It has been several weeks since strange things began to happen in the night sky. You, like many others, actively follow the news. The president is speaking, he is supported by astrophysicists, geologists and climatologists. He is nervous, but, paying tribute to tradition, he divides the news into "bad" and "good". The good news: we are not dead, the planet is not destroyed, it is not swept into space or spun in a gravity wheel. The bad ones are "very interesting climate changes." Trying to survive next to a black hole is like fleeing the Titanic - for a cold death in the ocean.
Before you reach for your alarm case or start going crazy: fear not, this is just a thought experiment. Black holes are one of the most terrifying phenomena in the universe. Their enormous weight bends space and time - and our understanding of their nature - to the limit, to one point. Supermassive black holes lurk in the cores of galaxies, engulfing millions, billions of stars.
What will happen if a black hole is born or is discovered near our solar system?
As with most hypothetical questions, the devil is in the little things. How close? Where from? What is the mass?
It should be noted right away that our sun will never become a black hole. This requires a mass that is in the order of magnitude greater than the sun - 10-15 times. Then there will be a gravitational collapse, under the influence of gravity, matter literally collapses into one point. A similar phenomenon is at the heart of hydrogen bombs and in the theory of cold thermonuclear fusion, unless gravity plays a different role. Moreover, other stars in neighboring galaxies are not suitable for the role of potential black holes. Most of them are red dwarfs and have a mass of 8-60% of our Sun.
Two options remain: either a black hole spontaneously appears in our vicinity, or it comes from nowhere. But the first, despite protesting against research at the Large Hadron Collider, is impossible (we'll explain why later).
As for the second, astronomers and astrophysicists have confirmed the existence of about 2,000 wandering black holes, but the chances of one of them reaching us are close to zero. And as writer Douglas Adams pointed out:
“The cosmos is great. You simply cannot realize how incredibly and mind-blowingly large it is. I mean, it may seem like a long road to the pharmacy, but by the standards of space, these are seeds."
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This means that the probability of such an event is too interesting not to consider it closer.
Influence of black holes on space and time
If you look at a black hole from a distance, it will look like any other massive object. As long as it is right in front of you, it obeys the laws of classical mechanics and Newton's law of universal gravity, which states that the attraction between two objects is proportional to their mass and decreases with increasing distance. In other words, there is no gravitational difference between R136a1, a "blue" dwarf weighing 265 suns, and a black hole of the same weight.
Get closer to the black hole to get into its gravitational field and you will be faced with two different sets of rules. Einstein's theory of general relativity, which allows black holes to bend space and time, and extreme gravity, which takes this curvature to the extreme.
If you want to study a black hole without getting out of a starship, you will find that the closer you get to the center of the immense mass, the more your engines will strain to keep you in a circular orbit. At first, small impulses from the rocket will stabilize it; but the further you go, the more energy you will have to spend in order not to go out of orbit. As a result, only the non-stop operation of the rocket engines will separate you from the all-consuming nothing.
As soon as you run out of fuel (or you go crazy and turn off the engines), you will cross the event horizon of the black hole, the border from which not even light can return. After that, you will have to answer for all your sins. Nothing will stop the inexorable movement towards the singularity - the core of infinitely compressed space and time, where physics, as we know it, curls up into a ball and whines.
Time will slow down as you progress. Very much. From your point of view, nothing will change, but your friends watching your trick will see like blurry lightning. But only to the event horizon - the light does not go beyond it, which means that no one can see you. Perfect crime, isn't it?
Gravitational time warps are common enough, but too weak to be noticed. On Earth, for example, having lived a billion years at sea level, you will be one second younger than your peer who lived at the summit of Everest. They say time is afraid of the pyramids, but you have to spend too much time leaning your cheek against it to feel the slowing down of time in Paris.
Time spins around in a black hole. When we say that falling into a singularity cannot be avoided, it means not only the inexorable action of gravity or the distortion of space. Time in a black hole shrinks to the point that the path to the singularity literally becomes your future. Escaping the singularity will be like trying to stop time.
Do you want to know what will happen in our solar system if it manages to get into such a maelstrom of forces? Read on.
Judgment Day
Suppose a black hole is trapped in a binary system, hugging a star that is about to go supernova. Suddenly it happens, the gravitational giant shoots in our direction at a speed of tens and hundreds of kilometers per second. How do we know about this?
The answer is simple: we won't know until it collides with something, since the massive gravity of black holes does not even release light. So, instead of trying to find black pepper on a black carpet, let's look at a few ways that will help us directly identify a black hole.
First, matter torn apart by the black hole will emit radiation as the accretion disk rotates. The space around will glow like a necklace of New Year's lanterns worn by a cat (strange fantasy, but so be it).
Secondly, the distortion of space around black holes can be detected by terrestrial methods. This is gravitational lensing as predicted by Einstein's general theory of relativity. The effect manifests itself near massive objects and is recorded by astronomers.
