Daniel and Kelly’s Extraordinary Universe - What's At The Center Of The Galaxy?

Episode Date: February 26, 2019

What's at the center of the Milky Way? How do we know? Can we explain it? Learn more about your ad-choices at https://www.iheartpodcastnetwork.comSee omnystudio.com/listener for privacy information.

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Get fired up, y'all. Season two of Good Game with Sarah Spain is underway. We just welcomed one of my favorite people, an incomparable soccer icon, Megan Rapino, to the show. And we had a blast. Take a listen. Sue and I were like riding the lime bikes the other day, and we're like, we're like, whee! People write bikes because it's fun. We got more incredible guests like Megan in store,

plus news of the day and more. So make sure you listen to Good Game with Sarah Spain on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. Brought to you by Novartis, founding partner of IHeart Women's Sports Network. You know how the center of things are always the most important things, you know, like in the cities, the center of the city is the most

important parts where all the action happens and like the eye of the storm. There's always something very special and significant about the center of something big. Yeah, exactly. And so the center plays a big role in our sort of mental organization. When I walk around a city, I'm always doing it with respect to the center. I have like an image of my mind of where are the skyscrapers, where am I going? Everything is oriented relative to the center. Right. Yeah. And it's Kind of interesting to think about the center of the galaxy, right? Like, is the center of the galaxy where all the action is in our neighborhood? The center of the galaxy is a hot, nasty place, and it's really interesting to think about what might be there.

So there could be a super cool, awesome galactic party in the center, but we have no idea. That's right. Somebody could be having the best dance party ever, and we weren't invited. It's happening downtown in the galaxy. Hi, I'm Jorge. I'm a cartoonist. And I'm Daniel. I'm a particle physicist. And we are the authors of the book We Have No Idea. And the host of this podcast, Daniel and Jorge, explain the universe.

I hope we're the host, because there's nobody else here recording with us. So it's not us. Who's in charge? Who's doing it? That's right. I'm just here to chat about science. Who's hosting this thing after all? Where are the adults?

How do they let to... How do they let two goofoffs host a podcast like this? Yeah, I've been asking that question myself for quite a while. My wife and I talk about that all the time. We look at each other and we're like, we're running a household. When are the adults going to come in and tell us what to do? We're actually making all these decisions? How did that happen?

I don't know. At some point we slept into from irresponsible adulthood into attempt at responsible adulthood. But anyway Well, I think we're it, Daniel. I think we are the people on this podcast. Well, we better get hosting then. Welcome everybody to Daniel Jorge Explain the Universe, where we try to take the universe

and explain it to you and make sure that it actually makes sense. Take deep, big philosophical questions that everybody wants to know the answers to and chat about them and make sure everybody goes away with a deeper understanding of what's going on around your planet, in your solar system,

and in your galaxy. Yeah. And today on the podcast, We are going to talk about What is at the center of the galaxy? Exactly. We are going straight to the heart of the matter. Yeah, we're going into the eye of the storm. That's right.

What matters in the galaxy? What is at the seething maelstrom that is the craziest, densest place in the galaxy? Yeah, what happens when everything swirls around and what's at the center? That's right. Are you imagining the galaxy is like one giant toilet? You can just throw your trash out and it all ends up in the center.

It sort of looks like a swirling toilet, doesn't it? Yeah, I think of it more like a dancing star, spinning its way through the universe. But you can go with your beautiful toilet analogy if that helps you. Spinning star, toilet humor. You know, it's all poetry in the grand scheme of the universe. Tell me why you were a comic and not a poet again, Jorge? Tell me why I'm not a physicist. I think it's pretty clear.

we can cross poet off the list also I think what you were saying before was really interesting about how the center is the most important place and I wonder if that's for physical reasons or like social and mental reasons I mean physically the center is always the densest because everything gets attracted there right

gravity will pull stuff together and make you have a dense core but I wonder if that's why we think of the center as important or if there's some other reason well it's technically the spot that is closest to everything else, right? Like, no other spot is closest to everything else in the center of something, right?

Mm-hmm, mm-hmm. That's true, yeah. Good geometric argument, yeah. Yeah, I mean, that's why cities build around a downtown, right? Because everyone wants to stay within a certain distance of the downtown. Mm-hmm. But in terms of, like, social planning, we've had these interesting cycles in cities, right?

