Torsion and the Probability of Inflation

TL;DR

This paper investigates how off-shell torsion in Einstein-Cartan theory influences the probability of universe creation, finding that torsion can lower the tunneling barrier and affect inflation likelihood.

Contribution

It provides a detailed analysis of torsion's role in quantum cosmology, showing that off-shell torsion can significantly alter the probability of inflationary universe formation.

Findings

Torsion can lower the tunneling barrier for universe creation.

Wave packet construction affects the probability outcome.

Higher order corrections may reverse initial conclusions for large torsion variance.

Abstract

We revisit the problem of the "probability of inflation" from the point of view of the Einstein-Cartan theory, where torsion can be present off-shell even in the absence of spinorial currents. An informal estimate suggests that the barrier for tunneling from "nothing" into a classical universe becomes thinner and lower, should torsion be present even if only off-shell. This is confirmed by a detailed calculation, where the usual assumptions are re-evaluated and repurposed in our situation. Interestingly some approximations used in the literature (such as the WKB approximation) are not needed in general, and in particular in our case. When we consider wave packets centered around zero torsion, however, the conclusion depends crucially how these are built. With a Klein-Gordon current prescription for the measure and probability, for small torsion variance, {\sigma}_c, we recover the plane wave results. Nonetheless, for large {\sigma}c, higher order corrections could reverse this conclusion.