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

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.

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Neil deGrasse Tyson?

  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.

• 0:25Neil deGrasse Tyson?

  Welcome to StarTalk. Your place in the universe where science and pop culture collide. StarTalk begins right now.

• 0:38Neil deGrasse Tyson?

  This is StarTalk. Neil deGrasse Tyson, you're a 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 to meet you. How you feeling? Yeah, real well. Been too long, been too long. It's exciting. And of course, we got Chuck Nice.

• 0:56Chuck Nice?

  What's happening, Matt? Good to see you.

• 0:58Neil deGrasse Tyson?

  Chuck, there's no cosmic queries without you reading the question.

• 1:01Chuck Nice?

  There is.

• 1:02Neil deGrasse Tyson?

  There is?

• 1:03Chuck Nice?

  There truly is, but I appreciate that.

• 1:07Neil deGrasse Tyson?

  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.

• 1:24Chuck Nice?

  Oh.

• 1:25Neil deGrasse Tyson?

  Did I pronounce that right? Milbs, as we say. Milbs, no, I'm not going there. No, no. We abbreviate. That's too intimate. I'm just... For you, Neil. University of Mel- Melbourne, Melbourne, Australia.

• 1:38Chuck Nice?

  That's right.

• 1:38Neil deGrasse Tyson?

  And you're into all the stuff that I like most about the universe. Extragalactic astrophysics, everything that's happening beyond the Milky Way.

• 1:48Chuck Nice?

  Right.

• 1:48Neil deGrasse Tyson?

  Quasars, active galactic nuclei, these are badass galaxies. They have supermassive black holes in their core.

• 1:55Chuck Nice?

  Right.

• 1:55Neil deGrasse Tyson?

  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.

• 2:04Chuck Nice?

  Oh.

• 2:05Neil deGrasse Tyson?

  The Bronx High School of Sciences on one side of the street, Lehman College is on the other. Separated by a field.

• 2:11Chuck Nice?

  Okay.

• 2:11Neil deGrasse Tyson?

  An athletic field.

• 2:12Chuck Nice?

  They had to keep you guys apart?

• 2:15Chuck Nice?

  There's some kind of beef between the college.

• 2:16Neil deGrasse Tyson?

  No chance of my people taking over the athletic field. Mark's High School of Science is not that kind of place.

• 2:22Chuck Nice?

  Oh, that's hilarious.

• 2:24Neil deGrasse Tyson?

  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, it's a YouTube program, Spacetime.

• 2:38Matt O'Dowd?

  Exactly, right.

• 2:39Neil deGrasse Tyson?

  Oh my gosh, what a following that has.

• 2:40Matt O'Dowd?

  Yes.

• 2:41Neil deGrasse Tyson?

  And a clever name.

• 2:42Matt O'Dowd?

  We busted through three million subscribers.

• 2:45Neil deGrasse Tyson?

  Three million?

• 2:46Matt O'Dowd?

  Just the other day, yeah.

• 2:47Neil deGrasse Tyson?

  Oh, congratulations on that.

• 2:48Matt O'Dowd?

  Who would have thought?

• 2:49Neil deGrasse Tyson?

  Congratulations. I think YouTube gives you a little memento for that.

• 2:52Matt O'Dowd?

  We got it at one million, the gold button.

• 2:56Neil deGrasse Tyson?

  Yes.

• 2:56Matt O'Dowd?

  Which, by the way, it does nothing when you push it.

• 3:00Chuck Nice?

  Well, nothing that you know of.

• 3:02Neil deGrasse Tyson?

  That's what you know.

• 3:03Matt O'Dowd?

  Push it a lot of times.

• 3:05Chuck Nice?

  I was gonna say, yeah. Every time you pushed it, somebody's computer exploded in their face.

• 3:10Matt O'Dowd?

  All right.

• 3:12Neil deGrasse Tyson?

  So, 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?

• 3:29Matt O'Dowd?

  Well, I do teach and communicate, so I see the division.

• 3:33Neil deGrasse Tyson?

  Yeah, how do you divide?

• 3:34Matt O'Dowd?

  I teach a nice astronomy class each semester at Leam.

• 3:37Neil deGrasse Tyson?

  With a textbook?

• 3:38Matt O'Dowd?

  Textbook!

• 3:39Neil deGrasse Tyson?

  And homework and exams.

• 3:41Matt O'Dowd?

  Slideshow.

• 3:42Chuck Nice?

  Pop quiz!

• 3:43Matt O'Dowd?

  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?

• 3:51Neil deGrasse Tyson?

  Right. You have to pretend that there's a human on the other side of the glass.

• 3:54Chuck Nice?

  Right.

• 3:55Matt O'Dowd?

  Yeah.

• 3:56Chuck Nice?

  Unless you see humans at all times, no matter where you go.

• 4:00Neil deGrasse Tyson?

  That's a different diagnosis.

• 4:01Chuck Nice?

  Even when you're alone, you see a human.

• 4:03Matt O'Dowd?

  Yeah, there's this point in the like 10 seasons of Spacetime 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.

• 4:22Neil deGrasse Tyson?

  Yeah.

• 4:22Matt O'Dowd?

  Yeah, just imagining that it's my mom or, you know, like your friend or whatever.

• 4:26Neil deGrasse Tyson?

  Right, so what you're saying, the early episodes, you were a little stiff. You were like delivering information rather than hanging out with the person in the camera.

• 4:34Matt O'Dowd?

  Yeah, I was thinking exactly what my hands were doing, and it was uncanny valley. Don't go back to those. Anyway, but yes, to get back to your question.

• 4:43Neil deGrasse Tyson?

  Ignore his first nine seasons.

• 4:45Matt O'Dowd?

  Exactly, yeah. Yeah, this was just last week, actually.

• 4:48Neil deGrasse Tyson?

  Uh huh.

• 4:48Matt O'Dowd?

  Uh, but, but no, talking to real students and having the, the interaction in real time is great. So I, you know, I, I teach classes and...

• 4:58Neil deGrasse Tyson?

  You get feedback.

• 4:59Matt O'Dowd?

  Yeah, it's a very different thing.

• 5:00Neil deGrasse Tyson?

  If you say something that befuddles them, they'll look befuddled.

• 5:04Matt O'Dowd?