But even under ideal conditions, finding a black hole in this way will be more difficult than finding fleas on a spotted dog at night with binoculars. With an eye patch. For a successful gravitational lensing, a black hole must pass between us and the star. And after that we still have to get lucky.
In addition, a black hole can make itself felt if it interacts gravitationally with celestial objects like planets, stars, asteroids and comets, which again brings us to the key question: how close will our hypothetical black hole, nestled in the neighborhood, be located?
Of course, the closer, the more dangerous. As the orbits of the planets and moons approach, they will dance salsa like a sparrow caught in a spider's web, dragging crooked orbits and disrupting the order that they have been trying to put together since the time of Nicolaus Copernicus.
Here on Earth, the ebb and flow and the color of the sky would change. If gravity, as ordered by Zhirinovsky, moves the planet's orbit farther from the Sun, brings it closer, makes it more elliptical, at best we will suffer from temperature changes and oddities with the seasons. In the worst case (apart from becoming part of a black hole), the Earth can fall into the Sun or go on a long voyage into the depths of space, dooming us all to cold death.
The famous astrophysicist Neil de Grasse Tyson once succinctly expressed the problems that would arise if a "black guest" starts nearby:
"If we visit a black hole, the solar system will have a bad day."
Well, let's not shift from foot to foot in front of the event horizon and dive at last.
Contact: good and bad news
There is a six-letter word in Russian that would best describe what awaits us. Let's just call it doom. Scientists learned to divide by zero, and we ended up in a black hole. Even Bruce Willis with a brave crew of oil workers, specially trained in Chelyabinsk, would not have saved us.
If a black hole appeared in the vicinity of Neptune, we would immediately feel it. Scientists know Neptune's orbit so well that they can even detect a deviation of 1 arc second (a unit of angular measure). An ordinary black hole with a mass of ten suns, flying at a speed of 300 km / s, would give itself out another tenth of a light year.
And here's the last piece of good news: a black hole this size will give us at least 100 years to complete our earthly affairs. Perhaps a danger of this magnitude will end all earthly wars or start one global one. Perhaps humanity will have time to destroy itself on its own, as soon as it learns that in a hundred years - everything, kaput. It doesn't matter yet. If the hole moves more slowly, the fatal waiting time will increase tenfold. And then there should be enough time to build an ark or collect a planetary suitcase with things.
As it approaches Neptune, the black death pulls the gas giant out of orbit. The planet begins to behave strangely: as it moves away from us, a redshift occurs - the wavelength of its radiation, including light, goes into the red spectrum. As soon as Neptune is behind the black hole, the gravitational lens is pulled over the black sphere and flows around it. When the planet appears again, already in front of us, its colors undergo a blue shift - the wavelength goes to this end of the spectrum.
Red and blue displacement, as a rule, is a consequence of the removal or approach of a stellar object in relation to us. It looks like the Doppler effect during an ambulance ride near us.
At the same time, as the black hole "eats" the planet, the gas will twist into a gravitational spiral, like sugar during the creation of cotton candy. From our point of view, the spiral will forever go into the event horizon. But the light emitted by the death of Neptune will be reflected from the black hole in the negative, like the solar corona during an eclipse.
The closer the black hole is to the Earth, the more the distortion effect surrounding it will manifest itself, as in a curved mirror. All telescopes will only see the void in the center of the black hole.
If our black death is a supermassive black hole, history will already end - its event horizon will be five times larger than the solar system. But this is boring. Let's see how one of these monsters looks from the inside.
End of the world, or through the looking glass
You climb the rabbit hole knowing that your acquaintance with him will be very short. We hope that we will have time to at least assess the interior of the black hole. Fortunately for us, but unfortunately for the solar system, this black hole is supermassive. We changed the rules, but if we didn't, it would have ended for some reason.
In a small black hole - say with a mass of 30 suns - tidal forces caused by an increase in gravity would tear us apart long before we reached the event horizon. But there gravity is somewhere around a million Earths. To enjoy the victory - after all, we have reached the event horizon - we will not have even 0.0001 seconds.
In a supermassive black hole with a mass of 5 million suns, like the one located in the center of our galaxy, a very different experience awaits us. Any black hole that has absorbed a mass of more than 30 thousand suns has tidal forces with gravity less than one Earth on the event horizon. We'll have 16 seconds to look around (and change the rules of the game) before we reach the singularity point. The more mass, the more time.
Falling through the event horizon is like falling asleep or falling in love: it is difficult to determine a starting point for when this will happen, but afterwards your sense of reality will be completely different. In a black hole, you will see stars (light enters, but not vice versa), but the space around you will resemble a soap bubble.
Well, after you are crushed into nothingness, you will find yourself in a point of infinite curvature, where the time and space we know comes to an end.
Ilya Khel