Instant Genius - Neil DeGrasse Tyson explains the Universe’s greatest mysteries

Episode Date: September 10, 2023

What’s beyond our Universe? Will time travel ever be possible? And what might aliens look like? All huge questions that today we’re asking a special guest, Neil DeGrasse Tyson – astrophysicist and author of the new book To Infinity and Beyond: A Journey of Cosmic Discovery.  In a wide-ranging conversation, DeGrasse Tyson unpacks the biggest scientific mysteries of our Universe, from whether space is really empty, to if humans are actually smart enough to make sense of the cosmos. Learn more about your ad choices. Visit podcastchoices.com/adchoices

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the bite-sized master class in podcast form. I'm Thomas Ling, digital editor at BBC Science Focus magazine. What is beyond our universe? Will time travel ever be possible? And what my aliens look like? All huge questions that today were asking a special guest, Neil deGrasse Tyson, astrophysicist and author of New Book to Infinity and Beyond, a journey of cosmic discovery. In a wide-ranging conversation, Tyson unpacks the biggest scientific mysteries of our universe, from whether space is really empty, to if humans are actually smart enough to make sense of, of the cosmos.

Neil, thank you very much for joining me today. Happy to be had. Thank you very much for your interest and your curiosity, cosmic curiosity in this case. Fantastic. So your new book, To Infinity and Beyond, A Journey of Cosmic Discovery, really is a vast journey through space and time,

starting from Earth, so I thought, let's start there as well. And what are the recent discoveries about our planet that have really grabbed you? I like a bunch of things. I mean, I come to it as an astrophysicist. So I have a bias. Part of that bias is when we search for life in the universe, it's, do we have any analogs for what that life might be like here on Earth? And what intrigues me is when you look at Hollywood films and they portray aliens,

the aliens look remarkably human when you think about it. They walk on two legs. They have two arms, shoulders. neck, a head, eyes, nose, mouth. And they generally don't have hair, which I find interesting. They're always just bald. Wouldn't it be cool if they came out with a pompadour or something as they walked off their spaceship? But if you look at Earth, the staggering biodiversity that's here, maybe nature elsewhere draws on similar models so that perhaps some other creatures achieve high consciousness on another planet across the galaxy. Could it be roaches or rats? I mean, who knows?

But what intrigues me are recent discoveries about life on Earth, new species that are discovered at the bottom of the ocean that don't require sunlight. We all learn biology hearing that life on Earth needs sunlight. And then we learn that their energy sources below the crust of the earth, that punch through, basically holes in the bottom of the ocean, and enable the ocean to sustain a biota that does not require sunlight at all. It uses chemical and thermal energy for its survival. Maybe there are life forms on other planets that parallel this. We also learned recently about the mycelium, this fungal network underground that connects trees and and animals and fungus.

And fungus is an entire branch of the tree of life. It was not fully identified as such, because that's how old I am. When I grew up, it was like, it was just the animal kingdom and the plant kingdom. All right. More a nuanced understanding of the world. We have the animals, the plants, fungus, and the entire sort of bacterial kingdom. And so when you add all this together, that's quite a bit of diversity there. And here we have this mycelium, which is a fungal network connecting three different kingdoms of life beneath the forest floor.

And I'm intrigued by that because it means there's an intercommunication going on. And we somehow think that we're the only ones communicating in this world. Maybe whales, okay, we don't know what they're saying. But I remember a comic with two porpoises are swimming together. and one turns to the other, speaking of the humans, because they're in like one of these water parks, right? One turns to the other, says, well, they face each other and make sounds,

but it's not obvious whether they're actually communicating with each other, said the porpoise of the humans. So looking at the range of life on Earth, and another feature here is that the more we study life on Earth, whatever was the species we first studied, later studies show that they're smarter than we ever gave them credit for being. Well, that's interesting. That tells me that we approached it with some kind of bias,

that we have some unique position in the portfolio of lives on Earth. Come to realize that there are certain birds that can count. And have you seen that video of the magpie bird where it's, oh, my gosh, there's a bottle of water in a park, you know, like a plastic bottle of water. And it's mostly full. And a magpie grabs a rock, a pebble, just the right size to fit through the opening of the water bottle, drops it in, puts its beak in, drinks water until its beak can't reach the water level anymore. Then go and get another rock.

Gets another rock, puts it in the water that raises the water level, and it continues. to drink. This is an Archimedean feat that I don't know that humans would figure out. And there's a bird just doing it. All right. So anyhow, starting on Earth, I love the discoveries of how smart other animals are relative to us. I love it. And also to learn about how much the entire world is dependent on itself, again, I'm old enough to have grown up and say, well, there's this part of the world and they have their climate and their weather and their ocean and their water supply. And then you realize, no, it's all connected. It's all connected.

