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StarTalk Radio

Cosmic Queries – The Complex Universe with Sean Carroll

20 Jan 2026

Transcription

Chapter 1: What is the main topic discussed in this episode?

0.031 - 2.053 Neil deGrasse Tyson

I love our stable of cosmologists.

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2.073 - 2.354 Chuck Nice

Yeah.

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2.374 - 10.183 Neil deGrasse Tyson

This time, Sean Carroll. Yeah, Sean Carroll. I love him. Awesome. Because he's brilliant and we don't have to help out his explanations. Yeah. Because they're better than anything we come up with.

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10.263 - 19.654 Chuck Nice

Yeah, and every time he's on, as well as Brian Cox or Jan Eleven or Blue or any of them, I realize I don't know Jack. Nothing. Coming up.

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22.037 - 45.231 Neil deGrasse Tyson

Welcome to StarTalk. Your place in the universe where science and pop culture collide. StarTalk begins right now. This is StarTalk Cosmic Queries Edition. Neil deGrasse Tyson, you're a personal astrophysicist. We got here, of course, Lord Chuck Nice.

45.271 - 47.313 Chuck Nice

Hey, what's happening, man?

47.433 - 64.492 Neil deGrasse Tyson

You're locked and loaded there. I'm locked and loaded because we got queries, man. And they're not just queries about anything to anyone. No. They're queries on, like, cosmology. Yes. To one of our... cosmologist about town. Yes. One of our fave interviews. We've got Sean Carroll on the line.

Chapter 2: How does Sean Carroll explain Hawking radiation and black holes?

64.512 - 65.674 Neil deGrasse Tyson

Sean, how you doing, man?

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66.034 - 68.618 Sean Carroll

Hey, how's it going? Lord Chuck, I didn't know you got a promotion.

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72.743 - 75.367 Neil deGrasse Tyson

If you try hard like he does, you might get one too.

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75.387 - 78.351 Sean Carroll

Yeah, I mean, no kings, but lords are okay. The occasional lord.

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78.331 - 83.039 Chuck Nice

There you go, that's right. I'm down with the Mill Kings, but I'm still Lord Nice.

83.58 - 101.25 Neil deGrasse Tyson

So let's catch people up on your trajectory through life. You spent a lot of your professional career at Caltech over in Pasadena, and now you joined us back on the East Coast in Baltimore at the Johns Hopkins University. And I've got you as the Homeward Professor of Natural Philosophy. Thank you.

101.23 - 104.935 Sean Carroll

That's right. There aren't that many of those. I'm basically the only one, so it's nice. Right.

104.955 - 106.537 Neil deGrasse Tyson

This is a very retro title.

107.258 - 107.718 Sean Carroll

It is. Okay.

Chapter 3: What insights does Sean Carroll provide about the theory of everything?

133.336 - 139.511 Neil deGrasse Tyson

You put all that together and there's no boring conversation you will ever have ever.

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140.073 - 143.421 Chuck Nice

True. But we're going to try to change that today.

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144.987 - 148.094 Sean Carroll

I'm going to take this as a challenge. Yeah, I bet I can do it.

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149.176 - 175.481 Neil deGrasse Tyson

So, Sean, you had a couple of books recently. I mean, you're always out there, you know, talking physics smack with an interested public. You have two in a row here, Space, Time, and Motion. That's what's left after that, right? That's a lot, yeah. That's pretty much everything, right? But no, not for Sean Carroll. He's got quanta and fields. Oh, wow, look at that.

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175.681 - 181.368 Chuck Nice

Now it is everything. Space, time, and motion, and then quanta and fields. What's left?

181.989 - 192.662 Sean Carroll

What's left will be volume three, which is complexity and emergence. That's what I'm nearly done with writing right now. So it's a whole three-part series called The Biggest Ideas in the Universe, yeah.

192.642 - 216.118 Neil deGrasse Tyson

That's definitely what that is. That is. For sure. For sure. You know, fields is a thing that if I didn't study physics, I'd still think they were kind of imaginary. Go back to Faraday, right, who says, well, there's magnetism there, but there's a field. Well, can I see it? No. But like the iron filings can see it. but I can't.

Chapter 4: How do fields play a role in our understanding of physics?

216.298 - 225.882 Neil deGrasse Tyson

Right. Okay. But if you take away the iron froth, is it still there? Yeah. And so just to, what did it take to get everybody comfortable with the idea of a field?

