When the first “photo” of a black hole came out six years ago (not exactly a normal photo, but reconstructed with years of observations) it was a sensation, defined as the photo of the century. As with gravitational waves, black holes were also foreseen in Albert Einstein’s relativity (which rightly also became a synonym for genius, “but who are you Einstein?”). Since then, however, the studies have not stopped.
The black hole in question is M87* (the asterisk is part of the name, don’t go looking for a note at the bottom), and we have made progress in understanding what happens in the plasma that surrounds it. The article was published in the journal Astronomy & Astrophysics, and Italy is also participating in the international study, with the National Institute of Nuclear Physics and the National Institute of Astrophysics. Comparing the 2017 observations with those of 2018, it was seen that the rotation axis of the black hole points away from the Earth, while the hot disk surrounding it rotates in the opposite direction. The brightest region of the black hole also moved by thirty degrees. In short, after a year it has been observed, thanks also to 120,000 simulation photos, how turbulent and unstable what surrounds M87* is.
Perhaps, however, if you are not an expert, you wonder why black holes are so interesting. First of all, they are not holes, as lay people think, but objects of infinite density. A sort of supercompressed planets formed by the implosion of a star (which must have a mass from 2.5 times that of our Sun up to billions of times greater), there are no longer even particles (the previous stage is in fact a star of Neutrons). To the point that not even light (which travels at three hundred thousand kilometers per second) can escape (that’s why they are black). They are also called “singularities”, and they are what is closest to what must have been at the beginning of the Universe. Nothing exists in there, and don’t listen to Christopher Nolan who in Interstellar has the protagonist enter a black hole to communicate “with the force of love” with his daughter in the past through the bookcase (of another galaxy) . Going beyond the Event Horizon of a black hole (the limit beyond which you can no longer go back) means you have no escape, American scientists have coined the term “spaghettification”, meaning the first thing that would happen to us is to be stretched ‘unlikely by the infinite force of gravity, for a moment become spaghetti of atoms, without ending up on anyone’s plate. Because that’s the most fascinating thing about black holes. Nothing and no one can exist within them, as at the beginning of the Universe, and as at the end.
However, if we could orbit around a black hole, time, precisely because of relativity, would slow down to such an extent that if an hour passed for you on Earth, decades would have passed. A kind of time machine (but you can “go”, let’s say, only into the future). But getting there is a black hole. Let’s go back to M87* for a moment, the aforementioned observations, made one year apart, study this black hole which is 56 million light years away from us. That is to say that light, at three hundred thousand kilometers per second, takes 56 million years to reach us. Everything we see in the sky is another time machine, from the past.
When what scientists saw was happening, the rotation of the plasma and its turbulence, the dinosaurs had recently become extinct here, and human beings would come just under 56 million years later. This is wonderful and terrifying.