Where, like, the center is the most important, and then people spread out to the suburbs, and then the center can sometimes die, right? We have this, like, urban decay. And then, of course, folks come in and rebuild condos, and then we have urban renewal. But we have these patterns in our cities where the center is really important. It's where everything's happening. And that's sort of, you know, like in L.A.

where it's just like a bunch of newspapers blowing around empty streets. And then people come back and move back in. Yeah, so that's the topic of today's podcast, is what is at the center of our galaxy, the Milky Way? What's going on in the center of our home, in the center of our galactic city? That's right. The center of mass of this beautiful bunch of hundreds of billions of stars that we call the Milky Way. And so as usual, before we dove into this topic, we went around town and we asked people. We said, do you know what's at the center of the galaxy? So those of you listening, think about it.

Think about the picture of the galaxy you may have seen on TV or online as this big swirling swirl of called our Milky Way. And what do you think is lying there in the center of that swirl? Is it turtles all the way down? Is it bananas all the way? Is the turtles eating bananas? But anyways, here's what people had to say. Black hole. Not a huge one, but it's not tiny either.

It's a decently sized one, probably from maybe a red giant. Like to stars. Okay, cool. Probably black hole. Probably some stars, some, like. But, like, that doesn't have to be some special thing, I guess. Didn't they say it's, like, a super massive black hole? Not the biggest, but one that's like, it's a super massive black hole.

I think it's a great warm hole. A big warm hole? Yes. Probably nothing, but, you know, it's just a relatively dense cluster of stars. Probably black hole. Isn't that a black hole? I thought that was the answer, but... All right.

All right, so not a lot of consistent answers here. No, the Center of the Galaxy PR team has some work to do in advertising the real estate opportunities down there. Yeah, nobody seems to know what's there. I mean, people had some pretty confident guesses, at least. Yeah, I fell into a couple categories. Some people are like, there's a big black hole. Other people are like, well, the galaxy is just stars, so more stars.

And then you have your exotic answer for somebody who thought that there was a wormhole of the center of the galaxy. And boy, I wish that were true. That would be awesome. Yeah. You mean like a toilet, like you get to the center and you flush somewhere else. Do you have something you need to get rid of Jorge? I feel like this is on your mind. You need to plunge something in your house.

You've got like some conjurvan you're looking to get rid of? No, I think it would be awesome to have a wormhole of the center of the galaxy from the sort of transportation point of view. Like, wouldn't that be the perfect place for a hub, right? If you wanted to get to the next galaxy over, just go to the center and there's a wormhole that connects you to other centers, other galaxies, and that's how you could get to other galaxies, right? That would be pretty awesome.

I mean, if I was designing the universe, definitely would go that way. Like the downtown train station or bus station? It's like you go to the center to go to another city. That's right. That's where you can go to get to another galaxy or, you know, score some illegal stuff. But the real answer is that any of these answers could be true, right? There could be a warm hole. We don't know.

There could be a black hole. We sort of don't know, right? The real answer is that all these answers are mostly true. Yes, there definitely are a lot of stars there. We have very strong evidence now that there is a huge black hole at the center of the galaxy. we don't know that there's a wormhole, but you know, we don't know that much about wormholes. We just recorded an episode about them,

and one hypothesis is that some black holes really are the openings to wormholes. So it could certainly be that the black hole of the center of our galaxy is actually a wormhole that could take you to other galaxies. You know, I think I'd probably bet it's more likely about your toilet theory of the universe,

but it's certainly a possibility, yeah. Are you flushing down my ideas down the toilet? And I'm putting them where they belong. Great. But let me, let's take a step back. So just to give our listeners a little recap, so we are on the planet Earth. The planet Earth is going around the sun in our solar system. And our solar system is actually one of the many billions of stars in the Milky Way galaxy.

That's right. That's very helpful if somebody's sending you a letter from another galaxy. I hope everybody was running that down. They're like, does this podcast apply to me? If you're listening to this podcast, and you're not on Earth, then send us a note. We'd love to hear from you. Yeah, we'd love to hear what you think of our bad humor.

That's right. Interstellar podcast jokes. We'll see if humor translates from here to other galaxies. Yeah, that's roughly the where we are in the galaxy. I think it's also helpful people know, like, how big is the galaxy? You know, it's just like, you know, a few solar systems. This is, you know, most of the universe. What's the scale of this thing we're talking about?

Yeah, I looked it up in these notes you sent me, and the galaxy is... I love the way you do research, by the way. It gets lazier and lazier as we go forward here. Somebody put these numbers in front of me. I will not vouch for them, but I will read them to you as if they were true. A physicist sent these numbers to me, so I'm pretty sure... No, you got an email from somebody who's claiming to be a physicist. You don't even know if it's from that person.

That's right. I haven't really seen your... I haven't really seen your diploma, Daniel. I should really check before putting myself out there. You know, I never had a defense. You never had a thesis defense? What do you mean? No, no thesis defense.

