“Something is happening here and this is going to have an impact.” -Robert Dijkgraaf, on Verlinde’s work
There are many attempts out there to reconcile the quantum field theories that describe the electromagnetic and nuclear forces with general relativity, which describes the gravitational force. Certain questions, about gravitational properties in strong fields and on small scales, will never be answered otherwise. In order to make that happen, we’d need a quantum theory of gravity. While string theory is the most popular idea, there are others, such as asymptotic safety, loop quantum gravity, and causal dynamical triangulations.
Outside the event horizon of a black hole, General Relativity and quantum field theory are completely sufficient for understanding the physics of what occurs. But near the singularity, a quantum theory of gravity is needed. Image credit: NASA.
But perhaps the most radical idea came from Erik Verlinde in 2009: the idea that gravity itself is not fundamental, but rather arises from a truly fundamental entity: the entropy of quantum bits of information. Verlinde’s work has been intriguing and especially controversial, and I myself have spotted a number of problem areas with his results so far, but it’s certainly an idea worth exploring further. ...