Pod Insights Radiolab The Nothing Behind Everything About this episode This week, two conversations from the archives about parts of the world that are imperceptible to us, verging on almost unthinkable. We start with a moment of uncertainty in physics. Inspired by an essay written by physicist and novelist Alan Lightman, called The Accidental Universe (https://zpr.io/4965dUdNqtpQ), taken from a book of the same name. Former Radiolab co-host Robert Krulwich pays a visit to Brian Greene to ask if the latest developments in theoretical physics spell a crisis for science. He finds that we've reached the limit of what we can see and test, and we’re left with mathematical equations that can't be verified by experiments or observation.
Then, come along as we kick rocks. And end up tumbling down a philosophical rabbit hole where the solid things around us might not be solid at all. We talk to Jim Holt, author of Why Does the World Exist? (https://zpr.io/UqHpLnDx2QNx) who points out that when you start slicing and sleuthing in subatomic particle land, trying to get to the bottom of what makes matter, you mostly find empty space. Your hand, your chair, the floor, it's all made up of mostly nothing. Robert and Jim go toe-to-toe over whether the universe is made up of solid bits and pieces of stuff, or a cloudy foundation that more closely resembles thoughts and ideas.
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Transcript 5,602 words · 12 speakers
0:01 Speaker 00 Wait, you're listening.
0:08 Speaker 01 You're listening to Radio Lab.
0:10 Speaker 00 Radio Lab.
0:11 Speaker 01 From?
0:12 Speaker 00 WNYC.
0:15 Speaker 01 Rewind.
0:20 Speaker 02 Hey, this is Radio Lab. I'm Leftip Nasir. And today I have got for you two Radio Lab segments that came out before I ever worked here. Both of them do a thing that I find myself craving more and more these days, which is they they pop you out. They pop you out of the news cycle. They pop you out of whatever interpersonal drama you're stuck thinking about. They pop you out of your own body. These are pieces about dimensions and even universes that are imperceptible, verging on almost unthinkable. I mean, I think I get it. I think I understand. Maybe I don't, but I still found it all really
1:01 Speaker 02 fun. So I hope you enjoy this pre-scheduled break from your perceptual reality. It begins with our emeritus host, Robert Krulwich, talking to our other emeritus host, Jad Abumrad, about a conversation he had with a legendary physicist.
1:19 Speaker 03 Okay, so this is about what you do for a living. You know that I have this neighbor and friend, Brian Greene.
1:25 Speaker 04 Brian Greene, professor of physics and mathematics, Columbia University.
1:28 Speaker 03 Yes, I do know that. And the thing about Brian is he is a theoretical physicist. Now, theoretical physicists say that it's theoretically possible to know everything there is to know in the universe. So one day they'll be able to explain not only how you could send a rocket to the moon, but the laws that govern space and energy and time and gravity, everything, the whole universe, one day they think might be totally understandable, using logic and mathematical equations.
1:58 Speaker 04 Now, you can't take that too far. None of us really imagined that if you asked the equations, what are we going to have for dinner tomorrow night, the equations will spit out fried tofu and, you know, spring rolls or something like that. But at the level of the fundamental ingredients, the particles that make up the universe, their properties, the hope and the goal is that the theories that we work out will apply everywhere and tell us about everything.
2:26 Speaker 03 You just said everything.
2:28 Speaker 04 Yes.
2:29 Speaker 03 As in, everything.
2:31 Speaker 04 Yes, that's the big, big goal.
2:34 Speaker 03 This is like playing poker. You're helping me. I don't know what you're gonna do. All right, we'll take it to the next step. Okay.
2:41 Speaker 04 Wait, so what are you, what are you up to here, Krolwich?
2:44 Speaker 03 All right, so. Well, you know, we argue. That's the fun thing we do. But, but unlike him, my position has always been that it's gonna be very hard to answer all the puzzles in the universe. And frankly, it's not a bad thing if some mysteries remain mysterious.
3:03 Speaker 04 Yeah.