Wow. You were indefensible. The best thesis defense is a good offense. You know, that's my favorite ex-PTCD cartoon. So you went into your committee's offices and you just tackled them before they even knew what was going on. No, at UC Berkeley, where I did my grad school, they do not have a thesis defense required. And in the physics department, there is no. defense. So you just turn in your thesis and then the margins lady checks that the margins

are correct, you know, that the number of pages is right and everything's in the right place. And then she gives you a lollipop that says, congratulations. And that's it. You have a PhD. Wow. So it happens offline in the, when you're writing it. Yeah. Well, you turn it into this windowless room in the basement of the library and she checks the margins personally. And then when she decides that your margins are acceptable, then you have a PhD. Oh, okay. So the fact that you have a lollipop

makes you qualify to talk about the galaxy in the universe. Yeah, problem is I don't know where that lollipop is anymore. You didn't frame it? It's not hanging in your office. Who has a framed lollipop?

That would be weird. So the galaxy is, our galaxy, the Milky Way, is about 100,000 light years wide. That's right. If you shine the light in one, then it would take 100,000 years for somebody on the other side to see this light turn on. That's right, which is really big, right?

But it's tiny compared to the distances between galaxies, which is much, much, much larger, right? So you can think of, you know, the stars in our galaxy as being pretty far apart. It takes light years to get to another star. The galaxy itself you can think of as a cluster, and then it's super far to get to the next one, right? The thing I love about the structure of the universe has all these hierarchies, you know, You know, we think the sun is really far away. Well, it's really close compared to the next star. Well, you think, like, all these stars are far apart from each other.

Well, they're really close to each other compared to the next galaxy over, right? So it's really fun to think about all these scales. But, yeah, the galaxy is about 100 light years, 100,000 light years across. Yeah. And we are about 25,000 light years from the center. Huh. So we're about a quarter, no, wait, halfway out from the center to the edge of it. That's right.

And I don't think that that's a coincidence because you can't have, life everywhere in the galaxy you cannot no you can't have life too close to the center right it's sort of the opposite of a city where things get more exciting is you get closer at the nightlife gets better and better um in a galaxy night life is pretty hard to come by in the center of the galaxy because there's so much radiation it's like basically it's deadly it's like it is like the center of the storm it's like the most the craziest part of the galaxy yeah it's the center of the nuclear storm and there's a whole bunch of stuff going on in the center of the galaxy we don't understand but what we do know is that there's a huge amount of deadly radiation coming from there and if we were much

closer to the center of the galaxy then life could not have formed the way we know it it would have to be like super radiation hard life or something something like that and you also don't want to be too far out away from the center of the galaxy because well you need enough stuff right to make to form stars and to form planets and you want to have big planets going around your solar system because that can help you protect yourself against asteroids and stuff like that like a lot of people think that Jupiter has helped life form on Earth by acting as sort of like a linebacker pulling in asteroids and meteors and comets that come into the solar system that might have smashed into Earth and protecting us. So the further out you get from the center of the galaxy, the less

stuff there is. And so the fewer number of these big planets there are. And so there's sort of like a Goldilocks zone, right? There's a Goldilocks zone around each star, but there's also a goldilocks zone around the center of the galaxy. Wow. So it's lucky that our solar system is where it is in the galaxy. It's convenient. It's convenient, yeah. I mean, if our star was somewhere else, we wouldn't have had life and we wouldn't be asking this question. Oh, okay. Or we'd be a lot thicker skin, maybe. To take all this radiation. We'd look a lot cooler. We'd be able to shoot laser beams at each other and all sorts of stuff. It's fun to imagine. It's fun to imagine how life might have evolved into totally different circumstances. Yeah, so we're a little bit away from the

center. Like if the galaxy was like a CD, we'd be halfway out. in the disk. Yeah, yeah, exactly. I think of it more like a city, you know, like if the center of the galaxy was Manhattan, then we're out in Connecticut somewhere, right? Like, we're out in the verbs.

Okay, and I read also that it takes about 250 million years for our solar system to go around the galaxy. That's right. The galaxy itself is rotating. Like, everything in space seems to be spinning. The galaxy itself is rotating.

And that's why you see these spiral arms that come out of the galaxy and they're not straight, right? sort of drag in behind, and that's because it's rotating, and it takes 250 million years for the galaxy to rotate. You could also sort of think of that as like a galactic year, right? It takes the Earth one year to go around the sun. We call that a year. And so it takes the sun 250 million years to go around the center of the galaxy, so that's one galactic year. Wow. And, you know, from that point of view, the universe is not that old. Right. But I mean, even from the age of

the Earth, that's not that much, right? Because Earth is... several billion years old and so we've gone around the galaxy a few times since the earth was born yeah only about 20 times yeah we've only done 20 times around the galaxy since the earth was born earth being four or five billion years old yeah not that many times around so far we're pretty young as a galaxy yeah so next year the earth will be able to drink legally that's right all bets are off next to you have no idea what's going to happen then it can go downtown to the center and really get into the the nightlife there exactly That's when things really start to go crazy.

