Black holes are invisible monsters Is there scientific evidence for their existence?

Of all the strange concepts in astronomy, black holes may be the strangest of all. It is a space in space in which matter is so tightly packed that nothing - not even light itself - can escape.

With the collapse of all the laws of natural physics within them, it is tempting to view black holes as the stuff of science fiction, yet there is a lot of direct and indirect evidence that they do exist in the universe, according to a report by the "Live Science" website.

Einstein's 'strong prediction'

As a theoretical possibility, the existence of black holes was predicted by Karl Schwarzschild in 1916, as an inevitable consequence of Albert Einstein's general theory of relativity. And if Einstein's theory is true, and all evidence points to it being true, then black holes must exist.

According to the University of Cambridge , Roger Penrose and Stephen Hawking then demonstrated that any object collapsing into a black hole would constitute a single instance in which the traditional laws of physics would break.

This became widely accepted; So much so that Penrose was awarded a Nobel Prize in Physics in 2020 “for his discovery that the formation of black holes is a powerful prediction of general relativity.”

Gamma ray bursts

According to NASA , in the 1930s Indian astrophysicist Subramanian Chandrasekhar looked at what happens to a star when it uses up all of its nuclear fuel, and found that the end result depends on the star's mass.

If this star is really large - for example 20 solar masses - its dense core, which may itself be 3 or more times the mass of the sun, collapses directly into a black hole.

The final collapse of the nucleus occurs at an astonishing speed within seconds, and it releases a huge amount of energy in the form of a gamma ray burst, and this explosion can radiate an amount of energy into space similar to what is emitted by an ordinary star throughout its life.

Telescopes on Earth have detected many of these explosions - some of which come from galaxies billions of light years away - so we can see black holes being born.

Gravitational waves

Black holes do not always exist in a single state, sometimes they occur in pairs, as two black holes orbit around each other. At this point, the gravitational interaction between them causes ripples in "space-time", and they propagate outward in the form of gravitational waves, which is another prediction of Einstein's theory of relativity.

With observatories such as the LIGO and Virgo laser gravitational-wave observatories, we have the ability to detect these waves. In 2016, the first discovery of ripples in "space-time" known as gravitational waves, which involved the merging of two black holes, was announced, and this was a discovery so important that it deserved the Nobel Prize in Physics in 2017.

The Invisible Companion

Black holes are by nature undetectable; The fact that it does not emit any light or other radiation means that it could be lurking in our neighborhood in the universe without astronomers realizing it. The only sure way to spot these dark monsters is through the gravitational effects they exert on other stars.

When observing a binary system of normal-looking orbiting stars - known as HR 6819 in 2020 - astronomers noticed an anomaly in the movement of the two visible stars that can only be explained if there is an invisible third body affecting them.

When they calculated its mass, they found that it was at least 4 times the mass of the Sun, so the researchers knew there was only one possibility; To be a black hole, the black hole closest so far to Earth, located a thousand light-years away within our galaxy.

X-ray vision

The first observational evidence of a black hole appeared in 1971, and this also came from a binary star system located inside our galaxy, called Cygnus X-1. This system produces some of the brightest X-rays in the universe, and it does not originate from the black hole itself, or from the binary star system The accompanying observable, which according to NASA has a mass 33 times the mass of our Sun.

What happens is that matter is constantly being stripped from the giant star and pulled into an accretion disk around the black hole, and from this accretion disk are emitted X-rays.

Just as astronomers did with the binary star system HR 6819, here they can also use the observed motion of the stars to estimate the mass of the invisible object affecting Cygnus X-1. According to the latest calculations, this invisible dark body reaches 21 solar masses concentrated in a small area; This cannot be anything other than a black hole.

Supermassive black holes

In addition to black holes created by stellar collapse, evidence suggests that supermassive black holes - made up of millions or even billions of solar masses - have been lurking in the centers of galaxies since the early history of the universe.

According to NASA, the central black holes in these active galaxies are surrounded by accretion disks that produce intense radiation at all wavelengths of light.

We also have evidence that our galaxy has a black hole at its center; Scientists believe that the stars in that region are spinning at a very fast speed, up to 8% of the speed of light, and they must revolve around something very small and huge. Current estimates place the Milky Way's central black hole at approximately 4 million solar masses.

Transformation into spaghetti

Another proof that black holes exist is spaghettification. This is what happens to you when you fall into a black hole, where they expand into thin strands of spaghetti-like pasta by the black hole's strong gravitational force. Of course, this is unlikely to happen to you or anyone else, but that could be the fate of a star wandering near a supermassive black hole.

In October 2020, astronomers witnessed this kind of rupture, or at least saw a flash of light from an unlucky star when it ruptured. It was in a galaxy 215 million light-years away from us.

Said Saeed - The implications of the image broadcast yesterday of the black hole Messier 87 - NASA - the black hole "Messier 87": the image and what is behind it

Finally a live picture

All the previous evidence is indirect, but convincing for the existence of black holes, but the certain news came in April 2019, in the form of a direct image of the supermassive black hole in the center of the Messier 87 galaxy.

This stunning image was captured by the "Event Horizon" telescope, which consists of a large network of telescopes spread all over the world.

According to NASA, the more telescopes that can participate, and the greater the distances between them; The final image quality was better. The result clearly shows the dark shadow of the black hole, which has a mass of 6.5 billion solar masses, and the orange glow of the accretion disk surrounding it.