Gravitational Couplings of Intrinsic Spin

TL;DR

This paper reviews how intrinsic spin interacts with gravity, highlighting a measurable quantum effect involving energy differences of spin-1/2 particles near rotating masses, which could be experimentally observed soon.

Contribution

It presents a detailed analysis of the gravitational coupling of intrinsic spin, including a specific prediction of energy differences in spin-1/2 particles near rotating bodies, linking quantum mechanics and gravity.

Findings

Energy difference of spin-1/2 particles is proportional to the body's angular momentum.

The effect depends on latitude and rotational parameters of the mass.

Potential for experimental detection of relativistic quantum gravitational effects.

Abstract

The gravitational couplings of intrinsic spin are briefly reviewed. A consequence of the Dirac equation in the exterior gravitational field of a rotating mass is considered in detail, namely, the difference in the energy of a spin-1/2 particle polarized vertically up and down near the surface of a rotating body is $\hbar\Omega\sin\theta$. Here $\theta$ is the latitude and $\Omega = 2GJ/(c^2 R^3)$, where $J$ and $R$ are, respectively, the angular momentum and radius of the body. It seems that this relativistic quantum gravitational effect could be measurable in the foreseeable future.