Fuzzball (string theory)

In string theory, a fuzzball is a hypothetical alternative description of black holes, proposing that they are not empty singularities surrounded by an event horizon, but rather are composed of a quantum "fuzz." This fuzz is made up of fundamental strings and branes in highly excited states, representing all possible configurations of these objects consistent with the black hole's external properties such as mass, charge, and angular momentum.

The fuzzball proposal aims to resolve several paradoxes associated with black holes, particularly the information loss paradox. According to this paradox, the formation and subsequent Hawking evaporation of a black hole seemingly destroys information about the matter that fell into it, violating fundamental principles of quantum mechanics.

The fuzzball picture suggests that the event horizon is not a sharp boundary but instead a region where space-time transitions into a complicated, fluctuating quantum state. Because the black hole interior is not empty, but filled with this "fuzz," information is not necessarily lost when matter falls in. Instead, the information is encoded in the specific microstate configuration of the fuzzball.

While the idea is promising, it remains a subject of active research and investigation. Constructing explicit fuzzball solutions for realistic black holes is a significant challenge, and the extent to which they can truly resolve the information paradox is still debated. However, the fuzzball proposal offers a compelling alternative perspective on the nature of black holes within the framework of string theory.