Yeah, and there's about a hundred billion stars in our galaxy, so we're nothing special. A hundred billion. So 100,000 million stars, and we're just one of them. And we're just one of them. And the other important thing to understand is that the stars in the galaxy are not just spread out evenly. It's not like you're spreading butter over a piece of bread, and you just spread the stars evenly throughout the galaxy. The galaxy really has a very strong gravitational pull, and so it sucks stars in towards the same. and it's much, much denser in the center of the galaxy than it is out here in the suburbs.

Yeah, I was reading this also, that as you get closer to the center, the space between stars get smaller and smaller. That's right. If you measure the density of stars out here where we are, then there's about 0.2 stars per cubic parsec. Parsec is a unit of distance. So cubic parsec is a unit of volume, right? Do you know what a parsec is?

I think there's just over three light ears in a parsec. Okay. So a cubic parsec is like 10 cubic light years. And there's 0.2 stars for 10 cubic light years. So that means, you know, you need like 50 cubic light years on average to have a star in it. Then that's where we live. So there's not that many stars. We're kind of out in the boonies almost.

Yeah, we're out here, you know, where you can look through the forest and maybe see another twinkle of your life from your neighbor, but you don't have a house right next to you, right? The other stars are not that close by. But if you go to the center of the galaxy, the story is very different. Yeah, I read that near the center of the galaxy, it's about 50 times more dense in terms of stars. No, I think it's 50 million times more dense. It's 10 million stars per cubic parsec. That was just off by six orders of magnitude.

We missed a little M there. 50 million times more stars per cubic volume than us here now. Yeah, exactly. Does that mean that if we're out there in the middle, of the galaxy and I look out into the night sky, I would see 15 million more stars than I would see right now. It would be a lot brighter,

yeah. Wow. And, you know, right now the brightest kind of nights that we have if you look up at the stars, if you look up at the sky is when you have a full moon, right? And that makes it pretty bright. You can walk around, you can see stuff. If we were near the center of the galaxy, then all the light from all those stars would be

about 200 times brighter than the light from a full moon. Wow. So it would be like, it would be, You'd rarely have darkness, right? What would life be like if it evolved on a planet that rarely had true darkness? It would be sort of daylight to hold all the time. Yeah, exactly. Exactly.

All those stars would be there at night. You would look up and the sky would just be full of dots and maybe circles, because some of the suns might be close enough that you would see them in a circle, possibly. That's right. And you could have all sorts of different kinds of experiences, right? You could get like a sunburn at night. You could call it a star burn, I guess, because there would be enough radiation from those stars to light up your life and even

you know, toast your skin. You have to wear a hat all the time. That's right. Sunscreen or star screen would be required even at night. Star screen. Getting ready to go to sleep, kids. Put on your star screen. Wow. So it's a lot crazier.

I mean, and wouldn't it just be sort of chaos because everything would be reacting gravitationally, you'd be pulled this way and that way. Things would be pretty chaotic, wouldn't they? Yeah, I think it is pretty crazy down there. You know, the dynamics of a three-body system are really hard to understand because there's three things tugging and pulling on each other. So if you get to

four, five, six, ten million things pulling on each other, it's a mess. Oh, man. It's really hard to understand how those things operate. And so things are moving and wiggling and bouncing. And it's a pretty crazy place. It's like, you know, it's like a dance club in the center of Manhattan or something. Wow. For those who are of age, clearly, of legal age, who have gone around the galaxy 21 times and are invited to the dance party at the center, you know, it's pretty crazy in there. Well, let's get it, let's go deeper and let's think about, let's talk about what's actually

at the center of the galaxy. But first, let's take a quick break. A foot washed up a shoe with some bones in it. They had no idea who it was. Most everything was burned up pretty good from the fire that not a whole

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Listen to America's Crime Lab on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. Hola, it's HoneyGerman, and my podcast, Grazie's Come Again, is back. This season, we're going even deeper into the world of music and entertainment with raw and honest conversations with some of your favorite Latin artists and celebrities.

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I won't say whitewash because at the end of the day, you know, I'm me. But the whole pretending and code, you know, it takes a toll on you. Listen to the new season of Grasasas Come Again as part of My Cultura Podcast Network on the IHartRadio app, Apple Podcasts, or wherever you get your podcast. I'm Dr. Joy Harden Bradford. And in session 421 of therapy for black girls, I sit down with Dr. Dr. Afia and Billy Shaka to explore how our hair connects to our identity, mental health, and the ways we heal. Because I think hair is a complex language system, right?

