It is argued that the thermal Hawking radiation emitted by a black hole is accompanied by a (highly correlated) soft radiation which may be enough to purify the overall state.

This is the latest schematic outline of how soft emission may resolve the black hole information paradox. This relies on the correlations between hard and soft particles being sufficient to purify the quantum state, and so no information (about the total system) is lost. The argument that the state can be purified rests on conservation laws in theories of pure gravity (with no stable matter). It is mentioned that for every additional massless particle one obtains a new (infinity) family of conserved asymptotic charges, which would need to be taken into account in order to distinguish different states in the Hawking ensemble.