The water, the air, what you do to the air, what you do to the water. And once we learn that we are interconnected in this way, it can change you. It should change you to thinking more holistically about our survival here on Earth and the survival of the rest of the life on Earth, on which our survival depends. Has it made you more cynical then about human survival on Earth? Yeah, I'm not a cynic. I'm a, what am I?

I'm a skeptical realist. That's what it is. It peeps, oh, the future will be bright. No, it's not. No, oh, we're all going to die. No, I want to say that a lot about a lot of things. You know, what's going to happen with AI? We're all going to die.

You know, what are we going to happen with nuclear war? We're all going to die. You know, that's the mantra. But I have a little more hope in humanity, but not so much hope that I believe we don't have to worry about being active participants in making it work. Okay. So moving beyond Earth a little bit then. What do you think is the most exciting part of space exploration in our own solar system?

Yeah. So let's back up for a moment. When we were here on Earth before science really figured anything out, and we look up and say, the stars there and we're here, we'll never reach the stars or the moon or anything. Then someone had said, well, can we ascend in the air? Birds do that. And what happens if we ascend in the air and keep ascending? Where will that get us?

All right? Now, we can go back to Icarus, the story of Icarus, where he built wings of wax and flew too close to the sun and the wings melted. What they didn't know, of course, is that the sun heat. the ground, the sun doesn't really heat Earth's air. Okay? So when it gets warm out, it's because the sun heated the ground, the ground heated the air, and then you feel warm.

That's what's actually happening when you experience weather and climate down here. There's some heating in the thermosphere, but that's not important for this example. So when Icarus ascended, he's leaving the heating source of the air, and the temperature would have actually dropped for him. We all know this because you've been in an airplane, most people who would be listening to this, have been in an airplane, and somewhere they give the outside air temperature,

40 below zero. We're higher in the air, closer to the sun, and it is not hotter, it is colder. They didn't know this in Icarus's day. So somebody's got to like do the experiment or go there and test it out. And they call them aeronauts at the time,

the first sort of balloon people. but the very first balloon creatures was a sheep, a duck, and a rooster. I don't know if you knew this. Generally, you send animals first, other animals first. If they come back alive, maybe you send yourself. By the way, you say, oh, but I care about the animals. I care about the blue, do you care about fine, but you care less about the person who's about to go up? I mean, if I, all right, I care more about the person who wants to do this experiment than the gerbil, all right?

Sorry, that's me. I'm species, speciesist that way. So now the atmosphere is, in a way, our backyard. We ascend at will by airplane, by helicopter, by, and we go where we want through this medium. So for me, finally getting to answer your question, what do I think about the planets? I think of the solar system as the next. iteration of our backyard. So we went to the moon 50 years ago, why not turn it into our backyard, and go there often, go into space often, go visit the moon, Mars, comets. Even if we're not visiting

it, let's have access to them. There's unlimited natural resources flying around the solar system right now. We have wars on Earth that we fight an entire category of war due to limited access to resources or access to limited resources. Both of those are the causes of armed conflict in the history of our species, going all the way back to what might have been fights over a well for your source of fresh water. So if the solar system becomes our backyard, that could remove an entire category of war that we have endured since we've been humans. So it may be that exploration in space could become one of the greatest

drivers of peace there ever was. Because what do you have left to fight over? Oh, I guess what gods you worship, or what your skin color is, or what side of a line in the sand you were born on, which all look completely ridiculous from space, by the way.

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Visit focal powered by name.com for more information. So I'm going to move you across the universe again, just outside our sort of solar system. And I guess I need to ask, what is in that space just beyond our solar system? Is it just a big giant void? Like, what is a void anyway? Yeah, it depends on what you consider stuff to be. Okay? We can have different definitions of stuff or things.

So if stuff to you, let's go back. So if you were in the same room and I would say, well, I can see you just fine. There's nothing between us. Well, there's nothing blocking visible light, but you would learn over the early centuries that there's this thing called air that you breathe. And it is a thing. And air has pressure. And there can be more air over here than over there. And pressure imbalance creates winds and air currents and storm patterns.

So, yeah, air is something. Well, let's go into space. Let's go to interplanetary space. There are particles there. Nothing nearly as dense as what you find at a planet, but there are particles of gas there. And there's like meteoroids. Any given night, if you look up, if it's clear,

you'll see shooting stars. This is debris. Earth is plowing through as it orbits the sun. We plow through several hundred tons of meteors a day. So, no, interplanetary space is not empty. In fact, it's damn near dangerous. All right. So now let's leave the solar system.

