\" and keep your money.\n\n\nScummy business.",
"I shop around diligently. I no longer find booking sites to be less expensive. They were WAY CHEAPER in the heyday and I used to get AMAZING Priceline deals. Now I shop around, visit the hotel home page, find the same price and book there. My 14 year old daughter has noticed a pattern, she thinks it’s thrilling that I “always get free upgrades.” I don’t always, but I do often enough that she’s noticed and my best friends have noticed. I’d LOVE if you could direct me to deals, but right now I’m getting the most value by booking direct, showing up about an hour before advertised check in and being super polite “hey, I know we’re early, can we leave our luggage with bell services, we’re early, we’ll just explore the neighborhood..... oh you DO have a room:.. it’s a suite? Well, sure, thank you SO MUCH!” \n\nETA: I’m not angling for this. It’s been coincidence. Who LANDS so late in the afternoon that it’s time for a 4 pm check in? ",
"They pay even less than that. I had a hotel once accidentally give me the receipt from the 3rd party booking site. I don't remember the number, but I paid something like $130 to the 3rd party, and then the 3rd party only Gabe the hotel like $80.",
"Third party sites have contracts (or should have contracts) with the hotels. The rates probably depend on the hotel’s strategy (for example, if the third party sites have more reach than their own direct sales, while some hotels have the cheapest option by booking directly with them). Then you also have to take into consideration the restrictions (full payment in advance or flexible payment). Or it could be hidden behind memberships. Also, some sites don’t show the full price (taxes and service charges) until the final confirmation page, so when you compare, you have to take that into account.",
"Buying in bulk is a large part of it. These companies are able to buy thousands of 'room-nights' from the hotel chain, and then sell them back individually to guests online. By doing so, they by them at a discount and get to name a price somewhat higher than that during reselling.\n\nThe reason why individual hotels (most don't belong to, for example, Hilton or Holiday Inn, they are franchised out and owned by people who just pay to be part of that company for a number of benefits) will price match 3rd party rates is because when you book through one of those, you're making a contract with the .com site, and that site is making a DIFFERENT contract with the hotel. So while the hotel might cost $100, and the .com might sell it to YOU for $75, they are paying that specific hotel only $50 for that night. The hotel would rather get your $75 than the 3rd parties $50.",
"Hotels know people use online travel agencies (OTAs) and 'opaque' channels to book and will not visit _URL_1_ to book a room.\n\nHotels dont want to miss out on those 'channels'.\n\nHotels pay the channel a commission on any room booked. Channel uses that to subsidize (their own points programs, not directly), but there is also price competition. \n\n_URL_0_ ends up having to match to keep guests happy, but the hotel doesnt pay commission so it still works better. Obviously the hotel would prefer everyone to just book through _URL_1_ (hence loyalty programs to encourage that).\n\nSource: former director of finance of a hotel and I work for a large hotel owner.\n\nA revenue manager would have more technicals than me. Revenue management is way to min/max for me and I avoid it like the plague, but god bless them.\n\nEdit: this might help, too. Revenue managers will open and close channels based on demand. If demand is high, third party sites will be cut and only _URL_1_ will be left open. The best available rate (BAR) will be talen down and only RACK (think msrp) is available. \n\nWhen demand is low, we need heads in beds so cheaper channels are opened and _URL_1_ BAR is opened for loyalty members."
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7htolc | how can facebook identify people in photos before they're tagged, but computers have difficulty recognizing other objects in a photo? | I've done several of those captcha tests where I had to identify things like windows or street signs. How can a computer not identify those, but be able to recognize faces in Facebook pictures?
Relevant XKCD: _URL_0_ | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/7htolc/eli5_how_can_facebook_identify_people_in_photos/ | {
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"Computer vision is developing rapidly. In just the last few years, capabilities like this have become routine.\n\nThe pictures in captcha tests have been specially chosen to be a mixture of ones computers have a hard time with, and ones computers already know the answers to.",
"You've misinterpreted those captchas as something that computers are *never* able to do\n\nIn fact, they've identified millions and possibly billions of windows and street signs. The ones that it gives you are the weird ones that have tripped up the algorithm and it wants a second opinion on. Bots are unlikely to be able to solve those efficiently because they were built for trolling the internet, not for identifying street signs and they don't have millions of correct identifications to draw quick conclusions from unlike a person\n\nMatching things *most* of the time is infinitely easier than matching things *all* of the time, the only ones you see are the hard ones. You'll notice that facebook often can't identify all the people in pictures, or it guesses weird ones because it pulled from data such as who it thinks you were likely with at the time.\n\nBig data is weird, and don't believe for a minute that google is outsourcing all of its sign locating to captchas",
"The captchas are designed to keep out spammers who create fake accounts or whatever. They're doing this in large quantities, and don't want to spend much computing power on any one site, so anything that slows them down means they're more likely to move on to easier targets.\n\nFacebook is a multi-billion dollar company and uses large server farms and has lots of computer power at their disposal. And of course, they want to keep their users happy. Programmers have spent a lot of time optimizing the programs to find faces in particular (not so much street signs and things). I remember years ago, my iPhotos program thought that a bowl of potato salad was my dad. Facial recognition has improved considerably since then!\n\nSo yes, those captchas won't work forever, but they are currently keeping out spammers."
]
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kp923 | why technology develops in a somewhat linear order? | I realize that it's not exactly linear, I'm essentially talking about Moore's Law here.
What I don't understand is why this law applies. E.g. my older computer has 2 GB of RAM, my newer one has 4 GB of RAM and I see computers on the market with 6 or 8 GB of RAM. Why doesn't one company spend the time to develop a 256 GB stick of ram that fits current computers?
A possible answer to this is that the companies want to sell more, so they can sell you upgraded RAM every few years rather than one giant stick of RAM that will last decades. My counter-question to this is, if it's the case, why wouldn't giant projects, like the formerly extant NASA space program develop this technology for space shuttles and other equipment that demanded perfect performance?
**EDIT:**If I had to summarize the answers here, it sounds like it's all about economics. Despite the advantages of beating out the competition, it seems to be most cost effective to develop tech in order. Great discussion, guys. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/kp923/eli5_why_technology_develops_in_a_somewhat_linear/ | {
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"1) In the typical Moores law graph, the Y axis is not linear, thus the growth is not linear \n\n\n2) What your describing is doubling and not really 'linear'. Going from a Commodore 64 (w/ 64K memory) in early 80's to a home computer with 8Gig Ram is 5 orders of magnitude. At that growth rate, computers in 2030 will have close to a terrabyte of Ram. \n\n3) going back over a period of 1000's or even 100's of years, there are technological \"explosions\" ... there was one at the turn of the last century, 1900, which led to some 'futurists' at the time to proclaim \"we have learned everything that can be learned\". \n\n4) Going from each generation of chip (pentium 4, pentium 5, --- > Core 2 Duo, Intel I7, etc) is pushing the extreme bounds of manufacturing and technical know how. If you can push the boundary and be 10x faster then your competitor, it is not commercial advantageous or viable to spend 1000 times more on research cost to get to be 1000x faster. It simply wouldn't sell.\n\nRight now if you could buy and I7 CPU for $400 that was 6GHz fast!!!!! ORRRRRR, you could pay $400,000 for a CPU that was was 600 GHz FAST!!!!!! ... really ... which one will you buy.....which one will sell a million units come Christmas time? Most people already rationalize cost/benefit analysis and find the sweet spot\n\n\n Computer XYZ#1 == $1,500\n Computer XYZ#2 == $2,500 (2 times faster then #1)\n Computer XYZ#3 == $4,000 (just 1.5 times faster then #2 )\n Computer XYZ#4 == $6000 (.75 times faster then #3)\n\n\nMost people say ... well #2 is the \"sweet spot\", and #2 would probably sell the best\n\n\n",
"256 GB of ram would be almost enough to play dwarf fortress at full graphics.",
"1) In the typical Moores law graph, the Y axis is not linear, thus the growth is not linear \n\n\n2) What your describing is doubling and not really 'linear'. Going from a Commodore 64 (w/ 64K memory) in early 80's to a home computer with 8Gig Ram is 5 orders of magnitude. At that growth rate, computers in 2030 will have close to a terrabyte of Ram. \n\n3) going back over a period of 1000's or even 100's of years, there are technological \"explosions\" ... there was one at the turn of the last century, 1900, which led to some 'futurists' at the time to proclaim \"we have learned everything that can be learned\". \n\n4) Going from each generation of chip (pentium 4, pentium 5, --- > Core 2 Duo, Intel I7, etc) is pushing the extreme bounds of manufacturing and technical know how. If you can push the boundary and be 10x faster then your competitor, it is not commercial advantageous or viable to spend 1000 times more on research cost to get to be 1000x faster. It simply wouldn't sell.\n\nRight now if you could buy and I7 CPU for $400 that was 6GHz fast!!!!! ORRRRRR, you could pay $400,000 for a CPU that was was 600 GHz FAST!!!!!! ... really ... which one will you buy.....which one will sell a million units come Christmas time? Most people already rationalize cost/benefit analysis and find the sweet spot\n\n\n Computer XYZ#1 == $1,500\n Computer XYZ#2 == $2,500 (2 times faster then #1)\n Computer XYZ#3 == $4,000 (just 1.5 times faster then #2 )\n Computer XYZ#4 == $6000 (.75 times faster then #3)\n\n\nMost people say ... well #2 is the \"sweet spot\", and #2 would probably sell the best\n\n\n",
"256 GB of ram would be almost enough to play dwarf fortress at full graphics."
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1c96ic | What exactly causes your eyes to get glassy? | For example, when you are tired and feverish and your eyes get glassy, what is happening in your body to cause it? | askscience | http://www.reddit.com/r/askscience/comments/1c96ic/what_exactly_causes_your_eyes_to_get_glassy/ | {
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"When you're tired, you may be experiencing dry eye which actually can make the eyes water. This tearing may increase reflectiveness which would make them appear glassy.\n\nIf you have a fever it's possible that you also have a form of viral conjunctivitis as well which is associated with a watery discharge.\n\nWithout more specificity though, it's tough to answer your question. What exactly do you mean by \"glassy\"? Dilated pupils? Reflectivity?"
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37yqil | How much did the world wars shake the religious faith of Europeans? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/37yqil/how_much_did_the_world_wars_shake_the_religious/ | {
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"Can only provide a very limited answer but will give you what i know!\n\nIn some circles it only solidified it, the wars showed the brutality of modernity, a project which was supposed to bring prosperity and peace. This distrust of modernity (and the science which came along with it) would have cemented religious belief in some\n\nAmong those who grew up during the war (especially ww2) there was a wave of disdain. This is shown in the Angry Young Men cultural movement (John Osborne/Kingsley Amis/John Braine). This disdain was aimed at the institution of the church rather than religion itself. It was felt that people no longer followed the word of God but what the Church told them to believe. In Britain this was rooted in the Spanish Civil War as much as the WW's. Many British fought against Fascism in Spain but due to Britain's neutral position they were treated poorly when they returned. Many struggled to reconcile the fact that family/members of the community went to fight Fascism but were then treated as lepers by the nation, a nation which claimed to be Christian. The book Look Back in Anger pushes this point of people being so busy going to church that they no longer feel compassion towards eachother.\n\nIt's only a small part of what you asked but hope this is of some use!"