3:03 Speaker 03 That's my view. But because Brian's so smart, when I tell him, how do you know this, whatever? He, he always wins the arguments. But a few months ago, this is, this is the thing that got this whole thing started. I was reading Harper's Magazine, and I found an article written by another physicist and a novelist, Alan Lightman. And I thought, oh, boy, this is gonna drive Brian bats. Because Alan says, there is a group of physicists, and Brian happens to be one of them, who've embraced a very exciting idea with an unfortunate effect. If this idea turns out to be true, Alan writes, it will then be impossible for physicists to know everything. Which I thought, ah, excellent.
3:40 Speaker 04 What is the, what is the idea?
3:42 Speaker 03 It has to do with, with more than one universe. You know, there is a very, we've, you know this, we've talked about it before, that there is a, a, a vogue now for the idea that instead of one universe encompassing everything, there might be more than one.
3:56 Speaker 04 Right, so there actually are a number of ways that physics comes upon this idea of other universes. Maybe the most intuitive is to think about the Big Bang, that sent space rushing outward, then matter could cool and yield to stars and galaxies, that wonderful picture that we've had with us since the 1920s. We have, in the interim decades, come to the possibility that the Big Bang may not be a one-time event. That is, there may have been many Big Bangs, there may continue to be Big Bang-like events, each spawning its own universe. If that were the case, then our universe would then be viewed as one of many in this
4:38 Speaker 04 grand collection emerging from all of these Big Bang-like events.
4:43 Speaker 03 Now, in this view of things, there could be not just one universe, or three, or nineteen, there could be ten thousand, there could be trillions, there could be an infinite number. And here's the crucial thing: each and every one of these universes can be different from its neighboring, vastly different.
4:58 Speaker 04 That's right. So, when we study the equations for the production of these universes, we see in the mathematics that the other universes could have different features, different particle compositions, different masses of the particles, different forces.
5:15 Speaker 03 Some of them might have atoms, some of them might not have atoms. You could have universes with lots of stars, some with no stars, some could be made of Muenster cheese. I don't know, the fundamental properties of each universe could be very different.
5:27 Speaker 04 That's exactly right.
5:28 Speaker 03 And that's the key to Alan Lightman's argument. Well, then, going back to the beginning of our conversation, if a physicist's job is to explore everything, that is, the universe, now the universe has just been demoted to a sub-universe, then, when you get your diploma from a great university, the president of the university says, "My friends, we are gathered here to meet the people who have earned the credentials to describe the sub-universe, a little bit of what we could know." It's like you've been demoted. You thought that you were going to get to learn about everything, your words, and now it turns out that your everything is very, is sub.
6:06 Speaker 04 Oh, I wouldn't describe it like that at all, as you might imagine. Rather than view this as an incredible loss of understanding, the right way of viewing it, I think, is to recognize that certain questions that we were asking when we thought there was just one universe were the wrong questions.
6:31 Speaker 04 Meaning, meaning what?
6:33 Speaker 03 Well, he says, "Here's the way to think about it. This is how it always goes."
6:37 Speaker 04 We've seen this before in the history of science.
6:42 Speaker 04 Take Kepler.
6:44 Speaker 03 Johannes Kepler was an astronomer and a kind of mapper of the solar system. He was trying to figure out where the planets were and the nature of their orbits and stuff.
6:53 Speaker 04 And Kepler spent a long time trying to find an explanation for why the Earth is 93 million miles away from the sun.
7:02 Speaker 03 93 million. Kepler thought that has to be a really important number, a key to a deeper mystery.
7:09 Speaker 04 But we now know that he was barking up the wrong tree.
7:15 Speaker 04 Why? There isn't just one planet. There are many planets. In fact, many planets around many stars. And the distances of those planets from their host star varies over a wide range of possibilities.
7:27 Speaker 03 Mars, for example, is 141 million miles from the sun. Jupiter, 483 million. And when you start comparing the different distances of planets from the sun, you realize that the fact that the Earth is 93 million miles away, it doesn't seem like a deep law of the universe anymore. It just feels kind of arbitrary.
