Nonunitary Newtonian Gravity Makes Semiclassical Gravity Viable for All Practical Purposes

TL;DR

This paper proposes that Nonunitary Newtonian Gravity can make Semiclassical Gravity consistent and viable by preventing superluminal communication through decoherence of macroscopic superpositions.

Contribution

It introduces a model of Nonunitary Newtonian Gravity that resolves superluminal communication issues in Semiclassical Gravity.

Findings

Nonunitary Newtonian Gravity prevents superluminal signaling.

Decoherence of macroscopic superpositions is achieved.

Semiclassical Gravity becomes practically viable with this model.

Abstract

Semiclassical Gravity replaces the energy momentum tensor $T_{\mu \nu}$ with its expectation value $\langle T_{\mu \nu}\rangle$ in Einstein equations, this making the Einstein tensor $G_{\mu \nu}$ a classical variable thus avoiding the quantization of the gravitational field. Jointly with the Copenhagen interpretation of QM, Semiclassical Gravity gives rise to cases of Superluminal Communication. It is shown in a specific instance that a model of Nonunitary Newtonian Gravity avoids Superluminal Communication by decohering linear superpositions of macroscopically distinct states, namely Schrodinger's cats.