A paradox in the global description of the multiverse

TL;DR

The paper targets a paradox in the global multiverse description, where Page shows that most observers could arise from quantum fluctuations rather than conventional evolution, conflicting with our observations. It analyzes the Page paradox and argues that a local causal-diamond viewpoint resolves the issue by removing global infinities and yielding finite, well-defined probabilities. It derives a nontrivial bound on vacuum lifetimes to avoid eternal inflation, and discusses broader constraints on the string landscape to suppress Boltzmann brains. The work advocates abandoning the global description in favor of a local perspective, with significant implications for cosmology and landscape-based predictions.

Abstract

We use an argument by Page to exhibit a paradox in the global description of the multiverse: the overwhelming majority of observers arise from quantum fluctuations and not by conventional evolution. Unless we are extremely atypical, this contradicts observation. The paradox does not arise in the local description of the multiverse, but similar arguments yield interesting constraints on the maximum lifetime of metastable vacua.