7:48 Speaker 03 And then that forces you to change the question. Not, "Why 93 million?" No. Why are all these different planets at different distances from the sun and yet they all stick around the sun? They're all trapped in the neighborhood. That question puts you on the road to a deeper thought. The theory of gravity. The point is, says Brian, if you're focused on one thing, you're going to think that one thing is the key to everything. When your one turns to many, then you think, ah, well, the one thing really wasn't so special. But the way Brian sees it...
8:19 Speaker 04 That is progress. That is understanding. And then it frees you up to ask other kinds of questions, such as, what's the law of gravity? What is the equation that allows us to understand how the sun formed? So those are real questions. And when you can toss out the ones that are red herrings, that you thought were deep, but they're actually just asking the wrong question, that frees you up to make progress.
8:40 Speaker 03 And Brian says you can make the exact same kind of progress if you compare universes.
8:47 Speaker 03 So instead of asking, "Why is our one universe the way it is?", now you can ask, "Well, what do all of these universes, so different one from the other, still have in common?"
8:57 Speaker 04 That would be pretty heavy and exciting, to describe the underlying laws that govern all universes regardless of their detailed features, and what it would be like in that universe, or that universe, or that universe way over there.
9:10 Speaker 03 But there are an infinite number of them. So if I told you that you could write anything down, and it might be a universe, black universes, white universes, green universes, soft universes, hard universes, muscular universes, teeny universes, huge universes, then the only one you know intimately is your own. It seems to me that, what do you know about those other universes, other than that they might be very different?
9:38 Speaker 04 We don't know very much observationally, sure. We can't see them. We don't know very much experimentally. So they're definitely on a very different footing from that perspective.
9:47 Speaker 03 But Brian believes that one day we might be able to experimentally detect these other universes, and somehow, you know, kind of pick up their distant vibrations, kind of like the way you hear your neighbor's music, it's just emanating through the walls. We might be able to listen in, he says, and take a couple of measurements.
10:03 Speaker 04 Which would be quite wonderful. And in that case, at least there's a chance that we'd get observational evidence of the existence of these other realms. And at that point, I would begin to say, "Hmm, maybe there's something really to this."
10:18 Speaker 03 So the physics you're doing says, "I can't go there, I can't observe it, at least for the moment. All I have is my brain and my math." And I say, from my brain, "I'm gonna just assume certain things are always true, there's always gonna be gravity, say, there's always gonna be some particle or wave that creates matter, there's always gonna be, uh, I don't know, what else? Are there things that there always gonna be? What are they, that are always gonna be?"
10:49 Speaker 04 The things that you are describing need not always be the case.
10:53 Speaker 03 Really?
10:53 Speaker 04 Yes. What would be the case is that the fundamental governing equations, the mathematical laws, would be the underlying architecture that governs what happens in those places. But environmental details can change things fairly dramatically.
11:08 Speaker 03 Gravity is an environmental detail?
11:09 Speaker 04 Yes, well, that's actually something you know at some level right now, right? On the moon, you could jump a lot higher than you can here. So if you didn't realize...
11:18 Speaker 03 But I do think that two bodies do attract each other.
11:21 Speaker 04 That's right. So there is a fundamental law of gravity that manifests itself in different ways based on the environment.
11:26 Speaker 03 All right, so let me say that again, or ask it again. Are there fundamental laws?
11:31 Speaker 04 Yes.
11:31 Speaker 03 That you think operate in all universes?
11:34 Speaker 04 Yes, yes, absolutely.
11:35 Speaker 03 And why do you think that?
11:36 Speaker 04 That is the starting point. When we come upon this possibility of other universes, it's not a crazy idea that we dream up late at night when there's nothing else to think about. These are ideas that emerge from the fundamental equations that we use to describe the things that we do see in the world around us, and we follow the equations, and the equations suggest to us there might be these other universes. So we have equations, we analyze them, and we interpret what they're telling us about reality. But those are the very equations that come to this possibility of other universes, then those are the equations that govern those other universes. The starting point is, let's assume that these are the fundamental...
12:15 Speaker 03 Doesn't this sound an awful lot like, why is God three in one? Or why was the world made in seven days? Aren't we getting close to some sort of... You're believing in certain things to be always true, the way religious people believe certain things are always true. Not because you've seen it, or it's just because you can't... You have a faith in it.
