Prof. Samir D. Mathur

In 1975, Stephen Hawking found a startling result: if black holes have the structure deduced by Chandrasekhar, then quantum theory will be violated. This result has been a crucial ingredient in the search for a unified theory of physics for the past 40 years. Over the past two decades, we have found a resolution to Hawking's paradox through string theory. Black holes do not have all their mass in a central singularity; instead, they are horizon sized quantum objects called fuzzballs. The large entropy of a black hole, called the Bekenstein entropy leads to a violation of the semiclassical dynamics which had been assumed by Chandrasekhar. This resolution of the puzzle has interesting implications for cosmology, which also manifests a horizon at the cosmological scale.