What is a Black Hole?
Stop. First we’re gonna talk about gravity.
Okay. What is gravity?
That is a hard question. Al you need to know about gravity is that it’s a force that pulls everything into more massive objects. If something has mass, it exerts a force on other things that have mass. The closer that the two objects are, the more force they exert on each other. It’s a complicated relationship.
Can we get back to the original question?
Fine fine fine. A black hole is basically a giant vacuum. But instead of sucking in air, it uses intense gravity to pull stuff in. Why does it pull stuff in? Because it has ridiculous mass. A black hole is a place in space where matter has been squeezed into a really really small space. And nothing escapes gravity. Not even light. In smaller gravity (like Earth), we don’t notice it, but in space over long distances, light gets refracted around massive objects. Telescopes like Hubble use this phenomena to see deeper into space, around other planets. It is called “Gravitational Lensing”.
Back to the point, because no light escapes black holes, we can’t see black holes.
So how do we know where these things are?
We use telescopes with special instruments. Those are confusing, there is literally no easy way to explain this.
Since a black hole has gravity, we can also observe the stars around it, because they tend to orbit at very large distances. We can observe the orbits and calculate where the black hole is and how large it is.
How do they form?
There are a few ways. The earliest black holes were theorized to have formed shortly after the Big Bang, and they’ve been sucking stuff in since the beginning of the universe.
Another kind of black hole is called “Stellar”, which is formed when a dying star gets too large and collapses under its own gravity. This is called a supernova. It is like a slow motion explosion that tells us a star just died (RIP). It shoots a chunk of the star into space, and the rest collapses in on itself and becomes the black hole. These are all over the place, there are millions in our Milky Way Galaxy. In fact, almost all of the largest galaxies contain a giant black hole in the center.
Will we be destroyed by a black hole?
Probably not. Black holes don’t go around space eating starts and planets like PacMan eats pixels.
What about Interstellar?
While the black hole in the movie could exist if it was that size, a planet that close to the black hole will not survive. For the time dilation on the planet for 1 hour on the planet to equal 7 Earth years, the planet would have to be skimming the edge of the black hole, teetering on the edge, which is not possible.
YAAAY now you have a basic knowledge of black holes.