# Gravitational Coupling from Active Gravity

## TL;DR

This paper proposes a novel gravitational coupling based on a new energy-momentum tensor motivated by quantum measurement, leading to an Einstein-Cartan type theory with additional torsion-matter interactions.

## Contribution

It introduces a new energy-momentum tensor for gravitational coupling, resulting in a theory with torsion-matter interactions derived from a second-derivative Lagrangian.

## Key findings

- New energy-momentum tensor motivated by quantum measurement.
- Derived Einstein-Cartan type theory with torsion-matter coupling.
- Potential for more general tests of relativistic effects.

## Abstract

We attempt to construct a gravitational coupling by pre-selecting an energy-momentum tensor as the source for gravitational field. The energy-momentum tensor we take is a recently derived new expression motivated by joint localization of energy and momentum in quantum measurement. This energy-momentum tensor differs from the traditional canonical and symmetric ones, and the theory we obtain is of an Einstein-Cartan type, but derived from a minimal coupling of a Lagrangian with second-derivative, and leads to additional interaction between torsion and matter, including the scalar field. For the scalar field, the theory can also be derived in the Riemann space-time by a non-minimal coupling. Our study gives hint on more general tests of general relativistic effects.