Zenith Grant Awardee

Dr. Laura Mersini-Houghton

University of North Carolina at Chapel Hill

Co-Investigators

Richard Holman, <i>Carnegie Melon</i>

Project Title

The Puzzle of the Initial Conditions and the Multiverse

Project Summary

We believe our universe started with high energy inflation. We also know it is inflating again at present. Both events seem extremely unlikely with our current understanding of physics. This disturbing fundamental issue seem to guide us to a picture where the missing piece in the puzzle is an extension of our theories to the multiverse framework and where the dynamics of gravity plays a crucial role. Three important theories predict a multiverse. Yet only one can correspond to physical reality. We thus need a better understanding of the ontology of the multiverse; its background space-time; and, potential observational imprints. We proposed to study the selection of the initial conditions by taking the multiverse to be the landscape of (3+1) dimensional worlds predicted by string theory. In this picture matter content in each initial patch tries to crunch the domain to a point while the energy of the vacuum (inflaton energy) tries to blow it apart. Thus the only way for our universe to grow large and to survive the pull of matter is by starting at high energies. One of our predictions here, the existence of a giant void was confirmed by observations only 7 months later.

Technical Abstract

The outstanding issue of the selection of the initial conditions of our universe has guided us to an investigation of the multiverse. We advocated that this puzzle can be resolved only by taking into account a dynamic evolution of the initial domains within the framework of the multiverse. Our working model for the multiverse has been the landscape of string theory. No theory can be taken seriously unless it makes predictions that can be tested. Thus the potential for observational imprints from the earliest times and for the multiverse, is an important direction we pursue.