Classically Stable Nonsingular Cosmological Bounces

Anna Ijjas, Paul J. Steinhardt

Research output: Contribution to journalArticle

69 Scopus citations

Abstract

One of the fundamental questions of theoretical cosmology is whether the Universe can undergo a nonsingular bounce, i.e., smoothly transit from a period of contraction to a period of expansion through violation of the null energy condition (NEC) at energies well below the Planck scale and at finite values of the scale factor such that the entire evolution remains classical. A common claim has been that a nonsingular bounce either leads to ghost or gradient instabilities or a cosmological singularity. In this Letter, we consider a well-motivated class of theories based on the cubic Galileon action and present a procedure for explicitly constructing examples of a nonsingular cosmological bounce without encountering any pathologies and maintaining a subluminal sound speed for comoving curvature modes throughout the NEC violating phase. We also discuss the relation between our procedure and earlier work.

Original languageEnglish (US)
Article number121304
JournalPhysical review letters
Volume117
Issue number12
DOIs
StatePublished - Sep 16 2016

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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