Torsion or not torsion, that is the question

TL;DR

This paper explores the hypothesis that spacetime torsion may not vanish, proposing a framework and empirical tests to detect torsion through its effects on spin-polarized particles, challenging a common assumption in general relativity.

Contribution

It introduces a framework to test the vanishing-torsion hypothesis and proposes original empirical experiments involving spin-polarized particles.

Findings

Torsion could induce new interactions between spin-polarized particles.

The framework links torsion to gravitational degrees of freedom.

Empirical tests can potentially detect nonvanishing torsion.

Abstract

A hypothesis of general relativity is that spacetime torsion vanishes identically. This assumption has no empirical support; in fact, a nonvanishing torsion is compatible with all the experimental tests of general relativity. The first part of this essay specifies the framework that is suitable to test the vanishing-torsion hypothesis, and an interesting relation with the gravitational degrees of freedom is suggested. In the second part, some original empirical tests are proposed based on the observation that torsion induces new interactions between different spin-polarized particles.