Speaker
Pankaj Saha
Description
Inflation is almost always described as small ripples on a fixed, smooth background --- but that picture is expected to break down when fluctuations grow large. We push into that regime with 3+1 lattice simulations in which the field and the local expansion evolve together. This lets us follow inflation into the strongly nonlinear regime relevant for primordial black holes, where the power spectrum becomes very large. I will show how differential expansion reweights the physical volume --- "volume selection" --- and can reverse the volume-averaged inflaton, and discuss what this means for perturbation theory.