The Black holes They are one of the most mysterious objects of space, but the fusion of two at the beginning of this year, registered with great precision thanks to the progress of the detectors, has served to validate some of the theories that they formulated on them Stephen Hawking.
When two black holes collide and melt into one the event distorts the space itself, creating waves in the space-time that spread throughout the universe, as sound waves that resonate from a bell that has been beaten.
This type of waves that deform the space, called gravitational, were first detected just ten years ago and provide a lot of information about the objects from which they come.
The fusion of the two holes captured at the beginning of the year was the subject of a detailed study that the Ligo-Virgo-Kafra collaboration published in Physical Review Letters.
The article gives information on the properties of black holes and the fundamental nature of space-time, which suggests how they fit quantum physics and the general relativity of Albert Einstein, in addition to confirming Hawking theories and mathematician Roy Kerr.
The astrophysicist Maximiliano Isi, of the Flatiron Institute (United States) and one of the signatories of the text, emphasizes that the recent detection is “the clearest vision that is until now of the nature of black holes.”
Thanks to this detection they have found, “says,” some of the strongest evidence to date “that astrophysical black holes are predicted by Einstein’s general relativity theory.
For massive stars, black holes are the final stage of their evolution and these are so dense that not even light can escape its gravity.
The collision of two of them creates gravitational waves and, like a large iron bell, produces a different sound from a smaller aluminum bell, the sound of a fusion of holes is specific, due to the properties of each of them, explains the Simons Foundation, one of those involved in the study has already a decade that scientists can detect gravitational waves with special facilities such as Ligo in the United States Italy and Kagra in Japan, which are increasingly sophisticated and allow to determine the characteristics of each hole.
The gravitational wave signal detected at the beginning of the year, baptized as GW250114, it is now known that it caused a fusion that formed a black hole with a mass equivalent to 63 soles and that turns at 100 revolutions per second.
The team had a complete vision of the collision, from the moment the black holes collided for the first time to the final reverberations, when the black hole fused was stabilized in its new state, which happened only milliseconds after the first contact.
“Ten milliseconds seems very little time, but our instruments are now so good that it is enough for us to really analyze the sound of the final black hole,” says ISI.
The new observations allowed to verify a key conjecture that dates back decades and is that black holes are fundamentally simple objects, which can be described with only two characteristics: spin and mass, as Kerr had pointed out in 1963.
Hawking predicted in 1971 that the horizon of events of a black hole (its outer limit, beyond which nothing, even the light, can escape) could never decrease in size and now one more evidence has been obtained that the surface of the result of a fusion is not less than the sum of the two initial black holes.
When confirming the Hawking theorem, the results point to connections with the second law of thermodynamics, which establishes that a property that measures the disorder of a system, known as entropy, must increase, or at least remain constant, over time.
“It tells us that general relativity knows something about the quantum nature of these objects and that information, or entropy, contained in a black hole is proportional to its area,” isi adds.
The scientist emphasizes that the fact that the size of the event horizon of a black hole behaves how entropy has “very deep theoretical implications”, since some aspects of black holes could be used to mathematically investigate the true nature of space and time.
For a long time, – this field “has been pure mathematical and theoretical speculation”, but now it is in a position to see “these incredible processes in action, which highlights the great progress that has been achieved and will continue to be achieved” in this area.