Einstein’s equations from thermodynamics and entanglement

It is well known that using Einstein’s equations one can prove a set of laws of “black hole thermodynamics” where the horizon area plays the role of entropy. In 1995 Jacobson showed that it is possible to reverse this logic and derive the Einstein equations by assuming that dynamical spacetime satisfies a first law of thermodynamics. More recently, in a related but different set up, the Einstein equations have been derived from a hypothesis about vacuum entanglement.