In terms of it can tell how old you are, your marital status, where you're from, you're a spiritual belief. But I think with social media, there's like a hyperfixation and observation of our hair, right? That this is sometimes the first thing someone sees when we make a post or a reel is how our hair is styled. We talk about the important role hairstylists play in our community, the pressure to always look put together, and how breaking up with perfection can actually free us. Plus, if you're someone who gets anxious about flying,

don't miss Session 418 with Dr. Angela Neil Barnett, where we dive into managing flight anxiety. Listen to therapy for black girls on the IHeart Radio app, Apple Podcasts, or wherever you get your podcast. All right, let's talk about what's at the actual center of the galaxy. Daniel, what's at the center of the galaxy? What's at the center of the galaxy is a supermassive black hole. Super massive, not just massive.

Super massive. And that's not something you should bandy around when you're talking to your mother-in-law about how her dress makes her look, right? But supermassive is definitely appropriate when we're talking about this black hole because it weighs as much as millions and millions of stars. I like how this is an actual technical physics term, supermassive black hole. Yeah, exactly. It was between supermassive or just effing heavy man, and they went with supermassive, yeah.

But it's crazy. So like if our sun turn into a black hole, like if you squished it and it turned to a black hole, it would have the mass of one sun, basically. So you're saying that these black holes at the black hole at the center of the galaxy, has millions of suns in it, kind of. Yeah, exactly. And it could have smaller suns and bigger suns,

but it's slurped them all together, and it's grown, and it's huge. It's incredible. It's a really massive blob. And the fascinating thing is that our galaxy is not unique. We have seen the black hole at the center of our galaxy, that we'll talk in a minute about what that means to see it. And we've also seen it at the center of other galaxies.

In fact, it seems to be more normal than abnormal to have a black hole at the center of the galaxy. Right. Most galaxies have a super massive black hole in the middle. That's right, yeah. And, you know, that's what happens when things get dense. You crowd enough stars together, and eventually you're going to get enough gravity to pull these things together to create black holes. Or one of them goes supernova and creates a black hole and then sucks in the other ones,

and it just grows and grows and grows. So it's not a surprise, right? It's sort of the best place to look for a black hole. Like, where should you find one? You should find one where there's the most mass, because that's what a black hole is. It's a really high concentration of mass. Oh, that's kind of what inevitably happens

when you have that much stuff together in the middle. Yeah, exactly. You squeeze enough stuff together and you're going to get a black hole. So is that what's holding the galaxy together in a way? Yeah, absolutely. I mean, the black hole at the center is a tiny fraction of the mass budget of the galaxy, right? The galaxy has hundreds of billions of stars, and the black hole at the center, it weighs as much as millions.

of stars. So we could do without it, right? If you deleted it, it would change the way the galaxy rotated because the basic dynamics of a galaxy is that it's spinning, right? Although stars are orbiting around the center, they're getting pulled in by all the gravity from all the stuff that's closer to the center than they are. And that black hole is a chunk of it, but it's a small fraction. So we could do without it, but yeah, it is playing a role in keeping the galaxy together. Oh, but it's not a huge role. It's not like the anchor of the galaxy. It's just like it's just helping the galaxy stay together. That's right, because also remember

most of the stuff in the galaxy that's providing gravity is not stars or dust or gas or even black holes. It's dark matter. There's much more dark matter in the galaxy than there is normal matter five times as much. So also in the center of the galaxy

is an enormous, dense blob of dark matter that we can't see at all. Wow. Well, we talk about dark matter in another podcast episode, but let's focus on this black hole How do we know there's even a black hole there if you can't see black holes? Yeah, you can't see them directly, which is really frustrating, right?

And the reason you can't see them directly is because they absorb light and they don't give off any light. It's easy to get confused about this topic. People think if something absorbs green light, for example, it makes it green. Remember, if something absorbs green light, then none of the green light gets to your eye

and so it doesn't look green. something only looks green if it reflects green light now a black hole absorbs all light no light can leave the black hole which is why it looks black right right so now you're looking for something black with black space behind it it's pretty tricky to see black on black it's camouflaged that's right it's perfectly camouflaged

and it's not that large like it's not like a huge thing and so it's dense and it's significant but you can't really see it right it'd just be like a little tiny dot black dot on a black background Yeah, exactly. It's like a black-domin-black background, which is really hard to spot. And the best way to see it is indirect, and the best way to indirectly study it is through its gravity, because that's really its dominant feature, right? It's a huge source of gravitational attraction. So what we can do is we can see the impact of the black hole on the stars around it. We can look to see how they're moving.

