Hawking's theory tested: "Strongest physical evidence"

LIGO, which first directly detected gravitational waves in 2015, announced a new historic observation on its 10th anniversary. The LIGO-VIRGO-KAGRA team detected a black hole merger similar to the initial discovery.

UNPRECEDENTED TESTS

This time, thanks to the increased sensitivity of detectors over the past 10 years, the signal was recorded much more clearly, allowing unprecedented tests of the theory of General Relativity to be performed. The research was published in the journal Physical Review Letters under the title "GW250114: Testing Hawking's field law and the Kerr nature of black holes." By examining the frequencies of the gravitational waves emitted during the merger, scientists announced that they had obtained the strongest observational evidence yet for the black hole field theorem, proposed by Stephen Hawking in 1971.

WHAT WAS HAWKING'S THEORY?

In 1971, Hawking proposed a physical law regarding the surface area of ​​black holes:

The surface area of ​​a black hole's event horizon can never shrink; it can only remain the same or grow. In other words, when black holes merge or absorb matter, their total surface area increases, but in no case does it decrease. According to this theory, the surface area of ​​black holes only increases over time. This is why it is also known as the "second law of black holes." Hawking's idea was a significant turning point, demonstrating that black holes possess thermodynamic properties and are, in fact, closely tied to the laws of nature.