What is on the other side of a black hole?
Black holes are formed when a star a lot bigger than our sun dies and its core is crushed. A black hole is a celestial body with an almost infinite amount of mass and density. Nothing is as dense as black holes. This is also why black holes have immense gravitational force. It is so powerful that even light that is sucked into its gravitational force cannot escape. However, even these mighty celestial bodies do not exist forever. Over a very long time, black holes lose mass and get smaller and smaller until they finally explode. This period, however, takes trillions of years; it takes so long that it probably has never even happened in the universe before.
You might think that there is light on the other side of a black hole as there has been a discovery recently, and many headlines formalised it in such a way. However, this can be a bit misleading. The actual discovery was that light from a light source behind a black hole can still illuminate an object on the other side. On the left you can see how it works in our solar system: light can directly shine onto our planet. On the right, there is a black hole directly between our sun and the earth. The light that comes from the sun toward Earth now vanishes into the black hole and is never seen again. The light that under normal circumstances without the black hole would not have hit planet Earth now makes a detour and hits Earth. Because the black hole has such a strong gravitational force the light around it bends. In other words, light that comes close to a black hole bends to go in a different direction.
Now let’s get to the real question; what is on the other side of a black hole? We do not know what is on the other side of a black hole for sure, but we can theorize. One theory is that the matter travels through a wormhole and a black hole is the entrance and the exit is a white hole. White holes are pretty much the opposite of a black hole. Instead of matter entering; matter would exit from a white hole, but it would be completely disorganized. However, we have not found proof that white holes exist, and there are also problems with white holes. White holes actually should have a gravitational force like everything else that has matter, especially something as big as a star. However, since white holes push matter away they would have to have no matter at all or no gravitational force, which physically should not be possible. This is why some theories suggest that white holes can only exist in a completely different universe, as maybe physics works in different ways there. This means that we might never find white holes.
There are also completely different theories, according to which black holes are not the entrance to a wormhole and also do not have a counterpart. These assumptions use the theory of Hawking radiation, which explains how black holes die. In outer space pairs of tiny atomic particles are created out of nothing and then destroy each other. The two particles also have opposite masses, one of them has a positive mass, and the other has a negative mass. When this kind of process happens close to a black hole, the positive particle has just enough energy to escape while the negative particle gets sucked into the black hole. When the negative mass enters the black hole, the particle decreases the black hole’s mass just a little bit. The positive particle is then observed as radiation. So, throughout its entire life, a black hole loses mass and becomes smaller and smaller. While it decreases in size, it also becomes hotter; so hot that it eventually explodes. Some physicists theorize that all the matter that enters a black hole just gets crushed together in the middle of the black hole. This place in the black hole is called the singularity. Here all the matter would be stored and crushed together in almost infinite density. Perhaps all the matter is returned to the universe when the black hole explodes. Others suggest that the matter that enters the black hole is ripped apart and exists as small particles. It would be an unknown process, but it is possible.
There are many theories as to where black holes lead. Some of them suggest that black holes are the entry to a wormhole and white holes are the exit. Others think that the matter sucked up by a black hole ends up in a completely different universe through an unknown process. Others still have the idea that the matter entering a black hole also exits the same spot, whether through an explosion or over a longer period. I think that the idea of wormholes sounds most convincing. The idea of interstellar space travel and the idea of flying into a black hole and exiting in a different spot in this universe fascinates me. The truth is though that we do not know what is on the other side of a black hole. There is still a lot we can find out about black holes, but there are some questions that humanity will probably never be able to answer. Perhaps the question of what is on the other side of a black hole is one of them.
Sources:
YouTube. (2008, April 3). Hawking radiation. YouTube. http://www.youtube.com/watch?v=S6srN4idq1E
What’s on the other side of a black hole? - JSTOR DAILY. (n.d.). https://daily.jstor.org/whats-side-black-hole/
Crookes, D., & Dobrijevic, D. (2022, January 5). Where do black holes lead to?. Space.com. https://www.space.com/where-do-black-holes-lead.html
YouTube. (2020, March 31). What’s on the other side of a black hole? YouTube. https://www.youtube.com/watch?v=T4oYvSH6jJ8
Crookes, D., & Dobrijevic, D. (2022, January 5). Where do black holes lead to?. Space.com. https://www.space.com/where-do-black-holes-lead.html
Independent Digital News and Media. (2021, July 29). Scientists see light coming from the other side of a black hole. The Independent. https://www.independent.co.uk/life-style/gadgets-and-tech/black-hole-light-far-side-other-b1892301.html
Black Hole Size Comparison chart gives new view of universe. Nerdist. (2021, August 4). https://nerdist.com/article/biggest-black-holes-size-comparison/
Schneider, J. (2022, April 1). Astrophysicists capture light from behind a black hole for the first time. PetaPixel. https://petapixel.com/2021/08/04/astrophysicists-capture-light-from-behind-a-black-hole-for-the-first-time/
