Sinks in the landscape, Boltzmann brains and the cosmological constant problem

By Andrei Linde. 2006

161 citations recorded by the source corpus.

This paper extends a recent investigation of the string theory landscape (Ceresole et al 2006 Phys. Rev. D 74 086010), where it was found that the decay rate of de Sitter (dS) vacua to a collapsing space with a negative vacuum energy can be quite large. The parts of space that experience a decay to a collapsing space, or to a Minkowski vacuum, never return back to dS space. The channels of irreversible vacuum decay serve as sinks for the probability flow. The existence of such sinks is a distinguishing feature of the string theory landscape. We describe relations between several different probability measures for eternal inflation taking into account the existence of the sinks. The local (comoving) description of the inflationary multiverse suffers from the so-called Boltzmann brain (BB) problem unless the probability of the decay to the sinks is sufficiently large. We show that some versions of the global (volume-weighted) description do not have this problem even if one ignores the existence of the sinks. We argue that if the number of different vacua in the landscape is large enough, the anthropic solution of the cosmological constant problem in the string landscape scenario should be valid for a broad class of the probability measures which solve the BB problem. If this is correct, the solution of the cosmological constant problem may be essentially measure-independent. Finally, we describe a simplified approach to the calculations of anthropic probabilities in the landscape, which is less ambitious but also less ambiguous than other methods.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/edb7300a9701e808e2ca62ec1b8f3496e76bff4e

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Citations in the corpus

Inflationary Cosmology after Planck 2013 (2014, background): “There were many attempts to improve this antiintuitive answer, but from my perspective these attempts were misplaced: The Hartle-Hawking wave function was derived in [24] as a wave function for the ground state of the universe, and therefore it describes the most probable final state of the universe”
Boltzmann brains and the scale-factor cutoff measure of the multiverse (2008, methodology): “[17], this measure is called the “pseudo-comoving volume-weighted measure.”