Uploaded April 2026 | Updated September 2026, 2 weeks ago
The third law of black hole mechanics asserts that it is impossible for a non-extremal black hole to become extremal in finite time (in classical General Relativity). Counterexamples were found recently: gravitational collapse of a massless charged scalar field can produce an exactly extremal Reissner-Nordstrom black hole in finite time, passing through an intermediate phase in which the solution is exactly Schwarzschild at the horizon.
These examples involve matter with a large charge to mass ratio. I will describe how if the charge to mass ratio of matter is suitably bounded then one cannot form an extremal Reissner-Nordstrom black hole in finite time. It is conjectured that one can form an extremal rotating black hole via gravitational collapse of gravitational waves. I will describe recent work showing that this conjecture is true in five spacetime dimensions.
Harvey Reall (University of Cambridge)
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Find this and many more scientific videos on carmin.tv - a French video platform for mathematics and their interactions with other sciences offering extra functionalities tailored to meet the needs of the research community.
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The third law of black hole mechanics asserts that it is impossible for a non-extremal black hole to become extremal in finite time (in classical General Relativity). Counterexamples were found recently: gravitational collapse of a massless charged scalar field can produce an exactly extremal Reissner-Nordstrom black hole in finite time, passing through an intermediate phase in which the solution is exactly Schwarzschild at the horizon.
These examples involve matter with a large charge to mass ratio. I will describe how if the charge to mass ratio of matter is suitably bounded then one cannot form an extremal Reissner-Nordstrom black hole in finite time. It is conjectured that one can form an extremal rotating black hole via gravitational collapse of gravitational waves. I will describe recent work showing that this conjecture is true in five spacetime dimensions.
Harvey Reall (University of Cambridge)
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Find this and many more scientific videos on carmin.tv - a French video platform for mathematics and their interactions with other sciences offering extra functionalities tailored to meet the needs of the research community.
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