Black holes are the strangest things in our universe. Formed from the death of a star, the laws of physics break down inside its inescapable border. Black holes are the most extreme things in our universe, being able to do things we thought were impossible. In this essay, I will discuss the birth of black holes, the strange physics of a black hole, and how we could use them to create the largest power source in the universe.
There are a few ways black holes can form. The core of every star is under immense pressure. Because of this pressure, the star begins to fuse hydrogen into helium. This fusion creates energy that pushes back the outside layer, as well as releasing energy that we perceive as heat and light. After all the hydrogen is used up, it begins to fuse helium. However, the outward energy released when fusing helium is much less. In smaller stars like our star, it shrinks and turns into a white dwarf. In supermassive stars however, a battle goes on between gravity and the core of the star. If the core wins, then the star turns into a neutron star, the densest thing in the universe apart from black holes. If gravity wins however, the star turns into a black hole. There is also one other way. When two neutron stars orbit each other and eventually collide. This collision is so violent that it can cause a black hole to form. While going over the birth of a black hole is important to understanding its bizarre physics, only talking about the birth of a black hole and not about the black hole itself is like only talking about the field and not the players.
The reason black holes are black is due to the fact that light cannot escape. In the centre of every black hole is something known as a singularity. At first, we believed a singularity was zero dimensional. However we failed to consider that black holes spin. Every star has a rotation, and when you reduce the size of an object, its rotational energy increases. This means that it is one dimensional, having a circumference, but lacks depth and width in the traditional sense. It is important to note that our understanding of black holes is very limited and potentially wrong, as by their very nature they violate our laws of physics.
There is a way we could extract nearly unlimited amounts of energy from a black hole. Kerr black holes have a special zone called the ergosphere. In order to stay still inside the ergosphere, you would have to be moving faster than the speed of light (Impossible!). However, the ergosphere is still outside of the event horizon, meaning that an object can still escape. Through something known as the Penrose Process, an object can “steal” some of the black hole’s rotational energy. Think of it like being in a whirlpool and instead of resisting the whirlpool, swimming along with it to gain some rotational energy. When launching an object into the ergosphere, and then splitting it in two (Such as in a rocket). One of the pieces falls into the black hole, and the other steals some of the black hole's rotational energy. This can be seen with sound waves. When twisted sound waves are reflected off of a rotating metal rod, they become rotationally "Doppler shifted" (The change in frequency or wavelength for an observer when the wave is rotating.). This causes the waves to obtain a negative frequency, and be amplified. A similar concept can be used with rotating black holes. By shooting a rocket into the ergosphere, and then detaching the boosters, the boosters fall into the black hole, while the rocket leaves with some of the black hole's rotational energy. Let's say an advanced civilisation built a mirror around a black hole. For a black hole with the mass of the sun, we would need only the resources of a large asteroid for a ten centimetre thick mirror. By shooting twisted electromagnetic waves inside, some of the electromagnetic waves get gobbled up by the black hole, while most of them get amplified. By opening up the mirror, the electromagnetic waves have much more energy than prior. If you don’t open up the mirror, the electromagnetic waves continue to amplify, to the point where they supernova. This would create a black hole bomb, the largest explosion any living being could make.
Black holes are the largest mystery in the universe. Remember, I’m just some random middle schooler, so make sure to do your own research. I’m Kmitav Arishna, and have a nice day.