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267id9 | - how does amazon estimate delivery time? | I ordered 2 things on Amazon from the same seller. Both were ordered at the same time, they're both exactly the same size and weight, and they're shipping from the same facility. One is expected to get to me tomorrow and the other on June 11th. How do they get these dates? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/267id9/eli5_how_does_amazon_estimate_delivery_time/ | {
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"Past experiences and logistics from past shipments."
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1364tx | Is there a definitive text for the history of New York City? | I'm moving to New York in two months and I'm looking for a really good book about the history of the city. Any recommendations, Reddit? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/1364tx/is_there_a_definitive_text_for_the_history_of_new/ | {
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"For more recent NYC history, Thomas Kessner, *Fiorello H. LaGuardia and the Making of Modern New York* is great. I have not yet read *Gotham: A History of New York City to 1898* by Burrows and Wallace, but it was highly recommended to me.",
"[This](_URL_0_) is an older book, but it's one of my favorites."
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3b4ci3 | why this goat faints. | * _URL_0_
I'd like an explanation to why this goat so happens to faint when he touches the grass.
Thank you!
| explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/3b4ci3/eli5_why_this_goat_faints/ | {
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"Fainting goats aren't rare. They usually do it as a defense mechanism or a reaction to being scared, like a possum playing dead. For some reason, this goat is afraid of grass.",
"Fainting goats (usually when younger, they often grow out of it) have a condition where, when startled, their leg muscles stiffen suddenly. This usually makes them fall over and look as though they appeared to faint.\n\nIt's a genetic disorder, as far as we can tell. We domesticated them because they produce lots of cashmere whilst being really easy to keep, so it's likely the disorder appeared in them after domestication, meaning evolution didn't get to weed them out because we were protecting them from predators that would otherwise have an easy meal. That's mostly conjecture though.\n\nIn this particular case, the goat is apparently startled by grass, at least enough to trigger the muscle reaction.",
"The goat doesn't faint. It doesn't lose consciousness. It's just a muscle spasm. They exist in numbers because humans bred them in numbers. In the wild they would all be dead because they would be eaten by wolves."
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5iunn8 | why is water a liquid? | Dumb question maybe, but, how can heavier materials like carbon dioxide and sulphur dioxide exist in a gas state while H2O exists as a liquid?
Edit: As stated in comments; at room temperature. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5iunn8/eli5_why_is_water_a_liquid/ | {
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"The state of any given material is based mainly on the interaction between two different things: The amount of energy in a given amount of the substance, and the strength of the attraction between the molecules/atoms of the substance. The stronger the attraction between molecules, the more likely it will be in liquid, or even solid, state, because it take more energy to overcome those attractive forces.\n\n\nIn the case of water, water has Hydrogen bonds, which draw the hydrogen of one molecule of water to another molecule. It also is polar, meaning one end of the molecule is positive, and one molecule is negative. This increases the attractive strength between the molecules. Carbon dioxide has neither of the these, and so can exist more easily as a gas because it takes less energy to break the attraction between molecules. Same Applies to sulphur dioxide."
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29vir5 | why are "bad" drugs sometimes ingested through snorting or smoking, but never "real" drugs? | Cocaine is snorted. Tobacco and cannabis are smoked. Why don't I ever get a prescription that is taken in in these forms? It's always a pill or syrup. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/29vir5/eli5_why_are_bad_drugs_sometimes_ingested_through/ | {
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"Some medical drugs are inhalants (many asthma and allergy drugs).\n\nMany other medical drugs are injectable.\n\nI imagine smoking and snorting are harder to control dosage with (how much are you inhaling versus letting escape into the atmosphere) and getting precise dosage is important when treating an illness.",
"I believe it is a matter of dosage--it is easier to know the exact dosage you are taking when you take a pill or syrup.\nThere are some medicines that are inhaled (steroid treatments for asthma for instance), but these are definitely the exception.",
"Some medics carry this adapter that screws on the end of a syringe replacing the needle, it is a foam triangle that sprays a very fine mist into your nose. It is used when starting a line on someone would take too long or is too difficult. I believe its mostly used with Narcan, which is used to treat heroin overdoses. If anyone one is really interested in what it looks like, I have a couple in my car, I can take a picture next time I'm in it. On another note, most pills can be snorted and have the same effects, they take affect quicker when snorted, but you don't get the same dose because not all will be absorbed into your bloodstream. I'm sure that they don't advertise this because most people wouldn't want to have to snort their daily med and you wouldn't want to crush up and snort something that is time-released. I have, on a couple of occasions snorted oxycodone because I was in an immense amount of pain and didn't want to wait 15-20 min for it to kick in if I just swallowed it. I did it at a hospital once, in front of a nurse. She flipped out until I explained why I did it and then just told me to ask for morphine via IV next time.",
"Both snorting and smoking are (or can be) bad for you. Smoking involves inhaling particles into your lungs, which is not something they were designed for. Snorting can damage the nasal cavity, and ruin the nasal septum. \nAside from smoking there are other forms of inhalation though. The drug/medicine can be vaporised (basically heated to the point it gives off the effective elements, but below burning temperature) or put into a mist in some other way. This is done both with recreational drugs (cannabis, e-cigs, etcetera) and with certain medicine such as asthma medication.",
"Well, Inhalers, you, well, inhale, Epi-pens for allergy you inject into your thigh, some Insulin you inject, and some insulin pumps are tubes going straight into your body, and i dont think many meds are \"smoked\" because almost anything besides air into your lungs isnt too good for you."
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9adj7d | Can someone explain the behavior of Superfluid Helium? | It has been stated that superfluid helium can flow indefinitely under its own inertia and without friction. How is this possible? | askscience | https://www.reddit.com/r/askscience/comments/9adj7d/can_someone_explain_the_behavior_of_superfluid/ | {
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"When all Helium atoms fall into their many-body–quantum-mechanical ground state, they can all move synchronously. So there is no friction between atoms, but there could still be friction between the superfluid and e.g. the walls of a tube.\n\nFriction implies the transformation of kinetic energy to heat. A superfluid is a gapped quantum system, so heat can only be added to the system in units of at least the gap energy. In a superfluid, this is allowed only if the superfluid flows faster than its critical velocity. If the flow is slow enough, there cannot be any friction due to a combination of constraints from quantum mechanics, conservation of energy, and conservation of momentum."
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1xqe5l | Is carbon dioxide uniquely able to make a beverage effervescent? | Or is it just the most cost effective and/or safest? | askscience | http://www.reddit.com/r/askscience/comments/1xqe5l/is_carbon_dioxide_uniquely_able_to_make_a/ | {
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"Draft Guinness is aerated with nitrogen as well as carbon dioxide, which creates less acidity and smaller bubbles. The yeast which create the alcohol in beverages also create carbon dioxide, just as the do in leavened bread, so carbon dioxide is the natural aerating gas for beer and sparking wine. Joseph Priestly created the first effervescent soft drinks by dissolving the carbon dioxide found above vats of fermenting beer into water.",
"There's also a variety of Monster energy drink out there that uses nitrous oxide alongside a bit of carbon dioxide. It creates an interesting almost creamy texture. So, other gases that are mildly water-soluble are able to make beverages effervescent, but the natural choice is CO2 due the reasons described by keithb.",
"Given the right solvent and a great enough pressure, any gas can be dissolved in a solution and then released by reducing the pressure. \n\nHowever the qualities of CO2 arise not just from its reasonably high solubility in water (the pressure in a soda can is only about 70% greater than the normal atmosphere) but from the formation of carbonic acid in water, giving it a tangy taste. Nitrogen dioxide exhibits similar properties, and forms nitric acid when dissolved in water, but is highly corrosive. Sulfur dioxide also dissolves in water to form a reducing agent (although technically sulfurous acid doesn't form, but a sulfite ion and hydrogen ion), and is actually used in winemaking as a preservative that prevents the wine from fermenting into vinegar, although its taste is actually quite horrible, and its smell even worse."
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78hydj | what are vectors and scalars? what is magnitude in this context? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/78hydj/eli5what_are_vectors_and_scalars_what_is/ | {
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"text": [
"A scalar is basically just a number. E.g. I am moving at 30mph. 30 is a scalar.\n\nA vector is a scalar plus a direction. E.g. I am moving *north* at 30mph. Here, the 30 is the \"magnitude\" of the vector, and north is the direction.",
"Picture a town, with a grid layout. You get on your bike and start cycling. Your bike has an odometer attached. That odometer will go up no matter which direction you go in. This is a scalar. It just has the one dimension. Total distance travelled. \n\nNow, instead of just the total distance you travel, you care about where you're going. You cycle north for a block, east for a block, north again, then west 2 blocks. You've travelled a total of 5 blocks, but you're not 5 blocks away from the start. \n\nYou can work out the distance and bearing, but it's just as useful to say you're 2 blocks north and 1 block west. This is a vector. The key here is that there are two components - Two dimensions. The north/south component (2 blocks north) and the east/west component (1 block west, or -1 block east), and we can write this as (2, -1). You can take multiple trips, and add the components together separately if you want. You could add a third dimension if you found a way to go up and down. \n\nMagnitude is the actual length of the vector. You can treat the north and west as two sides of a triangle, and work out the length of the third side to get the magnitude, using Pythagoras' theorem."
]
} | [] | [] | [
[],
[]
] |
||
1dgzad | Would photons emitted from a bioluminescent source allow plants to photosynthesise? | askscience | http://www.reddit.com/r/askscience/comments/1dgzad/would_photons_emitted_from_a_bioluminescent/ | {
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"text": [
"Depending on the photosynthetic mechanism at play, a certain wavelength of light is preferred. If the photon from the source has the right wavelength, I see no reason why the plant would care where it came from.",
"Yes, but the biolumenescent source would have to burn a _lot_ more energy than the plant gained from the light. In practice, all the biolumenescent sources I know of are much too dim to allow a plant to live."
