Well, I'm going to post this time about black holes. Black holes are the type of really cool thing that everyone know about but no one understands, so I'm going to focus a little less on what they are and more on what we need to understand about them.
Everyone knows the little thing about how black holes are places where gravity is so intense that light cannot escape, and most people know that they're formed by the explosion of old stars. But if you told people that they're actually a puncture in the fabric of spacetime, it's more than likely you'd get a few blank stares. So let's first talk about spacetime.
Spacetime is a very simple idea, really. What it means is that there's space and time are interwoven. And this might seem a little confusing, but it's actually pretty simple. Ever hear the phrase, "Lost time can never be regained?" Even though we can only move through time in one direction, we move through time. So, if we move through time, how is it any different from moving through space? In reality, space and time are interwoven into a "net" of sorts, which we constantly are moving through. In fact, what we call gravity is actually just a bend in the net. Just as if you take a bouncy ball and wrap playdough around it the playdough must bend around the ball, likewise, spacetime must bend around all mater it contains. Gravity is just an object being caught in the bend of a larger object and therefore falling towards it. Here's a good image of that:
But what happens when there's something incredible massive, like a red giant star? As the red giant swells outward, it must eventually release and collapse back in. This occurs in a supernova, when the start literally explodes and then the remains shrink back in. But the shrunk star is incredible dense, and what that means is that there's an incredible amount of matter packed into an incredibly small space. What this means is that there's an object with practically infinite density compacted into an infinitely small space, and what happens is a bend so sharp around the object that it is essentially infinite. Because of this infinite bend, nothing can escape, not even light, and it has become a black hole.
But black holes are not actually black: they're lightless. We see things when light reflects off of them and hits our eyes, and if there's no light or if light can't reflect off of something, we don't see it. Because the black hole is pulling in light and not letting any out, we can't see it, and it appears as a black spot in the sky.
Black holes sound terrifying, but they're actually pretty important for us. There's a black hole at the center of our galaxy that keeps the entire thing orbiting around it. If it weren't for the black hole, we very possibly couldn't have our galaxy, which means no solar system, which means no us. So, as long as we don't ever accidentally fly into one (and we would be able to sense it long before reaching the point of no return), we should be grateful for them.
I know this hasn't been a very deep or technical post, but I hope it's still been educational. With some luck, I'll remember to post something a little more often than once a year from now on.
