StarTalk Radio - Cosmic Queries – Planck Lengths to Supermassive Black Holes with Matt O’Dowd

Episode Date: April 2, 2024

Is space infinitely stretchable? Neil deGrasse Tyson and comedian Chuck Nice explore fan grab bag questions about supermassive black holes, Planck lengths, and the gravitational wave background with extragalactic astrophysicist and host of PBS Space Time, Matt O’Dowd.NOTE: StarTalk+ Patrons can listen to this entire episode commercial-free here: https://startalkmedia.com/show/cosmic-queries-planck-lengths-to-supermassive-black-holes-with-matt-odowd/Thanks to our Patrons Nick Francis, nick lopez, John deLeo, Jeff Otis, Deano F, Ekam Khaira, and Jeffrey Tallcott for supporting us this week. Subscribe to SiriusXM Podcasts+ on Apple Podcasts to listen to new episodes ad-free and a whole week early.

Coming up on StarTalk Cosmic Queries Edition, from here, my office at the Hayden Planetarium of the American Museum of Natural History, we talk about black holes, clusters of black holes. We talk about the Planck length, the Big Rip, dark matter, dark energy, and everything in between. And of course, I end it with a cosmic perspective. course, I end it with a cosmic perspective. Welcome to StarTalk, your place in the universe where science and pop culture collide. StarTalk begins right now. This is StarTalk. Neil deGrasse Tyson, your personal astrophysicist. Today we're going to do cosmic queries. And this time my special guest is friend and colleague, Matt O'Dowd. Matt, how you doing, man?

Great, Neil. How you feeling? Yeah, I'm doing well. Been too long. Been too long. It's exciting. And of course, we got Chuck Nice. What's happening, Matt?

Good to see you. Chuck, there's no cosmic queries without you reading the question. There is. There is. There truly is. But I appreciate that. So let me catch up our audience to the few of them

who might not know who you are. So first, you're a professor and science communicator, so in the same business in that part of your life. And you have a PhD in astronomy and astrophysics from the University of Melbourne.

Did I pronounce that right? Melbs, as we say. Melbs. No, I'm not going there. No, no. Reabbreviate. That's too intimate. I'm just…

Funial. University of Melbourne, Melbourne, Australia. That's right. And you're into all the stuff that I like most about the universe. Extragalactic astrophysics. Everything that's like most about the universe. Extragalactic astrophysics, everything that's happening beyond the Milky Way. Right.

Quasars, active galactic nuclei. These are badass galaxies. They have supermassive black holes in their core. Right. Just into that. You're also associate professor at the City University of New York at Lehman College. Exactly. Up across the street from my former high school.

Oh. The Bronx High School of Science is on one side of the street. Lehman College. Exactly. Up across the street from my former high school. Oh. The Bronx High School of Science is on one side of the street. Lehman College is on the other. Nice. Separated by a field. Oh, okay. An athletic field.

Oh, they had to keep you guys apart? Is there some kind of beef between the college and... No chance of my people taking over the athletic field. Bronx High School of Science is not that kind of place. Oh, that's hilarious.

And you're also affiliated here in our Department of Astrophysics as a research associate. But I think most people who know you know you as host of the PBS YouTube program, Space Time. Exactly right. Oh my gosh, what a following that has. And a clever name. We busted through 3 million subscribers. 3 million.

Just the other day. Well, congratulations. Who would have thought? Congratulations. I think YouTube gives you a little memento for that. We got it at 1 million, the gold button.

Yes. Which, by the way, it does nothing when you push it. Oh, wow. At least that I know of. That's what you know of. I've pushed it a lot of times.

I was going to say. Every time you pushed it, somebody's computer exploded in their face. All right. So, let's compare notes because we're both in the same business, if you will. So, you brand yourself as a science communicator, but not a science teacher.

So, how would you divide those two tasks? Well, I do teach and communicate, so I see the division. Yeah, how do you divide? I teach a nice astronomy class each semester. With a textbook. Textbook. And homework and exams. Slideshow.

Pop quiz. Exactly, yeah. Which is really fun. I mean, you don't get quite the intimate contact when you're staring at a camera and pretending it's your audience, right? Right. You have to pretend there's a human

on the other side of the glass. Right. Yeah. Unless you see humans at all times. Sure, sure. No matter where you go. That's a different diagnosis. Even when you're alone, you see a human.

Yeah, there's this point in the like 10 seasons of Space Time where you can kind of tell where I started to do that. A friend who's like an improv champion gave me this advice. Just imagine it's someone you know. And I became so much more natural as soon as I was doing that. I wasn't talking to this. Yeah, just imagining that it's my mom or, you know, my girlfriend or whatever. Right, so what are you saying?

The early episodes, you were a little stiff. You were like delivering information rather than hanging out with the person in the camera. Yeah, I was thinking exactly what my hands were doing and it was uncanny valley. Oh. Don't go back to those. Okay.

But yes, to get back to your question. Ignore his first nine seasons. Exactly, yeah. Yeah, this was just last week, actually. But no, talking to real students and having the interaction in real time is great. So I teach classes and... You get feedback.

