All about black holes

You might have seen black holes referenced as wormholes, portals, or inescapable balls of doom. But what really are they?

The NASA definition of a black hole is “A black hole is a place in space where gravity pulls so much that even light can not get out.” What does this mean?

Gravity and black holes

Gravity is a force that interacts between every object, pulling them together. Your body exerts gravity on your phone, and vice versa. It is just that these forces are too small to be noticed. You exert gravity on the Earth, you are just too small to make a meaningful difference. Gravity changes with the density of an object, basically how much stuff is in an object divided by the size of an object. The denser the object, the greater gravity it has.

The formation of black holes

Black holes are formed when the largest stars in the universe collapse. Even though these stars are heavy, they are large, and so they are not too dense. Stars are constantly in the middle of a tug of war, with the internal forces of the star trying to make it expand, and gravity trying to make it collapse. Usually, these forces are balanced. But when a star reaches the end of its life, the internal forces diminish, and gravity wins. That star collapses into itself. Because it is getting smaller and smaller, but still has the same mass, its gravity gets stronger, which in turn makes it collapse faster. Most of the time, this collapse restarts the internal forces, again reaching the equilibrium where the star stays the same. However, sometimes, the star keeps on collapsing until it becomes so small, its gravity traps even light.

Visualizing black holes

There is a pretty simple way you can imagine this scenario. Pretend that you are floating above a flat surface. Place a golf ball on it. The surface bends a little under the weight. Now place a bowling ball nearby. They will start to roll towards each other. That is gravity!

Now for the black hole.

Place the heaviest golf ball you can imagine on the surface. This ball is so heavy that you cannot see how far down the bend under the ball goes. That is a black hole?

The only picture of a black hole

So, what does a black hole really look like?

That is a hard question. Because black holes absorb light, it is impossible to take a picture of them. So scientists use a workaround method: take photos of the things around the black hole, until you can see a black circle in the sky. That is a black hole!

Questions about black holes

Among the many things that we do not know about black holes, these are the two most interesting ones:

What is on the edge of a black hole?

What is inside a black hole?

There are various theories about what is on the edge of a black hole: a firewall, nothing, a portal to a different universe.

While we can speculate about the universe we know, we know nothing about what happens inside a black hole. Is there life? Is it a portal? Does “inside” even exist?

One last question: Will a black hole destroy the earth? 

No. First of all, black holes do not travel through space, other objects travel to them, so we are no in any danger from any rogue black holes. Second, if the sun were to turn into a black hole, it would still have the same gravity as the sun. It would just be smaller than the sun. The planets would continue orbiting. Humans on earth are completely safe from black holes.

Do you have any idea what is on the edge or inside a black hole? Do you have any cool facts about black holes? Let me know in the comments below!