  And there's such a, you, you can get away with more when you're talking to the camera because there's no immediate accountability.

• 5:11Neil deGrasse Tyson?

  Right.

• 5:12Matt O'Dowd?

  In the classroom, there's accountability every single lecture. So when I first started, you know, proper professor lecturing, my, 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, is this feedback.

• 5:35Neil deGrasse Tyson?

  Yes, exactly.

• 5:36Matt O'Dowd?

  Oh, yeah. Oh, yeah, yeah, yeah, yeah. But, but it's also, you know, the, the, like, 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...

• 5:48Neil deGrasse Tyson?

  You leave them behind.

• 5:49Matt O'Dowd?

  ...etifice of knowledge and you have to do it right, right?

• 5:51Neil deGrasse Tyson?

  Right.

• 5:52Chuck Nice?

  And how do you know that they're just not sitting there glazed over it, receiving all the information and not really processing?

• 5:58Matt O'Dowd?

  Well, if they're glazed over, that's a hint. And so then you have to...

• 6:01Neil deGrasse Tyson?

  You have to know that they're glazed over.

• 6:03Chuck Nice?

  Yeah.

• 6:03Matt O'Dowd?

  For the, for the wrong reasons, yeah.

• 6:04Neil deGrasse Tyson?

  Part of your social skills is to be able to read that.

• 6:06Matt O'Dowd?

  To some extent, and, you know, one trick is there's always a few kids who are so into it that you can be totally teaching to them and everyone else suck up.

• 6:17Matt O'Dowd?

  Always sitting in the front. They bring an apple every class. Yeah, yeah.

• 6:22Chuck Nice?

  Two kids kissing their butt all day long.

• 6:29Neil deGrasse Tyson?

  So...

• 6:29Matt O'Dowd?

  And if you're one of those, thank you. Thank you so much.

• 6:33Neil deGrasse Tyson?

  So are you, um...

• 6:36Neil deGrasse Tyson?

  So which astronomy, how much math is in that intro astronomy class?

• 6:40Chuck Nice?

  Wow.

• 6:40Matt O'Dowd?

  This one is not much, okay? Because it's, you know, it's a, at CUNY, you gotta take a science class.

• 6:47Neil deGrasse Tyson?

  CUNY City University of New York.

• 6:49Matt O'Dowd?

  Yeah, exactly. Uh, so you gotta take a science class. And so there are, there are people with all sorts of trajectories who don't have a lot of math otherwise. So I've, I've pared it back semester after semester until now we have, like, if I teach them a core mathematical concept, they, they come out with one big intuition. Um, and for this class, it's like the, the nature of proportionality and, you know, so on understanding why these equations are what they are without having to solve too many of them.

• 7:19Chuck Nice?

  Hmm.

• 7:20Neil deGrasse Tyson?

  Yeah, cuz there are people who think astronomy is looking at pretty pictures.

• 7:24Chuck Nice?

  Right.

• 7:24Neil deGrasse Tyson?

  That's how the press delivers images from the James Webb Telescope, from Hubble. And no, behind closed doors, we gotta figure this stuff out.

• 7:32Chuck Nice?

  It ain't Instagram. You know what I mean? It's like Instagram for science.

• 7:37Matt O'Dowd?

  It was shocking when I discovered that, that it wasn't just taking pictures through telescopes.

• 7:41Chuck Nice?

  Yeah.

• 7:43Neil deGrasse Tyson?

  So, uh, just today, just today, uh, my assistant brought to my attention some paper mail, not email.

• 7:55Chuck Nice?

  Wow.

• 7:56Neil deGrasse Tyson?

  Paper.

• 7:56Chuck Nice?

  Snail mail.

• 7:57Neil deGrasse Tyson?

  Snail mail, and it's right here. This is two letters, one from a 10-year-old and one from an eight-year-old.

• 8:07Chuck Nice?

  Wow. Look at that.

• 8:09Neil deGrasse Tyson?

  See that? See that?

• 8:11Matt O'Dowd?

  Wow, those are real, right?

• 8:12Neil deGrasse Tyson?

  And I, and.

• 8:14Chuck Nice?

  Handwritten letters.

• 8:15Neil deGrasse Tyson?

  And this, I know this is Cosmic Queries.

• 8:17Chuck Nice?

  Yes.

• 8:18Neil deGrasse Tyson?

  But I, I don't think they're Patreon members.

• 8:20Chuck Nice?

  Well, they don't have a job, most likely.

• 8:25Chuck Nice?

  I'll read them, only because I know that they're probably unemployed. But I will tell you this much, um, let's see, one is from Dexter and the other is from Abby. And Dexter and Abby, I'm gonna let you know, uh, you owe us five dollars. 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 10 years old and cute, that we're just gonna do whatever you... Well, I got news for you. You need to get a job.

• 9:12Neil deGrasse Tyson?

  I think they got the point.

• 9:13Chuck Nice?

  Okay, yeah.

• 9:14Neil deGrasse Tyson?

  You think they got the point?

• 9:15Chuck Nice?

  At some point there, I morphed into talking to my own children.

• 9:21Chuck Nice?

  You will not just lay around this house. You're five years old. Exactly.

• 9:26Chuck Nice?

  You know.

• 9:26Neil deGrasse Tyson?

  So, you pick one from each?

• 9:28Chuck Nice?

  Okay, alright, here we go. Alright, let's go with, um, let's go with Dexter.

• 9:34Neil deGrasse Tyson?

  Okay.

• 9:34Chuck Nice?

  Who's coming from Middletown, Maryland.

• 9:37Neil deGrasse Tyson?

  Mm-hmm.

• 9:37Chuck Nice?

  And he says, "Dear Mr. Tyson," or should I say, "Dear Mr. Tyson." Okay, I'm not gonna do that. Because if he's watching, he's gonna be like, "Chuck, you know what? You're a real a-hole."

• 9:49Neil deGrasse Tyson?

  No, he's gonna say, "Chuck, my voice is deeper than that."

• 9:54Chuck Nice?

  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."

• 10:09Neil deGrasse Tyson?

  We're gonna take one of them.

• 10:10Chuck Nice?

  Okay, we'll only take one. And by the way, let me just say to Dexter, "Your handwriting is impeccable." And it's cursive.

• 10:20Neil deGrasse Tyson?

