text
stringlengths 0
44.4k
|
---|
FIG. 4. Cascade creation of bubble universes. In this figure, |
we assume trajectory Ais the eternal inflation trajectory, and |
trajectory Bis the non-eternal inflation trajectory. |
of the spatial volume remain in the old bubble universe |
at the instant of tunneling. |
If bifurcations of multi-stream inflation happen dur- |
ing eternal inflation, two kinds of new bubble universes |
can be created with similar probabilities. In this case, |
at the instant of bifurcation, both kinds of bubble uni- |
verseshavenearlyequalspatialvolume. Withachangeof |
probabilities, the measures for eternal inflation should be |
reconsideredformulti-streamtype bubble creationmech- |
anism. |
If the inflation trajectories recombine after a period of |
inflation, the different bubble universes will eventually |
have the same physical laws and constants of nature. On |
the other hand, if the different inflation trajectories do |
not recombine, then the different bubble universes cre- |
ated by the bifurcation will have different vacuum ex- |
pectation values of the scalar fields, resulting to different |
physical laws or constants of nature. It is interesting |
to investigate whether the bifurcation effect is more ef- |
fective than the tunneling effect to populate the string |
theory landscape. |
Note that in multi-stream inflation, it is still possi- |
ble that different trajectorieshaveexponentiallydifferent |
probabilities, as discussed in the previous section. In this |
case, multi-stream inflation behaves similar to Hawking |
Moss instantons during eternal inflation. |
Local terminations for eternal inflation . It is possible |
that during multi-stream inflation, a inflation trajectory |
bifurcates in to one eternal inflation trajectory and one |
non-eternal inflation trajectory with similar probability. |
Inthiscase,theinflatonintheeternalinflationtrajectory |
frequently jumps back to the bifurcation point, resulting |
in a cascade creation of bubble universes, as illustrated |
in Fig. 4. This cascade creation of bubble universes, if4 |
realized, is more efficient in producing reheating bubbles |
than tunneling effects. Thus it reduces the measure for |
eternal inflation. |
There are some other interesting issues for bifurcation |
in the multiverse. For example, the bubble walls may |
be observable in the present observable universe, and the |
bifurcations can lead to multiverse without eternal infla- |
tion. These possibilities are discussed in [5]. |
IV. CONCLUSION AND DISCUSSION |
To conclude, webriefly reviewedmulti-stream inflation |
during observable inflation. Some new issues such as do-main fences and connection with quasi-single field infla- |
tion are discussed. We also discussed multi-stream infla- |
tion in the context of eternal inflation. The bifurcation |
effect in multi-stream inflation provides an alternative |
mechanism for creating bubble universes and populating |
the string theory landscape. The bifurcation effect also |
provides a very efficient mechanism to locally terminate |
eternal inflation. |
ACKNOWLEDGMENT |
We thank Yifu Cai for discussion. This work was sup- |
ported by NSERC and an IPP postdoctoral fellowship. |
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arXiv:1001.0009v1 [q-bio.BM] 30 Dec 2009Jamming proteins with slipknots and their free energy lands cape |
Joanna I. Su/suppress lkowska1, Piotr Su/suppress lkowski2,3,4and Jos´ e N. Onuchic1 |
1Center for Theoretical Biological Physics, |
University of California San Diego, |
Gilman Drive 9500, La Jolla 92037, |
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