Horizon entropy and the Einstein equation

This mini-course of four lectures is an introduction, review, and critique of two approaches to deriving the Einstein equation from hypotheses about horizon entropy. 

It will be based on two papers: 

• "Thermodynamics of Spacetime: The Einstein Equation of State" arxiv.org/abs/gr-qc/9504004
• "Entanglement Equilibrium and the Einstein Equation" arxiv.org/abs/1505.04753

We may also discuss ideas in "Gravitation and vacuum entanglement entropy" arxiv.org/abs/1204.6349