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Title: Gravitational Waves Finally Prove Stephen Hawking's Black Hole Theorem

Link: https://science.slashdot.org/story/25/09/11/2...

Physicists have confirmed Stephen Hawking's 1971 black hole area theorem with
near-absolute certainty, thanks to gravitational waves from an exceptionally
loud black hole collision detected by upgraded LIGO instruments. New
Scientist reports: Hawking proposed his black hole area theorem in 1971,
which states that when two black holes merge, the resulting black hole's
event horizon -- the boundary beyond which not even light can escape the
clutches of a black hole -- cannot have an area smaller than the sum of the
two original black holes. The theorem echoes the second law of
thermodynamics, which states that the entropy, or disorder within an object,
never decreases. Black hole mergers warp the fabric of the universe,
producing tiny fluctuations in space-time known as gravitational waves, which
cross the universe at the speed of light. Five gravitational wave
observatories on Earth hunt for waves 10,000 times smaller than the nucleus
of an atom. They include the two US-based detectors of the Laser
Interferometer Gravitational-Wave Observatory (LIGO) plus the Virgo detector
in Italy, KAGRA in Japan and GEO600 in Germany, operated by an international
collaboration known as LIGO-Virgo-KAGRA (LVK). The recent collision, named
GW250114, was almost identical to the one that created the first
gravitational waves ever observed in 2015. Both involved black holes with
masses between 30 and 40 times the mass of our sun and took place about 1.3
billion light years away. This time, the upgraded LIGO detectors had three
times the sensitivity they had in 2015, so they were able to capture waves
emanating from the collision in unprecedented detail. This allowed
researchers to verify Hawking's theorem by calculating that the area of the
event horizon was indeed larger after the merger. The findings have been
published in the journal Physical Review Letters.

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