]
} | [] | [] | [
[],
[]
] |
||
1y68o3 | How do you isolate a gene from one organism, and insert it into another? | How is it possible to identify a certain gene that represents a certain trait in an organism, to isolate that gene, and insert the gene into some other organism? How do you go about it practically?
| askscience | http://www.reddit.com/r/askscience/comments/1y68o3/how_do_you_isolate_a_gene_from_one_organism_and/ | {
"a_id": [
"cfhte3h",
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"score": [
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"text": [
"It's actually pretty easy for some organisms, but much harder for others.\n\nI'll try to walk you through the process:\n\nFirst, we find a gene that we want \"expressed\" in another organism (probably non-pathogenic E. coli, the workhorse of molecular biology). Let's say we go looking in yeast genome (which is published online) and find a gene for an enzyme that breaks large sugars into smaller ones. The E. coli would not have this gene.\n\nNext, we take a culture of yeast (billions of yeast cells) and break the cells apart either mechanically or chemically to collect their DNA. This is the whole genome, or genomic DNA. It has our gene, but also genes we don't want.\n\nTo isolate the gene from the purified genomic DNA, we use [PCR](_URL_1_) which is a process that allows us to easily and efficiently amplify only the DNA we want, which is our gene. This requires that we order (from a company) short segments of DNA called \"primers\" that flank the gene. For example, if we had a sentence from a whole book: \"The cat was wearing a blue colored hat\", and used the primers \"cat\" and \"blue\", the PCR would give us back \"cat was wearing a blue\" isolated from the rest of the book. PCR also lets us add a little bit to the ends, so if we used primers that said \"My cat\" and \"blue sock\", then the PCR would give us back \"My cat was wearing a blue sock\". This is useful because we can add [restriction enzyme cut sites](_URL_0_) to both sides of the gene. This is important in the next step.\n\nTo get the gene into our E.coli, we need a transportation method. This comes in the form of a [plasmid vector](_URL_2_) which are circular pieces of DNA that many bacteria can uptake and then begin using as a source of information for new genes. Our plasmid would have a marker on it that usually codes for another gene, usually an antibiotic resistance gene as well as more restriction enzyme cut sites. Now, we can add our circular plasmid and gene together with the restriction enzyme itself. This enzyme cuts both our plasmid and the ends of our genes and produces complementary or sister strands that wish to find their \"mate\". Thankfully, this means that they will find each other and re-circularize into a larger plasmid that now contains our gene.\n\nNext we use a few chemicals to force the plasmid into the E. coli cells. These are then put on petri dish plates with food and antibiotics. The antibiotic will kill all cells without the plasmid and only allow the ones with the plasmid to live (remember that our plasmid had a marker that was resistance to the antibiotic). \n\nAnd that's it!\n\nThis is fairly easy for bacteria, yeast, and other smaller organisms. It becomes very difficult when you start talking about large organisms because often they cannot use plasmids.",
"The descriptions listed below are pretty fantastic. A favorite example of mine, is green fluorescent protein, which is used in all different fields within molecular biology. The protein originated from bioluminescent jellyfish, and later the sequence of the gene was identified. This gene sequence can be tagged on to other genes, so that when expressed in a cell, that particular protein is fluorescent. "
]
} | [] | [] | [
[
"http://en.wikipedia.org/wiki/Restriction_enzyme#Recognition_site",
"http://en.wikipedia.org/wiki/Pcr",
"http://en.wikipedia.org/wiki/Plasmid"
],
[]
] |
|
cjczkg | how does a software input into a computer physically change a transistor | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/cjczkg/eli5_how_does_a_software_input_into_a_computer/ | {
"a_id": [
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"text": [
"Input is made on a wire by turning a voltage on and off. (We call on 1 and we call off 0.) Transistors respond directly to voltage.",
"* As far as the hardware is concerned, everything is a value in memory. \n* Software tells the processor what values to put in memory.\n* Software tells the processor where in memory to get values from. \n* Transistors are part of the hardware they just react to changes in voltage.",
"Engineer here, this isn't 100% the entire story, but it's ELI5.\n\nSoftware input doesn't change the shape, state, or move or do anything physical to a transistor. A transistor is just another component whose shape and material will manipulate the flow of electricity in a specific and predictable way, just like any other component such as a resistor, inductor, or capacitor. What makes transistors so special is that they have three pins, where varying the power applied to one input can vary the amount of power that gets through from the other input.\n\nThese transistors can be arranged into units called logic gates, of which the most commonly used for commercial applications is the NAND gate. The way the NAND gate works is that it is always on (1) unless both inputs are on (1), in which case the gate turns off (0). By some clever methods, these NAND gates can be arranged to form any other logic gate.\n\nThese logic gates can then be arranged into something even larger, like an Arithmetic Logic Unit (ALU). Which takes inputs of high (1) and low (0) power on each individual wire and can do basic math like addition and subtraction and other things by assuming that the arrangement of these wires means a number.\n\nWhen someone writes software, they're writing a series of mathematical and logical operations that get put into a queue of sorts where they get fed into this big lump of logic gates in order."
]
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[],
[],
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||
2iv2uv | How "bulged" can a planet become? | Planets "bulge" at the equator because of rotation. How fast could a planet, rocky or gas, spin before it tore itself apart? Could we have a planet twice across as it is north to south? How would that affect surface gravity? Could we have a "Discworld?" | askscience | http://www.reddit.com/r/askscience/comments/2iv2uv/how_bulged_can_a_planet_become/ | {
"a_id": [
"cl5y3mj"
],
"score": [
9
],
"text": [
"Of the major planets in our Solar System, Saturn is the 'flattest' with a [flattening ratio](_URL_5_) of [1:10](_URL_4_).\n\nFor faster rotational speeds, the equilibrium shape is a Jacobi (scalene or tri-axial) ellipsoid rather than the familiar Maclaurin (oblate) spheroid (Wikipedia: [Ellipsoid](_URL_1_)). The Kuiper Belt object [Haumea](_URL_0_) is an example, with dimensions of ~1,920 x 1,540 x 990 km (which is pretty close to a 2:1 ratio between the longest axis and the shortest axis). See [Lockwood et al 2014](_URL_6_) and [Chandresekhar 1967](_URL_2_) (particularly the beginning of section 3).\n\nAt some rotation speed, self-gravity cannot hold a body together. For rocky-like densities (i.e. asteroids), this transition happens at a rotational period of ~2 hours (see [here](_URL_3_)). Any faster than that, only monoliths (a body consisting of single solid rock) can exist. At some point (which is highly dependent on composition), even the electrostatic forces between atoms in a monolith could be overcome, and the body would shear itself apart.\n\nUnfortuantely, no, you can't rotate fast enough to get a \"Diskworld\"."
]
} | [] | [] | [
[
"http://en.wikipedia.org/wiki/Haumea_%28dwarf_planet%29",
"http://en.wikipedia.org/wiki/Ellipsoid",
"http://people.ucsc.edu/~igarrick/EART290/chandrasekhar_1967.pdf",
"http://www.scilogs.eu/en/blog/go-for-launch/2010-03-09/simple-math-how-fast-can-an-asteroid-rotate",
"http://en.wikipedia.org/wiki/Equatorial_bulge#Other_celestial_bodies",
"http://en.wikipedia.org/wiki/Flattening",
"http://web.gps.caltech.edu/~mbrown/papers/ps/haumea_spitzer.pdf"
]
] |
|
3urd39 | why does the peanut butter in a reese's peanut butter cup have a different texture? | It feels totally different from regular peanut butter in a jar. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3urd39/eli5_why_does_the_peanut_butter_in_a_reeses/ | {
"a_id": [
"cxh514l"
],
"score": [
3
],
"text": [
"Oil and chocolate are quite buddy buddy and want to mingle together. Peanut butter contains peanut oil which makes it easier to spread. However, this oil will mix with the chocolate covering the peanut butter cup and cause the chocolate to get soggy and melt off. So, the peanut butter inside the cup is peanut butter with reduced peanut oil.\n\nIf you get peanut butter brands with just peanut butter and no other additives, you'll often find a layer of oil on top of all the peanut butter. If you manage to scoop some of that peanut butter without mixing the oil, you will get a texture similar to that of Reese's Peanut Butter Cups. Regular mainbranded peanut butter (Skippy's, Jif, etc.) have added ingredients that prevent the peanut oil from separating from the peanut butter."
]
} | [] | [] | [
[]
] |
|
8xvuc2 | the 15(+) different logical fallacies. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/8xvuc2/eli5_the_15_different_logical_fallacies/ | {
"a_id": [
"e2675hz"
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"score": [
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"text": [
"**Slippery Slope:** If we allow this to happen, it will lead to this other (loosely/hardly related) thing happening!\n\n**Hasty Generalization:** I know I'm right despite having little or biased evidence!\n\n**Post hoc ergo propter hoc:** This happened after this, so it must've caused it!\n\n**Genetic/Origins Fallacy:** This person/place/thing came from this other person/place/thing so it can't be any good!\n\n**Circular Argument:** Of course my argument is good because I argue well!\n\n**False Dilemma:** Only this or this can happen, no alternative bucko!\n\n**Ad hominem:** Sincd I cant think of counters to attack your argument with, I’m going to attack your character instead! Who’d even listen to a fortnite cheater!!\n\n**Ad populum/Bandwagon Appeal:** The good people put there will agree with me, you wannna be a good person right?\n\n**Red Herring:** What if I took your counter argument....and redirected it to an unrelated issue?\n\n**Straw Man:** What if I took your counter argument...and over simplified it to make me look better by comparison!\n\n**Moral Equivalence:** You're literally worse than Hitler when you cheated on fortnite.\n\n**Begging the Claim:** This law-abiding suspect shouldn't be convicted in this trial!\n\n**True Scotsman Fallacy:** Only true Americans vote for me....the ones who don't vote for me obviously aren't true Americans.\n\nI'm not sure which ones I'm missing, but that's the most common ones!\n\n---donated explantions from /u/deep-rabbit-hole ---\n\n**Argument from incredulity:** it seems so impossible... it couldn't have happened that way. e.g. evolution etc.\n\n**Argument from ignorance:** I cant think of any other way this happened so it must have happened that way.\n\n**Argument from authority:** she is an expert on this so she must be right."
]
} | [] | [] | [
[]
] |
||
2lawx1 | in an election, how is a write in candidate determined and notified if he/she wins? | In most, if not all, ballot questions there is an opportunity to write in your vote if opting to not select one of the supplied choices. In the event that one of these write ins won, say John Smith, how would it be known if all John Smith write ins were referring to the same person? Could every John Smith claim to have won? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2lawx1/eli5_in_an_election_how_is_a_write_in_candidate/ | {
"a_id": [
"clt2md2"
],
"score": [
3
],
"text": [
"Most write-in campaigns that actually win are public and fairly well organized. To the best of my knowledge, there has never been a candidate that is simultaneously popular enough to win a write-in campaign, and unknown enough for officials to have difficulty establishing their identity.\n\nTheoretically it could happen, and cause a problem, but it has just never come up."
]
} | [] | [] | [
[]
] |
|
8pkpxj | What would 'pagan' mean in 1896? | I'm working with some old atlases, and one of them (Tunison's Peerless Universal Atlas of the World, published in 1896) has a comparison chart of the populations of different religions. The biggest, at 500,000,000 million, is 'Pagans etc.' What would that mean to a contemporary reader?