12:40 Speaker 04 I couldn't disagree with you more.
12:42 Speaker 03 I thought not.
12:43 Speaker 04 It has absolutely nothing to do with faith. The reason why we trust the equations is because we've got centuries worth of observational and experimental evidence that the equations take us in the right direction.
12:56 Speaker 03 Here.
12:57 Speaker 04 Here. And it's those very same equations that work here that we are following to their logical conclusion to see where the mathematics takes us. Right? So if you remember the train of reasoning here.
13:09 Speaker 03 You may have just projected here into there. That's faith talking, though, because you can't go there. All you can do is say, "Well, what works?" But my deep understanding of here has to be there. I don't know why it has to be, but that's what you just said.
13:25 Speaker 04 No, it's actually the reasoning goes in somewhat reverse order from that. We build mathematical equations to describe here. We then follow those equations and say, "Oh, my goodness." Those equations that we developed to describe here are telling us that there is something over there. And then we're like, "Wow, the equations do a great job of describing things here, and the equations have this feature that they tell us there's another place over there. Maybe that's possible." The key thing also-
13:56 Speaker 03 This is logic in your mind. Logic and reason, not belief, just logic.
14:01 Speaker 04 This is just logic.
14:02 Speaker 03 Aren't you worried, though, that there's another Brian Greene in universe number 3,790,208,645, who is sitting there talking to another radio reporter in another university, and he's saying, "Well, we know all about the other universes because we're assuming that the math here is the same as the math there in that other place. But as it turns out, their math and our math aren't the same, so that they will not... You may just be wrong."
14:31 Speaker 04 Oh, that's always the possibility. In fact, it's likely the possibility. In fact, 99.99% of everything we do is wrong, not from the point of view we make a mistake, but which math-
14:41 Speaker 03 But the wrongness is a deep wrongness. You somehow are somehow feeling that the math is a clue that everything follows your math. If at some point the maths collide and then the universes collide, then that would be very unsettling to both of you, I would assume.
14:56 Speaker 04 In terms of whether the math somehow contradicts or incoheres in some way.
15:01 Speaker 03 Well, your tools of learning are not working.
15:04 Speaker 04 Yes, that would suggest that we were both wrong and that there's a deeper overarching framework. I mean, I hate to use the word faith, but the one point where I'll give you faith is this. I do have a deep faith that the universe is coherent. And by universe, call it multiverse, whatever word you want to use, the whole thing. I do believe that it's coherent. Now, whether that means it follows mathematical laws, I don't know. It could be the case that, you know, when we talk to those aliens that we encounter one day and they say, "Okay, show us what you got." We bring out our equations and they kind of laugh at us and say, "Oh, you guys are still stuck on math." You know? And they said, "Yeah, you know, 10,000 years ago, we were doing math too, but here's the real way of describing it."
15:48 Speaker 04 Now, what they'd be showing us with the real way of describing it, I have no idea. I can't even imagine what it would be that would be non-mathematical. So I do have a deep faith that it's coherent and the only tool that I know how to encapsulate that coherence are mathematical equations. So if Xantar, Brian, and Brian here come up with equations that collide with one another and don't work, to me, it just means that both were wrong and there's some bigger overarching coherence that we've yet to find.
16:20 Speaker 03 That's it.
16:27 Speaker 05 I don't even, I can't even begin to figure out if you, did you just win? Did you just lose? I can't tell. Wait, so this all came from Alan Lightman's article.
16:35 Speaker 03 Right, so...
16:36 Speaker 05 Do you think he beat the objections in the article?
16:38 Speaker 03 Did he beat the article? Well, I thought it would be fair to ask the author of the article, so I called Alan.
16:44 Speaker 06 Yep.
16:45 Speaker 03 It happened, as it turns out, to be in Nam Penh, Cambodia.
16:48 Speaker 06 I make all of my international calls on Skype.
16:51 Speaker 03 And I sent him the interview with Brian. He listened.
