Spin-Spacetime Censorship

Abstract

Quantum entanglement and relativistic causality are key concepts in theoretical works seeking to unify quantum mechanics and gravity. In this article, we show that the interplay between relativity theory and quantum entanglement has intriguing consequences for the spacetime surrounding elementary particles with spin. General relativity predicts that a spin-generated magnetic dipole field causes a (slight) bending to the spacetime around particles, breaking its spherical symmetry. However, through a gedanken experiment analyzed in the context of quantum information, we show that such a spin-related deviation from spherical symmetry would violate relativistic causality. To avoid this conundrum, the measurable spacetime around the rest frame of the particle must be spherically symmetric. This way, we show that there must be a censorship mechanism, compensating for the spin-spacetime bending and preventing the possibility of spacetime-based spin detection. The censorship mechanism may shed new light on the interface between quantum mechanics and general relativity.