User:Greg L/Fuzzballs (string theory)
Quantum description of black holes / From Wikipedia, the free encyclopedia
Fuzzball theory, which is derived from superstring theory, is advanced by its proponents as a description of black holes that harmonizes quantum mechanics and Albert Einstein’s general theory of relativity, which have long been incompatible.
Fuzzball theory dispenses with the singularity at the heart of a black hole by positing that the entire region within the black hole’s event horizon is actually an extended object: a ball of strings, which are advanced as the ultimate building blocks of matter and light. Under string theory, strings are bundles of energy vibrating in complex ways in both the three physical dimensions of space as well as in compact directions—extra dimensions interwoven in the quantum foam (see Fig. 2 and Fig. 9, below).[1]
Fuzzball theory addresses two intractable problems that classic black hole theory poses for modern physics:
- It dispenses with the gravitational singularity at the heart of the black hole, which is thought to be surrounded by an event horizon, the inside of which is detached from the space and time—spacetime—of the rest of the universe (see Fig. 1 ). Conventional black hole theory holds that a singularity is a zero-dimensional, zero-volume point in which all of a black hole’s mass exists at infinite density.[1][Note 1] Such a theory is highly problematic because spacetime breaks down catastrophically when gravitational acceleration is infinite. For over a century, these theoretical tensions helped motivate theoretical physicists to examine whether black holes could be extended objects composed of some form of degenerate quantum matter (see Exotic star ).
Importantly, a 2023 scientific paper by a prominent black hole theoretical physicist added impetus to the view that black holes may actually be singularity-free extended objects. That paper detailed how a journal paper published in 1965 had an error in its treatment of a mathematical term used in a differential geometry-based description of spacetime when it is maximally warped by gravity per general relativity. According to the 2023 paper, the error lead to a long-held but false canonical belief among physicists that singularities lie at the heart of black holes when a proper treatment of the mathematical term showed the opposite.[2][3]
- It resolves, in a theoretical sense, the black hole information paradox wherein conventional black hole theory holds that the quantum information describing the light and matter that falls into a classic black hole is thought to either be: A) extinguished within singularities, or B) somehow preserved within singularities but the quantum information cannot climb up against the infinite gravitational intensity inside a black hole to reach past the event horizon where it would be visible to regular spacetime. Either situation violates a fundamental law of quantum mechanics requiring that quantum information be conserved.[1][4]
Outwardly, fuzzballs are similar to gravastars inasmuch as they appear to outside observers as black holes, have a core comprising degenerate matter, possess no singularities at their centers, and resolve the information paradox.[5][6] See §Relationship to gravastars, below, for more.
As no direct experimental evidence supports either string theory or fuzzball theory, both are products purely of calculations and theoretical research.[7] However, fuzzball theory may be testable through gravitational-wave astronomy.[8]