  It's in cursive. Nobody...

• 10:21Chuck Nice?

  He's a 10-year-old in cursive.

• 10:23Neil deGrasse Tyson?

  Okay, what planet is he from?

• 10:24Chuck Nice?

  Do you see this, Matt? Look at this.

• 10:26Neil deGrasse Tyson?

  What planet?

• 10:27Chuck Nice?

  What planet is right?

• 10:28Matt O'Dowd?

  I didn't know they taught kids to write anymore.

• 10:30Neil deGrasse Tyson?

  They don't write at all. It's just the emojis, row after row.

• 10:35Chuck Nice?

  Yeah. Okay.

• 10:38Neil deGrasse Tyson?

  Pick one. You're the man.

• 10:39Chuck Nice?

  Uh, I'm going to say, here's one. I'm gonna pick the last question he asked, because he asked a lot of great questions. I wanna read them all. But here's the last one. Finally.

• 10:50Chuck Nice?

  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?

• 11:03Neil deGrasse Tyson?

  Oh, yeah, so he might have heard something I said at some other time about this. It's not that I want to die by falling into a black hole. It's that if I'm going to die and I could pick, I would pick the black hole. Instead of getting hit by a bus or laying up from some disease.

• 11:21Chuck Nice?

  Right.

• 11:22Neil deGrasse Tyson?

  If, if, if, if somebody said, "You're gonna die tomorrow, pick," I'm picking a black hole.

• 11:26Chuck Nice?

  Right.

• 11:26Neil deGrasse Tyson?

  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.

• 11:35Chuck Nice?

  That's true.

• 11:35Neil deGrasse Tyson?

  Wait, who would you tell? Well, so whoever's listening. That's the problem with the black hole. I need like a, like a, you know, a tin can.

• 11:44Chuck Nice?

  Yeah, a long cord that comes out.

• 11:48Neil deGrasse Tyson?

  So my, my, my signals will get redshifted 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, I would be broadcasting the entire time until the tidal forces ripped me apart.

• 12:20Chuck Nice?

  Right.

• 12:21Neil deGrasse Tyson?

  Now, it would first rip me apart at my midsection. You can calculate that.

• 12:25Chuck Nice?

  Right.

• 12:25Neil deGrasse Tyson?

  When the tidal forces exceed the molecular forces that hold together your flesh. If I'm broken at my midsection, I probably am still alive.

• 12:35Chuck Nice?

  Yes.

• 12:35Neil deGrasse Tyson?

  Because all my organs, you know, my, my vital organs are.

• 12:39Chuck Nice?

  They're, they're, yeah.

• 12:39Neil deGrasse Tyson?

  They're up here, and my brain, so. Sure. I'd probably stay alive. You're fine. My intestines will be hanging out. You're also a little thinner because of the speed of the acceleration. I didn't get there yet, so the intestines will hang out, but you don't need your intestines.

• 12:53Chuck Nice?

  Right, because you're not gonna have a meal in the black hole.

• 12:55Neil deGrasse Tyson?

  Exactly, right, okay. So, your 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'd be, become four pieces.

• 13:09Chuck Nice?

  Right.

• 13:09Neil deGrasse Tyson?

  And then eight. And at some point, it's just my head. Okay?

• 13:13Chuck Nice?

  Alright.

• 13:14Neil deGrasse Tyson?

  And then, after that, my head splits. So, and he says, "How would that feel?" "It would hurt!"

• 13:22Neil deGrasse Tyson?

  But also, as Matt made sure I included here, I'm being funneled down into a narrower and narrower channel through spacetime.

• 13:32Chuck Nice?

  Mm-hmm.

• 13:33Neil deGrasse Tyson?

  So not only am I being stretched head to toe, I'm being extruded through the fabric of space.

• 13:40Chuck Nice?

  Like toothpaste.

• 13:41Neil deGrasse Tyson?

  Like toothpaste through a tube.

• 13:42Chuck Nice?

  Right.

• 13:43Neil deGrasse Tyson?

  And we have a word for this!

• 13:45Chuck Nice?

  Mm-hmm.

• 13:46Neil deGrasse Tyson?

  Uh, 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.

• 13:55Chuck Nice?

  Oh, that's the most delicious way to die. Spaghettification?

• 14:00Neil deGrasse Tyson?

  Yeah. But anyhow, yes, it would hurt. And I would be, I would be stretched apart. So, what would we learn? Uh, Matt, is there something to learn if I get close to a black hole that you can't figure out theoretically?

• 14:10Matt O'Dowd?

  First up, so my favorite type of black hole is the supermassive type.

• 14:14Neil deGrasse Tyson?

  Oh, not just the massive black hole.

• 14:16Matt O'Dowd?

  No, no, super. They're a little smaller than the super-dupermassive, but bigger than the interme- 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.

• 14:32Neil deGrasse Tyson?

  I'd be able to talk about it.

• 14:33Matt O'Dowd?

  You're totally fine, totally fine. I mean, you still get the, the redshift, so you, uh, those weights, you might have to wait the entire age of the universe to get your message, crawl out of that black hole. But, you would, you would witness it yourself, and, and you would know. You'd be able to tell yourself the story about what's inside a black hole.

• 14:49Neil deGrasse Tyson?

  So once I'm inside the black hole, I'm alive, because I'm not spaghettified yet.

• 14:52Chuck Nice?

  Right.

• 14:53Neil deGrasse Tyson?

  The supermassive one.

• 14:53Chuck Nice?

  Because you're falling towards.

• 14:54Matt O'Dowd?

  Exactly.

• 14:55Neil deGrasse Tyson?

  Towards the singularity.

• 14:56Chuck Nice?

  The singularity.

• 14:56Neil deGrasse Tyson?

  And I would be enlightened to myself.

• 15:00Matt O'Dowd?

  To yourself.

• 15:01Neil deGrasse Tyson?

  What would happen, but that's about it.

• 15:03Matt O'Dowd?

  Yeah.

• 15:03Chuck Nice?

  Oh man, and, that, but that wouldn't have...

• 15:06Matt O'Dowd?

  But, you know, you gotta die some way, so...

• 15:08Chuck Nice?

  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.

• 15:14Neil deGrasse Tyson?

  Yeah.

• 15:15Chuck Nice?

  And you wouldn't be able to tell anybody.

