Hard Art of the Universe Creation

TL;DR

This work introduces a stochastic diffusion framework to study tunneling and baby-universe formation as an alternative to Euclidean quantum cosmology. By treating inflationary fluctuations as Brownian motion, it derives a stationary probability distribution $P(\phi) \propto \exp\left(\frac{3M_p^4}{8V(\phi)}\right)$ under suitable conditions and shows that stochastic results reproduce many Euclidean predictions for bubble nucleation and tunneling, while clarifying validity limits during inflation. It then extends the approach to quantify the likelihood of creating inflationary domains in Minkowski space and in laboratory settings, yielding explicit expressions such as $P(\phi) \sim \exp(-C\frac{4\pi^2}{\lambda})$ for a quartic potential and $P(\phi) \sim \exp(-C\frac{8\pi^2M_p^2}{m^2})$ for a massive scalar, with maximal probabilities set by $P_{\max}$ scales. The analysis highlights regimes (large $\lambda$ or Planck-scale masses) where baby-universe formation could be efficient, discusses conceptual and technical caveats (backreaction, contraction, non-local effects), and explores the broader implications for vacuum structure and possible nonlocal couplings between baby universes and our own.

Abstract

We develop a stochastic approach to the theory of tunneling with the baby universe formation. This method is applied also to the theory of creation of the universe in a laboratory.