Abstract

Theoretical insights from black hole physics combined with recent developments in string theory suggest that at a microscopic level the Universe has a holographic description in terms of degrees of freedom that live on the boundary of space. This is called the "holographic principle". By taking the holographic principle as starting point a simple dimensional argument naturally leads to the emergence of gravity as described by the laws of Newton, or after a relativistic
generalization by the Einstein equations. At a microscopic level the gravitational force is caused by a change in the amount of information, measured by entropy, as a result of the displacements of bodies. Hence, gravity is an entropic force. String theory provides an effective framework in which the entropic origin of gravity can be made manifest. Finally, I discuss the possible implications for quantum mechanics and cosmology.