Black holes and information — an update

For perspective on the information problem, one can state a “Black hole theorem,” and examine its possible loopholes, and what they tell us about the structure of quantum gravity. Different proposals can be characterized by how they might evade this theorem; for example an interesting question is how replica wormholes do so. Key questions are whether black holes can be thought of as subsystems in quantum gravity, and whether they have additional interactions with their environments not predicted by local quantum field theory.