(The other religions, for reference: Buddhists, Mohammedans, Roman Catholics, Protestants, Greek Christian, and Jews.) | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/8pkpxj/what_would_pagan_mean_in_1896/ | {
"a_id": [
"e0cmbo6"
],
"score": [
14
],
"text": [
"Since it includes the term etc. and is listed alongside these other religions, is there a reason not to take the trivial \"everything else\" answer at face value? Practitioners of other religions, with Hindus being a particularly notable exception to the list given?"
]
} | [] | [] | [
[]
] |
|
4ctirl | what the heck is going on with r/hearthstone right now? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4ctirl/eli5_what_the_heck_is_going_on_with_rhearthstone/ | {
"a_id": [
"d1lbkv4"
],
"score": [
2
],
"text": [
"It's April first in some parts of the world (in the US in just a couple of hours). Thus this is some sort of April fools joke, the purpose of which has not yet been revealed."
]
} | [] | [] | [
[]
] |
||
1ulp7h | why americans won't name their sons jesus? | Virtually every other religion honors their gods by naming children after them, and while I know it's common in Latin American countries, I have rarely come across a white Jesus. Why is that? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1ulp7h/eli5_why_americans_wont_name_their_sons_jesus/ | {
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"text": [
"We use Josh.",
"Because the name translates to Joshua in English. Edit: And we differentiate the Son of God by using Jesus, (the Greek name for Joshua). ",
"Americans do name their sons Jesus, if they are in hispanic families.",
"To flesh out and correct a couple of comments here:\n\nRe: Jesus/Joshua. The New Testament was written originally in Greek, and Jesus is the the English spelling of the Greek word. It is equivalent to the Hebrew name Joshua (hence why the Old Testament characters are called Joshua).\n\nThe name Jesus is associated uniquely with Jesus Christ (because there aren't any others mentioned in the New Testament).\n\nThe difference between white and latin american cultures I suspect may be a protestant/catholic divide. The latin american/hispanic cultures are predominantly catholic-rooted and name their children Jesus in much the way other religions do. Due to the Reformation, much of northern Europe (white) became protestant. For protestants, the concern is that naming your child Jesus is a bit like calling your son 'God' (note that you only get Muslim kids called Mohammed, not Allah) - it could be considered blasphemous, and that has become embedded in the culture - so now for an English family to name their child Jesus would come with a bunch of connotations.\n\nEdit: tl;dr: Protestant-background Americans don't call their kids Jesus because it could be considered blasphemous. Latin cultures have a Catholic background and therefore do, similar to other faiths."
]
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[],
[],
[],
[]
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|
1y241w | tesla's worldwide wireless system and why did it fail. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1y241w/eli5_teslas_worldwide_wireless_system_and_why_did/ | {
"a_id": [
"cfgokar"
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"score": [
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"text": [
"It failed because of the inverse square law. Whenever you radiate something (sunlight, heat, or whatever) from a central point, the intensity decreases according to the square of the distance from that point. So, if you double the distance between you and the sun, the intensity of the light reduces to a quarter. Triple the distance, and it's a ninth. Etc. \n\nSo if you transmitting wirelessly over any considerable distance, you're wasting most of it, and you have to drastically increase the power in order to increase the effective transmission distance a bit. It's horrifically wasteful. This could just possibly be worthwhile in an age where there isn't much that needs to be electrically powered in a customers home - a few light bulbs, perhaps. In an age where everything requires it, you'd burn through insanely and almost criminally wasteful amounts of power to get it to customers wirelessly. "
]
} | [] | [] | [
[]
] |
||
1t57o2 | why former spanish and portuguese colonies replaced their languages with spanish and portuguese respectively but former british and french colonies didn't? | or why did Spain and Portugal forced their language onto locals but Britain and French didn't ?
EDIT: e.g Only educated in India, Pakistan, Bangladesh can speak English and they still use their own languages primarily. Brazil, Mexico primarily speak Portuguese and Spanish as their first language.. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1t57o2/eli5_why_former_spanish_and_portuguese_colonies/ | {
"a_id": [
"ce4jgsg"
],
"score": [
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"text": [
"European colonization in the Americas started in the 16th century, opposed to African and Asian colonies which were established much later, under larger populations and a smaller interest in settlement. In less than a century, most indigenous American peoples were wiped out, along with their cultures.\n\nStill, during colonial times native and mixed languages were spoken by large groups, like the Jesuits using them to teach religion. Spanish and Portuguese were only for government matters. But as colonies went for a stronger administration and independence, the use of a single language was encouraged in education to integrate and unify all ethnic groups with a national identity."
]
} | [] | [] | [
[]
] |
|
5ecgyg | why isn't there a standard for microwave wattage? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5ecgyg/eli5_why_isnt_there_a_standard_for_microwave/ | {
"a_id": [
"dabc7o9"
],
"score": [
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"text": [
"A 1,000-watt microwave will cook quickly and efficiently. Microwaves with 700 watts or less are slower and may not cook evenly. In general, the higher the wattage, the faster the cooking time.\n\nHowever, Lower watts cost last and that's why they are out on the markets. "
]
} | [] | [] | [
[]
] |
||
5xxgqe | Help Identifying WWII Army Ribbons | My son was recently doing a project on World War II, and we were able to get my wife's grandfather's US Army uniform. Unfortunately, I've been unable to identify what his ribbons, and was wondering if anyone might have some insight. Thanks!
[Image](_URL_0_) | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/5xxgqe/help_identifying_wwii_army_ribbons/ | {
"a_id": [
"delr9vd"
],
"score": [
5
],
"text": [
"Top row:\n\n* [Purple Heart](_URL_1_), awarded for a wound received in combat against the enemy\n\nBottom Row, L-R; \n\n* A severely faded or worn [American Campaign Medal](_URL_5_), awarded for being in the boundaries of the American Theater from 7 December 1941 until 2 March 1946, and;\n\n > * On permanent assignment outside the continental limits of the United States.\n\n > * Permanently assigned as a member of a crew of a vessel sailing ocean waters for a period of 30 consecutive days or 60 nonconsecutive days.\n\n > * Outside the continental limits of the United States in a passenger status or on temporary duty for 30 consecutive days or 60 nonconsecutive days.\n\n > * In active combat against the enemy and...awarded a combat decoration or furnished a certificate by the commanding general of a corps, higher unit, or independent force that the Soldier actually participated in combat.\n\n > * Within the continental limits of the United States for an aggregate period of 1 year.\n\n* [European-African-Middle Eastern Campaign Medal](_URL_4_) with three bronze service stars. Army campaigns given stars for this medal include;\n\nCampaign|Dates\n:--|:--\nEgypt-Libya|11 June 1942-12 February 1943\nAlgeria-French Morocco|8-11 November 1942\nTunisia|17 November 1942-13 May 1943\nSicily|9 July-17 August 1943\nNaples-Foggia|9 September 1943-21 January 1944\nAnzio|22 January-24 May 1944\nRome-Arno|22 January-9 September 1944\nNorth Apennines|10 September 1944-4 April 1945\nPo Valley|5 April-8 May 1945\nAir Offensive, Europe|4 July 1942-5 June 1944\nNormandy|6 June-24 July 1944\nNorthern France|25 July-14 September 1944\nSouthern France|5 August-14 September 1944\nArdennes-Alsace|16 December 1944–25 January 1945\nRhineland|22 February–21 March 1945\nCentral Europe|22 March–11 May 1945\nAnti-submarine (blanket)|7 December 1941-2 September 1945\t\nGround Combat (blanket)|7 December 1941-2 September 1945\t\nAir Combat (blanket)|7 December 1941-2 September 1945\n\n * [Army Good Conduct Medal](_URL_3_), awarded for one year's infraction-free service in wartime\n\nSource:\n\n[Army Regulation 600-8-22 *Personnel-General, Military Awards*](_URL_0_)\n\n[EAME Campaigns](_URL_2_)"
]
} | [] | [
"http://i.imgur.com/qqX9Kjs.jpg"
] | [
[
"http://www.apd.army.mil/pdffiles/r600_8_22.pdf",
"http://www.tioh.hqda.pentagon.mil/Catalog/Heraldry.aspx?HeraldryId=15254&CategoryId=3&grp=4&menu=Decorations%20and%20Medals&ps=24&p=0",
"http://www.history.army.mil/html/reference/army_flag/ww2_eame.html",
"http://www.tioh.hqda.pentagon.mil/Catalog/Heraldry.aspx?HeraldryId=15263&CategoryId=4&grp=4&menu=Decorations%20and%20Medals&ps=24&p=0",
"http://www.tioh.hqda.pentagon.mil/Catalog/Heraldry.aspx?HeraldryId=15299&CategoryId=4&grp=4&menu=Decorations%20and%20Medals&ps=24&p=0",
"http://www.tioh.hqda.pentagon.mil/Catalog/Heraldry.aspx?HeraldryId=15297&CategoryId=4&grp=4&menu=Decorations%20and%20Medals&ps=24&p=0"
]
] |
|
e8reok | How did Amazon cities disappear so quickly? (further detail inside) | I just finished The Lost City Of Z (I know this isn't a history book), but it discusses how there were many great cities in the amazon that now are difficult to find traces of. My understanding was that the spread of disease had decimated cities quickly. But how did they become decimated so quickly that A) The traces were hard to spot by later explorers and B) the future generations didn't recall them. | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/e8reok/how_did_amazon_cities_disappear_so_quickly/ | {
"a_id": [
"faew4w0"
],
"score": [
14
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"text": [
"I am going to assume you are referring to the Inca and Aztec civilisations of South America? In that case, I will plough ahead and give you a reasonable response for the fall of both empires.\n\nFirstly, it is important to note that these cities were very advanced and were praised as such, particularly in Hernan Cortés' letters to Charles V. He praised Tenochtitlan in these letters, so it is clear that the civilisations of South America were quite sophisticated, although when measured against our own moral standards they fall quite short, but that comes with the study of history...\n\nFirstly, the Cortés' expedition led to the discovery of Tenochtitlan which subsequently fell in 1521. Cortés had exploited the fact that Tenochtitlan's military expansionism had led to it developing a number of enemies. Along with these enemies, such as those of Tlaxcala, Cortés captured the Aztec leader Montezuma and through him, he captured the city. Tenochtitlan consequently fell in 1521. Francisco Pizarro too arrived during a period of unrest within this time the Inca empire, and in 1530 his expeditionary force apprehended the Inca ruler Atahualpa, who had killed. Without their leader, the Inca empire withered away and its capital, Cuzco, fell in 1530. Therefore the fall of these empires is easily attributed to civil unrest within these two civilisations.\n\nNext, the population deteriorated rapidly due to ravaging disease. Since everybody has a general idea why, I'll throw in some statistics just to show you how drastically the population decreased. The indigenous population of central Mexico fell from 25 million in 1521 to 2.6 million in 1568. In Peru, it fell from 3.3 million in 1520 to 1.3 million in 1570. The diseases included smallpox and measles which destroyed the populations due to their lack of immunity.\n\nThe policy of *encomienda* was also a factor in the transposition of native and coloniser. It began as a form of lordship where a 'deserving person' could receive payment from indigenous towns and villages. However, it was soon more related to a form of slavery. They ranged in size, Cortés had up to 115,000 indigenous workers across 23 encomiendas. This oppressive dominance over the indigenous population was another factor in the dwindling of population. In less than a century their whole way of life was completely transformed. \n\nAlong with these, there were other factors such as the use of horses (which the indigenous population had interpreted as god-like) and sheer ruthlessness (massacres, etc). \n\nI have to study, so I'll wrap this up with Bartolomé de las Casas' own words on the treatment of the indigenous populations by the Spanish Conquistadors: \n\n*'The common ways mainly employed by the Spaniards who call themselves Christian and who have gone there to extirpate those pitiful nationsand wipe them off the earth is by unjustly waging cruel and bloody wars. Then, when they have slain all those who fought for their lives or to escape the tortures they would have to endure, that is to say, when they have slain all the native rulers and young men (since the Spaniards usually spare only the women and children, who are subjected to the hardest and bitterest servitude ever suffered by man or beast), they enslave any survivors. With these infernal methods of tyranny they debase and weaken countless numbers of those pitiful Indian nations.' -* Bartolomé de Las Casas, *Brevissima relacion de la destruycion de las Indias* (Sevilla, 1552)."
