How fast can a black hole release its information?

Understand

When a shell collapses through its horizon, semiclassical physics suggests that information cannot escape from this horizon.

• One might hope that nonperturbative quantum gravity effects will change this situation and avoid the `information paradox'.
• We note that string theory has provided a set of states over which the wavefunction of the shell can spread, and that the number of these states is large enough that such a spreading would significantly modify the classically expected evolution.
• In this article we perform a simple estimate of the spreading time, showing that it is much shorter than the Hawking evaporation time for the hole.