Brian Cox - 1 hour of Interesting Facts About the Universe

Ajouté : 2026-05-31

[00:00:00]that I find it almost impossible to imagine. Well, actually impossible to imagine one just the size and scale of it. I mean in the piece of the universe we can see uh there are something like roughly two trillion galaxies. We haven't counted them all but that's an estimate based on surveys of the local universe. Two trillion 2,000 billion galaxies. And each galaxy is let's say around the size of the Milky Way. Some are bigger, some are smaller, but the Milky Way has 400 billion stars in it.

[00:00:33]Takes light over 100,000 years to cross a galaxy. And there are two trillion of them in a piece of the universe we can see. And we're very sure that that piece that we can see is a small bit of what may be an infinite universe beyond. We don't know actually. And I always say, you know, don't get worried about that cuz nobody can picture it. It is impossible to visualize the scale of the universe. Well, we'll stop there for now, but just the size and scale of it, I think, is beyond imagination. So, there are lots of multiverses actually um in physics. One of them is called the inflationary multiverse, which is we have a theory of um essentially what happened before the big bang, right? You have to be careful with the language. So if you define the big bang really carefully as the time when the universe was very hot and very dense and as I said you you can't argue with that because we can see it because we can look out into the sky. Our best theory of how the universe got into that state is that there was a time before that and it's called inflation. So the idea is the universe was it was there in a sense cold and empty and expanding extremely fast and that expansion slowed down and stopped and the energy that was driving that expansion got dumped into space heated it up and made all the particles out of which we're made. That's what we call the big bang. So that that's textbook it's a textbook theory called inflation. It made predictions, some of which have been tested, some incredible predictions actually about the way that galaxies are distributed across the sky because they're not just random. If you look at the galaxies, they're in sort of flows and rivers of galaxies that across the sky in a pattern called the cosmic web. And inflation predicted that before it was seen actually. So it's an astonishing idea. And that theory has a kind of an extension called eternal inflation which is that the inflation essentially goes on forever and it just stops in little patches. So you imagine this this stretch the fabric of the universe spacetime stretch stretch stretch and then it slows down and stops in little patches and each one of those patches is basically a big bang and a universe of which ours is one. So you end up with this sort of picture of a an infinite fractal universe of of basically an infinite number of big bangs and that's called the inflationary multiverse. And that that there's some it answers some neat questions that because it if you say why is our universe the way that it is? Why are the laws of nature such that life can exist for example? Um well the the answer might be that all possible combinations of all the laws of nature exist in the inflationary multiverse. So then it's not surprising there are universes that permits things like us to exist because every possible universe exists in the inflationary multiverse. And that that's a a wellsupported theory. It's a theory. So this is not the same as saying there was a big bang which we know. This is kind of what's a theory? It's a guess basically. But it is a theory that in its simplest form has made predictions that have sub subsequently been verified. And we could go on then. There's the the so-called many worlds interpretation of quantum mechanics which is more kind of Marvel film kind of multiverse where um so quantum mechanics is it's a probabilistic theory. Imagine a a quantum coin I call it. And the quantum coin can be it doesn't have to be heads or tails. It can be heads and tails. So, it can be mixed up. Can be both heads and tails at the same time. You might have heard of Schroing as cat, which is a cat in a box. And it's both alive and dead until you observe it or interact with it in some way and then you find out which one it is. But before you looked at it or before you interacted with it, it was both. I say sometimes in my live shows, there's only it's kind of a joke, right? So, I'm not insulting philosophers here, but I say there's only one interesting question in philosophy, right? And I don't really mean it, but I think it sounds funny.

[00:04:41]And so the interesting question is, what does it mean to live a finite, fragile life in an infinite eternal universe? So that's not that funny, right? It's a good question. What does it mean to live a finite fragile life in an infinite eternal universe? And um I think the answer is that sort of paradoxically whilst we are definitely physically insignificant. I've just said that the earth is one planet around one star amongst 400 billion stars in one galaxy amongst two trillion galaxies in a small patch of the universe. Right? So we're definitely small. You can't argue with that. We're just specks of dust. But if you think about what we are, so everybody, me and you, everybody, we're we're just collections of atoms, right?

[00:05:26]Some of them are as old as time pretty much. And some of them were the other ones, everything else other than the hydrogen in our bodies was made in stars, right? So we all cooked over billions of years. And really this pattern that can think so suddenly as the great Carl Sean said you have a means by which the universe understands and explores itself which is us. And that sounds unlikely when you put it like that that you can have a few things that were cooked in the hearts of stars. You stick them together in a pattern and suddenly it has some ideas and starts writing music and and arts and thing that's that's quite difficult to comprehend. Right? But that what that happened here. We know that because we're sat here having a conversation.

[00:06:11]And so the question then becomes well on how many other worlds did that happen.

[00:06:15]And that's where I think the value can come in because uh it's a reasonable guess and it's just a guess right but it's reasonable. You can make the argument that there aren't any other worlds where this happened certainly in our galaxy. So it could be that this planet notwithstanding its physical insignificance is the only place where anything thinks right for millions of light years in every direction. And suddenly therefore you end up considering this planet as being the most valuable place in the local universe notwithstanding the fact that it's small. And that idea it it's not just a complete random guess. By the way, we've had a bit of a look.

[00:06:56]Astronomers have pointed radio telescopes up at the stars for a while, 50 years or more now, and heard nothing.

[00:07:03]We've seen no evidence of any civilizations out there beyond Earth.