Yeah, it's a very different thing. If you say something that befuddles them, they'll look befuddled. And there's such a... You can get away with more when you're talking to the camera because there's no immediate accountability. Right. In the classroom, there's accountability every single lecture. So when I first started proper professor lecturing,

my mood at any time was completely based on how the last lecture had gone. Like if I flubbed the lecture, I would feel like crap until the next lecture. And if it was amazing, then I would be on top of the world. So there's a lot of, there's this feedback.

Yes, exactly. Oh yeah, oh yeah, yeah, yeah. But it's also, you know, the stakes are high because if you don't get it right this class, the next class, they'll be lost from the beginning.

Right? So you're like, you're building this edifice of knowledge and you have to do it right. Right. And how do you know that they're just not

sitting there glazed over receiving all the information and not really processing it? Well, if they're glazed over, that's a hint. And so then you have to... You have to know that they're glazed over.

Yeah. For the wrong reasons. One of your social skills is to be able to read that. To some extent. And one trick is there's always a few kids who are so into it

that you can be totally teaching to them and teach everyone else. Suck up. Always sitting in the front. They bring an apple every class. Yeah, yeah. This kid is kissing his butt all day long. Yeah, yeah.

The kid is kissing his butt all day long. And if you're one of those, thank you. Thank you so much. So which astronomy, how much math is in that intro astronomy class? Wow. This one is not much, okay? Because at CUNY, you've got to take a science class. CUNY, City University of New York. Yeah, exactly. So, you got to take a science class. And

so, there are people with all sorts of trajectories who don't have a lot of math otherwise. So, I've paired it back semester after semester until now we have, like if I teach them a core mathematical concept, they come out with one big intuition. And for this class, it's like the nature of proportionality and, you know, so understanding why these equations are what they are without having to solve too many of them. Yeah, because there are people who think astronomy is just looking at pretty pictures.

Right. Because that's how the press delivers images from the James Webb Telescope, from Hubble. And no, behind closed doors, we've got to figure this stuff out. It ain't Instagram. You know what I mean? It's like Instagram for science. It was shocking when I discovered that, that it wasn't just taking pictures through telescopes. Yeah.

pictures through Jalisco. So, just today, just today, my assistant brought to my attention some paper mail. Not e-mail. Wow. Paper. Snail mail.

Snail mail. And it's right here. This is two letters. One from a 10-year-old and one from an 8-year-old. Wow. Look at that. See that? Wow.

Those are real. And written letters. I know this is Cosmic Queries. Yes. But I don't think they're Patreon members. Well, they don't have a job, most likely. Patreon members? Well, they don't have a job, most likely.

I'll read them only because I know that they're probably unemployed. But I will tell you this much. Let's see. One is from Dexter. And the other is from Abby. And Dexter and Abby, I'm going to let you know, you owe us $5. And the moment you get a job, you need to join Patreon and send us our money. Okay?

Because you have cut the line and you have displaced many people who take their hard-earned cash and send it to us so that they may inquire of Dr. Tyson, the wonders of the universe. But you think because you're 10 years old and cute that we're just going to do whatever you... Well, I got news for you. You need to get a job. I think they got the point. You think they got the point? At some point there, I morphed into talking to my own children. Get a job.

You will not just lay around this house. You're five years old. Exactly. You pick one years old. Exactly. You know. So, you pick one from each? Okay. Let's see. All right, here we go.

All right, let's go with, let's go with Dexter. Okay. Who's coming from Middletown, Maryland. Mm-hmm. And he says, Dear Mr. Tyson, or should I say,

Dear Mr. Tyson. Okay, I'm not going to do that. Sorry. Because if he's watching, he's going to be like, Chuck, you know what? You're a real a-hole. He's going to say, Chuck, my voice is deeper than that. I'm like, dear Mr. Tyson. I don't know what his problem is. Anyway, he says, dear Mr. Tyson, my name is Dexter.

I'm 10 years old, and I have a few questions if you have time to answer them. We're going to take one of them. Okay, we'll only take one. By the way, let me just say to Dexter, your handwriting is impeccable, and it's cursive. It's in cursive. He's a 10-year-old in cursive. Okay, what planet is he from? Do you see this, Matt?

Look at this. What planet? What planet is right? I didn't know they taught kids to write anymore. You don't have to write at all. It's just the emojis, row after row. Yeah. Okay.

You pick one. You're the man. I'm going to say, here's where I'm going to pick the last question he asked, because he asked a lot of great questions. I want to read them all, but here's the last one. Finally, why do you want to die by jumping into

a black hole? I mean, it sounds awful. What would it feel like? What could you actually learn? Yeah, so he might have heard something i said at some other time right about this it's not that i want to die by falling into a black hole is it if i'm going to die and i could pick i would pick the black hole okay instead of getting hit by a bus right or

laying up from some disease right if if somebody said you're going to die tomorrow, pick, I'm picking a black hole. Right. Okay? Because how many people get to tell you what happens while they're falling into a black hole? I'd be the first person sharing that information. That's true. Wait, who would you tell? Well, so whoever's listening. That's the problem

with the black hole. I need like a, you know, tin can. A long cord that comes out. So my with a black hole. I need like a, like a, you know, a tin can, a string, a long cord that comes out. So my, my signals

will get red shifted as I get closer to the black, you're a black hole man, right? So my signal, I'm dubious. You don't think

I could pull this off? So, so I would send signals as I descended but those signals would get shifted by the gravity difference between where I am and where you are receiving my signals.