16:55 Speaker 06 The thing that I listened to...
16:56 Speaker 03 And I asked, "Well, what do you think about Brian's argument?"
16:59 Speaker 06 Well, I don't think that he's wrong, but I think that the problem is philosophically...
17:06 Speaker 06 More disturbing than what he is confessing.
17:10 Speaker 03 He said, "Well, I think it's going to be much harder than Brian thinks to actually sense or encounter or measure these other universes, if they exist at all."
17:20 Speaker 06 We don't even know whether the other universes exist in the same space and time that we do. And there are other physicists who feel that these universes are, even in principle, never, never observable by us, that we will never be able to have any physical evidence of their existence. And that possibility is what I find disturbing. It may be that this is the way nature is.
17:52 Speaker 03 What does that mean?
17:53 Speaker 06 Well, I mean, it may be that we've done as much explaining as is possible.
17:59 Speaker 03 Hmm.
18:00 Speaker 06 Uh.
18:01 Speaker 03 And that we'll never, ever really understand everything?
18:06 Speaker 06 Yes. In other words, we may be, we may have pushed the human mind as far as it can possibly go.
18:28 Speaker 02 Huge thanks to Brian Greene, professor of physics and math at Columbia University, as well as Alan Lightman up at MIT, whose essay Robert read, "The Accidental Universe." It appears in a book of the same name. When we come back, we have another story that will break your brain in a whole different way. This time, it's not distant, unobservable universes, but maybe every single thing around you right now. Stick around.
18:57 Speaker 07 WNYC Studios is supported by Odoo. When you buy business software from lots of vendors, the costs add up and it gets complicated and confusing. Odoo solves this. It's a single company that sells a suite of enterprise apps that handles everything from accounting to inventory to sales. Odoo is all connected on a single platform in a simple and affordable way. You can save money without missing out on the features you need. Check out Odoo at O D O O dot com. That's O D O O dot com.
19:28 Speaker 08 After some actual fake polls came to light, pollsters are in the hot seat. But they say, don't be too quick to dismiss the entire industry.
19:37 Speaker 09 People want to raise taxes on the rich. I can tell you that definitively because we know it from polling. And if we lose trust in polls, we have no way to understand what Americans want to be done.
19:50 Speaker 08 On this week's On the Media from WNYC. Find On the Media wherever you get your podcasts.
20:00 Speaker 02 Latif, Radiolab, we are back. Today's episode is about the nothing behind everything, and I'll pass it back over to our amorous hosts, Chad and Robert.
20:10 Speaker 05 Let's just start it up. I'm Chad Abumrad.
20:12 Speaker 03 I'm Robert Krulwich.
20:13 Speaker 05 This is Radiolab.
20:14 Speaker 03 The podcast.
20:15 Speaker 05 We're going to continue the conversation we've just been having all week about, well, perfection, striving for things which seem perfect versus living in the real world.
20:25 Speaker 03 Right.
20:26 Speaker 05 And recently.
20:28 Speaker 03 I got into a bit of a kerfuffle with a guy who yearns like you do for an idea.
20:32 Speaker 00 Bliss.
20:34 Speaker 03 His name is Jim Holt.
20:35 Speaker 00 Okay.
20:36 Speaker 03 And he wrote this really good book called, Why Does the World Exist? And just to get us started, in that book, he quotes a poem.
20:46 Speaker 00 Yeah.
20:46 Speaker 03 Remember the line?
20:47 Speaker 00 Yeah, kick at the rock, Sam Johnson, break your bones, but cloudy cloudy is the stuff of stones.
20:54 Speaker 03 Cloudy cloudy is the stuff of stones.
20:57 Speaker 00 Yeah.
20:57 Speaker 03 Meaning what?
20:58 Speaker 00 It's something, well, Samuel Johnson, who lived in the 18th century, was a contemporary of Bishop Barclay. And Bishop Barclay was an idealist. He believed that the world was essentially pure appearance. It was like a thought, not like a solid reality. It was a thought in the mind of God.
21:15 Speaker 03 Like the rock really had no substance.