We get rid of the meteorids. All right. The gas is way less there. But there's still a little bit there. Okay? How about exit the galaxy and go between galaxies is even less there? Oh, back up, back up, back up. We think the solar system started with maybe 30 planets or so, dozens of planets,

and not all early planets are on stable orbits. They crash down into the sun or they are ejected because the gravitational orbits are not stable, but only for a few that remain. When you run the math on this, it may be that interstellar space has, billions and trillions of planets, rogue planets, moving homeless through the void. Could there be life on them? Yeah, I think so, because if they still have heat, the way Earth still has heat within, the Earth is still cooling.

Oh, forget the sun. Earth has an energy source. We talked about this earlier. If they have an energy source, you could have life thriving deep within. and so maybe the galaxy is teeming with life around planets that are not even orbiting stars. Okay, so it gets even less. Now you get between the galaxies, there's still some particles there. All right.

But how about between the particles? Okay, is that nothing? How about that? Are you satisfied with the space between the particles where there are no particles? Do you want to call that nothing? Say yes to that. I would. But I think you're going to correct me.

So here's a problem. It's still space. Okay, we known from Einstein that space has a texture. The fabric of space has poetic and semi-literal meaning because space can be curved by the influence of sources of matter and energy. And so what you say is empty actually has a shift. shape. So can something that has a shape be nothing? I don't think so. You got to sort of give it that. Not only that, quantum physics tells us that in the vacuum of space, which is really what we're talking about here, there's no such thing as a vacuum. Quantum physics tells us, and there

particles popping in and out of existence. We call them virtual particles. They pop in and out of existence and they fill the void of space. Have we detects? Have we detected? these particles? No. We predict their existence based on quantum physics that's gotten everything else right. So no one is really doubting this just because of how successful quantum physics has been. It's been the most successful theory of physics and the universe we have ever put forth. So, no, there's really no such thing as nothing. And even if you could get rid of the virtual particles and get rid of the curvature, do the laws of physics still apply? If I were to take an electron and put it into that space, will it still have a negative charge?

That would be the laws of physics manifesting on that particle. Because if the laws of physics apply, then that's still something. So no, give up looking for nothing. Well, what about if, and this might be a very loaded question, if we go even further along this journey, and could there be a point where we go outside of the universe? Do you think that's possible to do. We don't know how to do that. I don't want to say that I'm not going to say that we'll never figure out how to exit the universe. It could be pretty dangerous.

For example, if you tunnel from our universe to like a parallel universe, let's say, tunnel would be a way to puncture a hole, a tunnel through the fabric of space time that matches up with a hole coming the other way and then you step through. Okay. She's talking about a wormhole. Basically a wormhole. I would worry that maybe that other universe has slightly different laws of physics. Because you exist in this universe with all the laws of physics working in such a way that you are alive and you are you.

If I put you across that wormhole and the charge on the electron is slightly different, then all your atoms could like fly apart spontaneously or collapse into a puddle of goo. So once again, bring a germ. with you. Send it through the wormhole first. You don't have to, maybe, it wouldn't have to be animate. You could take like a stick or something or rock.

All right. Rocks are held together. Unless you really have it in for that gerbil. So actually, my sister had gerbils growing up. Hams, pick anything. Rock would do because a rock is held together by electromagnetic forces

just the same way we are. So if the rock fell into a pile of goo or exploded, stay away. So, but you might ask, what's outside of all universes? I don't know. Is it not even space, not even time, not even the laws of physics? So maybe that would be our best case for a nothing. But if it's a place where there's not even nothing, you'd have to call it like nothing,

nothing, because we're defining nothing as not having matter or anything, but it still has the laws of physics. But it doesn't even have the laws of physics is not. even nothing. Call it nothing, nothing. So we've had a big journey across like space, but what about time? And I guess one of the big questions you speak about in the book is, is time travel possible? Yeah.

So because to infinity and beyond as a book title is, you know, you start where the results might have seemed infinite to those doing it, like ascending to the top of the atmosphere. Who would ever do that? Can we do it? I don't know. Is it possible? sort of the infinity things today. And time

time is a fascinating coordinate. Let me introduce it in a way that I think will make people most comfortable. If I say to you, meet me on the London Bridge, why do you say, meet me on the London Bridge?

Okay? Yeah. What's your next question to me? What time? What time? Okay. I specify, a place and you know intuitively that's insufficient information for us to meet. And you say what time? And now I say, meet me tomorrow at three o'clock. Your next question is where? So this juxtaposition of space and time, which Einstein formalized in 1905 is

is something we think about intuitively, if not actively. So you're saying, how could time be a coordinate? How, oh my gosh, time and space? Whoa, oh, oh. You're already there. We're all already there. By the way, one of the revolutions of Zoom rising to prominence during COVID was, Zoom took away the where from Einstein's equations.