Oh, I see. So kind of like you can tell there's a sun in our solar system because all the planets are going around in a circle. You can tell there's a black hole because of the way the stars, near the center are going in a circle. Exactly. Imagine you couldn't see the sun for some reason. You were blind to the sun. And you saw all these planets orbiting the same location. You'd be like, hmm, what's going on?

There must be something there that's providing this gravitational force, right? And you can calculate it. You can tell exactly how much it weighs and where it is just based on the motion of the planets. So we use exactly that same strategy and then look at the stars that are near the center of the galaxy and ask, are they orbiting something? Is there something there that they're moving around? and absolutely there are and it takes a long time

because these stars are moving pretty quickly but this stuff is far away and so to watch a star orbit the center of the galaxy takes years or decades and there's a couple of groups one of the leading ones is at UCLA

and they've been watching these stars near the center of the galaxy and they are doing crazy stuff they are swinging around at crazy high velocities and changing directions in a way that only makes sense if there's some enormous source

of gravity right there at the center but we don't see anything, right? So that's a pretty big clue. It's like the observations and the math tell us there should be a black hole there. But then how do you separate that out from dark matter? Or how do you separate that out from just a lot of regular stars clumped together? Right, well, we don't see stars there, right?

I mean, if there were stars are luminous, they're bright. And so if there were stars there, we would see them. So we don't see any stars in that location, right? It's dark. And how do we know it's not dark matter? Well, there definitely is dark matter there also. But we have a hard time studying dark matter because it's not as localized. It tends to be more spread out.

It's sort of a smoother blob as far as we know. But that's a whole other area of discussion. One way that we can tell it's probably a black hole and not just something else, is that we do see some radiation from it. That can only come from a black hole? Yeah, that's consistent with coming from a black hole. And somebody out there's probably thinking, hold on a second. It's a black hole.

It doesn't emit any radiation. It's black. Except for hawking radiation. And we're not talking about hawking radiation. We're not talking about the little wiggles that come off the edge of the black hole when particles decay near their edge. We can talk about that in another podcast. Instead, we're talking about the radiation that comes from the stuff around the black hole that's not yet in it, but getting squeezed and pulled into the black hole. This is something called an accretion disc.

It's like the stuff swirling around the edge of the black hole that's not yet there. It's undergoing tremendous pressure. It's being really pulled and squeezed. It's like the chaos right before it falls down the toilet. That's right. Just before it gets flushed, it does a few last circles, and the little bits that are about to go in get squeezed together, and that causes radiation. And that has a very specific signature that you can say, okay, that's stuff that is about to fall into a black hole. Yeah, and it's sort of like a flickering behavior.

It's not constant. It's something that happens sometimes, and it's exactly what you would expect from a black hole. black hole. And again, you can't see this directly, right? It's really hard to study the center of the galaxy because it's obscured with huge clouds of gas and dust. And so these stars we want to image and this radiation is really difficult to see. We have to use all sorts of techniques, some combination of radio waves and infrared and x-ray emissions and all sorts of stuff. And so we see this radiation. We also see x-rays, right? X-rays and other things? Yeah. But each of these are absorbed differently by the gas and the dust that are between

between us and the center of the galaxy. And they're absorbed in different wavelengths, et cetera. And so we have to have really good maps of that dust in order to account for how much that's been absorbed. You know, how much of the signal are we missing because we're looking through a big sandstorm, essentially. And that's why it's really important to have different ways to see because infrared and radio and x-ray,

these are just different frequencies of light, essentially, of radio, of electromagnetic waves that are going through the galaxy. and the different frequencies are differently affected by the stuff that's between us and them. So having different handles is really helpful because you can tell what's there and what's not there and it gives you a clearer picture. It's like having multiple ways to ID somebody, right? You have their picture and you know their voice and you have their fingerprint or something like that

and you build up this picture slowly because we only have fragments of each of them. But if you had fragments of somebody's voice and their picture and you knew what they smelled like or something that you could identify somebody even if you couldn't see them clearly. Okay, so that's what's at the center of the galaxy. It's just a lot, it's a party in there. A lot of stars. 10 million stars per cubic parsec.