]
} | [] | [] | [
[]
] |
|
195ddj | Who had the best/most wanted cigarettes during World War II? What about other products? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/195ddj/who_had_the_bestmost_wanted_cigarettes_during/ | {
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"I don't know about best/most wanted cigarettes, but Lucky Strikes was easily one of the most widely seen. Lucky strikes, aka Luckies, was the top selling cigarette in the US during the 1930's, and would have been well established by the time of WW2. They even had to change their packaging from the staple green to white, due to shortages of the green dye they used. Lucky strikes still use the white package to this day. Also with a father who smokes and a former smoker myself, lucky strikes have consistently been a decent brand for cigs, they're toasted!\n\nCigarettes were actually a part of GI's rations, with some of the most popular brands at the time finding their way around the world. Many of the popular brands, such as Camels, Kools, Pall Malls, and Chesterfields would face shortages back in the states. \n\n[Source](_URL_0_)",
"In Alamein: War Without Hate, both sides (German and British in North Africa) are shown to fetishise the supplies of the other side. Germans preferred English tea while English soldiers felt that German meat rations were superior, I believe, though I don't have the book to hand. The creation of a mythology of the opponent having superior rations is easy to imagine, though."
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ftxki | How does basic light reflection really work? Confused. | Hey Reddit,
So I'm trying to get my head around what's happening at a fundemental level when light reflects off of a highly reflective surface like a mirror. For a given photon, I'm assuming it doesn't "bounce" in any way when it reaches the atoms of the reflective surface (ie isn't repulsed), but rather is absorbed and re-emitted. What's confusing me is how the momentum / angle of reflection is maintained through the absorption / emission process. I kinda see it when viewing light as a wave, but picturing water bouncing off a containing wall doesn't help, because its not really absorbed + emitted in any way. Can anyone help me with what's going on? How does an electron absorbing the photon and jumping to a higher energy level maintain momentum?
Thanks | askscience | http://www.reddit.com/r/askscience/comments/ftxki/how_does_basic_light_reflection_really_work/ | {
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"The way Feynman explains it, individual photons don't know or remember their momentum. It's just that, if you have a light source and a light sensor and a mirror, you will find that the photons are most likely to have followed the path that we expect from classical optics. The wave function of a photon taking a slightly more acute path cancels out with the wave function of a photon taking a slightly less acute path, and all we're left with is the proper\n\nSee Feynman's explanation here: _URL_0_ He goes into your question early in part 2, but I recommend watching all 4 segments.",
"On an ideal conductor, the re-emitted photon has to cancel out the parallel component of the electric field. This results in a re-emitted photon that has to have the same momentum in the parallel component, and the opposite momentum in the perpendicular component.\n\nOr, the angle in equals the angle out.",
"It's actually pretty mindblowing when you think about it.\n\nWhen a photon is absorbed by an atom in, say, glass, it is re-emitted a very short time thereafter. The problem is: the direction it is emitted is random. How then does light reflect in one direction? Turns out that the phase of the photons in *all directions except for the \"expected\" angle* just about cancel out (\"just about\" to account for the fact that there are only a finite number of photons). Along such an angle, all photons constructively interfere, giving you the angle you expect.\n\nMost modern undergraduate optics books will have a short section on QED in this respect. But Feynman does a great job too in the videos the others link to.",
"The trick is, the common mirror isn't formed with individual electrons, it's rather formed with electron fluid, which handles electromagnetic waves collectively like the elastic membrane. When the photon is absorbed, it forms an undulation at the surface of electron fluid (so called the surface plasmon), which maintains the original momentum/angle of reflection of incoming wave. Because of many electrons are involved, the absorption/emission process is merely classical, i.e. the falling waves are reflected immediately back again, because there are no distinct energy levels, in which the energy of photon could be trapped and/or deformed (or better to say, these energy levels still possibly exist here, but they're so many and tiny, they appear like (nearly) energetic continuous and/or the inclined plane instead of distinct stepwise stairs). \r\n\r\nBriefly speaking, the light is reflecting from surface of metals like from elastic membrane and virtually no deformation of its momentum/angle of reflection occurs there in similar way, like when the ball bouncing from inclined plane instead of stairs. \r\n\r\nThe formation of surface plasmons can be observed at the case of large atoms (gold, silver, copper, cesium, bismuth), around which the electrons are forced to move in relativistic speed, which gives them higher mass, therefore their surface waves are of longer wavelength, i.e. long enough to be observed in visible spectrum like the colored surface of metal."
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ti41s | Is it possible for a male phenotype to somehow
evolve into a female looking phenotype and vice
versa? | Is there a possibility that the modern day XY male phenotype to eventually evolve into a form that would resemble the female phenotype and vice versa?
As far as I know, the female and male body has a a number of homologous structures in its reproductive system, but can it in a way, evolve into one or another and if so, under what circumstances would it occur? | askscience | http://www.reddit.com/r/askscience/comments/ti41s/is_it_possible_for_a_male_phenotype_to_somehow/ | {
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"XY is the genotype, phenotype is the observable characteristics. Are you asking if an XY *genotype* can develop a female phenotype? Yes, [androgen insensitivity syndrome.](_URL_0_)",
"You might enjoy [this book](_URL_0_), which has a whole chapter on cross-sexual transfer of traits. This has certainly happened with specific traits in other species (eg, the pseudopenis of female [spotted hyenas](_URL_1_)), but I agree with preceding comments that there's no foreseeable selection pressure for something like that to happen in humans."
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xnsru | how well-supported is the big bang theory? are we fairly certain it's true? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/xnsru/eli5_how_wellsupported_is_the_big_bang_theory_are/ | {
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"Yes, and overwhelmingly so. However, you have to be careful about what you mean when you say \"Big Bang Theory\", for it is *not* a theory about how the universe was *created*, but rather how it has *evolved*. Despite what anyone will tell you, we physicists currently have no idea how the universe was created.",
"It's the best explanation based on current understanding and experimentation. ",
"Well, \nmy ELI5 version is:\nif we look at the universe, everything is getting bigger, like blowing up a balloon, or an explosion, so if that's true, then you can follow it back and imagine a time when everything was crunched up into one small bit of of stuff and it exploded and that's where we are today, in the middle of a big huge lost lasting explosion. ",
"you may need to ask /r/askscience ",
"We have a lot of evidence. The big two are the cosmic microwave background and the expansion of space/Hubble's Law.\n\nHubble was the guy who figured out that there are other galaxies. He found a super bright star and when he did the math on how far away it should be, it turned out to be outside of the milky way. He also figured out that space is growing. \n\nIt's a lot like the Doppler effect. When a train runs past you, it's louder when its moving toward you and quieter when it has passed you. Light has a similar effect, where stuff moving towards you is a teensy bit bluer and stuff moving away is a teensy bit redder. He discovered that the further away stuff was, the redder it got, which means that it was moving away faster. Hubble's Law measures the rate of this expansion.\n\nWe use Hubbles Law for a lot of things. Since we can use it to see how fast things are moving apart, we can use it to guess how things were in the past. If you know how fast a car is moving, you can guess where it was a minute ago. When we take the universe today and use hubbles law to see where things probably were 13.7 billion years ago, everything is mushed together in one spot - this is consistent with the big bang theory.\n\nThe Cosmic Microwave Background is another huge piece of evidence. Everywhere we look in space, we see microwave radiation. The microwaves are even redder the further away they are. We also see that everything is about the same temperature. In order for the radiation and temperatures to be so consistent everywhere, everything must have been touching at one point. We also know that Hubble's Law predicts a point in time in which everything was in the same place.\n\nThe last major piece of evidence is the distribution of elements. Right after the big bang, it was too hot for atoms like hydrogen to even form. When space cooled off a bit, atoms started to form. Simulations of this predict that mostly hydrogen would be made with a bit of helium and very, very tiny amounts of other elements. When we look in space, we see this distribution of elements everywhere."
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6wghqv | why do so many sicknesses and diseases start with the basic symptoms? (fever, rash, headache, vomiting, etc.) | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6wghqv/eli5_why_do_so_many_sicknesses_and_diseases_start/ | {
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"It's because those symptoms aren't something the disease does to your body, it's something your body does to the disease. Fever puts your immune cells in high gear and hampers some pathogens. Vomiting and diarrhea eject the contents of your gastrointestinal tract; because your body suspects it may be poisoned or contaminated. Rashes and headaches associated with infections are typically caused by inflammation, which is another response to infection - the body pumps immune cells and plasma out of the blood vessels and into the affected flesh to kill pathogens and get rid of dead cells."