So we'd have to figure out a way to make that work. But I would be broadcasting the entire time until the tidal forces ripped me apart. Right. Now, it would first rip me apart at my midsection. You can calculate that. Right. Now, it would first rip me apart at my midsection. You can calculate that. Right. When the tidal forces exceed the molecular forces that hold together your flesh.

Mm-hmm. Now, if I'm broken at my midsection, I probably am still alive. Yes. Because all my organs, you know, my vital organs are... They're, yeah. They're up here, and my brain. Sure.

I'll probably stay alive... You're fine. But intestines will be hanging out. You're also a little thinner because of the spatter of skinification. Oh, yeah. Sure. I'll probably stay alive. You're fine. Intestines will be hanging out. You're also a little thinner because of the spatter. Oh, yeah. I didn't get there yet. I didn't get there yet. So the intestines will hang out, but you don't need your intestines.

Right. Because you're not going to have a meal in the black hole. Exactly. Right. Okay. So the intestines will spill out. But my heart, lungs, you know. All right.

So. But then my other, those two other parts would snap into, that would become four pieces. Right. And then eight. And at some point, it's just my head. Okay. All right.

And then after that, my head splits. So, he says, how would that feel? It would hurt. What do you think? But also, as Matt made sure I included here, I'm being funneled down into a narrower and narrower channel through space-time. So not only am I being stretched head to toe, I'm being extruded through the fabric of space.

Like toothpaste. Like toothpaste through a tube. Right. And we have a word for this. You should be impressed with the English language for how many words we have for how to die. And one of them is spaghettified.

I guess spaghettification. Oh, that's the most delicious way to die. Spaghettification. Yeah, but anyhow, yes, it would hurt, and I would be stretched apart. So, what would we learn? Matt, is there something to learn if I get close to a black hole that you can't figure out theoretically?

First up, so my favorite type of black hole is the supermassive type. Oh, not just the massive black hole. No, no. The supermassive. They're a little smaller than the super-dupermassive, but bigger than the intermediate. Anyway, those ones are so big, like they can be the size of our solar system.

You don't get spaghettified until you're deep in the interior. So you can cross the event horizon. I'd be able to talk about it. You're totally fine. Totally fine. I mean, you still get the red ships. Those waiting might have to wait

the entire age of the universe to get your message, crawl out of that black hole. But you would witness it yourself and you would know. You'd be able to tell yourself the story, crawl out of that black hole. But you would witness it yourself and you would know. You'd be able to tell yourself the story about what's inside a black hole.

So once I'm inside the black hole, I'm alive because I'm not spaghettified yet. Right. The supernatural. You're just falling towards. Exactly. Towards the singularity.

Towards the singularity. And I would be enlightened to myself. To yourself. What would happen, but that's about it. Yeah. But that wouldn't have... But, you know, you've got to die some way. What would happen, but that's about it. Yeah. But that wouldn't have... But, you know,

you've got to die some way. That would be almost worse because, you know, you would have all this knowledge of the only person who's ever seen a black hole and you wouldn't be able to tell anybody.

Yeah. Depends how selfish you are, really. Yeah. For me, I'd rather tell people, but if it's just me, you know, it's still good to know. It's good to know. It's good to know.

I got you. Hi, I'm Ernie Carducci from Columbus, Ohio. I'm here with my son, Ernie, because we listen to StarTalk every night and support StarTalk on Patreon. This is StarTalk with Neil deGrasse Tyson. So Chuck, you got Abby there. What do you have? This is Abby and she's eight years old. She says, firstly, what has been your favorite discovery so far? And what do you predict they will discover in the future?

Ooh. All right, Matt, next going to you. Wow. My favorite discovery. Yeah. Not of mine, because those are a little crappy. Yes, of yours. I thought, you know, historically.

Oh, no, no. Your favorite. This is a personal letter, handwritten. Wow. I found some pretty cool gravitational lenses that… Okay, that's geeky. That are pretty awesome. Yeah.

So, I mean, you know, at this point… So, a gravitational lens would be a mass in the universe that sits between you and something behind it, and the light from behind it got lensed. What makes one lens better than another? Okay, so... I'm old enough to remember the very first lens discovered. That's how old I am.

Wow. Yeah, we were losing our shit. Yeah. Oh, sorry, she's an eight-year-old child. Eight-year-old kid. Sorry. It's a grown losing our shit. Yeah. Oh, sorry. She's an eight-year-old child. Eight-year-old kid. Sorry. It's a grown-up show.