21:18 Speaker 00 And Samuel Johnson, when he heard this, he thought it was ridiculous and he went and kicked a stone and said, "I refute Berkeley thus."
21:27 Speaker 00 Anyway, that's the story.
21:28 Speaker 05 Wait, one guy thought it was a thought, the other guy thought the rock was a... What are they arguing about exactly?
21:33 Speaker 03 Well, they're arguing about reality.
21:35 Speaker 00 Just what is this world? What is its essential nature?
21:40 Speaker 03 When you hold a rock in your hand, like, what's it made of?
21:43 Speaker 05 What's it made of?
21:44 Speaker 03 Yeah.
21:47 Speaker 05 Minerals?
21:47 Speaker 03 No.
21:48 Speaker 05 Is that the right answer?
21:48 Speaker 03 What I'm really asking is, what is the most essential nature of the rock? So if you look deep, deep, deep down into the rock, do you find something concrete? Do you find a little bit of thing?
21:58 Speaker 05 Yeah.
21:58 Speaker 03 Or do you find something more ethereal? Something you can't touch? Something you can't pin down? Something like, oh, a thought? This is Jim's notion.
22:09 Speaker 00 And this sounds like a... It sounds like I've been eating lotus leaves. I mean, it's a pipe dream. But this is what science has increasingly led us to.
22:17 Speaker 05 That rocks are thoughts?
22:19 Speaker 03 Well, to follow Jim's logic, he goes all the way back to the Greeks, to the first real attempt to get to what's really at the bottom of a rock.
22:26 Speaker 00 You know, even in ancient times, the atomists, Democritus and Lucippus, thought that if you keep cutting up the stuff of reality that we see around us, tables and chairs and rocks and so forth, eventually you cut them up into such itty-bitty pieces that you can't cut any further. And then you've got atoms. So there you've got... You've clearly got a fundamental stuff, the atoms.
22:47 Speaker 03 Yeah, that sounds very pleasing.
22:49 Speaker 00 Right. But even going back to Newton, there were reasons to suspect that there was something a little funny about reality. It wasn't quite as substantial as we believed. Now, Newton, of course, came up with the theory of gravity. And the theory of gravity says if you've got the sun and a planet, the sun exerts a gravitational force on the planet.
23:11 Speaker 03 Right.
23:12 Speaker 00 And Newton's contemporaries wanted to know...
23:14 Speaker 03 Well, how does it do that?
23:15 Speaker 00 What is the mechanism that... By which gravity is mediated? How does the sun, as it were, reach out to the earth and force it to move around in this orbit?
23:26 Speaker 03 So if I were an atomist, if I were looking for stuff, then I'd need some kind of thing that carried gravity.
23:34 Speaker 00 Yeah, yeah, but the problem is that it looks like there's nothing between the earth and sun except a void.
23:39 Speaker 03 All that Newton had to fill that void was a mathematical equation that told him how the sun and the earth interact. And the thing is, it worked. You could plug in the numbers and you could know how one was influencing the other. But Newton had no idea at all why the equation worked. He couldn't point to any, like a little particle thing, like a graviton, and say, "There's your reason." It almost seemed like gravity was created from the equation itself. And this disturbed a lot of people. Because at that time, everybody thought-
24:10 Speaker 00 That nature has to be made out of hard, durable stuff.
24:15 Speaker 03 You know, gears, sprockets.
24:17 Speaker 00 Pushing and pulling. That's the essence of reality.
24:21 Speaker 00 Then in the 20th century, of course, it got much, much worse. You know, the atom, which was thought to be very, very tiny, and you couldn't cut it any further. It was the limit to this, you know, splitting process.
24:31 Speaker 03 Right.
24:32 Speaker 00 And as we know all too well from the 20th century, you can split an atom. Yeah, it has pretty interesting consequences. But we also discovered the atom is almost entirely empty space.
24:44 Speaker 00 It's, if you took a baseball and put it in the middle of Madison Square Garden, that would be like the nucleus. And the, you know, the first level of electrons are as far away as the exterior of the garden.
24:57 Speaker 03 So you can think of this baseball, this nucleus, as a tiny dot all alone.