• 15:17Neil deGrasse Tyson?

  Yeah.

• 15:19Matt O'Dowd?

  It's been so selfish, you are, really. For me, I'd rather tell people, but if it's just me, you know, it's still one of those.

• 15:25Chuck Nice?

  It's good to know, it's still good to know. I got you.

• 15:36Speaker 03

  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.

• 15:46Neil deGrasse Tyson?

  This is StarTalk with Neil deGrasse Tyson.

• 16:01Neil deGrasse Tyson?

  So Chuck, you got Abby there, what do you have?

• 16:03Chuck Nice?

  Oh, 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.

• 16:17Neil deGrasse Tyson?

  Alright Matt, next going to you.

• 16:19Matt O'Dowd?

  Wow, my favorite discovery?

• 16:21Neil deGrasse Tyson?

  Yeah.

• 16:22Matt O'Dowd?

  Not of mine, because those are

• 16:24Neil deGrasse Tyson?

  Yes, of yours!

• 16:24Matt O'Dowd?

  A little crappy. I thought, you know, historically.

• 16:27Neil deGrasse Tyson?

  Oh no, no, your favorite, this is a personal letter, handwritten.

• 16:30Matt O'Dowd?

  Hmm, wow, I've found some pretty cool gravitational lenses that

• 16:37Neil deGrasse Tyson?

  Okay, that's geeky.

• 16:38Matt O'Dowd?

  That are pretty awesome, yeah, so, I mean, you know, at this point

• 16:42Neil deGrasse Tyson?

  What, does it, 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?

• 16:55Matt O'Dowd?

  Okay, so

• 16:56Neil deGrasse Tyson?

  By the way, I'm old enough to remember the very first lens discovered. That's how old I am.

• 17:00Chuck Nice?

  Wow.

• 17:00Neil deGrasse Tyson?

  Yeah, we were losing our shit.

• 17:03Matt O'Dowd?

  Yeah.

• 17:03Neil deGrasse Tyson?

  Yeah, oh, sorry, she's an eight-year-old child!

• 17:06Chuck Nice?

  Eight-year-old kid.

• 17:07Neil deGrasse Tyson?

  Sorry, it's a grown-up show.

• 17:09Chuck Nice?

  Right.

• 17:10Matt O'Dowd?

  Yeah, so we think of, 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 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, like holes to us, and so instead of seeing one, we can see many, well, four.

• 17:47Neil deGrasse Tyson?

  Many images of that one object.

• 17:48Matt O'Dowd?

  Many images of that one object, yeah, yeah, yeah.

• 17:49Neil deGrasse Tyson?

  So why, why do you have a favorite one? But they all sound like they'd look the same after a while.

• 17:55Matt O'Dowd?

  There are some that are just, you would call them golden lenses.

• 17:59Neil deGrasse Tyson?

  Oh.

• 17:59Matt O'Dowd?

  Because just 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, the, one of the very, was it the first one? The Einstein Cross?

• 18:12Neil deGrasse Tyson?

  Yeah, yeah. Yeah, yeah. That was early.

• 18:15Matt O'Dowd?

  Yeah, yeah. That, 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. And we just, uh, we can, we can do really cool stuff. We can, we can essentially map that distant black hole by looking at how the thing flickers and...

• 18:38Neil deGrasse Tyson?

  You know how we first discovered that it was an actual, so a lens, we have two images of a quasar. Initially, there's just two different quasars.

• 18:44Matt O'Dowd?

  Right.

• 18:45Neil deGrasse Tyson?

  Until someone discovered that a variation in one quasar?

• 18:49Matt O'Dowd?

  Was the same?

• 18:50Neil deGrasse Tyson?

  Was repeated.

• 18:51Matt O'Dowd?

  Exactly.

• 18:52Neil deGrasse Tyson?

  In the other quasar, but with a time delay.

• 18:55Matt O'Dowd?

  Uh, look at that.

• 18:56Neil deGrasse Tyson?

  Okay, so it meant the two path lengths were different. And it was like, whoa. And everything that changed matched.

• 19:03Matt O'Dowd?

  That's really cool.

• 19:04Neil deGrasse Tyson?

  One, yeah, so it was the same object.

• 19:05Matt O'Dowd?

  Yeah, yeah.

• 19:06Neil deGrasse Tyson?

  We, we freaked out.

• 19:08Matt O'Dowd?

  Yeah, yeah.

• 19:08Neil deGrasse Tyson?

  In a, in a joyous way.

• 19:09Matt O'Dowd?

  Yeah.

• 19:10Neil deGrasse Tyson?

  That's how old I am. Back in my day, we, we found the first, we discovered Earth in the first planet. First, we thought it was a copycat quasar. Playing Simon Says.

• 19:22Matt O'Dowd?

  We did, we thought these could be like binary quasars.

• 19:25Neil deGrasse Tyson?

  Yeah, yeah, that was a whole lot of first thought about it.

• 19:27Matt O'Dowd?

  Right, right.

• 19:28Neil deGrasse Tyson?

  Because no one's seen a lens, why would you, that's not your first thought.

• 19:31Matt O'Dowd?

  Yeah, Einstein knew that his theory predicted these lenses, uh, general relativity. But he didn't think it would ever be seen.

• 19:38Neil deGrasse Tyson?

  Right.

• 19:38Matt O'Dowd?

  Because it was such a small effect, same with gravitational waves.

• 19:40Neil deGrasse Tyson?

  Mm-hmm.

• 19:41Matt O'Dowd?

  You know, then we built some pretty good telescopes.

• 19:43Neil deGrasse Tyson?

  Yeah, better than he imagined. So, what's the second part of that question? The second part is, what do you think they'll discover in the future? Yeah, yeah, give us your best prediction.

• 19:52Matt O'Dowd?

  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, 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. Like, you know, we discovered that the universe is expanding by looking at, um, 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. But, and all of this showed us, for one thing, that the universe is expanding. If we, if we track the, 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.

• 20:37Matt O'Dowd?

  Okay, that's what the supernova showed us. Um, but in order to, 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, in the kind of 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 best.

• 21:17Neil deGrasse Tyson?

  You're, you're giving all this hypothetical, we might see it, it could be, the kid wants to know what your prediction is.

• 21:25Matt O'Dowd?

