Physical Society Colloquium

How string theory resolves the black hole information paradox

Samir Mathur

Department of Physics
Ohio State University

General relativity tells us that we can make black holes. Some 35 years ago, Stephen Hawking showed that quantum effects cause the hole to slowly evaporate away, in a way that violates the basic principles of quantum theory. Thus if general relativity and quantum theory are to fit together, we must resolve this ‘black hole information paradox’. In this colloquium I will show how string theory has now offered us a way out of this puzzle. Quantum gravity effects turn out to not be confined to within the planck length, but rather extend over distances that grow with the number of quanta involved in the interaction. Black holes are made from a very large number of quanta, and these quantum effects change the entire interior of the horizon into a ‘fuzzball’. The essential physics emerging here may be relevant in other problems where we have dense matter, for example in the early Universe