So yeah, it's a pretty hot and dense place. Yeah, and there's dark matter, and there's super massive, there's a super massive black hole in there also. That's right. And pretty soon we're hopeful that we'll get an even better view of what's going on in the center of the galaxy

because we have this project. It's called the Event Horizon Telescope. Event horizon is the name for the edge of the black hole beyond which nothing else can come out of and they're building this telescope it's essentially just tying together a bunch of different telescopes on Earth but if you do that if you use data from different telescopes all at the same time it makes like a huge virtual telescope

one that's effectively the size of the distance between the telescopes and so they're making one that's basically the size of the Earth and they were supposed to have essentially a picture of the black hole of the event horizon of the black hole imagine that image from interstellar you know the picture of the black hole from interstellar that's become sort of famous yeah the one that looks like a

basically a big black ball surrounded by kind of a halo yeah yeah to me it looks a bit like a pizza that somebody sat on a pizza a pizza that somebody flushed down the toilet exactly it's a big flushed pizza anyway we're going to see pretty soon

what the center of the galaxy actually looks like thanks to the new event horizon telescope The data was supposed to come out. The image was supposed to come out last year, but they're still processing. So it could be any day that we're going to have this historic first image of the event horizon of a black hole. Of a black hole. And you will see details like in the movie? I don't know.

I don't know what it's going to look like. I don't know what kind of resolution they have. But it's going to be pretty exciting. All the black holeologists I know are very excited about it. Wow. That is an actual job description. Absolutely. And I should mention that in preparing for this podcast, I actually did some research.

myself. And I spoke to one of my esteemed colleagues, Professor Aaron Barth, and he is a black hole ologist. He studies super massive black holes. And he thinks about how do you make them and does it make sense? And why do we have them? And do they work the way we expect? There's a lot of open questions about the way black holes work. Even though we know they're there, we don't really understand why they're there and how they got to be there. Black holeologist. Wow. You can't get over that, right? You're like, I wasn't aware that that was on the list. I wouldn't become a cartoonist. I would have gone with something better, maybe, like, black holy man.

That would have been a little more. I think that could be confused with something else. A black holistic person. Doctor. Okay, so I heard there's a huge mystery surrounding black holes at the center of galaxies. And we should totally get into it. But first, let's take a quick break. A foot washed up.

A shoe with some bones in it. They had no idea who it was. Most everything was burned up pretty good from the fire that not a whole lot was salvageable. These are the coldest of cold cases, but everything is about to change. Every case that is a cold case that has DNA. Right now in a backlog will be identified in our lifetime. A small lab in Texas is cracking the code on DNA. Using new scientific tools, they're finding clues in evidence so tiny

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All right. So there is a huge super massive black hole at the center of the galaxy, and there's a huge mystery surrounding these black holes, which is that nobody knows how they came to be. They're inexplicable. That's right. They're too big, right? You know, and some people like big black holes and they cannot lie, but we don't know how these black holes got to be so big. The reason is that it's, you might think, well, the black hole sits at the center of the galaxy.

Of course, it just sucks up a bunch of stars. Yeah, it's just been eating a lot. Yeah, but, you know, it's not easy for black holes to suck in all those stars because the stars are orbiting, right? The same reason that the Earth doesn't just, like, fall into the sun to make the sun a tiny, bigger those stars are orbiting the black hole and their angular momentum keeps them from falling in and so according to our models the black holes should not be that big they're like a thousand times bigger than they should be if we understand you know how they started and how they grew so the fact that they're so big is kind of awesome but also a big mystery they're mysteriously big

like we don't know where all the food came from we don't know how they got that big yeah we don't know what are they sucking in and where did it come from and who's been feeding them and people have crazy ideas. You know, they think maybe there was a time in the universe when galaxies were colliding a lot more than they are now. And so it could be that, you know, a bunch of galaxies crammed together and what we have at the center of our galaxy is basically the black holes of a bunch of galaxies all merge together. Or, you know, maybe when that merger happens, the black hole just like gobbles up a bunch of stars because they come into its path. There's a lot of fun, really fun, but really crazy, dramatic ideas. And the amazing thing to me is that these

these dramas are incredible right black holes eating stars but they also happen really slowly you know like over millions and billions of years you see these galaxies colliding and merging and things getting sucked up right you know i love the idea of huge violence happening really slowly well it's slow for you but you know our lives would be slow to an ant right or to a microbe yeah exactly and on the microbe universe podcast they probably talk about that all the time right daniel we're talking so slowly The disaster that is this podcast, or it's all happening so sweet. Why is this podcast so long? Maybe the black hole in our galaxy, the one at the center of the supermassive one,

came from two galaxies crashing into each other and their black holes joining into one. Or it could be that we just don't understand the process that starts a black hole, and then maybe they started off much bigger. and that explains why they are larger than we understood. There's just a lot of basic questions. And every time we do this in science, we see something interesting, then we ask, can we explain it? Do our models predict exactly what we're going to see?

It's not just like, oh, we figured there'd be a black hole. Yeah, there is. Now, we come up with detailed, quantitative models that say, how big should it be? Or is our black hole unusual? And let's look at all the other black holes, and we try to really understand the details of the process. This is how we find problems, and this is how we crack them.