Right. Yeah, so we think of the universe as, you know, the light comes to us, it follows straight lines, and wherever you see a star or a galaxy or whatever, that's where it is. That's not the case. Okay, the universe is wibbly-wobbly, so there's gravity everywhere that makes this space like this stretchy fabric.

And so light travels by these, you know, slightly wiggly paths. But sometimes if there's a big mass like a galaxy lined up, then the light can travel multiple paths from some distant object like to us. And so instead of seeing one, we can see many, four. Many images of that one object. Many images of that one object. So why do you have a favorite one? But they all sound like they'd look the same after a while.

There are some that are just, you would call them golden lenses because everything's lined up. They are more photogenic. Everything's lined up so perfectly that we just see amazing stuff. Like we, you know, there's this, one of the very, was it the first one? The Einstein cross. Yeah, yeah.

That was early. Yeah, yeah. That one's really cool because the lens is really close to us. And so everything that's happening happens much more quickly. So we see the quasar flickering really quickly as the stars in that lens move around.

We can do really cool stuff. We can essentially map that distant black hole by looking at how the thing flickers. You know how we first discovered that it was an actual... So in Lens, we have two images of a quasar. Initially, there's just two different quasars. Right. Until someone discovered that a images of a quasar initially there's just two different quasars until someone discovered

that a variation in one quasar was repeated in the other quasar but with a time delay oh look at that okay so it meant the two path lengths

were different and it was like whoa and everything the chains matched that's really cool yeah so it was the same object.

Yeah, yeah. We freaked out in a joyous way. Yeah. That's how old I am. Back in my day, we discovered Earth in the first planet. First, we thought it was a copycat quasar. Playing Simon Says. We did.

We thought these could be like binary quasars. Yeah. That was a whole lot of first thought about it. Right. Because no one's seen a lens. Why would you, that's not your first thought. Einstein knew that his theory predicted these lenses,

general relativity, but he didn't think it would ever be seen. Right. Because it was such a small effect. Same with gravitational waves. You know, then we built some pretty good telescopes. Yeah, better than he imagined.

So what's the second part of that question? What's your favorite discovery? The second part is, what do you think they'll discover in the future? Yeah, give us your best prediction. Well, one thing that you can do with gravitational lenses, I'm on the bandwagon today, with this whole time delay thing, so you see one change and you see the other change, this lets you measure the distances to these galaxies, to the quasars and that's one of the hardest things to do in astronomy

as I'm sure you know. We discover that the universe is expanding by looking at these fluctuating stars in Andromeda and more distant. And now we use supernova explosions to try to get the distances to more distant galaxies. And all of this showed us

for one thing, that the universe is expanding. If we track the size of the universe looking back through cosmic time, we see that it's expanding. We also see that that expansion is accelerating dark energy. That's what the supernovae showed us. So we have no idea what dark energy is.

But if we have a way to track the rate of expansion over cosmic time to the greatest distances, then we can see if dark energy is the thing that fits into Einstein's equations in the most simple way, the way that Einstein actually wrote it himself, the so-called cosmological constant, or if dark energy is changing over time, okay, in which case it could be something really crazy. So we can use these time delays to figure out what the hell dark energy is. And this is, I would say, one of the…

Wait, wait, you're giving all this hypothetical. We might see it. It could be the kid wants to know what your prediction is. see it. It could be the kid wants to know what your prediction is. My prediction is that this is that what dark energy is, is one of the

biggest unsolved questions and one that we really have a hope of finding. So, knowing what dark energy is, I'm going to say. It could happen. That's the prediction. We will find out. Next year, five years, ten years, twenty years?

One of those. One of those. Yeah. I mean, that's the thing with science. You just don't know. You don't know which experiments are going

to pan out. Yeah. Yeah, all right. All right. All right, so, Chuck. Yeah. Let's get straight to the Cosmic Queries

Patreon edition. But for the, not the freeloading con. The freeloading con. Do the freeloading con. The freeloading con. Do the real Patreon. Okay.

We're going to find out that Dexter and Abby had to go to therapy after listening to your... Those guys are the best. Eight and ten years old and listening to this show? Yeah. I mean, that's impressive enough. You know, that's outstanding.

And one of them said their favorite show, their favorite variant of this is Explainers. Yeah. I mean, that kid is pretty advanced. Way to shame all the other kids out there. I like that. All right, what do you have? This is Kylie Ronning.

Kylie Ronning. Dear Neil, Matt, and Chuck, I have been waiting for this moment for so long. Thank you for reading my question. I'm wondering

if you think it is possible that there is no such thing as the smallest particle and that we can zoom in on matter infinitely. The big rip theory assumes that there is a finite end to the universe's ability to stretch out. Why do we assume this? And what if this assumption is wrong?

Ooh. Hmm. Man. Man. Look at that. That's so easy. I'm going to let Matt take that one, okay? Let's. Matt. Look at that. That's so easy. I'm going to let Matt take that one, okay?

