Comment on "Emergent Gravity and the Dark Universe" by Erik Verlinde

TL;DR

This paper discusses Verlinde's emergent gravity theory, its theoretical derivation of Milgrom's constant, and observational analyses showing a smaller preferred value of this constant in galaxy rotation curves, aligning with recent cosmological findings.

Contribution

The paper provides observational evidence that a smaller Milgrom's constant than Verlinde's original prediction better fits galaxy rotation data.

Findings

A preferred Milgrom's constant about 30% smaller than Verlinde's original value.

The preferred value aligns with recent applications to the FLRW universe.

Supports emergent gravity as a viable alternative to dark matter.

Abstract

Verlinde suggested a new theory of gravity called ``emergent gravity,'' which resembles Modified Newtonian Dynamics, the alternative to dark matter theory. For his version of Milgrom's constant, he theoretically derived $a_M=cH_0/6=1.1\times 10^{-10}$m/s$^2$ by assuming that our universe is a flat de Sitter space, which is not certainly true. In 2022, when Park and us applied Verlinde's emergent gravity to galaxy rotation curves, we discovered that a slightly smaller value of $a_M$ is preferred. We re-ran our codes and obtained that a value about 30\% smaller than Verlinde's original value of Milgrom's constant is most preferred. This agrees with the value obtained recently by applying Verlinde's emergent gravity to the general FLRW universe.