Why do knuckles pop?
For some people, knuckle popping grosses them out. For others, it feels so good to bend those knuckles and hear that satisfying “POP.” But how can your knuckles “pop”? The popping sound that you hear is actually something called synovial fluid rushing in-between your bones. Synovial fluid is inside the membrane that caps off your bones, and it sort of acts as a buffer that stops your bones from grinding down against each other. When you crack or pop a joint, you’re actually creating a bubble of air in-between your bones. When the fluid rushes in to get rid of that bubble, that’s where the sensation and sound of your knuckles popping comes from. Is popping your knuckles bad for you, though? The myth that it causes arthritis has been busted, but there’ve been some reports that it causes hand swelling later in life. Still, no one is sure if knuckle popping has any effects, so I say keep popping!
What are black holes?
The textbook definition of a black hole is “a region of space having a gravitational field so intense that no matter or radiation can escape.” However, I’m going to take a wild guess and assume that the majority of individuals reading this article don’t have doctorates in space science. Imagine a sponge the size of a bar of soap. You can squish that sponge in your hands and make it smaller, but it still has all the mass of the original sponge. This is essentially what happens when a star dies. It explodes and shrinks. Soon you have something smaller than an atom but with all the mass of the original star. This mass also includes the gravitational pull. Just like earth’s gravitational pull, it attracts objects. Keep in mind that stars are often millions of times larger than the Earth. With such an incredible amount of mass and gravitational pull, absolutely nothing can escape a black hole, including light.