Landmark Gravity wave Detection Confirms Hawking‘s Black Hole Area Theorem
A newly observed gravitational wave event,designated GW250114,is providing the strongest observational evidence yet for Stephen Hawking’s groundbreaking black hole area theorem.The event, originating from a black hole merger 1.3 billion light years away, has allowed astronomers to rigorously test Einstein‘s theory of general relativity and validate a key prediction about the essential nature of black holes.
The merger involved two black holes, one 34 times the mass of our sun and the other 32 times the mass of our sun, resulting in a new black hole with a mass 63 times that of the sun. This newly formed black hole spins at an astonishing rate of 100 times per second. Crucially, the clarity of the GW250114 signal – standing out distinctly from instrument background noise – enabled precise measurements to confirm theoretical predictions.
the Hawking area theorem, proposed by Stephen Hawking in 1971 and further developed with Jacob Bekenstein in 1972, states that the total surface area of a black hole can never decrease, even during a merger. Bekenstein initially proposed the concept that black holes possess entropy, with the surface area being proportional to it. Together, Hawking and Bekenstein concluded that the area of the resulting black hole after a merger would always be greater than or equal to the sum of the areas of the original black holes, even accounting for energy loss through gravitational waves.
Astronomers confirmed this prediction with GW250114. Before the merger,the combined surface area of the two progenitor black holes was approximately 243,000 square kilometers. Following the merger, the surface area of the new black hole increased to around 400,000 square kilometers, demonstrably verifying the theorem’s prediction of increasing entropy.
Sadly,Stephen Hawking passed away in 2018 and was unable to witness the observational confirmation of his theory.
The GW250114 signal also provides strong validation for the Kerr metric, an exact solution to Einstein’s general relativity developed by mathematician Roy Kerr. This equation accurately describes the spacetime geometry surrounding a rotating black hole.
This discovery marks a significant milestone in gravitational wave astronomy. A century after Albert einstein predicted the existence of gravitational waves - ripples in spacetime caused by accelerating massive objects – the Laser Interferometer Gravitational-Wave Observatory (LIGO) has opened a new window into the universe.
The research, detailed in a new paper published in Physical Review Letters, highlights the transformative power of gravitational wave detection. As more advanced detectors come online, the precision with which these events can be localized and analyzed will continue to improve, further refining our understanding of the cosmos.
(First image source: Max Planck Society)
(Event diagram source: California Institute of Technology)
https://journals.aps.org/prl/abstract/10.1103/kw5g-d732
https://www.caltech.edu/about/news/ten-years-later-ligo-is-a-black-hole-hunting-machine
https://www.mpg.de/25343549/clearest-gravitational-wave-signal
