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  • Open Access

On the Quantum Mechanics of Entropic Forces

Daniel Carney1,*, Manthos Karydas1, Thilo Scharnhorst1,2, Roshni Singh1,2, and Jacob M. Taylor3,4

  • *Contact author: carney@lbl.gov
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Phys. Rev. X 15, 031038 – Published 11 August, 2025

DOI: https://doi.org/10.1103/y7sy-3by1

Abstract

It was conjectured 30 years ago that gravity could arise from the entropic rearrangement of information. We offer a set of microscopic quantum models which realize this idea in detail. In particular, we suggest a simple mechanism by which Newton’s law of gravity arises from extremization of the free energy of a collection of qubits or oscillators, rather than from the exchange of virtual quanta of a fundamental field. We give both a local and a nonlocal version of the construction and show how to distinguish a range of these entropic models from ordinary perturbative quantum gravity using existing observations and near-term experiments.

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Popular Summary

The fundamental nature of gravity at the quantum level remains one of the biggest mysteries in physics. A popular idea is that gravity, like electromagnetism, is carried by particles—gravitons—just as light is carried by photons. But an alternative view, proposed by Jacobson and later refined by Verlinde, suggests that gravity might not be fundamental at all. Instead, it could emerge from some deeper, microscopic structure—similar to how sound waves arise from the collective motion of molecules in a gas. In this work, we present a detailed microscopic model that realizes this idea, offering a concrete picture of the ”molecules” that might make up spacetime.

We construct a quantum-mechanical model in which the gravitational field appears as a large-scale, thermodynamic phenomenon, just like pressure or temperature in a gas. This model allows us to describe the underlying quantum constituents of the gravitational field and to show how gravity could emerge from their collective behavior. Crucially, we go beyond theory and propose real-world experimental tests that can distinguish our emergent model from traditional particle-based theories of gravity. Our analysis shows that current or near-future experiments could detect these differences.

This marks a major step forward in the study of emergent gravity. For decades, the idea that gravity might emerge from a thermodynamic picture remained untestable, because no one could show how it worked in a fully quantum setting or what experimental signatures it might produce. Our results propose concrete answers to both of these long-standing questions and provide a road map to test the entropic nature of gravity in the lab.

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Outline

Information

Phys. Rev. X 15, 031038– Published 11 August, 2025
  • Received 26 February 2025
  • Revised 25 May 2025
  • Accepted 14 July 2025
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

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