Hawking's black hole theorem confirmed by gravitational waves

A black hole has often been portrayed as the ultimate villain in sci-fi movies due to its mysterious nature. From the death of a large-enough star it emerges with such a strong gravitational field that not even light can escape from within its grasp.

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However, in spite of its wildly mysterious behavior, the black hole obeys certain simple rules. One of those rules, first proposed in 1971 by English physicist Stephen Hawking, has been proven correct by the help of gravitational waves.

The area law, derived from Einstein's general relativity, states that it is impossible for a black hole to decrease in size, at least in the short term. Mathematically:

Recently, a team led by astrophysicist Maximiliano Isi from Massachusetts Institute of Technology studied the gravitational wave data released by the merger of two black holes.

Their calculations show that the total surface area of the resulting black hole is greater than the combined areas of the two smaller black holes. Therefore, Stephen Hawking was right.

However, while black holes cannot shrink according to Einstein's general relativity, they can do so as per the quantum mechanics.

Hawking worked that out too in 1974 – a concept known as Hawking radiation, which is predicted to emit because of strange quantum effects near the black hole's event horizon.

In his 1988 book A Brief History of Time, Hawking thus wrote: Black holes ain't so black. The release of these radiations would cause the black hole to shrink over longer time period and evaporate eventually.

Hence, theoretically speaking, both general relativity and quantum mechanics hold true. Maximiliano Isi said: "I am obsessed with these objects because of how paradoxical they are."

Now that the area law has been established for short to medium time frames, the researchers' next step would be to detect Hawking radiation by observing older black holes; no substantial evidence has been recorded so far.

Isi concludes: Black holes are those phenomena where gravity meets quantum mechanics, which makes them the perfect playgrounds for our understanding of reality.