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8juzsu | if the universe is constantly expanding, why do the stars appear as if they haven’t moved? | Isn’t there a place in Egypt where the pyramids line up perfectly with the Belt of Orion? How does this make sense if the universe is expanding outward from a point of origin? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/8juzsu/eli5_if_the_universe_is_constantly_expanding_why/ | {
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"Expansion of the universe occurs at *extremely* large scales. Far larger than even the entire Milky Way galaxy. \n\nAll the stars you can see with the naked eye are *relatively close by* and within the Milky way. Expansion is simply not significant on this scale.\n\nAlso it is not expanding outward from a *point of origin,* like an explosion. Rather, it is decreasing in density over time. If you take any two extremely distant points, then over time they become increasingly far apart. There's no preferred direction of motion from a center or towards an edge, nor is there believed to be such a thing as a center or edge to the universe, in currently well regarded theories. ",
"The stars have moved. They're moving constantly for multiple reasons (not just expansion). They are just very far away so it isn't readily apparent that they're moving without precise tracking and measurements.\n\nAnd the universe isn't expanding outward from a point of origin. Every point in space is expanding. No matter where you are in the universe you'll see everything moving away from you. ",
"All of the stars we can observe are in the Milky Way galaxy. The galaxy is not expanding, although all the stars are circling about a massive blackhole that is approximately 30,000 light years away from us.\n\nThe universe however is expanding, but the universe is trillions times the size of the galaxy. Generally speaking, the galaxies are drifting apart from one another, but this can only be observed through extremely powerful telescopes over a long period of time. ",
"They do. The light from stars are red\\-shifted \\(That is, all of the light is shifted toward lower frequency, higher wavelength, areas of the spectrum\\). This is essentially a visual form of the Doppler effect. It is because of this red shift that we know that they are moving away from us and that the universe is expanding.",
"The whole Orion thing is a crock of shit.\n\nIt was invented by a mining engineer who noticed the belt of Orion isn't quite a perfect line and claimed the pyramids of Giza were misaligned in the exact same way, and they cherry-picks various Egyptian and non-Egyptian legends to manufacture some sort of mystical significance. His ideas are rejected by actual scholars, and only really embraced by the ancient aliens crowd and other crackpots.\n\nThe theory is wrong on a number of counts:\n\n* the pyramids and the stars are *not* in the same configuration, the angles are more than a few degrees off\n* the misalignments are in the opposite direction\n* the pyramids are in fact designed to be in a perfect line with respect to one of the corners, not their apexes\n* they were arranged not to have astrological significant, but to look striking from boats traveling along the river\n\nTurns out that Orion has changed [quite a bit](_URL_0_) over the years."
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158jeg | Where did the tradition of flying flags half-mast after a tragedy come from? | The recent Sandy Hook tragedy made me wonder about this. | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/158jeg/where_did_the_tradition_of_flying_flags_halfmast/ | {
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"First recorded instance of a flag being flown at half mast was on the British ship *Heart's Ease* in 1612 when the captain was killed by a native during the voyage in search of the Northwest Passage. It seems likely that this was already a recognized symbol at the time. \n\nIt is speculated that the flag was lowered to allow the invisible flag of death to fly above. That may be why originally in Britain the flag at half mast was flown exactly one flag height lower than usual. ",
"To piggyback OP's question, does flying a flag upside down as a distress signal predate the American flag?"
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4r2aq4 | why are there so many rules on the american flag? | Also, do any other country's have such a hard-on for their flag? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4r2aq4/eli5_why_are_there_so_many_rules_on_the_american/ | {
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"Most customs regarding the American flag are not uniquely American, and are shared (in at least a similar form) with most countries of the world. For example, not flying the flag in darkness, flying it half-staff in mourning, or not letting the flag touch the ground or get dirty. However, Americans are known for their patriotism and love of the flag, so knowledge about proper flag etiquette is a bit more widespread here than in other places.",
"Mexico has a pretty strict set of rules (even though violations are not necessarily punished) that are all listed in the constitution, and their violation constitutes a military crime.\n\nThat's why you won't see any underwear or swimwear with the flag (unlike the American flag, that I've seen in every single piece of clothing I can imagine) unless special permission has been acquired (representing Mexico in the olympics, for example).\n\n"
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avfw1t | How and Why did the Franks and Visigoths start speaking Romance Languages? | After the fall of Rome, Germanic tribes migrated into the former Roman territories and set up their own kingdoms- Francia, Visigothic Spain, Ostrogothic Italy and the Vandal Kingdom of North Africa. I understand the Arab conquests of North Africa and Justinian's reconquering of Italy as the reasons for why those Gothic languages died out, but what made the Franks (who ruled their own land for centuries and were often united with their German counterparts) and the Visigoths (who were conquered by Arabic speakers, not Latin speakers) drop the Germanic languages in favor of Romance? Was it that the common people continued speaking Latin so the elites adopted it, or some other reason? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/avfw1t/how_and_why_did_the_franks_and_visigoths_start/ | {
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"Well let's look at a case study in the opposite direction and then circle back.\n\nBritain. Britain was a more or less fully Romanized province of the Empire with its own Romance speaking population, form of Roman urban life, and unity within the broader Roman economic and political world. Then it wasn't. The why isn't super important, the tl;dr is \"terrible economic crisis\". This resulted in quite a few important knock on effects, namely the collapse of urban life in Britain, the destructing of Britain as a politically cohesive whole, and the removal of Britain from the broader Roman economic world. \n\nIn the wake of this economic collapse and the coming political collapse of Roman power in Britain, Roman identity lose a great deal of its cultural cachet in Britain All of a sudden it became a lot less important to look and sound like the Romans than it did the newcomers. Assimilating to Anglo-Saxon society was the new way of career advancement and opportunity, not embracing Roman identity. Now it might behoove the native British to look and sound like a Germanic person. Now through in all the other things humans do, they intermarry, they live next to each other, and so on. This eventually created a new cultural identity that was not the sole production of the wholesale slaughter of the native British by the Angles and Saxons, but by the assimilation of the Germanic newcomes and the native British into a new culture, that while much more obviously Germanic, did retain aspects of Roman life. Robin Fleming breaks down this entire process in her *Britain after Rome* and while there is some disagreement about the scale of violence in this transitional period, I for one think she down plays it far too much, this central narrative of assimilation is currently quite dominant. \n\nSo how is this different from the experience of Iberia, Gaul, Italy, and so on? Well for one, Roman cultural cachet never totally lost its luster, and to say it did in Britain would be a mistake as well (both the surviving British polities and later Anglo-Saxon polities would later ape Romanitas, or the quality of being seen as Roman) We should also keep in mind that this is perhaps a question of numbers as well. While it is inconclusive and controversial among historians, some DNA evidence has suggested that the modern English on the east coast have a higher level of genetic material from Scandinavia and Northern Germany. These findings are not conclusive and are still controversial and may be problematized by later movements of peoples. Yet if this number is anywhere near accurate, we are seeing a truly mass migration into England, nearly 1/3, probably closer to 1/4 or even 1/5th of the populating being newcomers. This far outstrips any sort of estimate for the number of newcomers into Italy, Gaul, or Iberia, and so on. While these groups may have attempted to delineate themselves as a separate ethnicity as we see in laws such as the Salic Law, at first the newcomers would have absolutely paled in number to the established population. \n\nPeter Heather argues that the groups such as the Visigoths and Ostrogoths were not even ethnic groups originally, but essentially armies that eventually coalesced around a shared identity even if the actual constituent members of the group were far flung originally. But armies, even very large ones, could not really be as thick on the ground in places like Gaul and Italy as they could in Britain.\n\nFurthermore in Gaul, Italy, and Iberia Romanitas never really lost sway. There might have been some differences in dress, one certainly can imagine Romans gossiping about how the uppity social climber is now sporting a mustache and trousers instead of keeping to good Roman fashion, but by and large Roman identity managed to hang on and retain some cultural status and importance on a level it did not in other areas. \n\nThis extended to language as well. Language assimilation was not a quick process but it nonetheless happened. Indeed there are, few admittedly, loan words into French and Spanish from Frankish and Visigothic, but they do exist. We really shouldn't imagine that overnight the Franks and Goths woke up and decided to start speaking the local variant of Latin, it was a slow process taking a few centuries to really take hold. \n\nCertainly in much of these areas romance would have been the language of the majority of people and even of a relatively large number of aristocrats and other notables. Now we shouldn't envision the newcomers shedding their language in an effort at greater understanding or in the interests of clarity, it was a far slower process. Some individuals may have elected to learn the language and teach their children, others would have learned it from nurses and mothers, but there was still a great deal of importance placed on maintaining seperate identity as a Frank for example, just see the Salic Law on how laws applied differently to Franks vs Romans. \n\nSo in these areas you've mentioned the Germanic newcomers were a tiny fraction of the population, and despite efforts to strictly mark off Romans vs Franks for example in practice these sorts of identities were fluid and relied a great deal on societal expectations as well as a slow process of assimilation."
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93gcc9 | what are the differences between a parliament, senate, assembly and so on? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/93gcc9/eli5_what_are_the_differences_between_a/ | {
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"These are names applied to legislative bodies, and the specific authority and structure varies with each version. There's no official definition of what a specific term requires.\n\nThey may be quite powerful like the US Senate, or practically useless like the Iraqi Parliament during the Hussein regime."
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28yqky | Was Einstein's theory of relativity necessary for nuclear weapons to be created? | I just want to know if nuclear weapons could possibly have been invented without Einstein's theory of relativity.
I've read that it may have been as much as a half-century before anyone else discovered the theory of relativity and that's why Einstein has such a special place in the pantheon of famous scientists. I don't think this is a 'historical what if' question because it's specific and probably well-understood by knowledgeable people, because it's a very important question. If the theory of relativity was necessary for nuclear weapons to be invented then Einstein is a gigantically influential person in a way that I'd never fully realized before.