  My prediction is that this is, that, 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 gonna say, it could happen.

• 21:40Neil deGrasse Tyson?

  That's, that's a prediction, that's a prediction, we will find out. Next year, five years, 10 years, 20 years?

• 21:46Matt O'Dowd?

  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 gonna pan out.

• 21:54Neil deGrasse Tyson?

  Yeah, yeah, all right, all right. All right, so Chuck. Yeah. Let's get straight to the cosmic queries. All right. Patreon edition. Hmm. For the, not the freeloading, Connor.

• 22:05Chuck Nice?

  Oh, did a real Patreon.

• 22:12Neil deGrasse Tyson?

  You gotta find out that Dexter and Abby like had to go into therapy after listening to your.

• 22:19Chuck Nice?

  Those guys are the best. Eight and 10 years old and listening to this show?

• 22:24Neil deGrasse Tyson?

  Yeah.

• 22:24Chuck Nice?

  I mean, that's impressive enough. You know, that's outstanding.

• 22:29Neil deGrasse Tyson?

  And one of them said their favorite show, the favorite variant of this is.

• 22:33Chuck Nice?

  Is Explainers. Yeah, I mean, that kid is pretty advanced. Way to shame all the other kids out there.

• 22:44Chuck Nice?

  I like that.

• 22:44Neil deGrasse Tyson?

  All right, what do you have?

• 22:45Chuck Nice?

  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?

• 23:20Neil deGrasse Tyson?

  Ooh.

• 23:21Chuck Nice?

  Hmm.

• 23:23Neil deGrasse Tyson?

  Man.

• 23:24Chuck Nice?

  Look at that.

• 23:25Neil deGrasse Tyson?

  That's so easy. I'm gonna let Matt take that one, okay?

• 23:30Neil deGrasse Tyson?

  I don't wanna, I, I, I, it's beneath me. Yeah, Matt.

• 23:33Matt O'Dowd?

  No, this keeps me awake at night. This whole idea of, of is there you know, an end to scale? Like, is there, so, you know, we, we had 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.

• 23:53Neil deGrasse Tyson?

  So Planck length, remind me, that's the distance over which light travels in?

• 24:01Matt O'Dowd?

  A Planck time. Imagine, right, so you have this, this ruler and you, you, you break it down, you know, so it's a, 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?

• 24:18Neil deGrasse Tyson?

  At a Planck length.

• 24:19Chuck Nice?

  At a Planck length.

• 24:20Matt O'Dowd?

  You know, there's no more rulers? Why? And, and it's not, I don't think it's understood, honestly. I think we don't know what the dimension of space even is.

• 24:28Neil deGrasse Tyson?

  Or you don't think you understand? The it and the I are different things.

• 24:32Matt O'Dowd?

  Yeah, yeah. I definitely don't understand it. And I think there are others who have better ideas, but it's certainly not known.

• 24:40Neil deGrasse Tyson?

  Right.

• 24:41Matt O'Dowd?

  It's certainly not known.

• 24:41Neil deGrasse Tyson?

  So there is an I and it.

• 24:43Matt O'Dowd?

  So the limit, the limit comes from these, 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, there's no other reason besides the value of those constants.

• 25:07Neil deGrasse Tyson?

  It's unmeasurable well before then. It's just unmeasurable in principle.

• 25:11Matt O'Dowd?

  In principle, yeah, exactly.

• 25:12Neil deGrasse Tyson?

  You ain't measuring, you ain't coming near that with your, with your school ruler.

• 25:18Speaker 04

  I have a protractor, so it has to work.

• 25:23Neil deGrasse Tyson?

  So.

• 25:24Matt O'Dowd?

  Anyway, so, so what happens when you try to subdivide even smaller than?

• 25:28Neil deGrasse Tyson?

  Okay, so maybe the big rip is a hypothetical thing. So at what point is anyone declaring that space cannot stretch?

• 25:36Matt O'Dowd?

  So the big, I mean, so the idea of if the space is, is space infinitely stretchable? The, 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.

• 25:52Neil deGrasse Tyson?

  After you've stretched it.

• 25:54Matt O'Dowd?

  Yeah, space treads. And so if the dominant theory of what happened at the big bang is right, which is inflation, so the, so the idea that the universe multiplied its size by a factor of 10, like 60 times, then, you know, that's pretty stretchy. And, and so, so if it could do that, then the current pretty gentle rate of expansion isn't going to be a problem.

• 26:22Neil deGrasse Tyson?

  Using past evidence.

• 26:24Matt O'Dowd?

  Yeah, yeah. If, if inflation is right, which, you know, some smart folks believe.

• 26:29Neil deGrasse Tyson?

  Okay. Well, it's more fun to think we're all going to end in a tear in the fabric of space and time.

• 26:34Chuck Nice?

  And they're just gonna get fat and bloated. And we'll get stretched out. Just gonna keep getting stretched out until we can't stretch. I 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, very good. Uh, 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?

• 27:18Chuck Nice?

  And use that to help justify the acceleration that we're seeing in the expansion of the universe vis-à-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.

• 27:39Neil deGrasse Tyson?

  Ooh, okay. That's a hell of a, that's a mouthful of questions right there.

• 27:42Chuck Nice?

  That's a lot, man.

• 27:43Neil deGrasse Tyson?

  So it sounds like they're, they're wondering, since everything makes gravitational waves, however small,

• 27:49Chuck Nice?

  Right.

• 27:50Neil deGrasse Tyson?

  that these go out into the universe and form this, this, this pressure that we measure as the dark energy?

• 27:59Matt O'Dowd?

  Yeah, uh, I mean, I haven't heard this idea, and I, I need to think about it more. You know, a couple of nitpicks is that, you know, the, 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, into anything. It's, you know, by, it, 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, there's no middle of the universe. There's definitely no middle of the universe to, to, you know,

• 28:33Neil deGrasse Tyson?

  To push out.

• 28:34Matt O'Dowd?

  To push out, so.

• 28:35Chuck Nice?

  You, you can think of it as like a cake rising in a pan.

• 28:39Matt O'Dowd?

  You, you, you could try, but, you know, I don't think you'd get to the right answer if you did.

• 28:44Neil deGrasse Tyson?

  If you did, okay. Just eat the cake and then call it a day.

• 28:48Chuck Nice?

