  In a recent publication in this journal, Erik Verlinde attempts to show that
gravity should be viewed not as a fundamental force, but rather as an emergent
thermodynamic phenomenon arising from an unspecified microscopic theory via
equipartition and holography. This paper presents a challenge to his
reformulation of gravity. A detailed examination of Verlinde's derivation leads
to a number of questions that severely weaken the claim that such a theory
correctly reproduces Newton's laws or Einstein gravity. In particular, we find
that neither Newtonian gravity nor the Einstein equations are uniquely
determined using Verlinde's postulates.