I'm guessing the answer to this question is obvious to historians of science and is an example of me forgetting some basics of 20th century history. I read a biography of Einstein 10 years ago and don't remember it delving into this issue though. | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/28yqky/was_einsteins_theory_of_relativity_necessary_for/ | {
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" > I've read that it may have been as much as a half-century before anyone else discovered the theory of relativity \n\nThat's only General Relativity. Special Relativity was actually a pretty obvious theory - all you needed to do was add an assumption that there's a velocity that's constant for all inertial frames. Someone else would've quickly figured it out if not Einstein.\n\n---\n\nSpecial Relativity is useful to compute energies and velocities of particles and gives rise to mass-energy equivalence which is also extremely useful for calculations in nuclear and particle physics.\n\nSo, yes, the theory of special relativity is very important to nuclear physics. But no, there's no strong indication that without Einstein this leap would've not been made during that time period.\n\nIt's speculated, however, that General Relativity was a huge leap given the existing state of physics and would've taken longer to derive without Einstein. But that's a very subjective and speculative statement and there's no evidence or science you can use to gauge these things - so you're unlikely to get a useful answer regarding that.\n\nYou might enjoy the following Wikipedia pages:\n\n_URL_0_\n\n_URL_1_\n\n---\n\nEdit: To definitively answer your question: No, the creation of atom bombs was not possible (unless by accident, somehow) without early quantum mechanics and special relativity.",
"Disclaimer: I'm a physicist and not an historian.\n\nSo... Einstein was hugely influential in that he wrote to the president to warn him about the possibility that the Germans were building an atomic bomb, and this was a factor that resulted in the start of the Manhattan project. \n\nRegarding the impact of the theory of relativity, instead, I wouldn't really know, I'm not aware of sources that explore this. Anyway, I can tell you that back then (starting about 1900) was a time of huge revolutions in physics. Discoveries in different fields happened one right after another, sometimes in apparently independent fields. So... Theory of special relativity, with its E=mc^2, is fundamental to justify how can nuclear reactions deliver so much energy. Otherwise it couldn't be explained in any way! Yet again, even today, nuclear physics is usually handled without taking relativity into account. Research on nuclear physics, particle physics and x-rays was already going on independently from relativity at a full pace. Radioactivity was already known, somehow, in 1902. The first cross-over between quantum mechanics and relativiy, the Dirac equation that accounted for particles at relativistic speeds, was developed only in 1928 and it was important only for particle physics, not for standard nuclear reactions. \n\nTherefore I'd guess that they would have been able to build a bomb even without knowing relativity at all. (indeed no relativistic knowledge is needed to build one at any time, if one is fine with knowing that starting from x grams of uranium one obtains x-y grams of other elements and lots of energy, without asking himself how it's possible to convert energy into matter.)",
"No it would not be necessary. E = mc^2 applies to chemical reactions as well as nuclear reactions, but people were doing chemistry long before relativity. \n\nRelativity allows us to understand the underlying mechanisms of nuclear weapons, but that understanding is largely academic with existing technology and would not be necessary to actually make the bomb.\n\nSource: Am physical chemist.",
"Since you seem interested primarily in the historical context of making atomic bombs, here's a rough overview with relation to Einstein:\n\n* 1895, Röntgen discovers X-rays. People say, \"whoa, there is a whole invisible physical world to probe!\"\n\n* 1898, Becquerel finds that X-ray like emissions come out of uranium. The Curies look into this and dub the phenomena radioactivity. They recognize that in some substances, e.g. radium, the amount of energy being released is _tremendous_ compared to the volume of the atoms in question — that it is much, much more energetic than any chemical combustion, but it is hard to extract that energy because you can't make it all be released at once. Soddy and Rutherford determine ca. 1900 that this is because of atomic transmutation, i.e. the atom is breaking down. They also start some of the first experiments to modify atomic compositions.\n\n* 1905, Einstein publishes his four papers that constitute Special Relativity. One of them derives the mass-energy relationship. It is interesting but has no obvious applications. The two papers that get the most attention from this series is the one on the photoelectric effect, which helps establish the physical reality of the \"quantum,\" and his work on the Lorentz contraction which discards with the idea of a preferred \"rest frame\" and the aether. (Neither have anything specific to do with atomic bombs.)\n\n* 1909, Rutherford et al. do experiments which imply that atoms contain most of their mass in a centralized nucleus, surrounded by whirring electrons. This work is important both for its establishment of an influential (if problematic) atomic model, but also its illustration of the value of using radioactive particles (e.g. alpha particles) as experimental tools. \n\n* 1913, Bohr modifies Rutherford's atomic model, replacing the whirring electrons with electrons in stable orbits that make \"quantum leaps\" between orbits. This resolves some of the problems with Rutherford's model but raises new questions (e.g. why are some orbits stable and some not?). \n\n* 1915: Einstein publishes his General Theory of Relativity, which is essentially a theory of gravity. It has nothing to do with energy release. In 1918 it is apparently confirmed by observations by Eddington which catapults Einstein into a celebrity level of scientific stardom.\n\n* 1910s-1920s: Bohr, Heisenberg, and others develop quantum mechanics. This is distinctly different from the quantum theory of Einstein and Planck. It is full of many unintuitive notions regarding the nature of information, the nature of reality, and the nature of physical theory itself. Einstein hates it and has many impassioned disputes with Bohr about it. (Einstein doesn't disagree with the quantitative results but refuses to believe in a universe where anything is fundamentally unknowable.) \n\n* 1932: Lawrence invents and builds the cyclotron, the first of a new type of high-energy particle accelerator — a machine that lets researchers shoot various particles at targets and see the results. Over the course of the 1930s Lawrence builds successively larger accelerators that allow for higher energies to be achieved, and are used to explore many new atomic and subatomic phenomena. \n\n* 1932: Chadwick establishes the existence of the neutron, a neutrally-charged subatomic particle in the atomic nucleus. It immediately is obvious that it will be a valuable new tool for probing how atoms are made, because of its lack of an electrical charge. (Protons are positively charged and thus repel one another; electrons are repelled by other electrons. Neutrons are repelled by nothing.)\n\n* 1934: The Joliot-Curies announce their discovery of artificial radioactivity — that bombarding elements with radioactive particles can change their atomic makeup and make them radioactive in turn.\n\n* 1934: Fermi conducts experiments involving the irradiation of uranium with neutrons. He finds that when the neutrons are slowed down (moderated, in modern terminology) by first bouncing off of lighter atoms (e.g. carbon and oxygen), they are more readily absorbed. He observes radioactivity after shooting uranium with the neutrons and concludes that new heavy elements are being created.\n\n* 1938: The chemists Hahn and Strassmann, in Berlin, finalize their work that replicates Fermi's experiment but use very subtle and careful nuclear chemistry techniques to isolate the byproducts of the uranium + neutrons reaction. They do not find new heavy elements, they find only unusually radioactive light elements (like barium). They find this inexplicable. Hahn writes to Meitner (a Jewish physicist who worked in their lab but was exiled to Sweden by the Nazis) to ask for her interpretation. She discusses this with her nephew, Frisch, and they conclude the uranium atoms must be splitting. They use E=mc^2 to calculate the predicted energy release — a lot per individual atom, though still not a lot from a human point of view. They dub this splitting process \"fission.\"\n\n* Early 1939: Hahn, Strassmann, Meitner, and Frisch publish papers on nuclear fission. Physicists around the world are fascinated and shocked — it is an entirely new, unexpected physical process. Some suspect that maybe there is a lot of energy that can be released from it but most think that industrial applications are decades off. A few start to wonder about weapons. Szilard, a Hungarian physicist in exile in the USA, immediately suspects a bomb may be possible, because he has long been thinking about the possibility of neutron-based nuclear chain reactions. He attempts to convince other non-German scientists to not publish on the possibility of using fission in a weapons context, and is largely successful. \n\n* Spring 1939: Joliot-Curie and his team do not agree with the self-censorship and publishes evidence (the number of secondary neutrons per fission) that implies that nuclear weapons may be possible. Bohr and Wheeler publish the first theoretical treatment of fission which establishes that two isotopes of uranium are involved and that only one of them is fissionable by both fast and slow neutrons (U-235). They conclude that making an atomic bomb would be extremely difficult.\n\n* Late 1939: Szilard, frustrated that most physicists in the USA are not taking the idea of an atomic bomb seriously — and the idea that the Germans might be able to get one — goes to Einstein and tells him of his fears. Einstein agrees to collaborate with Szilard on a letter to Roosevelt. Roosevelt agrees to establish a government committee with responsibility to look into whether fission is a military question worth worrying about. Einstein is essentially uninvolved with future fission work. \n\n* Late 1942: After a series of slow starts and disinterest, the American work on fission begins in earnest, and the Manhattan Project — the project to actually build an atomic bomb, not just study whether they are feasible — begins. \n\nI've obviously picked and chosen the events to include here, but it reflects my feeling on what sorts of things mattered or didn't. As you can see, Einstein and his work only shows up here and there. There is an entirely separate trajectory of investigation of particle physics that leads directly to the bomb. It was not begun by Einstein's work and Einstein's work played a very minor role in it. E=mc^2 is a convenient way to calculate energy release from fission (though not the only way at all, and not necessarily the most intuitive way), but it is not actually required for any of this. It does however provide a complement to work already going on regarding atomic structure, radioactivity, particle physics, and eventually fission. \n\nWithout getting too counter-historical, I think you can imagine a trajectory of science that develops an understanding of nuclear fission entirely without relativity. The fission process itself is non-relativistic. It is more intuitive to calculate the energy release primarily in terms of electrostatic repulsion of distended parts of a deformed nuclei. In terms of what actually happened, Einstein's work is not entirely alien to it — knowledge of his work was definitely in the heads of the people who worked on this stuff. However if Einstein had never existed and special relativity had never existed, it would not change the above timeline all too much, I don't think. \n\nFor people who are interested in what kinds of things physicists were thinking about in the exciting late-19th/early-20th century, Helge Kragh's _Quantum Generations_ is an excellent (if sometimes perhaps too technical) history of physics, and is not teleological like many bomb-centric histories of physics are (e.g. Rhodes' book on the history of the atomic bomb, while excellent, of course is interested primarily in what led to the bomb — Kragh's book does include the bomb of course but is not oriented around it). "
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|
385syr | selfIs there a definitive book/encyclopaedia of Australian Indigenous history? | I'm looking into Indigenous history, and I'm wondering if there is one particular collection on the various tribal histories. I know these are immense and varied, but I'm wondering if in Australian Indigenous Studies there is a text (or set of texts) that are held above others.
Not doing an assignment/research, just curious about looking into this topic, and wondering if anyone here happens to be an expert and could lead me in the right direction (or at least a good starting point)
| AskHistorians | http://www.reddit.com/r/AskHistorians/comments/385syr/selfis_there_a_definitive_bookencyclopaedia_of/ | {
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"Definitive no, there are hundreds if not a 1000+ tribes originally in Australia. Not all were well documented. It depends which side you are interested in, the view of the colonials or Aboriginal people writing about their own specific tribe/language. ",
"You might be interested in u/Reedstilt's recommendations [here,](_URL_0_) though they might not be what you wanted."
]
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31pzh4 | why does heat aggravate the taste of spice? and cold the affects of menthol? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/31pzh4/eli5_why_does_heat_aggravate_the_taste_of_spice/ | {
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"Because the chemical responsible for \"spice\" capsaicin, activates the same receptors that actual heat does, so when you add temperature heat to it, its magnified. Similarly, menthol activates the same receptors that actual cold does, again magnifying the effects when you expose it to both menthol and actual cold."
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1kmcmp | Why have there been so many animals that are called harlequins? | For example, the harlequin shrimp, duck, fish(rasbora), macaw, and toad, to name a few. I know a harlequin was some sort of character in Italian(correct me if I'm wrong) books for romance, though most of the harlequin animals are colorful, they don't have extravagant mating behaviors. So what is popular naming species Harlequin? | askscience | http://www.reddit.com/r/askscience/comments/1kmcmp/why_have_there_been_so_many_animals_that_are/ | {
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"The harlequin was a character in the Commedia dell'arte who traditionally wore a *patchwork* costume. So anything that has the characteristic of looking like a patchwork can be reasonably compared to a harlequin."
