Speaker 1: Black holes, the biggest puzzle in our universe. They're massive. And they swallow literally everything in their path, including light. But if they're so mysterious, then how do we know they're there at all? And why do we have images of them? I'm Claire Riley and I'm CNET resident space nerd. I'm here to break down everything you need to know about black holes. I'm gonna cover what they are, how we find [00:00:30] them and what these all consuming space monsters can teach us about the universe in short, I'm gonna work out exactly why space sucks, but you didn't expect me to say that black holes are everywhere in science fiction, terrifying vortexes, that suck in everything around them. But is there any truth to that fiction? Well, to work out what a black hole actually is, I went to the experts at NASA's Godard's face flight center who have dedicated [00:01:00] their life to this fascinating part of the universe.
Speaker 2: My name is Regina Caputo, and I'm a research astrophysicist at the NASA Goddard space flight center. A black hole is just a region of space where gravity is so strong, that light can't escape,
Speaker 1: Essentially that huge gravitational pool comes from a lot of mass being crammed in a really small space. There are a few types of black holes. The smallest ones are called primordial black holes. According [00:01:30] to NASA, they were formed in the first fraction of a second of the life of the universe. They can be as small as an atom, but contain the mass of a mountain. Next up, we have stellar black holes. They can cram the mass of 20 suns into a space 10 miles across that's 20 suns across the length of Manhattan. Then at the top of the size scale are the super massive black holes. No, it's not just a muse song. They're the equivalent of the mass of millions or even billions of suns. [00:02:00] And they sit at the center of galaxies with how big and dense they are. It's pretty impressive that there are so many in our universe kind of makes you wonder how these giant space sinks are formed. Oh, don't worry. I asked Regina about that as well. Yeah, we became quite good friends.
Speaker 2: So we know that the smaller ones, the ones that are on the scale of the mass of the star, those are generally created through the gravitational collapse of a massive star. And so what happens is the star is [00:02:30] so massive. It's burning up all of its fuel. And at the end of its lifetime, gravity will actually win out over the other forces and cause all of the star stuff to collapse, but for the super massive black holes. So these are black holes that are at the centers of galaxies. Um, we don't actually know how they get that big.
Speaker 1: There's a lot of research around super massive black holes, but [00:03:00] the current thinking is that they could be created by black holes merging. Yes, black holes also eat each other. Neat. So if light can escaped the center of a black hole, how do we know what they actually look like? Now? I'm no physicist, but I do know the one notorious property of light is that it lets us see things well. It turns out that we are not actually looking at the hole itself when we see them, but the hot ring of gas and dust that's swirling around the black hole [00:03:30] and getting sucked into the middle. That's known as the accretion disc and the boundary between the bright swirl of gas and the dark hole at the center. That's known as the event horizon as for what's at the very center of the void beyond the event horizon. Well, scientists only really have mathematical theories about that.
Speaker 2: We can't see it cuz light can't escape the event horizon, but lots of theorists have come up with ideas as to what [00:04:00] would be at the center. And right now we follow this idea that it's like a singularity. And so it's just a, a single point in space and that somehow has the mass of a billion stars. <laugh>
Speaker 1: All right. So how do we find these black holes in space after all we are talking about something we can't actually see? Well, we do this and I say, we, even though very much, I'm not the one doing it by looking for the [00:04:30] x-rays emitted by the super hot swells of gas and dust around black holes instruments, like NASA's Chandra x-ray observatory can measure the movement of particles, which tells us things like how fast a black hole is spinning and what kinds of matter it's sucking up. In fact, the cer x-ray observatory has also managed to capture the sound of a black hole scientist translated sound [00:05:00] coming from a black hole, 200 million light years away. It was a note about 57 octaves below middle C and they synthesized it up to the range of human hearing. So good to know what my existential crisis now sounds like, but we haven't just heard black holes. Now we've seen evidence of them. Two in 2019 scientists revealed the first ever image of a black hole shadow from the event horizon telescope. This is [00:05:30] a radio light image taken of the shadow cast by the event horizon of a black hole. In this case, a black hole, 6 billion times, the mass of our sun that's billion with a B,
Speaker 1: There are eight radio telescopes that make up the event, horizon telescope kind of like a planet wide observatory. They all collected light from around the black hole gathering petabytes worth of data, but there were still some gaps in that data. So scientists use algorithms to fill those gaps, [00:06:00] reconstructing the most likely image of the black hole. The resolution of the EHT is so sharp that it could count the dimples on a golf ball in LA all the way from New York. That's not the actual distance between LA and New York, but you get what I mean. But in this case, it's not zooming in on a golf ball. It's zooming in on a galaxy 54 million lie ears away in 2022, the EHT released a second image of the super massive black hole known [00:06:30] as Sagittarius a star. It was the first direct evidence of the black hole at the center of Al galaxy. So why do we study this weird and wild part of space? Well, scientists hope images like the ones produced by the EHT can teach us about how matter behaves around black holes. And perhaps what's even beyond the event horizon. These
Speaker 2: Are one of the most extreme objects that exist and, you know, understanding [00:07:00] like the, the catastrophic death of stars and how it relates to the rest of the environment around it. Like, you know, you think about it and it's like, man, like, I'm trying to figure out how the universe works. <laugh>
Speaker 1: So there have it. Science fiction makes black holes look huge and fascinating and mysterious. And the truth is, well kind of the same. We're only just scratching the surface, but this is one part of science [00:07:30] that could prove to be even cooler than science fiction. If you wanna know more about the deepest, darkest parts of our universe, then I've linked a video I made on the James web space telescope. It's on the hunt for invisible light, from deep space. And if you wanna know more about space, closer to home, then we've got that too. In the meantime, make sure you like and subscribe and hit me up in the comments. If you wanna know anything more about space or you want any cool concepts explained until [00:08:00] next time I'm Claire Riley for CNET.
