Black holes are confusing and shrouded in mystery. Not much is known about these destructive objects, but many people believe that it may provide means for time travel. Although black hole is a phrase synonymous to annihilation, it is also believed that they play a major roll in the formation of planets, stars, solar systems, and even entire galaxies.
If asked for the definition of a black hole, you would be correct to say something like "It is a big hole in space that sucks stuff in." But how exactly did that big hole in space form, and why does it suck stuff in? It is a lot more complicated than you might think, and the science behind black holes can be mind-boggling, to say they least. In this article, you will learn what a black hole actually is, where they come from, and how they work.
Let us begin with an example. Imagine that you at your local gym, lifting weights. You are doing your typical two-hand curls with two eighty-pounders. Your arms are starting to get a tad wobbly, and you decide to get a lighter set, say, seventy pounds. For some reason, however, the weights aren't labled, and you have to guess which set weighs seventy. You grab the next set down the rack, and you start again where you left off. But you notice that there isn't much of a difference in weight between the two sets. You mumble under your breath, "Man, I am out of shape." So you decide to go another set down, and you notice the same thing is happening. What's going on? Are you really that out of shape? You begin to worry. Still, you keep going down the rack. You pick up every weight, but they all feel the same. You are conviced that someone is playing a joke on you, but you keep going. Your down to the last set. Each weight is the size of a flip phone. You think to yourself, if this weight is the same as the last ten, I'm going to have a tantrum. And it is. You strain to pick the first weight up, and you're afraid that if this tiny thing slips out of your fingers, it will crack the floor. You decide that you have had enough of this foolery, and leave. You cancel your membership to the gym, and decide to work out at home from now on.
Wait a second, how do absurdly heavy weights have anything to do with giant, hungry, space vortexes? Gravity. Yep, that same force that keeps our feet firmly planted on the ground is also responsible for those edacious enormities that are black holes. But don't worry. You won't come home one day to find that your entire house is gone, except for your little five-pounder. No, black holes occur on a much, much bigger scale. Like, ten-times-the-size-of-the-sun big. Think of a sponge. It is light and fluffy. Now take a rock that is the same size as that sponge. Much heavier, isn't it? That's because it is more dense than the sponge. Density, as described by Merriam-Webster, is "the distribution of a quantity (in this case, a quantity of matter) per unit of space (as length, area, or volume). Basically, it is the amount of stuff that is squeezed into a certain area of space. A black hole is something with an enormous amount of density. So much density that the gravity it creates has the ability to suck in anything that gets too close. Including light. How can something get so dense? Normal black holes form when a star that is at least ten times the mass of our own sun dies. As you may know, a star is a giant nuclear fusion reactor. The core of the star is so hot, that it has the ability to combine two particles of a single element, effectively creating another element. This process creates a huge amount of force, pushing the star outwards. At the same time, the gravity of the core is always trying to pull the outer layers of the star towards it. These two opposite forces, the exploding nuclear force, and the imploding gravitational force, balance each other out, preventing the formation of a black hole. But when a star runs out of energy to continue fusion, gravity takes over and begins crushing the star down to its' core. But the smaller the start gets, the more intense the gravity becomes. Eventually, the start will be so small, and so dense, that its' own gravity will literally swallow itself. You now have a black hole. To get an idea of how incredibly dense this newly formed black hole is, imagine crushing the Earth to the size of a ping-pong ball. I don't thinky you would have fun playing ping-pong with a 6,000,000,000,000,000,000,000,000 kilogram ping-pong ball.
As I meantioned earlier, nothing, not even light, can escape the gravity of a black hole. This is because everything with mass has soemthing called an escape velocity. An escape velocity is the speed that must be reached in order to escape the gravity of an object. For example, Earth's escape velocity is about 11km/s. That is how fast spacecrafts must travel in order to leave Earth. The escape velocity after crossing the black hole's 'event horizon', or 'the point of no return' is about 300,000km/s, or just above the speed of light. This is why light cannot escape, because it cannot reach escape velocity.
If we know how they are formed, then where, exactly, is the 'stomach' of the black hole? Where does all the matter go? Most scientists agree that at the center of a black hole, is something called a singularity. The singularity is infinitely small, yet infinitely dense. Technically, even though it is physically impossible to detect the singularity (becuase it is infinitely small), we know it is there, becuase it is also infinitely dense. Of course, 'infintiy' is a pretty confusing subject, and it is a bit difficult to wrap your head around.
Gravity has another interesting property: it bends time. Earth's gravity only bends time by a a very tiny fraction of a second; time is faster in space than on Earth. But the average black hole slows time much more. This means that if it were possible for you to enter a black hole unharmed, you could sit there for five years, while only experiencing one year. When you go back home (ignoring the fact that escape is impossible), you would have only aged a single year, while the rest of your family had aged five. It's a confusing concept, but it answers some interesting questions about time travel.
At the center of most galaxies, scientists believe that there are super-massive black holes, at least 50 million times the mass of our sun. There is even thought to be one in our own Milky Way galaxy. These monsters are thought to be responsible for the formation of many galaxies; their gravity draws matter into a huge clump around it, creating a sort of 'breeding ground' for new planets and starts. Although black holes are synonymous with destruction, they are also most likely responsible for the Earth, and the Sun, and the whole galaxy around us.