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226.123 - 246.94 Sean Carroll

That's a great question because it wasn't easy. It took a while. You know, Isaac Newton worried about the fact that he didn't know about the concept of fields. He said that there was a gravitational force between the sun and the earth, and it depends on the distance, you know, the inverse square law, the bigger the distance, the less the force. But he didn't know how it got there.

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247.1 - 269.173 Sean Carroll

How does the earth know where the sun is, how far away it is, how massive it is? And he said, you know, this is over my pay grade. I'm going to leave this for future generations to decide, which is not the kind of thing that Isaac Newton said very often. So it wasn't until the 1800s. So he knew something was up. He knew something was up. It needed further explanation. Wow. Action at a distance.

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269.314 - 290.826 Sean Carroll

You know, Einstein famously said spooky action at a distance for quantum mechanics. But even in Newton's time, there was this weird thing. What is it that takes the gravitational force and moves it from the sun to the earth, et cetera? And vice versa. Yeah. And in some way, there was an answer there from Laplace, Pierre-Simon Laplace.

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290.866 - 309.252 Sean Carroll

But it wasn't until Faraday, like you said, that he starts moving magnets and watching electrical currents pop up in a wire next to it. Like, not there, not touching it, right? Through empty space, something happened. And the great thing about Faraday was he was an absolutely genius philosopher.

Chapter 5: What is the significance of entropy in the universe?

309.232 - 335.003 Sean Carroll

intuitive physicist he was not the math expert that you sometimes need to be so maxwell james clark maxwell came along was a huge admirer of faraday and basically made it all mathematically respectable and said yeah there's these things called the electric field and the magnetic field and they fill all of space and you can't see them but we can predict what they're going to do and they're super duper important for explaining everything

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335.202 - 341.228 Neil deGrasse Tyson

I think Faraday, if memory serves, in none of his published papers does an equation of any kind appear.

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341.849 - 362.61 Sean Carroll

That's possible. I didn't know quite that factoid, but it's absolutely in keeping. He was thinking about, in fact, it wasn't even fields that he primarily focused on. He imagined lines of force. So like out of an electron, there's an electric field, we would say now, but he thought they were like literally lines of force filling all of space. And Maxwell's

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362.59 - 377.018 Sean Carroll

first papers were about trying to make mathematical sense of lines of force. And he eventually said, no, it's better to think of fields with little vectors, so like little arrows at every point, and then the lines are sort of moving in the direction of the arrows.

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377.258 - 378.861 Neil deGrasse Tyson

And that all happened in the 19th century.

378.841 - 406.384 Sean Carroll

All happened in the 19th century. And the great thing was, you know, if you think of the number of different apparent phenomena in the world that we now think of as electricity and magnetism in action, right? Heat, light, radio waves, x-rays, you know, the magnets, all this stuff, like very, very different things, all explained in just two fields talking to each other, electricity and magnetism.

406.364 - 407.045 Chuck Nice

That's amazing.

407.145 - 434.886 Neil deGrasse Tyson

That's completely crazy. It's just crazy. And I was just thinking, I go through this sort of existential moment maybe once a month. I'm sitting there, and I press a button on my smartphone, and it changes the channel on my TV. Right. And then I press another button. It starts my car, which is three miles away. Yeah. And I'm thinking, this is magic. Yeah.

434.866 - 462.173 Sean Carroll

basically yeah and that's this is why writing books is good because you write a book and you say like you you point your remote control your tv and a radio wave comes out and turns it on and you get many emails saying that's an infrared wave not a radio wave you don't know what you're talking about but they're all different manifestations of electromagnetism and so no no wait wait but my cell phone is not your cell phone is not but your remote control is yeah that's for sure yeah

Chapter 6: How does the concept of time relate to entropy?

467.158 - 485.136 Chuck Nice

It's funny, while you guys are talking, I'm sitting here with my iPad, and I'm taking my finger and moving the screen up and down. Into this void above your... Right, and it's exactly the same thing. Isn't that the electromagnetic field on my finger?

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485.196 - 502.853 Sean Carroll

Basically everything is the electromagnetic field. Other than gravity, it's all electromagnetism all the way down. We live it. We just live it. There's a hugely important philosophy of science lesson here, because like Neil said, you can't see the electric field or the magnetic field, but they're clearly everywhere.

