The black hole’s horizon – the boundary from which nothing can escape – can never shrink. At least, that’s what Stephen Hawking mentioned in 1971. It is now the so-called surface theory of black holes Confirmed for the first time With gravitational wave measurements.
To test Hawking’s theory, physicists looked at GW150914, and The first discovery of a gravitational wave. This gravitational wave, discovered in 2014 by US LIGO detectors, originated from two merging black holes.
If Hawking’s fifty-year-old theory is correct, then the horizon area of a newly formed black hole should not be less than the sum of surfaces of black holes horizon that merged. This appears to be true with the GW150914. “The outer surface is likely to be about one and a half times larger than the sum of the original black holes before the collision,” the researcher wrote. Maximilian Issy From the Massachusetts Institute of Technology, USA.
Horizon = mass and rotation
Hawking’s idea that the horizontal surface of black holes could never shrink arose when he did the calculation using Einstein’s general theory of relativity. They found that black holes prevent the surface of the horizon from decreasing thanks to changes in their mass or rotation on their axis.
Thus, the size of the horizontal surface of a black hole is related to its mass and rotation. By measuring these two properties, using gravitational waves, you can also determine the surface.
When Hawking learned in 2015 that LIGO detectors had measured gravitational waves from merging black holes, he was excited. He asked LEGO researchers to test his superficial theory. Unfortunately, the analysis techniques at that time were not good enough to determine the necessary information about the masses and cycles of black holes before and after the collision. Hawk, die He passed away in 2018, so he was unable to see confirmation of his theory.
It was only in 2019 that Isi and his colleagues succeeded in developing an analysis technique that can reconstruct the echo of GW150914. This was necessary to calculate the black hole’s mass and spin due to the merger. When they published this finding, they were contacted by Kip Thorne, Nobel laureate, LIGO founder and friend of Hawking. They were also asked to use this technique to determine the mass and rotation of black holes before colliding in order to verify Hawking’s theory.
Essie and his colleagues calculated that the total horizon areas of the black holes before the collision were about 235,000 square kilometers. It turned out that the surface of the black hole horizon after the collision was about 367,000 square kilometers.
So for GW150914, Hawking’s theory is correct. But one affirmation is not enough. So Essie and his colleagues plan to apply their method to more measurements of gravitational waves.
Issey: “Other theorists have created models that produce things that look like a black hole, but that don’t follow the surface theory.” Further observations of gravitational waves can confirm or refute the existence of these compact objects.