Transient Observers and Variable Constants, or Repelling the Invasion of the Boltzmann's Brains

TL;DR

This paper explores how slight variations in fundamental constants could prevent the dominance of Boltzmann's brains in an eternally expanding universe, challenging assumptions about observer typicality.

Contribution

It demonstrates that small changes in physical constants can significantly alter the prevalence of Boltzmann's brains, questioning the reliability of long-term cosmological predictions.

Findings

Tiny variations in fundamental constants can suppress Boltzmann's brains.

Assumptions about the universe's future laws are uncertain and impactful.

Conclusions based on fixed laws may be unreliable in the distant future.

Abstract

If the universe expands exponentially without end, ``ordinary observers'' like ourselves may be vastly outnumbered by ``Boltzmann's brains,'' transient observers who briefly flicker into existence as a result of quantum or thermal fluctuations. One might then wonder why we are so atypical. I show that tiny changes in physics--for instance, extremely slow variations of fundamental constants--can drastically change this result, and argue that one should be wary of conclusions that rely on exact knowledge of the laws of physics in the very distant future.