When people think about a black hole, practically most of the time they ask: How does a black hole form? Not many people know how a black hole really forms, and what black holes do. Nearly all black holes develop when a massive star dies and its core collapses in on itself. Countless amounts of black holes exist in space today. The idea of a black hole was proposed by Albert Einstein in 1916 with his general theory of relativity. However, the first one wasn’t discovered until 1971(Redd, Nola Taylor). After the discovery, scientists did more research and found out that there are three types of black holes, primordial, stellar, and supermassive (Wild, Flint). The most common kind are called stellar black holes. They are formed when a star dies and collapses in on itself (Wild Flint). Primordial black holes are the smallest black holes. They are thought to be the size of an atom but have the mass of a large mountain (Wild, Flint). While scientists do not know how they formed, they think that early in the universe the rapid expansion of some matter might have compressed slower moving matter enough to contract into primordial black holes (Wild, Flint). The largest black holes are called “supermassive.” They have a mass of over one million suns combined and would fit in a ball with a diameter of the solar system. Again, scientists aren’t sure how they formed, but they think they are a product of galaxy formation, due to the existence of a majority of them in the center of galaxies. It is also thought that supermassive black holes might be the result of hundreds or thousands of tiny black holes merging together (Wild, Flint). All planets have an escape velocity. Escape velocity is the speed you need to be going to escape the planet’s atmosphere. The escape velocity of earth is 6.8 miles per second (hubblesite.org). That means anything that wants to leave the planet’s atmosphere must be going at least 6.8 miles per second. The escape velocity of a black hole is the speed of light (hubblesite.org). Since light isn’t fast enough to escape the force of a black hole, it gets sucked in. The only way we see things is when light bounces off of them. Because of that, black holes are invisible (Wild, Flint). While they are invisible, scientists can still see black holes because its strong gravity and the effects it has on stars and gases around it (Wild, Flint). With the idea of an invisible, destructive force in space, people tend to worry if earth will be swallowed by a black hole. Black holes don’t wander around the universe, indiscriminately swallowing planets (Wild, Flint). They follow the rules of gravity like every other object in the universe. The sun will not turn into a black hole because it is not big enough (Wild, Flint). A black hole can only form when the star that died had a mass of about three times that of the sun (Wild, Flint). Even if the mass of the sun was turned into a black hole, our planet and the planets around it would still orbit it the same way. That is because it would have the same mass as the sun and the same pull of gravity on the planets in our galaxy. The event horizon is the point in a black hole in which any escape is impossible because it requires moving faster than the speed of light. If the mass of the sun were a black hole, it would be much smaller and none of the planets would get close enough to be sucked in. Black holes do not have an infinite life. Their life is finite because black holes emit what is called hawking radiation. Hawking radiation is electromagnetic radiation that black holes give off (Mastin, Luke). Black holes are constantly emitting energy. While they are emitting energy, they have to be taking in the same amount, if not more (Mastin, Luke). If they are not taking in enough energy to balance out the amount they are giving away, they will shrink and die. Most stellar and supermassive, though, are big enough that they just naturally take in enough mass to balance out the deficit in energy (Mastin, Luke). The Schwarzschild radius is a formula made by Karl Schwarzschild about black holes. The formula can solve the size some object would need to be compressed to, to form a black hole (Stein, James). The formula is extremely confusing, and would take a well-trained mathematician the better part of an afternoon to solve. But it is extremely helpful to scientists (Stein, James). While they can’t usually turn the object they measure into a black hole, it still helps them learn the mass of a black hole if they know the size and other details (Stein, James). Scientists still don’t fully understand the math and science behind a black hole. Einstein’s general theory of relativity gave an idea that scientists today still don’t fully understand (Hubblesite.org). The theory basically explains that light bends when in the effects of gravity, even though it has no mass. That is because of space time. Space time is a confusing concept (Hubblesite.org). The best way to describe it is to think of a stretched out a sheet of rubber. If you place a ball in the middle of the sheet, representing a planet, the rubber bends. If you take a marble and roll it in a straight line on the rubber it will curve when it gets close to the ball. The rubber is like space time. It is flat, and bends in the presence of matter. What gets even more confusing, however, are how black holes affect space time. When a black hole is present, it is said that space time bends infinitely (Hubblesite.org). That is why scientists will probably never fully understand black holes. In the center of a black hole is the gravitational singularity, a one-dimensional point which contains a huge mass in an infinitely small space (Mastin, Luke). In the small space, laws of physics and everything we know about science goes out the window. Density and gravity are said to be infinite. Space time curves infinitely (Mastin, Luke). If someone or something were to get close to the point of singularity, it would get “spaghettified,” or stretched out. The reason for that is because if you were to get close to a black hole, different parts of your body would be closer to it depending on your position (Mastin, Luke). Because of the strong gravity of the black hole, it would pull those parts of the body faster, thus stretching you out. If someone was watching from outside the black hole, they wouldn’t see the spaghettification. Instead, they would see you very slowly approach the black hole. When you would reach the event horizon, you would stop completely (Mastin, Luke). That is because time had stopped. This is also confusing (Mastin, Luke). Scientists have proved that as you go faster, time goes slower. They have predicted that if you were to travel speeds approaching the speed of light, time will stop completely. Since you are getting sucked in at the speed of light, time has stopped, and all someone can see is you stopped at the event horizon (Mastin, Luke). Black holes seem very confusing. The truth is, they are. The math is extremely puzzling, the concept is hard to grasp, and the science behind it doesn’t make sense when it comes to the laws of physics and quantum mechanics. But we still know that nearly all black holes develop when a massive star dies and its core collapses in on itself. The singularity is also very baffling. The fact that a point can be one dimensional and bend space time infinitely will probably never be understood. The fact that scientists have figured out what they have today is a scientific miracle. But now you know what black holes are and how they form. When you hear the words “black hole” you will really know what it means.