What are white holes, the “bad twins” of black holes

Perhaps not everyone knows that black holes have opposite “bad twins”, white holes, which are currently only theorized by physicists. Here’s what it is.

Credit: NASA

We have all heard of the mysterious black holes, very dense celestial bodies with such a strong force of gravity that nothing can escape beyond the event horizon, the “boundary,” within which even light cannot break free. This is why astrophysicists call them black holes: they are completely invisible, but we know of their existence because of the great greed they exert towards the substance that surrounds them, inexorably drawn to the heart of darkness. There are two basic types of black holes: those born from collapsing stars and supermassive black holes in the center of each galaxy. In 2019, researchers from the International Event Horizon Telescope (EHT) project even published the first extraordinary image of a black hole, the image of the 6.5 billion solar mass “monster” in the heart of the galaxy Messier 87 (M87). , located 50 million light-years from Earth. Black holes are real, they were predicted by Alber Einstein’s theory of relativity fascinating and mysterious, but maybe not everyone knows that they have “bad twins” the so-called white holes, which at least so far remain among theories, there is no confirmation of their existence. But what exactly are these white holes?

White holes are essentially purely theoretical mathematical concepts. To be clear, astrophysicists did not observe any phenomena in the cosmos and then thought “it could be caused by a white hole”. There is no model to describe them built from observed data. White holes are currently only on paper, and it is not excluded that they will remain there, even though they are “possible” objects among the mysterious wonders of the universe. In short, white holes are the opposite of black holes. In general theory of relativity, they are areas of space-time with mass, they can spin like black holes and also have an event horizon, but unlike the famous twins, the singularity does not allow anything to enter beyond the limit, while matter can emerge from within. To an outside observer, a white hole would be exactly the same as a black hole, except that it draws particles of matter instead of consuming them. “It is only when things come out that you can say ‘ah, it’s a white hole,'” says theoretical physicist Carlo Rovelli of the Center de Physique Théorique (France), one of the leading white hole theorists. .

Conceptually, nothing and no one can cross the event horizon of a white hole while being attracted to the celestial body, while that which is inside can liberate itself and interact with the outside world. Although such objects are theorized by general relativity, it is difficult to explain how they can be formed. The reason is simple: they would violate the basis of entropy. It is as if a star is formed from a black hole and not the other way around, a time-reversed process that is impossible to explain according to the theoretical concepts we know. For this reason, scientists believe that black holes are short-lived, which may represent a “stage” in the life of black holes. “I think a long-lived white hole is very unlikely,” Professor Hal Haggard, a theoretical physicist at Bard College in New York, told Space.com. A white hole could be the end of a black hole, but even then we would break established laws. “How does a black hole die? We do not know. How does a white hole form? Maybe a white hole is the death of a black hole. The two questions are well connected, but one must violate the general theory of relativity when jumping from one to the other, ”Professor Rovelli explained.

In the study “The Revival of White Holes as Small Bangs” conducted by the Israeli physicists Alon Retter and Shlomo Helle, it was assumed that white holes could explain the Big Bang, the event that triggered the expansion of the universe by a sudden emission of matter and energy, exactly what a white hole would do. But at the moment, as specified, they are only fictitious objects and no model is able to describe them without violating the accredited laws and concepts.

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