The black hole field theorem, which Hawking derived from Einstein’s general theory of relativity in 1971, says that it is impossible for a black hole’s surface area to decrease over time. Because no object approaching black holes can escape and is swallowed by them.
Therefore, according to the theorem, the surface area of a black hole increases with its mass. This is closely related to a fundamental law of physics that states that entropy (randomness and disorder in a system) always increases in a closed system. So, since the entropy of a black hole is proportional to its surface area, both must always increase.
But also because of the loss of small amounts of energy, known as Hawking radiation, the surface area is expected to shrink as the black hole spins.
MIT researchers Maximiliano Isi, Will M. Farr, and others wondered whether it would be possible to hurl an object into a black hole so hard that the black hole could spin it causing the area to shrink.
Because, according to the area theorem, the increase in surface area from more mass should always outweigh the decrease caused by rotation.
To test this, the researchers examined data from GW150914, the first gravitational waves ever detected.
These waves were obtained from two black holes merging to form a larger spinning black hole and were discovered at the LIGO observatory in 2015.
NASA also visualized the waves in question as follows:
The researchers divided the data into pre-merger and post-merger and calculated the surface areas of the black holes.
The surface area of the newly created black hole was larger than the combined surface areas of the first two black holes. The findings confirmed Hawking’s field theorem with 95 percent accuracy.
The authors of the study, published in the peer-reviewed scientific journal Physical Review Letters, said the results were in good agreement with what they hoped to find.
In the next step, the researchers aim to examine data from more gravitational waves to gather more information about black holes.
Source: The Independent
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