Black holes always cause a lot of questions because of their unusual nature. However, in terms of strangeness, they are still inferior to another unusual object. Today we will meet with white holes.
We know that black holes are so dense that even light cannot escape from the event horizon. If you delve into the calculations, then mathematics will provide you with a massless singularity - a white hole. These celestial bodies are often called black holes inside out. If nothing can escape from the black hole, then nothing hits the white one.
These two opposites have arisen from the equations of Albert Einstein’s general theory of relativity. The concept itself has been developed and studied since the 1970s. The nature of the objects and the “anatomy” are similar, but their behavior is completely opposite. The black hole event horizon is the boundary that prevents matter from escaping. But the horizon of events of the white hole prevents any attempt to get inside. Yes, even the light can not enter the white hole.
If white holes exist, they must be incredibly bright and energetic objects. If we speak hypothetically, then this is how to wind up time in a black hole, which throws into space everything that it managed to absorb. Scientists have never officially seen white holes, and science believes that they cannot exist in reality. The main question is: how can they form? We have realistic models for creating a black hole, but what about white? In essence, one needs to start singularities and head in the opposite direction, which tears matter and contradicts the second law of thermodynamics.
The only option if the singularity was originally in the universe. But it would be very strange and would require to turn over all physics. However, even if by some miracle white holes appeared, their life span would have ended billions of years before the first organisms appeared on Earth.
Although it is worth noting that black holes were once considered only theoretical objects, and more recently we could observe the first photo of the event horizon. Therefore, white holes are not written off. Some even believe that black and white holes make up wormholes through which you can travel in time and space (“Can you travel in space and time through wormholes?”). There is also a hypothesis that at the end black holes should evolve into white holes, but it has few supporters.
Interestingly, a group of researchers put forward a proposal for an event that could be a white hole. This is a gamma-ray burst recorded in 2017. Event GW170817 was created due to the collision of two neutron stars. Such collisions emit more energy in 10 seconds than the Sun in 10 billion years. Perhaps the blow formed a white hole.
There is also a wild suggestion that the Big Bang itself was a real supermassive white hole. Interestingly, in mathematical terms, this concept works, but in reality there are not many supporters of this hypothesis. Therefore, white holes remain even more mysterious objects than black ones.