In a new scientific study, researchers have proven the validity of one of Stephen Hawking’s most famous theories, using gravitational waves generated by the merger of two distant black holes. But this proof is not good news for scientists seeking to resolve the incompatibility of relativity and quantum theory.
The black hole area theory, which Hawking derived in 1971 from Einstein’s general theory of relativity, states that it is impossible for a black hole’s surface area to decrease over time. Read also The bet that Stephen Hawking lost .. New facts about the first black hole discovered in 1964 Scientists determine the conditions for “safe” travel inside black holes .. “possible” without return Black holes swallow half of this year’s Nobel Prize in Physics A study proves a theory dating back half a century… Extracting energy from black holes is possible
What is entropy?
In order to understand this law in a simple way, suppose we have two closed containers, each containing a specific gas – oxygen and hydrogen for example – at the same temperature and pressure.
If we make between the two vessels an outlet for the gases to pass between them, we will eventually find that the gas composition in both is identical and stable, and it is not possible to automatically return to the initial state when the oxygen and hydrogen were separated from each other. So scientists say that turbulence within a physical system can only increase.
This principle also applies to black holes that devour the bodies around them. Since the entropy of a black hole is directly proportional to its surface area, Hawking believes that this area can only increase with time.
But it seems more complicated for black holes, if this cosmic monster devoured a physical object, it would gain more mass, which increases its surface area. But, at the same time, the mass of this object can make the black hole spin faster, reducing the surface area.
So, after all, will the hole area increase or decrease? Theoretically, according to Hawking’s law, the increase in surface area due to extra mass will always outweigh the decrease in surface area due to additional rotation. But this needs to be proven in reality.
In the new study, published in Physical Review Letters, researchers from Stony Brook University and the Flatiron Institute in New York set out to test Hawking’s surface area law for black holes.
For this purpose, the researchers used, according to a by report the scientific site “LiveScience”, space-time ripples driven by two black holes in the process of merging to form a larger black hole. They determined the surface area of the black hole through the event horizon, which is the limit at which it is impossible for any physical object to escape from the hole.
According to Hawking’s theory, the area of the event horizon of a newly formed black hole should be at least the size of the event horizon regions of the two original black holes combined.
The team analyzed data from the first gravitational waves ever detected, which were detected in 2015 by the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO).
The researchers divided the gravitational wave data into two time periods, the period before and after the merger, and calculated the surface areas of black holes each period. They found that the newly formed black hole’s surface area is larger than the two first black holes combined, which supports Hawking’s theory.
So far, black holes are well described by general relativity. But scientists do not fully understand what happens when general relativity – which usually applies to large objects such as black holes – meets quantum mechanics, which applies to small objects such as atoms and subatomic particles. And in this quantum world, strange things can happen.
For example, black holes can emit a faint “fog” of particles called Hawking radiation, another idea developed by the British scientist in the 1970s.
This effect would allow black holes to shrink, violating the law of space, but only over very long periods of time, so it would not affect the relatively rapid merger of black holes observed by LIGO.
Physicists are searching for one new and improved theory of quantum gravity. Any failure of general relativity would point scientists in the right direction to find this new theory.