  Just drown, drown your sorrows in the cake itself.

• 28:51Matt O'Dowd?

  You know, that's it. Could you, could gravitational waves do this for some of the, what the universe actually is?

• 28:57Neil deGrasse Tyson?

  Let's ask it differently. What is happening to all those gravitational waves?

• 29:01Chuck Nice?

  Oh, yeah.

• 29:03Chuck Nice?

  Because we measured it, it washed over us. We know that it's happening. The black holes collided. We had the waves. So what happens to them?

• 29:10Matt O'Dowd?

  They slowly dissipate, right? So they get weaker and weaker, but then they...

• 29:15Neil deGrasse Tyson?

  Especially in an expanding universe.

• 29:17Matt O'Dowd?

  Even more. They get redshifted, etc. But they become part of what we call the gravitational wave background.

• 29:24Chuck Nice?

  Oh, okay.

• 29:25Matt O'Dowd?

  So there's this very...

• 29:27Chuck Nice?

  I forgot about that.

• 29:28Matt O'Dowd?

  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...

• 29:41Neil deGrasse Tyson?

  There's a background din.

• 29:43Matt O'Dowd?

  A background little wiggle, wiggle, wiggle, wiggle.

• 29:45Chuck Nice?

  Can we talk about this? Because this is the first I have ever heard.

• 29:49Neil deGrasse Tyson?

  I knew about it. I forgot to connect the dots.

• 29:51Chuck Nice?

  Background gravitational.

• 29:53Neil deGrasse Tyson?

  I forgot to connect the dots.

• 29:54Chuck Nice?

  Gravitational wave background.

• 29:55Matt O'Dowd?

  The coolest observatory ever, I'm not going to say built, because it wasn't built, but invented, is looking for it, conceived, which is the pulsar timing array, which is just the most awesome thing in the world.

• 30:09Neil deGrasse Tyson?

  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.

• 30:21Matt O'Dowd?

  Exactly.

• 30:21Neil deGrasse Tyson?

  And that way you can track gravitational waves going bump in the night, even if they don't come across.

• 30:26Matt O'Dowd?

  Galaxy-sized gravitational waves.

• 30:28Chuck Nice?

  Galaxy-sized gravitational waves. 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?

• 30:40Matt O'Dowd?

  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 so when, and they also shoot out these beams of particles that sweep by the earth. And so we see this...

• 31:02Chuck Nice?

  Okay, right.

• 31:03Matt O'Dowd?

  Much faster. And so we see these across the galaxy.

• 31:05Neil deGrasse Tyson?

  If they were simply spinning, you wouldn't.

• 31:07Chuck Nice?

  You wouldn't be able to do it.

• 31:08Neil deGrasse Tyson?

  They 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.

• 31:16Chuck Nice?

  Okay.

• 31:16Neil deGrasse Tyson?

  So it's not just particles and energy being spewed out the poles of the axis.

• 31:22Chuck Nice?

  Right.

• 31:22Neil deGrasse Tyson?

  The spewing part is actually tipped relative to that.

• 31:26Chuck Nice?

  Got you.

• 31:26Neil deGrasse Tyson?

  So as it spins on its axis.

• 31:28Chuck Nice?

  Right.

• 31:28Neil deGrasse Tyson?

  This other pole swings by.

• 31:30Chuck Nice?

  That's even better. That's a better gauge.

• 31:33Neil deGrasse Tyson?

  This is the beacon.

• 31:34Chuck Nice?

  That's a better gauge of the spin.

• 31:35Neil deGrasse Tyson?

  Like Earth's magnetic pole doesn't align with our spin pole.

• 31:38Chuck Nice?

  Right, right.

• 31:38Neil deGrasse Tyson?

  If we had one of these, it would spin around.

• 31:40Chuck Nice?

  Okay.

• 31:40Neil deGrasse Tyson?

  Every day, you'd see this beam.

• 31:42Chuck Nice?

  This makes great sense.

• 31:43Neil deGrasse Tyson?

  No, no, it's great, it's great. Okay, so keep going.

• 31:45Matt O'Dowd?

  Yeah, so, so in some cases, like a thousand times a second.

• 31:49Neil deGrasse Tyson?

  Yeah.

• 31:49Matt O'Dowd?

  And, and so we see just slight variations in the, in the, 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 ways.

• 32:06Chuck Nice?

  At the speed of light.

• 32:07Matt O'Dowd?

  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.

• 32:24Neil deGrasse Tyson?

  That was the question.

• 32:25Chuck Nice?

  That's basically the question.

• 32:26Matt O'Dowd?

  The answer is, I don't know. I, I surely, they've asked this, but no one's told me.

• 32:33Neil deGrasse Tyson?

  Mm-hmm.

• 32:33Matt O'Dowd?

  Shall we Google it?

• 32:38Chuck Nice?

  That's awesome.

• 32:40Neil deGrasse Tyson?

  All right.

• 32:41Chuck Nice?

  Well, there you go.

• 32:42Neil deGrasse Tyson?

  So we don't know.

• 32:43Chuck Nice?

  We don't know. Okay, Jeremy, what a great question. That was enlightening.

• 32:48Neil deGrasse Tyson?

  All right.

• 32:48Chuck Nice?

  That was my pulsar joke. See? All right, never mind.

• 32:51Neil deGrasse Tyson?

  Enlightening, I get it.

• 32:53Chuck Nice?

  Okay, never mind.

• 32:53Neil deGrasse Tyson?

  Yeah, you had to actually explain that, didn't you?

• 32:55Chuck Nice?

  Yeah, you know, seriously, you gotta explain them. You know, they're not working. That's all there is to it.

• 33:18Chuck Nice?

  All right, this is Town Poem.

• 33:21Chuck Nice?

  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? 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?

• 34:00Chuck Nice?

  Damn, these people are...

• 34:02Neil deGrasse Tyson?

  Where these people come from?

• 34:03Chuck Nice?

  Where are they coming from? That's like three questions in a row where they're just like, like, yo, man, I'm gonna make sure you went to school on this. Like, I gotta make sure that your degree is legit. Here's a question.

• 34:20Matt O'Dowd?

  So, there was a paper on the first idea. It was, it was pretty recent.

• 34:25Neil deGrasse Tyson?

  A paper, a research paper.

