Can a black hole swallow our universe? Scientists explain the "voraciousness" of space giants
Black holes can be called one of the most terrifying "creatures" in the Universe. They have a super-powerful gravity that even light traveling at nearly 300 thousand kilometers per second cannot avoid them. They can completely swallow stars, planets, and even other black holes. But are they so voracious that they can swallow the entire Universe?
LiveScience found out whether such a scenario is possible, as well as whether black holes are really as voracious as people think. Spoiler alert: not really.
According to NASA scientists, there is no way that a black hole could eat not only the entire universe but even a galaxy.
Black holes are formed as a result of the collapse of massive stars. During this process, the star shrinks, becoming an extremely dense object whose gravitational pull is so powerful that even light cannot overcome it. However, as Gaurav Khanna, a black hole physicist at the University of Rhode Island, explains, the idea that a black hole can swallow the universe is wrong. It is probably based on the misconception that black holes work like vacuum cleaners. But this is not the case.
"They only suck in things that are very close to," Khanna says.
According to him, the object itself has to get close to the black hole, or rather, to the event horizon (the point of no return), for it to tear it apart and swallow it.
As the scientist explained, the event horizon is not infinite, so its strength is also limited. For example, a black hole with the mass of our Sun will extend only 3 kilometers, while a black hole with the mass of the Earth will extend only a few centimeters.
As for the gravity of black holes, it can make planets and stars move in a certain way, but it does not lead to their being swallowed up. In particular, the orbital dance of objects in our Milky Way galaxy is also regulated by the black hole in its center, but this does not mean that we are all heading towards death.
To better understand this, Paul Delaney, a professor of astronomy at the University of York, suggests imagining that a black hole of the same mass would form in place of our Sun. Despite all the claims about the power of gravity, it would have no effect on the Earth.
"Our planet would not notice any changes in the gravitational force acting on it and would continue to move in the same orbit," he said.
In turn, Alex Filippenko, a black hole expert at the University of California, Berkeley, explained that a black hole can only swallow a star if the star itself comes to it. That is, it is not a matter of pulling the star through but of its orbit coinciding with the black hole. In particular, as the expert explained, it would take "a really gigantic amount of time" for this to happen to our Sun.
In addition, as Khanna explained, nature also regulates the voracity of black holes. The fact is that a black hole absorbs matter, but releases tons of radiation in return. This causes the matter around the black hole to heat up and ionize, which makes it harder for gas and dust to cool and fall into the black hole. This slows down the rate at which the black hole can feed. This self-regulation prevents black holes from swallowing entire galaxies, let alone the entire universe.
In addition, we should not forget that the Universe is in a state of expansion, so even as the black hole grows, space objects move away from it.
Earlier, OBOZREVATEL also shared that black holes can work as a time machine.