Tuesdays 10:30 - 11:30 | Fridays 11:30 - 12:30
Showing votes from 2017-07-25 11:30 to 2017-07-28 12:30 | Next meeting is Tuesday May 12th, 10:30 am.
The usual theory of inflation breaks down in eternal inflation. We derive a dual description of eternal inflation in terms of a deformed IR CFT located at the threshold of eternal inflation. The partition function gives the amplitude of different geometries of the threshold surface in the Hartle-Hawking state. Its local and global behavior in dual toy models shows that the amplitude is low for surfaces which are not nearly conformal to the round three-sphere, and essentially zero for surfaces with negative curvature. Based on this we conjecture that the exit from eternal inflation does not produce an infinite fractal-like multiverse, but is finite and reasonably smooth.
In much of the literature on linearized gravitational waves two completely different notions are called transverse traceless modes and labelled $h_{ab}^{TT}$, often in different sections of the same reference, without realizing the underlying inconsistency. We compare and contrast the two notions and find that the difference persists even at leading asymptotic order near future null infinity $\mathit{I}^+$. We discuss why the distinction has nonetheless remained largely unnoticed, and also point out that there are some important physical effects where only one of the notions gives the correct answer.