I don't want to, I've got books beneath me. Yeah, exactly. Yeah, Matt. No, this keeps me awake at night. This whole idea

of, is there an end to scale? Like, is there, so, you know, we have this idea that there is a sort of smallest measurable distance,

the Planck length, right? So we can't do experiments that can probe space distances down below that? So Planck length, remind me, that's the distance over which light travels in... A Planck time. Imagine, right, so you have this ruler and you break it down.

It's a meter ruler. Okay, break it down to a centimeter. Okay, now it's made up of millimeters. Break the millimeters down, blah, blah, blah. You can go all the way down. Why is it that you have to stop being able to break it down into smaller... At a Planck length.

At a Planck length. You know, there's no more rulers. Why? And I don't think it's understood. Honestly, I think we don't know what the dimension of space even is. Or you don't think it is understood? Or you don't think you understand? No.

The it and the I are different things. Yeah, yeah. I definitely don't understand it. And I think there are others who have better ideas, but it's certainly not known. Right. It's certainly not known. So there is an I and it.

So the limit comes from these combinations of these fundamental constants, like the speed of light, the Planck constant, the gravitational constant. And when you put them together in certain ways, you see, including things like the Heisenberg uncertainty principle, you see that it is unmeasurable at this scale. But there's no other reason besides the value of those constants. It's unmeasurable at this scale. But there's no other reason besides the value of those constants.

It's unmeasurable well before then. It's just unmeasurable in principle. In principle, yeah. Exactly. You ain't measuring. You ain't coming near that with your school ruler. I have a protractor. So it has to work.

Anyway, so what happens when you try to subdivide even smaller? Okay, so maybe the big rip is a hypothetical thing. So at what point is anyone declaring that space cannot stretch? So the idea, if the space is infinitely stretchable, the idea of the Planck length doesn't preclude that. So you could take whatever's smaller than the Planck length and make it bigger than the Planck length, and then it's measurable.

But it doesn't... After you've stretched it. ...care space to shreds. And so if the dominant theory of what happened at the Big Bang is right, which is inflation, so the idea that the universe multiplied its size by a factor of 10, like

60 times, then that's pretty stretchy. And so if it could do that, then the current pretty gentle rate of expansion isn't going to be a problem. Using past evidence. Yeah, yeah. If inflation is

right, which, you know, some smart folks believe. Okay. Well, it's more fun to think we're all going to end in a tear in the fabric of space and time. And we're just going to get fat and bloated. And we'll just get stretched out. And we'll just get stretched out until we can't

stretch. I mean, forever. Forever. Just continuously stretching. Wow, that's a great mean, forever. Forever. Just continuously stretching. Wow, that's a great question, Kylie. Way to go. Way to go with the question there. Nice. Very good.

This is Jeremy Corbello. He says, hello, Dr. O'Dowd, Dr. Tyson, Lord Nice. This is Jeremy from Austin, Texas. Considering all moving objects in the universe are causing gravitational waves, as proposed by Einstein's general theory of relativity, can we mathematically accumulate all of the outward momentum from gravitational waves from the inner portion of the universe and use that to help justify the acceleration that we're seeing in the expansion of the universe vis-a-vis dark energy. Everything from the beginning of the universe has always been pushing outward, and every bit of gravitational wave energy would be accelerating that expansion.

By the way, love the show. Ooh. Okay. That's a mouthful of questions right there. That's a lot, man. Yeah. So it sounds like they're wondering, since everything makes gravitational waves, however small,

that these go out into the universe and form this pressure that we measure as the dark energy. Yeah. I mean, I haven't heard this idea, and I need to think about it more. A couple of nitpicks is that, you know, the normal way we think about the universe is not as it having a center and an exterior. So we don't have, it's not pushing out into anything. It's, you know, by, it's either, according to the standard general relativity,

it's either infinite and expanding, or it's this kind of closed volume that doesn't have an exterior. So there's no middle of the universe. There's definitely no middle of the universe to push out. You can't think of it as like a cake rising in a pan. You could try,

but I don't think you'd get to the right answer if you did. If you did. Okay, just eat the cake and call it a day. You could try, but I don't think you'd get to the right answer if you did. If you did. Okay. Just eat the cake and call it a day. Just drown your sorrows in the cake itself. That's it. Could gravitational waves do this for some of what the universe actually is? Let's ask it differently.

What is happening to all those gravitational waves? Oh, yeah. Because we measured it. It washed over us. We know that it's happening. The black holes collided. We had the waves. Oh, yeah. Because we measured it. It washed over us. We know that it's happening. The black holes collided. We had the waves. What happens to them? So they slowly dissipate.

So they get weaker and weaker. Especially in an expanding universe. Even more. They get redshifted, etc. But they become part of what we call the gravitational wave background. Oh, yeah. So there's this very... I forgot about that. but they so they become part of what we call the gravitational wave background oh okay so there's this I forgot about that

right on so it's everywhere the ones we've detected are relatively nearby big gravitational waves but black holes have been merging since the beginning of time

close to there's a background din a background just a little wiggle wiggle wiggle, wiggle, wiggle. Can we talk about this? Because this is the first I have ever heard. Right. I knew about it.

