On gravity as an entropic force

TL;DR

This paper reexamines Verlinde's entropic gravity theory, showing it aligns with Newtonian gravity for neutron quantum states but cannot explain certain quantum transitions without additional assumptions, suggesting the need for a quantized gravity framework.

Contribution

The paper clarifies the compatibility of entropic gravity with neutron quantum states and highlights its limitations in explaining quantum transitions, indicating the necessity for a quantum theory of gravity.

Findings

EG aligns with Newtonian gravity for gravitationally-bound neutron states

EG cannot explain spontaneous decay transitions of neutron quantum states

A quantized gravity theory may be necessary to explain observed phenomena

Abstract

We consider E. Verlinde's proposal that gravity is an entropic force -- we shall call this theory entropic gravity (EG) -- and reanalyze a recent claim that this theory is in contradiction with the observation of the gravitationally-bound ground state of neutrons in the GRANIT experiment. We find that EG does not necessarily contradict the existence of gravitationally-bound quantum states of neutrons in the Earth's gravitational field, since EG is equivalent to Newtonian gravity in this case. However, certain transitions between the gravitationally-bound quantum states of neutrons, in particular spontaneous decays of excited states, which can hopefully be observed in future experiments, cannot be explained in the framework of EG, unless essential ingredients are introduced into it. Otherwise, a quantized description of gravity will be required.