  Combining a variety of results in string theory and general relativity, a
picture of the black hole interior is developed wherein spacetime caps off at
an inner horizon, and the inter-horizon region is occupied by a Hagedorn gas of
a very low tension state of fractionated branes. This picture leads to natural
resolutions of a variety of puzzles concerning quantum black holes. Gravity
Research Foundation 2015 Fourth Prize Award for Essays on Gravitation.