I forgot to connect the dots. Background gravitational. I forgot to connect the dots. Gravitational wave background. The coolest observatory ever, I'm not going to say built because it wasn't built, but invented, is looking for it.

Conceived. Conceived. Which is the pulsar timing array, which is just the most awesome thing in the world. This is not using pulsars across the galaxy, carefully timing them, and watching waves move through your line of sight, changing the pulse rate that you had so carefully measured.

Exactly. And that way you can track gravitational waves going bump in the night. Even if they don't come across. Galaxy-sized gravitational waves. This is crazy. Galaxy-sized gravitational waves. I get shivers every time I do that. Okay, so now I'm going to be honest

because you lost me. Let's go back. You're tracking what? The spin of the pulsar? Or what is the spin of the pulsar? So pulsars are these exquisite cosmic clocks. They're the cores of dead stars

that weren't quite massive enough to make black holes, but they spin incredibly rapidly. And very precisely. And they also shoot out these beams of particles that sweep by the Earth. And so we see this... Okay, right. And so we see these across the galaxy.

That's right. If they were simply spinning, you wouldn't be able to do it. You also have something spinning off of them. Yes, yes. For you to see the difference in... So it's actually a little more interesting than that. Okay. So it's not just particles and energy being spewed out the poles of the axis.

Right. The spewing part is actually tipped relative to that. Gotcha. So as it spins on its axis, Right. this other pole swings by. It's even better.

That's a better gauge. This is the beacon. That's a better gauge of the spin. Like Earth's magnetic pole doesn't align with our spin pole. Right, right.

If we had one of these, it would spin around. Okay. Every day, you'd see this beam. This makes great sense. No, no, it's great. It's great.

Okay, so keep going. Yeah, so in some cases like a thousand times a second. Yeah. And so we see just slight variations in the that are correlated across the galaxy. So a little lag here that becomes a little lag here that becomes a little lag here and we can reconstruct.

We can reconstruct these waves. At the speed of light exactly and so recently there was this the first you know tentative but still pretty intriguing detection of the gravitational wave background and how how big it is and so you know could the could that gravitational wave background be dark energy uh i don't know. That was the question. That's basically the question. The answer is I don't know. Surely they've asked this, but no one's told me. Should we Google it?

That's awesome. All right. Well, there you go. So we don't know. We don't know. Okay, Jeremy, what a great question that was enlightening

alright that was my pulsar joke alright nevermind enlightening I get it okay nevermind yeah you had to

actually explain that didn't you seriously you gotta explain it ain't a joke that's how it is to it ain't a joke All right, this is Town Poem.

Hello, world. This is Jesse from West Virginia. Uh, hello, world. This is Jesse from West Virginia. Is there any correlation between the increasing amount of space being compressed in the interior of black holes and the increasing amount of space stretched by the expanding universe? Uh, kind of the same, but here's the difference. Could radiation and dark matter be thought of as counterparts? Since radiation is a wavelength without mass, and dark matter is a

mass without wavelength. What? Since radiation is produced by matter interacting with radiation, could dark matter be produced by matter interacting with mass? Ooh. Damn, these people are...

Where are these people coming from? That's like three questions in a row where they're just like, yo, man, I'm going to make sure you went to school on this. Like, I got to make sure that your degree is legit. Here's a question. So there was a paper on the first idea. It was pretty recent.

A paper, a research paper. A research paper. Published by scientists. So the first paper was in the 60s. It was by a Russian physicist named Gleiner. And he had this notion that there could be this coupling between the interior of the black hole and cosmological scales. Right?

And Gleiner was this sort of forgotten genius. And it sort of got forgotten. But there was a recent paper that sort of tried to resurrect it and to argue that this coupling between the interior of the black hole and the cosmological scale, by what mechanism I don't know, would lead to this global negative pressure and negative pressure is what you need to accelerate the expansion of the universe and i crazily i actually read these papers but i don't remember why i

strongly objected to them which i but i do remember objecting to them. Okay. Like, I don't think there was a meaningful mechanism to have that communication between the scales, right? In theory of a black hole. You're just asserting it as a plausible account rather than... No, there was like a loose interpretation of general relativity that I thought was unjustified. So I thought there was a slightly crappy interpretation of

of GR. I was just going to say it's crap. Yeah, it's crap. Yeah, like it felt like you know, looking at the I'm going to call it to another

your work is crap. Yeah, I just I didn't buy it. I didn't buy it. We did an episode. Right. We did an episode on this actually.

Of space time. Yeah, of space time. Isn't that the whole you know, that's the whole crux of science. That's the whole point. That's the whole point. Yeah, of space time. Isn't that the whole, you know, that's the whole crux of science, right? That's the whole point. That's the whole point.

Yeah. Is for you guys to hate on each other's work. You're worse than rappers to be honest. Scientists are worse than rappers. You think you solved,

you think you good? You think you solved this? You think you solved this? How about this? Your work is crap. Scientific method. Yeah, exactly. That's pretty cool, though.

