Euclidean path integral, entanglement entropy, and quantum boundary conditions

Abstract: To understand the information loss paradox in a consistent way, we provide a brief big picture that describes both outside and inside a black hole. We summary several ideas including the Euclidean path integral, the entanglement entropy, and the quantum gravitational treatment for the singularity. This integrated discussion can provide an alternative point of view toward the ultimate resolution of the information loss paradox.