The Equivalence Principle in a Quantum World

TL;DR

This paper explores how quantum corrections affect the classical Equivalence Principle in quantum gravity, showing that while some classical concepts are challenged, the principle's core symmetry remains fundamental in organizing the theory.

Contribution

It applies modern methods to quantum gravity at low energy, explicitly analyzing quantum corrections' impact on the classical Equivalence Principle.

Findings

Quantum corrections introduce non-locality and challenge classical EP concepts.

The core symmetry of general coordinate invariance remains central in quantum gravity.

Effective field theory framework organizes quantum gravity despite EP violations.

Abstract

We show how modern methods can be applied to quantum gravity at low energy. We test how quantum corrections challenge the classical framework behind the Equivalence Principle, for instance through introduction of non-locality from quantum physics, embodied in the Uncertainty Principle. When the energy is small we now have the tools to address this conflict explicitly. Despite the violation of some classical concepts, the EP continues to provide the core of the quantum gravity framework through the symmetry - general coordinate invariance - that is used to organize the effective field theory.