So, Chuck, we only have a couple of minutes, so maybe we can speed up our answers. Yeah, yeah, yeah. Okay. All right, here we go. This is Gina Martin. She says, hello, smarty pants. I was wondering, since space is expanding,

what is filling in the gaps? Is matter being created to fill and expand our universe volume i've heard space compared to a balloon is expanding with dots on the surface oh you know the old balloon right but a balloon is only able to expand if something is put inside of it so what exactly is inside of our universe that's making it expand so i i love it. These people are like taking all the examples. Yeah, yeah. Like, you know, the rubber sheet

and the balloon and all of that and they're just like, yo, man, what's the deal? Like, what's inside? I don't know. I think it's possible

to extend a metaphor too far. Oh. And that might be what's happening here. You've gone too far. So, Gina, Gina, you're the problem. You're the problem.

You're the problem, Gina. You went too far. You went too Gina, you're the problem. You're the problem. You're the problem, Gina. You went too far. You went too far, Gina. Well, I can say, because I'm the senior member here, back in my day, before we confirmed that the universe, well, we knew the universe was expanding. We didn't know whether it would one day re-collapse. Okay. Okay? Right.

Plus, there was no direct evidence for the Big Bang. Okay. Because that's how old I am. Okay. At the time, Fred Hoyle said, I get it. We live in an expanding universe, but I don't like the Big Bang. Like, he named it the Big Bang pejoratively. Oh. And then it

stuck. Look at that. Okay. Wow. He said, well, you want a Big Bang? Right. A copping attitude about it. That's a Big Bang. Right. And then it stuck. So, he at that. Okay. Wow. He said, well, you want a big bang? Right. You got a copping attitude about it. That's a big bang. Right. And then it stuck. So he hypothesized. Like Obamacare.

Right. Now we earn it. So the problem was, if we're expanding, how do you keep the universe approximately looking the same at all times? Right. If you're expanding. Okay. Okay. keep the universe approximately looking the same at all times. Right. If you're expanding.

Okay. Okay. So he said, hydrogen molecules are being hatched into the expanding vacuum. And those molecules then create clouds and then form new generations of stars. Wow. So if that were true,

you'd be able to see new galaxies being born today. Today. Or at any time. Right. But we didn't. Right. All galaxies are approximately the same age. Ah. So it's a steady creation of matter. He just hypothesized that.

Right, right, right. But people said to him, how is it that you can just assume matter is popping in out of nothing? That's crazy. And he said, is it any crazier than you popping matter is popping in out of nothing? That's crazy. And he said, is it any crazier than you popping the universe into existence out of nothing? And that shut everybody up. Right. He was a smart guy.

He was still wrong. He was still wrong. He was still wrong. But he knew how to shut people up. But I'm just saying, in the day, this idea that matter is being created in the vacuum. In the vacuum. Expanding vacuum. Yeah, I mean, this is like how much can you stretch space thing.

And the answer is maybe infinitely. But there's also no interior to the balloon in the case of our universe. There's no analogous interior. Right. So there you go. Wow, that's pretty cool, man. All right, this is...

A couple more questions and we can even speed up our answers. Go. Okay. This is Euclid A. Loguidice, who says... His name is Euclid? Euclid.

Okay, I'm afraid. Euclid A. Loguidice is the last name. Aloha, Dr. Tyson, Dr. Dowd, and Sir Nice. It's Lord Nice, thank you. Lord is above, sir. Lord is above, sir, just in case you didn't know. Euclid here from the Big Island. I tried asking this question before.

Not sure if I missed the deadline. There's no... Dude, relax. There's no deadlines, okay? You're okay. All right. Here we go. Could there have been...

But the Big Island, he's from Hawaii. He's from Hawaii. That's right, the Big Island. Where we have our big telescopes. There you go. Could there have been much more massive clouds of gas and dust in the early universe with strong enough gravity to cause supermassive black holes to form rather quickly?

So, that's your deal, man. That's all you. I feel mildly qualified for once. The answer is yes. Okay. So there is a big mystery, especially with JWST, the James Webb Space Telescope.

We're seeing these quasars in the early universe that are powered by these black holes that are just too big. Okay. These things had to grow and they had to grow by either eating gas or by merging little black holes

into bigger ones. And so the ones we see back there that are a billion times the mass of the sun, there's no way that in our current understanding they could have grown that big. And so a lot of people have been asking how did they start? Was there some crazy mechanism by which they could just gobble up all the gas super quickly?

Did all these black holes form near each other and then fall together? Or did supermassive black holes spontaneously form? Or at least, if not supermassive, the one tier below it, which is intermediate mass black holes. So there are ways to collapse clouds of gas directly into black holes. Normally what happens when you have a giant cloud of gas is it starts to collapse, but then it fragments. It breaks apart and it forms stars, right? But in the early universe,

the gas was, let's say, more pure. The thing that makes gas fragment today is that it's polluted. It's polluted by... Enriched. Enriched, all right. Oh, look at that. We're made of that stuff. I'm saying enriched. He's polluted by… Enriched. Enriched. All right. Oh, look at that. We're made of that stuff.

Let's be positive. I'm saying enriched. He's talking about oxygen, carbon. Right. So all this stuff. So all the other novae. Is it novae? Supernovae.

