Physicist Stephen Hawking in year 1971 presented Hawking’s Area Theorem based on his interpretation of general relativity, which states that a black hole’s surface area can’t decrease over time. And only recently (50 years later) the physicists at MIT have confirmed this theorem for the first time, by the observation of gravitational waves, as appear in the *Physical Review Letters*.

This is the first observational confirmation of Stephen Hawking’s prediction. In the Year 2015 the first gravitational wave, GW150914 was detected with the help of Laser Interferometer Gravitational-wave Observatory or LIGO.

It is known that Hawking’s area theorem states, that the area of the event horizon (the boundary beyond which nothing can ever escape_ shouldn’t shrink smaller than the total horizon area of its parent black holes, and this was reanalyzed and confirmed by the signal from GW150914 pre-merger and post-merge. The theorem is confirmed by 95% accuracy.

The researchers believe that it’s just the beginning and such observations and calculations have to be repeated over time, because,” It is possible that there’s a zoo of different compact objects, and while some of them are the black holes that follow Einstein and Hawking’s laws, others may be slightly different beasts,” believes lead researcher Maximiliano Isi, a NASA Einstein Postdoctoral Fellow from MIT’s Kavli Institute for Astrophysics and Space Research. There is a whole new horizon to test and understand the mysterious objects beyond our previous limits, thanks to the new tools.

Stephen Hawking believed that the entropy of the black hole is proportional to its surface areas, and both should increase. But because according to him the surface area of the black hole gradually shrinks as it spins further, because of the loss of a small amount of energy (Stephen Hawking radiation), so no emissions have yet been detected. And now with the observation of fluctuation in space-time due to the merger of 2 distinct black holes, the validation of this theorem is made possible for the first time. This gravitational wave is thought to be created some 1.3 billion years ago by two giant black holes, inspiraling towards one another at a tremendous speed.

The merger signals were also analyzed to calculate the mass and spin of two pre-merger black holes. The researchers have succeeded in calculating the event horizon of all three objects because the mass and spin are related to the area of the event horizon.According to their calculations, the two smaller black holes had a total event horizon area of 235,000 square kilometers (91,000 square miles). The final black hole had an area of 367,000 square kilometers. Thus, the researchers were able to claim that the horizon area increased after the merger as per the Area Law.

Isi said, “We can keep teasing out pieces of information that speak directly to the pillars of what we think we understand. One day, this data may reveal something we didn’t expect.” This is one of the foundations of a new and creative way of understanding and unveiling data about the gravitational wave.

### Keywords:

Astronomy, Astrophysics, Black holes, Kavli Institute, LIGO, Physics, Research, NASA, Stephen Hawking Area Theorem, Gravitational-wave, GW150914

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