• 34:27Matt O'Dowd?

  A research paper.

• 34:27Neil deGrasse Tyson?

  Published by Scientists Peer Review.

• 34:28Matt O'Dowd?

  So, all right, so the first paper was in the 60s. It was by a Russian physicist named Gliner. And, and he had this notion that there could be this coupling between the interior of the black hole and cosmological scales, right? And, and so Gliner was this sort of forgotten genius. And it, it sort of got, you know, got, 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.

• 35:10Matt O'Dowd?

  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. Like, I don't think there was a, a meaningful mechanism to have that communication between the scales, right? Interior of a black hole.

• 35:31Neil deGrasse Tyson?

  You're just asserting it as a plausible...

• 35:34Matt O'Dowd?

  No, there was, there was like a, there was like a loose interpretation of...

• 35:40Matt O'Dowd?

  General relativity that I I thought was unjustified. So I thought there was a slightly crappy interpretation of of GR.

• 35:48Neil deGrasse Tyson?

  Say crap.

• 35:49Chuck Nice?

  Yeah, it's crap.

• 35:49Matt O'Dowd?

  Yeah, like it felt like, you know, looking at the.

• 35:52Neil deGrasse Tyson?

  I'm gonna call it to another. Your work is crap.

• 35:54Matt O'Dowd?

  Yeah, I just I didn't buy it. Didn't buy it. We did. We did an episode.

• 35:58Chuck Nice?

  Right.

• 35:59Matt O'Dowd?

  We did an episode on this, actually, so.

• 36:01Neil deGrasse Tyson?

  Of space time.

• 36:02Matt O'Dowd?

  Yeah, of space time.

• 36:02Chuck Nice?

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

• 36:08Neil deGrasse Tyson?

  Yeah.

• 36:08Chuck Nice?

  Is for you guys to hate on each other's work. Just you're worse. You're worse than rappers, to be honest. Scientists are worse than rappers. No, you think you think you saw it. You think you good. You think you solved.

• 36:21Neil deGrasse Tyson?

  You solved this?

• 36:21Chuck Nice?

  You think you solved this? How about this? Your work is crap.

• 36:24Matt O'Dowd?

  Scientific method.

• 36:25Chuck Nice?

  Yeah, exactly. That's pretty cool, though.

• 36:27Neil deGrasse Tyson?

  So Chuck, we only have a couple of minutes, so maybe we can like speed up our answers and we can.

• 36:31Chuck Nice?

  Okay, 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.

• 37:06Neil deGrasse Tyson?

  Yeah, yeah.

• 37:06Chuck Nice?

  Like, you know, the rubber seat and the balloon and all of that. And they're just like, yo, man, what's the deal? Like, what's inside?

• 37:15Matt O'Dowd?

  I don't know. I think it's possible to extend a metaphor too far. And that might be what's happening here.

• 37:20Neil deGrasse Tyson?

  You went too far.

• 37:21Chuck Nice?

  Dingo Gina, Gina, you're the problem. You're the problem, Gina. You went too far. You went too far.

• 37:27Neil deGrasse Tyson?

  Well, I can say, because I'm old, I'm the senior member here.

• 37:31Chuck Nice?

  Yeah.

• 37:31Neil deGrasse Tyson?

  Back in my day.

• 37:32Chuck Nice?

  Right.

• 37:33Neil deGrasse Tyson?

  Before we.

• 37:35Neil deGrasse Tyson?

  Confirmed that the universe, well, we knew the universe was expanding. We didn't know whether one day we 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. Right. Fred Hoyle said, I, I get it. We, 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's, it stuck. Yeah, look at that. Okay. Wow. He said, we want a Big Bang? Right. You know, cop an attitude about it. That's a big bang. Right. And then it, it stuck. So, he hypothesized. Like Obamacare.

• 38:12Matt O'Dowd?

  Now we own it.

• 38:15Neil deGrasse Tyson?

  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. 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. Mm-hmm. 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, this, it's, it's a steady creation of matter. He just hypothesized that. Right, right, right. And, but people said, people said to him,

• 38:59Neil deGrasse Tyson?

  uh, how is it that you can just assume matter is popping in out of no, out of nothing? That's crazy. And he said, is it any crazier than you popping the universe into existence out of nothing? Mm-hmm. And that shut everybody up. Right. He was smart.

• 39:12Matt O'Dowd?

  He was still wrong.

• 39:12Neil deGrasse Tyson?

  He was still wrong. Still wrong.

• 39:15Matt O'Dowd?

  But he knew how to shut people up.

• 39:16Neil deGrasse Tyson?

  Yeah, no, but I'm, I'm just saying, in the day. Right. This idea that matter is being created in the vacuum. In the vacuum. Expanding.

• 39:23Matt O'Dowd?

  Yeah, I mean, this is, this is like our, how much can you stretch space thing? And, and the answer is maybe infinitely. But there's also no interior to the. Balloon in the case of

• 39:33Chuck Nice?

  Right.

• 39:34Matt O'Dowd?

  Our universe. There's no analogous interior.

• 39:36Chuck Nice?

  Right. So there you go. Wow, that's uh, wow, that's pretty cool, man. All right, this is Couple more questions and we can even speed up our answers. Go. Okay. This is Euclid A. Loguiche, uh, who says Name is Euclid? Euclid. Okay, I'm afraid. Euclid A. Based on those other four questions. Loguiche 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. Uh, Euclid here from the big island. I tried asking this question before. Not sure if you missed, 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 Big Island, he's from Hawaii.

• 40:20Chuck Nice?

  He's from Hawaii. That's right, the big island. Where we have our big telescopes. Yeah, 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.

• 40:40Matt O'Dowd?

  I feel like I'm

• 40:41Chuck Nice?

  That's all you.

• 40:42Matt O'Dowd?

  I feel like, I feel mildly qualified for once. The answer is yes.

• 40:48Chuck Nice?

  Okay.

• 40:49Matt O'Dowd?

  So, there, 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, how did they start? Did, was there some crazy mechanism by which they could just gobble up all the gas super quickly? Was there a, did they, all these black holes form near each other and then fall together? Or, did supermassive black holes spontaneously form?

• 41:33Matt O'Dowd?

  Or at least, if not supermassive, the one tier below it, which is intermediate mass black holes. So, there, 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, 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, alright.