Supernovae. And those elements cause these clouds to cool down too quickly, which causes them to fragment. But in the early universe, it was just hydrogen and helium. None of these elements had been made because there had been no stars to make them. Right. And so the clouds cooled down very slowly, It was just hydrogen and helium. None of these elements had been made because there had been no stars to make them. Right.

And so the clouds cooled down very slowly, which means they could hold together as they collapsed, not fragment. Make one giant mass. Exactly. And when you get… Wow. It's like if it's a million solar masses the size of our… Oh, the answer's not shorter as it should be.

Well, cut the crap. So the answer is, some people think so. Some people think these things could have formed. By the way, that's fascinating. All right, slip in one last one. One last one. Okay, 30-second answer. 30-second answer.

Okay. All right. All right, here we go. This is Bogart Dieter. Okay, i think it's bogart dieter hello professor i'm hailing from belgium could you please describe plank second by plank second on a quantum scale what happens the moment a black hole event horizon is created so he wants you to, step by step, give us the breakdown of the event horizon

in the next 30 seconds. Which, I mean, measured by Planck seconds. Can I talk that fast? So, black holes these days are created by a collapsing cause of dead massive stars. And the first thing that happens is that

the supernova occurs, which results when the core collapses into a neutron star. Most of the stuff gets flung off. The neutron star, if it's big enough, will shrink. The bigger it is, the smaller it ends up. But at some point, a virtual event horizon forms in the core. And it doesn't really exist, but it grows. And if the black hole, if the neutron star isn't too big,

then the virtual event horizon doesn't quite reach the surface and it's a neutron star. But if it is big enough, then as the neutron star shrinks, the virtual event horizon expands. When they meet each other, it becomes a black hole. The escape velocity of the surface becomes the speed of light and in that instant everything goes dark whoa that is pretty damn dope i so that's cool so the event horizon is actually born within

and then expands out well the earth has a virtual event horizon also. It's about one centimeter in diameter at the core. And it's not real. It's just how much you would have to crush the Earth down. To get down to that point. I'm talking about the size of a plum. I thought I did the math on that. If Earth were a black hole. I've been telling people it's a centimeter.

Holy crap. I have to contact a lot of students if that's wrong. Maybe that's a really tiny plum. I think it's nine millimeters. But is it diameter or radius? Oh, so two of those. So two centimeters is a little closer to a plum. Have you been telling them that's the diameter?

I think it's the diameter. You've been telling them it's the diameter. Oh, no, it's the Schwarzschild radius. Yeah, no, I get it. No, you're right. It's the diameter. You've been telling them it's the diameter. Oh, no, it's the Schwarzschild radius. Yeah, no, I get it. No, you're right. It's the radius. The radius. So two of those gets you two centimeters.

That's about like that. Yeah, small plum, about an inch. About an inch. Less than an inch. Yeah, about an inch, yeah. I was getting a plum. Look at that. You're right.

Ooh. That's pretty cool, man. Yeah. So that's still a cool thing to think about is that. It's crazy. Yeah, that's just cool man yeah so I that's still a cool thing to think about is that yeah that's just

mind blowing yeah so every object has its own virtual event horizon you just collect within that you're a black hole you ain't coming out

exactly so are there any okay I know you need a certain mass in order to actually achieve black hole-ism okay but density density right so yeah because the mass itself Okay, because I know you need a certain mass in order to actually achieve black hole-ism. Okay, but…

Certain density. Density, right. So, yeah, because the mass itself has to go down to a certain density to create that. But are there any localized black holes that, you know, like we have clusters. Do we have black hole clusters? Yes. Yes? Crazily, we do. At black hole clusters? Yes. Yes? Crazily, we do.

At the center of our galaxy. And so this has been hypothesized for a long time because we think that because black holes tend to be a bit denser, just as dense materials fall to the bottom of whatever material, they slowly trickle into the center of our galaxy. And over the billions of years, the inner core of our galaxy, the black holes,

should have ended up in the center. Okay, so you can do these dynamical calculations that show that. But there were recent observations with, I think it was the NuSTAR X-ray Observatory. NuSTAR is it? Exactly. N-U-S-T-A-R. That saw them.

So it took these X-ray images of the core of our galaxy and saw these bright spots. Too many of them. And so we do expect there to be this swarm of black holes in the core of our galaxy. Like thousands of them. That's amazing. Yeah.

Avoid the galactic center. Avoid, avoid, avoid. Avoid the galactic center. Detour. So guys guys this is great thanks for enlightening us absolute pleasure i'm sorry you like us not guys thanks for enlightening us matt thank you for enlightening us you really made us laugh but i'm reminded that with the power of math and knowledge of the laws of physics that we're not limited by

just what you can see. We're only limited by what you can think. Which brings the question, is there a limit to how far the mind can go in the universe? How far beyond where we can physically travel can our mind take us? That's the real future of science. Wow. You just came up with

that shit on yourself right then? This has been StarTalk Cosmic Craze Edition. Of course, all about the universe. Until next time, keep looking up.