Violation of the Third Law of Black Hole Mechanics in Vacuum Gravity
A team of researchers at Cambridge (JRV Crump, M Gadioux, HS Reall, JE Santos) has demonstrated numerically that the third law of black hole mechanics can be violated in pure vacuum gravity, without any matter fields present.
Image: aps.org - Violation of the Third Law of Black Hole Mechanics in Vacuum Gravity
The third law states that a black hole cannot reach extremality (zero temperature) in finite time. This paper shows it can. Working in five-dimensional vacuum general relativity, the authors found solutions describing:
- An extremal rotating black hole forming in finite time from a pre-existing Schwarzschild black hole
- An extremal rotating black hole forming from vacuum initial data containing no black hole at all
The paper was published in Physical Review Letters (2026, vol. 136, 171405), according to Harvey Reall's Cambridge faculty page.
Image: phys.org - Violating the 3rd law of black hole mechanics in vacuum gravity
As Phys.org summarized on X-Twitter (cancel) on June 3, 2026: "A zero-temperature black hole emerged in finite time in vacuum gravity simulations, challenging a rule long thought to block that path."
The result is significant because previous violations of the third law relied on specific matter models, leaving open the possibility that the law held for vacuum gravity. This work closes that loophole, proving the third law is false independently of any matter content.
Sources: arXiv, Cambridge Faculty of Mathematics, Phys.org on X(cancel)