25:01 Speaker 00 So it's basically, the atom is a big, empty space.
25:04 Speaker 03 Well, it doesn't feel that way. Like, watch this. I'm gonna do this.
25:08 Speaker 00 Aight.
25:11 Speaker 03 If my hands are all atoms, and as you say, atoms are mostly empty space, then why don't my hands just go right to each other like two clouds? But you'll notice-
25:20 Speaker 00 Yeah, yeah. Why don't I fall through the floor here? Because the floor is mostly empty space and I'm mostly empty space. That too, if you look at it on the micro level, this apparent solidity is the product of a purely mathematical relation.
25:33 Speaker 03 Well, that can't... Isn't it more like my electrons don't like similar electrons? So the electrons in my hands just hate the electrons on the other hand?
25:42 Speaker 00 No. It basically comes down to a pair of mathematical relations, the Pauli exclusion principle and the Heisenberg uncertainty principle. I mean, all of this gets very abstract.
25:52 Speaker 03 I understand it perfectly, of course. But I don't want to bore you with the details of his argument.
25:57 Speaker 05 You have no idea what he's saying, do you?
25:59 Speaker 03 Well, I'll say this. According to Jim, it's not that the electrons in my left hand are repelling the electrons in my right hand. It has to do with a law of nature that says two particles, identical particles, cannot be in the same place at the same time. So when you hear that sound, you can hear it as the sound of a law saying, "No, not allowed, not in nature."
26:22 Speaker 00 Exactly. And here's a slightly different way of putting that.
26:27 Speaker 03 But wait, isn't this law that we are announcing, isn't this law about particles? Like, we're talking about atoms and electrons. Those are things. So we're still talking about things.
26:39 Speaker 00 Well, if you study quantum field theory, which is what all physics graduate students begin with in graduate school, you discover that even particles are unreal.
26:52 Speaker 00 They're just temporary properties of what are called fields. And fields are just distributions of mathematical quantities through spacetime. It's all... They're not... They don't seem to be grounded in anything.
27:05 Speaker 03 According to Jim, a field is kind of like a stream of numbers.
27:09 Speaker 00 Pure information.
27:11 Speaker 03 Numbers that tell you where a particle, like an electron, might be. So maybe the electron's over here. Oh, no, no, maybe it's over there. Or maybe it's with this group, or maybe it's with that group. The problem is, you can't ever see the thing itself. You can only see the effect it has on other things. So you can't observe it.
27:29 Speaker 00 And if something is, in principle, unobservable, you may as well say it doesn't exist.
27:35 Speaker 05 Wait a second. No, no, no.
27:37 Speaker 03 Why?
27:38 Speaker 05 I mean, I'm on his side, but you could say that it's just not observable down there at the micro scale. Up here, it's pretty observable. I mean, this table exists, this mixer. I mean, something is happening to give the world substance.
27:50 Speaker 03 Well, according to Jim, what we think happens, and this admittedly is a gross oversimplification, but in these fields, you're going to get these little fluctuations, these little events, sudden hiccups of energy, little bursts, and that's where stuffiness flickers into existence. But it's a very flickering existence. Stuff isn't permanent.
28:15 Speaker 00 So what is a rock? I mean, a rock looks like a good, solid, persisting object, but it's really, our perception of it is energy transitions, changes in the distribution of energy from one state to another. When that happens, the energy is irradiated, it goes through my retina, goes through my pupil, rather, and strikes my retina, and I perceive the rock.
28:36 Speaker 03 I don't know if Jim would call a rock, like Bishop Barclay did, a thought in the mind of God, but he might say that, deep down, what a rock is, is an expression of rules or math. It's just here, like a shadow of an idea.
28:51 Speaker 00 Yeah, yeah. I've heard one physicist say that the cosmos is ultimately a concept.
28:58 Speaker 03 Are you increasingly convinced that the reason you can clap, the reason you don't fall through the floor, the reason that gravity works, is all because of certain ideas that govern? Ideas rule the world.
