## "The Born Again Universe"

**Speaker:**David E. Kaplan, Johns Hopkins University

**When:**October 4, 2017 (Wed), 03:45PM to 04:45PM (add to my calendar)

**Location:**PRB 595

*This event is part of the HET Seminar Series. *

We present a class of non-singular, bouncing cosmologies which do not rely on unstable, null energy condition (NEC) violating fluids. These cosmologies evade singularity theorems through the use of vorticity in compact extra dimensions. The vorticity combats the focusing of geodesics during the contracting phase. The compact extra dimensions rely on stable NEC violating sources such as Casimir energy. The four dimensional effective theory contains an NEC violating fluid of Kaluza-Klein excitations of the higher dimensional metric. These spacetime metrics could potentially allow dynamical relaxation to solve the cosmological constant problem. These ideas can also be used to support traversable Lorentzian wormholes.