So it's really all in getting into these details. I have a question. Can a black hole suck in dark matter? Absolutely, yeah. There's nothing preventing that. Yeah. Oh. Absolutely.

I mean, dark matter feels gravity, right? And so it's going to get pulled by the black hole. And there could be dark, there could be black holes made mostly of dark matter, right? Dark holes or whatever you want to call them. Dark black holes. Yeah, exactly. No, dark matter is definitely not immune from the gravitational pull of a black hole. Wow, it's amazing to think we have this huge mystery in the center of our galaxy.

A huge hole in our knowledge about the universe is there literally and figuratively, right? That's right. It's at the center of everything we live around. We've been orbiting it for billions of years and still don't understand it. And the list of mysteries at the galactic center is huge. We don't understand a lot of the radiation that's coming from there. We think there might be weird stuff happening that we don't understand strange stars being made, it all sorts of other kind of processes. Another big mystery is like, where do all the high-energy cosmic rays come from?

These particles from space that have so much energy, we can't explain it. Yeah, we did a podcast episode on that, right? Yeah, and one possibility is maybe they're coming from centers of galaxies with these enormous pressures and huge gravitational forces. So far it doesn't look like it because we don't have a whole lot of examples of these high-energy particles, but we can't point them all back to the centers of galaxies, but we don't know. And so there's a lot of stuff to be discovered. It's a really, really rich source of astronomical mystery.

Yeah. It really makes you think how dynamics things still are. You know, things seem pretty chill right now in our solar system, but we're really part of this larger history of this crazy, giant, swirling, active disaster crash zone, toilet. That was the alternate name for the galaxy we considered instead of Milky Way. Active crash disaster toilet. but it didn't quite roll off the tongue the same way I didn't think it was going to sell t-shirts

no but you're absolutely right and remember the galaxy is young we've only been around for 20 spins of the galaxy and so in terms of galactic years the whole universe isn't even that much longer it's like you know 60 or 70 galactic years old so things are just getting started so in that center is just getting started

the party yeah the downtown party that's right but it's interesting to think that inside of that galactic center are clues about how the galaxy formed and how this whole universe got put together, right? Exactly, absolutely. And that's what makes it so exciting. And you know, that's the process of science. Like, let's look around and see what we don't understand and then ask basic questions about it and try to figure it out. And along the way, we come up with better and better and more accurate models of what's going on. And that's how we figured out, like, the dark matter is a thing. And that's how we discovered black holes and a lot of the really

great transformative discoveries of the modern age have come from asking simple, basic questions about stuff. I'm not flushing them down the toilet right away when your podcast partner says them. That's right. Or asking questions about how to flush things down the toilet. Like, can I flush a black hole down the toilet? Yes or no. Only the dark matter, please.

That's right. That was such an obvious joke. Nice job. Well, thank you for joining us. that's the mystery at the center of the galaxy. That's right. So now you know what is at the center, the hop and party at the center of the galaxy.

But we don't recommend you spend any time there. Join us in 250 million years when the Earth turns 21. That's right. Thanks for listening. See you next time. If you still have a question after listening to all these explanations, please drop us a line we'd love to hear from you. You can find us at Facebook, Twitter, and Instagram at Daniel and Jorge, that's one word, or email us at Feedback at Danielandhorpe.com.

Every case has a story to tell, and the DNA holds the truth. He never thought he was going to get caught, and I just looked at my computer screen. I was just like, ah, gotcha. This technology's already solving so many cases. Listen to America's Crime Lab on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. Hi, it's Honey German, and I'm back with season two of my podcast. Grazias, come again. We got you when it comes to the latest in music and entertainment with interviews with

some of your favorite Latin artists and celebrities. You didn't have to audition? No, I didn't audition. I haven't auditioned in like over 25 years. Oh, wow. That's a real G-talk right there. Oh, yeah. We'll talk about all that's viral and trending,

with a little bit of cheesement and a whole lot of laughs. And, of course, the great bevras you've come to expect. Listen to the new season of Dashes Come Again on the IHeartRadio app, Apple Podcast, or wherever you get your podcast. Get fired up, y'all. Season 2 of Good Game with Sarah Spain is underway. We just welcomed one of my favorite people, an incomparable soccer icon, Megan Rapino, to the show, and we had a blast.

Take a listen. Sue and I were like riding the lime bikes the other day, and we're like, we're like, people ride bikes because it's fun. We got more incredible guests like Megan in store, plus news of the day and more. So make sure you listen to Good Game with Sarah Spain on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. Brought to you by Novartis, founding partner of IHeart Women's Sports Network. This is an IHeart podcast.