29:13 Speaker 00 Yeah, yeah. Maybe, you know, at 100 years from now, when string theory has finally worked out, we might have a very different conception of it, but what it looks is that it's going to be mathematics and structure all the way down.
29:25 Speaker 03 You're OK with this?
29:27 Speaker 00 Well, I'm a sort of mathematical romantic. I love the idea that the essence of reality is not stuff. You know, stuff is kind of ugly. I mean, you want to get rid of stuff. There's too much stuff in your apartment.
29:38 Speaker 03 I like stuff.
29:39 Speaker 00 It's clutter. It's gross, viscous, absurd.
29:41 Speaker 03 I don't know what to do if I don't have stuff.
29:43 Speaker 00 Well, you know, this is a temperamental difference between us. I like the The idea that reality consists, it's a flux of pure information with no further substance.
29:52 Speaker 03 I don't know why this makes you so happy. I mean, here, I would love, if I'm clapping, or if I'm hitting someone in the face, I would love to think the billiard ball of me is hitting the billiard ball of them, and that explains what's going on. Now, you've offered-
30:07 Speaker 00 But we're living in almost in a spiritual realm. You want to live in this gross material realm, where there's a lot of stuff.
30:14 Speaker 03 Yeah, but your spiritual realm, it's literally empty. It's just so intuitively wrong.
30:22 Speaker 00 But if you go back to the old 19th century view, that we're made up of these little hard particle atoms that are all bumping around, is it any more plausible that you and I are just a bunch of dumb, hard particles in a certain configuration? And if that's true, how are certain configurations of these particles tantamount to the horrible feeling of pain?
30:47 Speaker 03 You could say, "Pain, oh, that's-"
30:49 Speaker 00 Just a lot of elementary particles in a certain configuration.
30:52 Speaker 03 But we all know that explanation isn't enough. So when you look down to the bottom of everything-
30:57 Speaker 00 Whether it's a mathematical object, or whether it's little billiard balls knocking around, it's still miraculous and probable that it should produce subjective experience, that it should produce pleasure and pain.
31:14 Speaker 03 And that mystery, how you go from the most basic things, or actually, the most basic nothings, to everything we see around us?
31:23 Speaker 00 I find that to be exhilarating, to worry about the metaphysics of physics and the nature of reality, even though it doesn't lead you to any sort of comfortable intellectual closure. It's a good way of idling away an otherwise boring afternoon, as we've just proved.
31:41 Speaker 03 It also explains why, when I head-butted him with my very strong forehead, he seemed to think of it as a fascinating thought.
32:00 Speaker 03 Special thanks to Jim Holt, who, actually, we're both too shy to ever headbutt each other. Too weak ever to try it. Anyway, the book is called Why Does the World Exist? An Existential Detective Story.
32:13 Speaker 05 Okay, well, I guess that's it for this podcast. I'm Jad Abumrad.
32:16 Speaker 03 I'm Robert Krulwich.
32:17 Speaker 05 Thanks for listening and existing.
32:19 Speaker 03 Temporarily.
32:31 Speaker 10 Hi, I'm Amy Beth, and I'm from Longmont, Colorado. And here are the staff credits. Radiolab was created by Jad Abumrad and is edited by Soren Wheeler. Lulu Miller and Latif Nasser are our co-hosts. Dylan Keefe is our Director of Sound Design. Our staff includes Simon Adler, Jeremy Bloom, Becca Bressler, W. Harry Fortuna, David Gabel, Rebecca Latif, Maria Paz Gutierrez, Sindhu Nandan Sambandhan, Matt Keelty, Annie McEwen,
33:08 Speaker 10 Alex Neeson, Sarah Kari, Sarah Sandback, Anisa Vitza, Ariann Whack, Pat Walters, Molly Webster, and Jessica Young, with help from Rebecca Rinn. Our fact-checkers are Diane Kelly, Emily Krieger, Anna Pujol Mazini, and Natalie Middleton.
33:39 Speaker 11 Leadership support for Radiolab's science programming is provided by the Simon's Foundation and the John Templeton Foundation. Foundational support for Radiolab was provided by the Alfred P. Sloan Foundation.
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