• 42:03Chuck Nice?

  Oh, look at that.

• 42:04Matt O'Dowd?

  We're made of that stuff. I'm saying enriched. Okay, he's talking about oxygen, carbon. Yeah.

• 42:09Chuck Nice?

  So all the stuff, so all the other novae, is it novi?

• 42:13Matt O'Dowd?

  Supernovae.

• 42:13Chuck Nice?

  Supernovae.

• 42:14Matt O'Dowd?

  And those elements caused these clouds to cool down too quickly, which causes them to fragment. But in the old universe, it was just hydrogen, helium. None of these elements had been made because there had been no stars to make them.

• 42:24Chuck Nice?

  Right.

• 42:25Matt O'Dowd?

  And so, the clouds cooled down very slowly, which means they could hold together as they collapsed, not fragmented. Make one giant pass. Exactly. And when you get, when you get-

• 42:36Chuck Nice?

  Wow.

• 42:36Matt O'Dowd?

  It's like if it's a million solar masses the size of our- Oh, but this answer is 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.

• 42:51Chuck Nice?

  By the way, that's fascinating.

• 42:53Matt O'Dowd?

  Alright, I'll slip in one last one.

• 42:54Chuck Nice?

  One last one.

• 42:55Matt O'Dowd?

  Okay, 30 second answer.

• 42:57Chuck Nice?

  30 second answer, okay. Alright, um, alright, 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-

• 43:30Matt O'Dowd?

  In the next 30 seconds.

• 43:30Chuck Nice?

  In the next 30 seconds, which, I mean, measured by plank seconds.

• 43:37Matt O'Dowd?

  Can I talk that fast? So, so black holes these days are created by collapsing cores of dead massive stars. And the first thing that happens is that- 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.

• 44:21Matt O'Dowd?

  When they meet each other, it becomes a black hole. Okay, the escape velocity of the surface becomes the speed of light. And in that instant, everything goes dark.

• 44:30Chuck Nice?

  Whoa. That is pretty damn dope. And so that's cool. So the event horizon is actually born within and then expands out?

• 44:42Matt O'Dowd?

  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.

• 44:54Chuck Nice?

  To get down to that point.

• 44:55Neil deGrasse Tyson?

  It's something about the size of a plum. I did the math on that. If Earth were a black hole.

• 45:00Matt O'Dowd?

  I've been telling people it's a centimeter. Holy crap. I have to contact a lot of students if that's wrong.

• 45:06Chuck Nice?

  Maybe that's a really tiny plum.

• 45:09Matt O'Dowd?

  I think it's nine millimeters, but is it diameter or radius?

• 45:12Neil deGrasse Tyson?

  Oh, so two of those, so two centimeters is a little closer to a plum. Have you been telling them that's the diameter?

• 45:22Matt O'Dowd?

  I think it's the diameter.

• 45:24Neil deGrasse Tyson?

  You've been telling them it's the diameter?

• 45:25Matt O'Dowd?

  Oh, no, it's the sphraschild radius.

• 45:27Neil deGrasse Tyson?

  Yeah, no, I get it, so.

• 45:28Matt O'Dowd?

  No, you're right, it's the radius.

• 45:29Neil deGrasse Tyson?

  The radius. So two of those gets you two centimeters, that's about like that. Yeah, small plum, about an inch.

• 45:34Chuck Nice?

  About an inch, a little more, about an inch, yeah.

• 45:37Neil deGrasse Tyson?

  I was getting a plum.

• 45:39Chuck Nice?

  Look at that.

• 45:39Matt O'Dowd?

  You're right.

• 45:40Neil deGrasse Tyson?

  Ooh.

• 45:40Chuck Nice?

  That's pretty cool, man. Yeah, so I, I, I, I, that, wow, that's still a cool thing to think about, is that. Yeah, that's just mind blowing.

• 45:49Neil deGrasse Tyson?

  Yeah, so every object has its own virtual event horizon. If you just collapse within that, you're a black hole. You ain't coming out.

• 45:57Chuck Nice?

  Exactly, so, yeah, are there any, okay, cause I know you need a certain mass in order to actually achieve black hole-ism, okay, but.

• 46:05Matt O'Dowd?

  Certain density.

• 46:06Chuck Nice?

  Density, not, yeah, right, so, uh, yeah, cause 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, like?

• 46:23Matt O'Dowd?

  Yes.

• 46:24Chuck Nice?

  Yes?

• 46:25Matt O'Dowd?

  Crazily, we do, the, the, at the center of our galaxy, and so this has been hypothesized for a long time because we think that, cause black holes tend to be a bit denser, they, just as, you know, dense materials fall to the bottom of, you know, whatever material, they, they slowly trickle into the center of our galaxy, and over the, the billions of years, the, 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.

• 46:59Neil deGrasse Tyson?

  NuStar is a telescope, N-U-S-T-A-R.

• 47:01Matt O'Dowd?

  That saw them, so it, it took these X-ray images of the core of our galaxy and saw these bright spots, too many of them, and so there, that we do expect there to be this swarm of black holes in the core of our galaxy, like thousands of them.

• 47:18Chuck Nice?

  That's amazing.

• 47:20Matt O'Dowd?

  Yeah.

• 47:20Neil deGrasse Tyson?

  Avoid the galactic center.

• 47:22Matt O'Dowd?

  Avoid, avoid, avoid, avoid.

• 47:24Neil deGrasse Tyson?

  Avoid the galactic center. So guys, this is great, thanks for enlightening us.

• 47:29Matt O'Dowd?

  Absolute pleasure.

• 47:30Neil deGrasse Tyson?

  I'm sorry.

• 47:31Chuck Nice?

  You enlighten us, not guys, thanks for enlightening us, Matt, thank you for enlightening us.

• 47:39Matt O'Dowd?

  You really made us laugh.

• 47:41Neil deGrasse Tyson?

  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?

• 48:07Neil deGrasse Tyson?

  How far beyond where we can physically travel can our mind take us? That's the real future of science.

• 48:16Chuck Nice?

  Wow.

• 48:18Chuck Nice?

  You just came up with that shit on yourself right then?

• 48:22Neil deGrasse Tyson?

  This has been StarTalk, Cosmic Craze Edition. Of course, all about the universe. Until next time, keep looking up.