Black Holes are as bold as “bowling balls”
Black Holes are as bold as “bowling balls”
Black holes are the most mysterious objects in space as well as the most dangerous. Scientists are still not sure why and how they appear since the beginning of the world. Perhaps they are formed by massive stars after their death, so the answer lies somewhere in the future. All we know is that a black hole is an astrophysical object in space that has gravity so strong that nothing, not even the light quanta, photons that travel with the maximum possible speed in the Universe, can escape it.
First, there were only hypotheses that something like this can exist. Nowadays the presence of black holes has been proved by many explorations. The unique photo of a black hole in the center of the galaxy Messier 87 dated 10 April 2019 proved one more time that the theory of general relativity is correct.
It took a lot of time to come from mathematical predictions to real explorations. Its believed that every single galaxy has its own supermassive black hole in their center and it joins all the stars in the galaxy in the beautiful cosmic dance. Just don’t come too close to it because tidal forces of gravity are so enormous that they can easily destroy even the biggest known star.
These exotic wonders of the cosmos created a lot of theories in the minds of scientists. One of them is the “No-hair theorem”.
Nowadays, with the help of the existing technical devices for the detection of gravitational waves, we can finally study the “no-hair theorem” of the black holes. It was reported by an international group of experts.
Of course, it’s not about real hair, this is just a joke of scientists.
There is a theory in astrophysics, and it says that black holes have no “hair”. The name for this theory was expressed by physicist John Wheeler, who also created such definitions as “wormhole” and “black hole”.
This theory determined straightforwardly: all black holes can be explained with Einstein’s equations and have only three characteristics: electric charge, mass and angular momentum (or let’s just say “amount and speed of rotation”).
All other data disappear in the bowels of the black holes forever.
So, if we compare two black holes, with the same parameters mentioned above, but one of them was formed from matter and other from antimatter, then for an outside observer they will look identical, roughly saying, like two bald people.
So, for example, let’s imagine that we have made three black holes: from trees, from TV and the last one from rocks. If in the result they have the same mass and angular momentum (electric charge not really important for astrophysical objects), they will be absolutely identical. The same concerns matter that they absorb, nothing changes, except mass and rotation.
Nevertheless, Stephen Hawking thought that black holes have a little “hair”. And the reason for that is photons, that have very little activity, and yet helping some data leave this amazing astronomical objects.
However, mistakes are typical for every person even for outstanding scientists, which is evidenced by numerous explorations.
Although this theory seems to be reasonable and not very complicated, official confirmation by mathematical methods has become a rather difficult task.
So far, not a single brilliant theoretician has given affirmative answers, even though many bright minds have been working on this theory for decades.
Several scientists still tried to pick up the keys to this task in other ways.
They were collecting and studying information about gravitational waves, which had been detected by the LIGO detector. The first time these waves were detected in 2015. The detector caught gravitational waves, which were formed by two merging black holes. They can be compared by mass with a black hole living in the heart of the Milky Way.
After these two black holes had merged into giant supermassive one, it created gravitational waves for several milliseconds, just like a trembling bell emits sound waves, and then calms down. If you convert that data into sound, you will hear a little “whoooop! “. This is a “sound” of two enormous black holes became a twice bigger one. Merging black holes don’t create gravitational waves at a single frequency, they are accompanied by frequencies called overtones. This can be compared to guitar strings or bell ringing. Thanks to that overtone you can, for example, hear the difference between a guitar and piano.
Studying the main frequency and overtones scientists compared available information with the “diagnosis” of the “hairless collapsars”. The results of this research coincided with the expected ones on approximately 20 percent.
Using only these results, experts also calculated the mass and rotation of this new black hole. The resulting values matched all data of the whole event, including two black holes orbiting each other radiating gravitational waves thus losing energy and coming closer and closer to form a new black hole.
All this just proved one more time that the behavior of every black hole is determined only by its mass and angular momentum.
Of course, it doesn’t mean we have all prove that there is no hair there, but it still means so much for further explorations.
It’s extremely difficult and unsafe to directly affirm the correctness of this theory by creating and comparing black holes in various laboratories. Although we don’t have such technologies yet. But we have already methods for studying it at a distance.
Scientist Visveshwara in 1970 said that using linearized general theory of relativity the intensity of a gravitational field created by a black hole can be distributed over quasinormal modes. These are weakening waves, the duration, and amplitude of which depends on the power and duration of the black hole’s burst.
For example, this process occurs at the final stage when binary systems of black holes (or neutron stars) merge, turning into the much heavier black hole, it emits gravitational radiation. Thus, the sizes of quasinormal modes directly depend on the characteristics of gravitational vibrations. Scientists compare these parameters with general relativity predictions using modern gravitational detectors. If the results turn out to be different from the predictions of the theory, then we can say that black holes have hair, and Steven Hawking was right. Or in the same way, it can happen the opposite.
The union of professors from Great Britain, the Netherlands, Italy, and China, headed by Chris van Den Burke, determined that such measurements are already possible nowadays. Moreover, if black holes have no hair, then in the most successful scenario, it will be proved with an accuracy of more than 90 percent.
But its not only about black holes and their hair. Scientists received a new instrument to explore the whole Universe after they had revealed these gravitational waves.
Let’s wait for new discoveries!