The Black Hole Information Problem: Observation, Measurement & Evidence

The problem connects event horizons, black-hole entropy, Hawking radiation, quantum entanglement, and the final state after evaporation. Proposed resolutions involve subtle information encoding in radiation, holography, modified horizon physics, remnants, or changes to semiclassical assumptions.

The issue is theoretical because astrophysical Hawking evaporation has not been directly observed. Progress comes from consistency tests, quantum-information methods, holographic models, and calculations in simplified gravitational systems.

Quantum fields near a black-hole horizon can produce Hawking radiation while partners and outgoing modes become entangled. Continued evaporation creates a tension between smooth horizon physics and preservation of quantum information, often expressed through the Page curve and entanglement arguments.

Progress comes from quantum-information arguments, holographic models, semiclassical calculations, and consistency tests rather than direct evaporation measurements.