Gravitation and vacuum entanglement entropy

Understand

The vacuum of quantum fields contains correlated fluctuations.

• When restricted to one side of a surface these have a huge entropy of entanglement that scales with the surface area.
• If UV physics renders this entropy finite, then a thermodynamic argument implies the existence of gravity.
• That is, the causal structure of spacetime must be dynamical and governed by the Einstein equation with Newton's constant inversely proportional to the entropy density.