Non-singular bounce transitions in the multiverse

Abstract

According to classical GR, negative-energy (AdS) bubbles in the multiverse terminate in big crunch singularities. It has been conjectured, however, that the fundamental theory may resolve these singularities and replace them by non-singular bounces. Here we explore possible dynamics of such bounces using a simple modification of the Friedmann equation, which ensures that the scale factor bounces when the matter density reaches some critical value ${\rho }_c$. This is combined with a simple scalar field `landscape', where the energy barriers between different vacua are small compared to ${\rho }_c$. We find that the bounce typically results in a transition to another vacuum, with a scalar field displacement $\Delta \varphi \sim 1$ in Planck units. If the new vacuum is AdS, we have another bounce, and so on, until the field finally transits to a positive-energy (de Sitter) vacuum. We also consider perturbations about the homogeneous solution and discuss some of their amplification mechanisms (e.g., tachyonic instability and parametric resonance). For a generic potential, these mechanisms are much less efficient than in models of slow-roll inflation. But the amplification may still be strong enough to cause the bubble to fragment into a mosaic of different vacua.

29 pages, 11 figures, references added

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Cited by in corpus (18)

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• Bounce cosmology from $F(R)$ gravity and $F(R)$ bigravity
• A Cosmological Super-Bounce
• Bouncing cosmology from warped extra dimensional scenario
• Past incompleteness of a bouncing multiverse
• Accessibility Measure for Eternal Inflation: Dynamical Criticality and Higgs Metastability
• Search Optimization, Funnel Topography, and Dynamical Criticality on the String Landscape
• Vacuum statistics and stability in axionic landscapes
• Non-singular AdS-dS transitions in a landscape scenario
• Parity violation in pre-inflationary bounce
• A quantum measure of the multiverse
• Inflation in multi-field random Gaussian landscapes
• Bouncing universe with modified dispersion relation
• Inflation in Random Landscapes with two energy scales
• Loop Quantum Cosmology: Physics of Singularity Resolution and its Implications
• Black holes and up-tunneling suppress Boltzmann brains
• Populating the landscape in an inhomogeneous universe
• The nucleation of false vacuum bubbles with compact geometries