Imagine a region in space that not a single particle of matter can penetrate. It spews incredibly powerful streams of radiation and shines with the strength of thousands of ordinary stars. This is a white hole, the mysterious "antipode" of a black hole.
Black holes are some of the most mysterious objects in the universe. These unusual regions are thought to be the collapsing cores of dead stars and are widely known for their ability to trap any matter through powerful gravitational pull. As far as astronomers know today, black holes are so dense and massive that nothing can leave their event horizon. However, they are not the only kind of cosmic "holes".
Massless singularity
Let's say you're trying to create a mathematical model that describes the spacetime around a black hole. At some point, you take and just … subtract all the mass, all the really existing matter, from the calculations. What ultimately remains in the equation is known to theorists as a "white hole," or massless singularity.
As the name suggests, and as many have probably guessed by now, a white hole is the antipode of a black one. Its concept first appeared in the 1970s, and astrophysicists do not tire of playing with it to this day.
If the event horizon of a black hole prevents even light from reaching the speed of separation, for white this region is an absolute, impenetrable shield. It is impossible to escape from a black hole, and it is impossible to penetrate into a white one. A black hole absorbs matter, a white one spews it out. If you imagine the existence of such an object in the real world, then it will be an incredibly bright object that radiates energy into space with monstrous strength.
Until now, astronomers have never observed a white hole. Some physicists believe that in the real world such objects cannot exist by definition, because there are a number of reasons.
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The first and most basic is the formation mechanism. We already have plausible models for the origin of black holes, even if they are just hypotheses. However, a literal rewind of time is necessary for a white hole to appear, and this borders on science fiction. In fact, the object must start at a singularity and move in the opposite direction until it gathers back into a star. This would require a decrease in entropy, which grossly violates the second law of thermodynamics.
Singularity is not so simple either. The only way to establish the presence of a singularity is to determine its physical coordinates in the Universe. In other words, a specific area of space should initially be formed with a ready-made template in the form of a singularity. Astrophysicist Karen Masters explains that until now, scientists have had no reason to believe that such a "template" formation of the Universe took place at all.
When a myth comes true
But let's imagine for a second that a white hole did appear in the real world. According to mathematical equations, there can be no matter inside it in space-time, including a black hole. That is, even the size of this matter is not important: as soon as it somehow enters the indicated region of space, the very fact of the existence of a white hole in this region becomes impossible. And there is a lot of matter in space. In other words, if a white hole is born in the Universe, then it exists for a very short time. And if we assume that such holes were in the world from the beginning, from the moment of its inception, then they would have been destroyed billions of years before even a hint of life appeared in the depths of the primary ocean of the Earth.
So today white holes only exist on paper. However, it should be noted that until recently black holes were also just a beautiful theory. In fact, scientists have even found a phenomenon in the universe that can be explained by the existence of white holes. Its name is gamma-ray burst. This is one of the brightest and most energetic events in space, during which more energy is emitted in 10 seconds than our Sun can generate in 10 billion years!
Gamma-ray bursts are accompanied by a residual glow, indicating that this is the result of a star explosion. In 2017, astronomers were even lucky to observe such a burst caused by the collision of two neutron stars. This refuted a number of hypotheses - a few years earlier, scientists assumed that the notorious white holes were the source of gamma-ray bursts. However, in the process of discussion, a rather daring, but more realistic idea was born: what if the Big Bang was really just a supermassive white hole?
There is another interesting hypothesis according to which a white hole is the final stage in the development of a black hole. Probably, we do not observe them just because our Universe is quite young, and not a single black hole has yet had time to "grow old" sufficiently. But, be that as it may, the enthusiasm of astronomers does not subside, and they continue to search among the vast expanses of space for traces indicating the presence of these phenomenal phenomena.
Vasily Makarov