All you had to be was when. Think about that. It's amazing. Just be when. You don't have to be where. And look at how that opened up people's access to one another, because you just had to be at the same time. So it's just this one-dimensional space.

one dimensional space let's call it we removed our dependence on three of those four dimensions and look how easy it was to connect with people how constraining space can be well suppose we removed the time dimension and only had a space dimension well that would be bad because you would never know when to connect with people so if we think of time as a coordinate how does it differ from our space coordinates. Well, we know it is just life that we are prisoners of the present, forever transitioning from our inaccessible past to our unknowable future. Whereas in space, you can move forward and backwards, you can repeat that, go left and right, up and down, you could retrace your positions in our three space.

coordinates, but XYZ, height with depth. But you can't do that without time coordinate. That's why we are prisoners. Now, using relativity, you can actually leapfrog into the future. Okay? You still exist in your present, but now you'll land in the future of all the world that you left. Previously. All right.

And if you do this too well, you'll return to your home in their future. and if you were gone too long, nobody will remember you. They'd forgotten all about you. So you don't want to overdo that, okay? Backwards time travel is a little more problematic. There are ideas about how you could do that successfully, but Stephen Hawking is one among many, I would count myself in this camp, that we may one day discover what he called the time travel conjecture.

which is, no, you cannot travel backwards in time. We'll discover some law of physics that prevents it because of the damage you could do to the present for having traveled backwards in time. So here's an example of why going back in time won't work. Right. So you say, I'm going to go back in time and prevent my parents from meeting each other. So you do that, they don't meet, then they never matter. and they never give birth to you,

the person who goes back in time to prevent them from meeting each other. So that's a paradox, and that's what Stephen Hawking suggested. There might be a conjecture waiting to be discovered that prevents that. For me, I look at it another way. I look at it more holistically.

You're walking down a corridor, and there's a banana peel in the corridor, and I'm watching you, and then you step on the banana peel, slip and fall. Okay. But you're my friend and I don't want that to happen to you. So I pull out my phone. I can send signals using tachions. This is the future. Tacions travel backwards in time. Tacios from the Greek, tachios meaning fast, like tachometer, measures the cycle rate of your engine if you drive an internal combustion engine car. Okay. So I have to throw that out there. So the

tachyone is a hypothetical particle that travels backwards in time. So let's say we have tacky on a texting service and I send you a text a minute before you step on the banana peel and I say watch out for the banana peel. So now it goes back in time. It hits your cell phone. Your cell phone vibrates. You pick it up. Read the text from me. Watch out for the banana peel. Watch out for the banana peel, and because you are reading the text, you didn't see the banana peel, and you step on the banana peel and slip. So that maybe I caused the slip on the banana peel by communicating with you in your past. Just sleep on that one.

So we've delved into a lot of sort of big questions about sort of time travel, moving across the universe. But do you think there's actually any questions we need to stop asking about the cosmos? No. No. Questions are innocent. It's what you do with the answer once you get it that can cause problems. Okay, I can ask, is there energy locked in the nucleus of an atom? It's a completely innocent question. Then I start poking around the atom. I said, oh, yes, there is. Oh, we're at war. We want to make a bomb. Okay, wait, slow down. Well, in an elective democracy, these are. are people, you know, in a republic, they represent voters. And if that's what they want to do with the energy, the physicist just discovers in the nucleus, then you don't blame the politician. You don't blame the war general. You blame the electorate for that, because you created the system that would exploit that discovery. If you don't like bombs and you don't like war, which I presume is most

people, but, you know, nowadays, who knows? So, no. As a scientist, I am fundamentally curious about all things I do not yet know. So what is your favorite question or mystery about the cosmos? Yeah, I don't have one in the traditional sense of that question. So I'm going to give you an answer, but it's not the answer you're looking for, but it's my answer. You deal with it. Okay? My question is, are we smart enough? You know, let's assume humans. are the smartest creature there ever was on Earth. Okay? I don't think that's debatable,

even though people want to debate it. Look, we have the, you know, the James Webb Space Telescope. What do the whales have? Okay. Okay. So I agree the whales are smart, but they're not flying in the space.

All right. So let's assume that. I think we can legitimately ask the question. Are we smart? Is that enough smarts to solve all the questions we pose about the universe. Is our brain matter sufficient to fully understand what's out there? And to be able to answer the questions we pose,

or more significantly still, are we smart enough to even know what questions to ask? That's what leave me awake at us. That was Newell de Grasthyssen, astrophysicist, an author of New Book to Infinity and Beyond, A Journey of Cosmic Discovery. Thank you for listening to this episode of Instant Genius, brought to you by the team behind BBC Science Focus magazine, which you can find on sale now in supermarkets and newsagents as well as your preferred app store. You can, of course, also find us online at sciencefocus.com.

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