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502.953 - 515.005 Sean Carroll

Like we have equations that describe them exactly and make predictions and fit all the data. Therefore, we accept that they are there. You don't need to see them with your eyes to have evidence that they're part of reality.

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515.405 - 518.509 Chuck Nice

I do a whole... Stand up bit about that.

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519.471 - 526.743 Neil deGrasse Tyson

And I try to beat that into Chuck every time when I say the universe is under no obligation to make sense to you.

526.883 - 535.798 Chuck Nice

Which, believe it or not, I can't accept. You must make sense to me because I am the center of all things.

535.778 - 548.055 Neil deGrasse Tyson

And so, Sean, what's this latest paper we have you publish here, co-authored, what Hawking radiation looks like as you fall into a black hole? Was that something that needed to be addressed?

548.135 - 569.225 Sean Carroll

It's something that I've worried about for decades, and honestly... Really? Yeah, well, so here's the question. There's two things that we think are true about a black hole. One is, if you're standing very far away... And you look at the black hole, Stephen Hawking says, black holes give off radiation. Okay, not that much radiation, admittedly, especially for a big black hole.

569.245 - 587.954 Sean Carroll

But he, again, has an equation that predicts exactly how much you should see. The second thing is we have this feeling, no one's ever done it, but we have this belief that if you fall into a black hole, you see nothing special when you cross the boundary, when you cross the event horizon. horizon, right? It just looks like ordinary empty space everywhere.

Chapter 7: What are the implications of the many worlds interpretation?

599.612 - 615.98 Sean Carroll

I let myself fall in, you know, Neil, that you should see that red shift, that, that radiation get blue shifted. It should look brighter and brighter and more and more energetic, right? So why does it turn off when you hit the event horizon? What actually happens? What is it that you see?

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616.041 - 646.245 Sean Carroll

And it turns out this is 100% implicit in all the equations that we have, but it took a lot of work to actually pull it out. And the answer, in a very short, slightly oversimplified form, is there is high-intensity radiation when you're crossing the event horizon, but your move Wow. Yes. Wow.

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647.44 - 651.786 Neil deGrasse Tyson

I mean, in a Heisenberg uncertainty principle way, you don't have time to observe it.

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652.087 - 668.892 Sean Carroll

Yeah, exactly right. And by the way, before I forget, I got to give huge credit to Chris Shalhoub, my co-author on this. Your co-author, yes. He was a grad student at Harvard who just graduated, did all the heavy lifting on this and other projects, and he was fantastic. So he got the right answer after other people's got it wrong.

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668.872 - 675.001 Neil deGrasse Tyson

Graduate students, they have to have an exception to the slave amendment in the Constitution for graduate students.

675.021 - 675.341 Chuck Nice

Right.

675.361 - 675.862 Neil deGrasse Tyson

Just so you know.

675.882 - 679.487 Chuck Nice

Why are they not? Are they only three-fifths of a person? No, no.

679.507 - 680.729 Neil deGrasse Tyson

Three-fifths of a scientist.

Chapter 8: How do we measure dark matter and its effects on the universe?

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693.627 - 701.42 Sean Carroll

OK, that's the whole idea. I would have loved to do the heavy lifting, but for his sake, I needed to let him have that experience. You know how it is.

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701.6 - 714.181 Chuck Nice

Of course. Yes. I mean, listen, Leonardo da Vinci, when he painted, he had artisans that worked under him. Yeah. And they do a bunch of the work. Yeah. And then you come in and you sign your name.

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718.265 - 735.726 Neil deGrasse Tyson

No, but I will tell you this, that in physics and astronomy, in our journals, it is not our tradition to put our degrees after our name, the way it is in the social sciences. And why is that? Well, I made up a reason why that's good, but I don't know if it had different origins. And Sean, you might have some insight here.

735.987 - 756.44 Neil deGrasse Tyson

If you didn't otherwise know the people, you have no idea who is senior, who is junior, because a brilliant idea can come out of anybody, even your students. And so there's no reason to segregate who's got title and who doesn't, because a brilliant idea is a brilliant idea no matter the package, and a stupid idea is a stupid idea.

756.5 - 760.147 Chuck Nice

True. No matter who comes up with it. Yeah. I like that. I like that system.

760.167 - 762.312 Neil deGrasse Tyson

It's very egalitarian. Yeah. I like that.

776.652 - 790.915 Ernie Carducci

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.

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