]
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3s667l | why does the cold virus survive longer on non-porous surfaces (stainless steel, doorknobs) than on porous surfaces (clothes, tissues) and skin? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3s667l/eli5_why_does_the_cold_virus_survive_longer_on/ | {
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"Actually it depends on envelope status. A non-enveloped virus means that it is what we refer to as \"hardy\" so it could potentially survive equally as well on any of these surfaces, which we would then refer to as fomites--especially hardy viruses like the adenoviridae are even capable of surviving chlorinated pool water for sufficient time to cause disease spread. Rhinovirus though, is less hardy and can really only survive at slightly lower body temperatures, making it slightly less hardy and therefore slightly easier to kill...I hope this is helpful! "
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8vyn6x | why do a lot of basement storage rooms/laundry rooms have a string to turn on the light but all other rooms use a light switch? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/8vyn6x/eli5_why_do_a_lot_of_basement_storage/ | {
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"Its easier to to install a fixture with a draw string than to wire to a switch. There are fixtures with the draw string already set up and because basements are usually less likely to be seen by company, the aesthetics are less important.",
"Because it works. Yeah, I guy could run power to a switch and back, but a pull string answers and utility rooms don't have to impress anyone. Running extra cable is just a waste of money. ",
"In the UK a lot of bathrooms still have a string. My understanding was that this was to avoid potentially wet hands touching a switch and causing an electric shock (very unlikely sure but still). As cellars can flood or are susceptible to damp could this factor be another consideration perhaps?",
" Because a keyhole light fixture is the absolute cheapest fixture and electrical wiring installation you can get.\n\nAlso useful to light as yet unfinished spaces where the layout isn’t determined yet",
"These basements were made to be finished at a later time. Don’t know where the walls (or eve the lights) may eventually be, so you just tack them up. You can add a switch leg later when plans are made and you know where the switches will be. Until then, pull cords. ",
"Because it's cheaper. You'll usually find the pull string in unfinished basements, and that's what they are, unfinished. The assumption is that if you finish the basement you'll install switches, otherwise this gets the job done.",
"1. It's cheaper to install than running a line to a switch.\n\n2. It's safer in rooms where water is present or that could potentially have water on the floor. Touching a poorly insulated switch with wet hands or standing in a pool of water could kill you.",
"Running electrical through concrete without proper conduit violates building code.\n\nIt is very expensive to do this and still be up to code, so this is done as a cost saving thing, and as a safety thing as others have mentioned. ",
"I wonder how many countries the string light switches are used in. Here in Sweden noone has it. Perhaps it is not allowed. If we have concrete basement we just attach the cables to the wall and put up a light switch.",
"Is t it so you do t touch the electrical while possibly standing in water or just the damp basement in general",
"I’m pretty sure the National Electrical Code does not mandate a light switch in closets, like it does for other rooms, but I don’t have my code books handy to check the exact wording. ",
"Electrician here. It’s just easier than running wires to a switch. Pull chain on the fixture serves as the switch. Simple and effective cheap way to add light to an unfinished area. ",
"I can think of 2 (ok, 3!) main reasons:\n\nConvenience - these switches could be easier to install in more difficult places \n\nRisk of electrocution - String pull switches were also used in lieu of nornmal switches in rooms where moisture build up was a problem as it increased the risk of electrocution. Eg bathrooms etc...\n\nCombination of both of the above - some basements and cellars were prone to flooding so having the electrical components in the ceiling as opposed to the wall (at risk of wetting due to flooding) drastically minimised risk of shorting or electrocution.\n\n",
"Probably because the walls are generally concrete, also if there’s a chance to flood it keeps the electrical up high to not get submerged ",
"these are meant as \"Storage/Mechanical\" rooms, so \nthey will have an outlet or two, that is required by code, so\nthey tap that for the bulb outlet.\n\nessentially it's like everything in construction, driven\nby cost.\n\n",
"Basements have block walls. it's hard to run electricity through block walls easier to suspend in the ceiling",
"Usually cost.\n\nFor a string pulled light, you just need to run one power wire to the light, put the (usually very cheap) fixture up and done. For a switched light, you need to run a power wire to a switch, buy the switch and box, install them and run a switch leg to the light. May not sound like much but if you're on a budget you can probably save $100 that way for parts and labor.",
"Also, basements/cellars are prone to flooding so the higher up the electrical items the less likely to ever have a short.",
"This is common in older houses. The answer in those cases is usually because a light switch wasn't put in originally, and no one bothered to put one in later because they're infrequently used. When I bought a 110 year old two family, there were no light switches in the bedrooms either, just wall sconces or pull strings. First thing I did was update the lighting in the rooms and basement (fortunately knob and tube had already been taken out).\n\nEdit: to clarify, originally houses had knob and tube wiring, and a basement would need wiring down the wall to get to a switch, which is tricky for knob and tube as you wouldn't want exposed wiring for that. So running the wiring through the ceiling and using pull strings was much simpler and worked just fine."
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61gnd5 | how come when you're on a roller coaster you can feel how fast you're going, but on an airplane everything feels normal? [physics] | From my VERY limited knowledge I think it must have something to do with the fact that a plane is enclosed and a roller coaster isn't lol
A plane also obviously goes way faster than a rollercoaster so that's another thing | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/61gnd5/eli5_how_come_when_youre_on_a_roller_coaster_you/ | {
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"On a roller coaster:\n\n* you can feel the wind in your face\n* much of what you perceive as \"fast\" is actually acceleration, as roller coasters are constantly changing speed and velocity...a good pilot keeps their airplane's acceleration to a minimum, mostly during takeoff and landing",
"There are two things at play here. To start with we do not every feel how fast we are going, we feel the *change* in speed. \n\nWhen an airplane speeds up down the runway to take off you feel yourself getting pushed back into your seat. But once it is at a steady speed you no longer feel that. \n\nThe other aspect is wind. In an airplane you do not feel any wind, on a roller coaster you do. You can experience this driving in a car. While inside the car you feel almost nothing, if you stick your head out the window you feel the rush of air. \n\nThose two things are what make all the difference. Together with the added quick direction changes of a roller coaster and that is why they feel completely different."
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b2egwi | Why does rain have a smell before it starts to rain? | askscience | https://www.reddit.com/r/askscience/comments/b2egwi/why_does_rain_have_a_smell_before_it_starts_to/ | {
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"Some of the smell is from soil bacteria released when the rain drops start hitting the ground. Some may be from ozone. I was told once that a culture of Streptomyces erythraeus smelled very similar to rain, as it had been used to make erythromycin, the antibiotic, in industrial quantities.",
"Actually what happens is that when the first drops of rain hit the ground, various chemical reactions take place between the water and the soil to form a substance known as \"petricor\". This substance rises up through \"aerosol bubbles\" and diffuses into our nose, producing that fragrant effect.",
"Petrichor (Greek ‘petra’ = rock / ‘ichor’ = ethereal fluid flowing in the veins of gods) was the name given to that smell by Australian scientists back in the 60’s. It’s the semi volatile compounds found in plant oils trapped in the soil and on the surface of rocks, metabolites of certain bacteria (geosmin as already mentioned) and ozone creation in the presence of electrical storms. \n\nThe Australian bush is amazing to experience the petrichor aroma in - there is often loooong stretches between rain, which means dense build up of the plants volatile oils which are then released with rare episodes of moisture. \n\nAnd it’s such a nice word to say! Petrichor! \n\n",
"Petrichor is the scent after rain fall, OP is asking about the smell before rail falls. Basically, warm moist air carries more odor molecules than cold dry air. Rain generally comes with lower barometric pressure and wind to pick up and blow odors around, maybe blowing odors from where it's already raining.\n _URL_0_",
"I've seen a lot of other answers, and they are getting close. But the correct answer to the specific smell \"before it rains\" is actually ozone.\n\n > Ozone—O3, the molecule made up of three oxygen atoms bonded together—also plays a role in the smell, especially after thunderstorms. A lightning bolt’s electrical charge can split oxygen and nitrogen molecules in the atmosphere, and they often recombine into nitric oxide (NO), which then interacts with other chemicals in the atmosphere to produce ozone. Sometimes, you can even smell ozone in the air (it has a sharp scent reminiscent of chlorine) before a storm arrives because it can be carried over long distances from high altitudes.\n\nSource: _URL_0_\n\nThe wet earthy smell comes from bacteria in the soil, the sharper scent is the ozone as explained above. And if you're smelling it before it rains it's most likely the ozone.\n",
"So if you really mean **before** there could be a few factors. First the pressure drop which means change in the density of gasses and flow. Second the winds, believe it or not scent travels in your area; when scents from one region overwhelming diffuse to another region through that fresh change in pressure or winds it will become the natural scent. Finally the actual water in the air. Ever notice how plants gather droplets of water on its surface? Most plants will excrete some wax, and in greater view lots of animals like worms also prepare for the water. Why does this matter? It doesn't, but it gives you an idea and links to the greater point of scent in general. Lots of plants have their natural scents that get lifted when these changes occur. So scents of chlorophyll aren't uncommon. \n\n\nPS. Note that lots of storms have smells they create like Ozone through lightning (electricity running through air splitting oxygen's stable form) or the smell of the ocean if it runs over water.",
"It's called petrichor, and it's a caused by a combination of oils released by plants that have settled on the soil and geosmin, a by-product of some bacteria. When rain droplets hit the soil, small air bubbles form and make aerosol compounds that carry the scent on the wind. "
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66gzxo | Is the term "frequency" meaningless for a square wave because it consists of nearly infinite harmonics of some fundamental sinusoidal frequency? | Can we find the frequency of a square wave? | askscience | https://www.reddit.com/r/askscience/comments/66gzxo/is_the_term_frequency_meaningless_for_a_square/ | {
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"No, the frequency of a square wave is not meaningless. Although a square wave can be represented by a sum of sines or cosines, bear in mind that this sum has infinite terms, which is difficult for us to get our heads round.\n\nThe sum of a million, a googol, or even a gogolplex factorial terms will still have tiny oscillations on the flat part of a square wave, but infinity is si incomprehensibly greater than any of these numbers that the sum of infinite terms will be a perfect square wave, with a single meaningful frequency.",
"It's not nearly infinite, it's actually infinite series. You can find the formula on [wiki](_URL_0_). Frequency isn't meaningless, because it's defined as number of occurrences per second. Square signal repeated x times per second makes perfect sense.",
"\"Frequency\" is defined as the number of occurrences of a repeating event per unit of time. In the case of a square wave, the square itself (or any particular feature of it, like the onset edge) is the event. And so there's no problem to count up the number of times that event recurs per second. And that's the frequency of the square. \n\nThere's no need to say that a square wave is \"really\" the superposition of a bunch of harmonics. That's true mathematically, and can be a useful way to analyze the square wave for some purposes, but it's also true that a square wave is \"really\" a square wave."
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