[00:07:08]And that's a surprise. There's a reasonably plausible explanation for that, which is biology, which is that if you look at the history of life on Earth, then you see that life began pretty much as soon as it could here on Earth. We we have evidence there was life 3.8 billion years ago, something like that. And the earth's 4 and a half billion years old. So pretty much pretty quick in geological time you get life.

[00:07:30]But then if you if you talk about advanced life, complex life, multisellular life, then there's no evidence at all beyond back beyond a billion years actually really in the fossil record 650 million years ago or something you start seeing the first evidence of complex creatures. So that means that on he on this planet it took over three billion years to go from a single cell life to anything more complex than a single cell and then another half a billion years or so to go from the multisellular things to a civilization. So it's it's 3 and a half to four billion years. It's a third of the age of the universe. That is a really long time. If you say that's an unbroken chain of life on a little piece of rock in a violent universe and that chain was not cut for 4 billion years in order to get us and that might be a big ask, right? We live in a really violent universe. You look at the Milky Way and you look at that arc of stars across the sky, 400 billion suns. All though all there will be up there at best is slime.

[00:08:40]That's where I start from. I mean, I wouldn't be surprised if that's wrong.

[00:08:45]Then you go, okay, good. Well, fine.

[00:08:47]That but at the moment, it looks like there isn't anything else other than slime. We haven't even discovered slime, by the way, yet. We're still in the position where we've not seen any not even a single cell on the Mars or, you know, the moons of Jupiter or somewhere like that. So, at the moment, we are alone as far as we can tell.

[00:09:07]>> Favorite planet? Well, um, it's it's a cliche, right? But I I saw I I actually asked this is a name draw. I asked Jeff Bezos that question and he said correctly, Earth. And that's true. So So because of everything I've just said, right, I just said it's the only place where meaning exists potentially in a galaxy of 400 billion suns. So that would be your favorite planet as a result of that. But beyond that, it's in in the solar system. So let's go to to Elon Musk. Let's mention the other rocket rocket engineer. Um so he wants to go to Mars. Um might well get to Mars. Um that's the only other planet you could go to actually in our solar system because Mercury is way too hot.

[00:09:53]Venus is horrendously hot and 90 atmospheres pressure and sulfuric acid rain. It melts lead on the surface, right? So you're not going there. And the rest of them are made of gas. So you're not going there either. So, so Mars is the only place beyond Earth that we could feasibly ever go planets. We could imagine perhaps going to some of the moons of Jupiter and Saturn in in the far future. That's much more difficult. So the old answer of what happens if you jump into a black hole is you go to the end of time. That's this pure Einstein, right? You just so you you get spaghettified on your way to the end of time which means you get squ stretched infinitely actually and then squashed and you so all you get dissociated into a train of atoms and then everything goes to the end of time now as of 2019 I would say uh we think that if you think of yourself as information so if you think of a let's say think very 2022 right let's say you burn a book very fashionable current political climate so burn a book um and collect everything that comes out of the book, all the ashes and all the gas and everything. Then in principle you can reconstruct the book. Not in practice, right? But you can imagine if you collect every single thing and measure it in principle you can reconstruct the book. Information is conserved in in all of physics which means that so so basically if you can measure everything perfectly you can you can predict what happened in the past and what's going to happen in the future. It's called determinism that right so the the old picture of black holes and Stephen Hawin believed this for a long time had a bet about it actually is that they seem like they destroy information you can kind of see it goes to the end of time right it's gone but and then they evaporate away and it seemed that there there was no way even if you gathered all the hawking radiation that come off of trillions of years there's no way you could reconstruct what went in so therefore he jumped into a black hole you be erased from the universe. But that breaks pretty much every law of physics, right?

[00:11:58]Things don't erase information. They scramble it up, make it difficult to read, but they don't destroy it. But now we think actually no, even black holes don't destroy information. So it turns out that now we think, and this is very 2022 papers, right? If you if if you jumped into a black hole, then we do think that if a super being in the far future could collect every bit of Hawking radiation that was came off the black hole for trillions and trillions of years and stick it into a giant quantum computer, then they could reconstruct everything that fell in. So actually in some sense you come out.

[00:12:40]Stephen Hawking had a bet with John Prescll about this. So, and it was I can't remember. I think it was the 90s when he conceded the bet. It might have been the late 80s. But he so he had a bet and the bet was that black Steven's calculation initially from the 70s said that black holes destroy information.

[00:13:00]And so he thought that was true for a long time. And and he had a bet with John Prescll. It turned out that the bet was a set of encyclopedias. So, whoever lost the bet would have to give the other one a set of encyclopedias. And uh John Prescll asked for baseball encyclopedias.

[00:13:18]And uh because of some work by someone called Maldcina, actually ultimately Steven said, "No, no, they don't destroy information. The information comes out.

[00:13:26]It's conserved." So he conceded the event and gave John Prescll the encyclopedias. He said, "What I should have done is I should have burnt the encyclopedias and given him the ashes."

[00:13:35]Well, so the the world the way that the world the earth will end ultimately is as a cinder, right? Because what's going to happen is that the sun in about well starting in a few billion years time actually, but it's going to start growing. It's going to be it'll grow as it gets older and it'll swell up. It probably won't engulf the earth, but it'll get close. Uh the earth will probably drift out cuz the sun will lose some mass. So it probably but it'll toast it basically. So the the earth will end up toasted as a cinder probably still orbiting the remains of the sun which will be what's called a white dwarf star which is just something that basically fades away. So that's what's going to happen in about 5 billion years. I'm laughing cuz it's you know well that's what's going to happen. So um so that's that's how our world ends as as a crisp basically as cinder. Um if you mean by the end of the world you mean the end of civilization then um long before that we we'll have had to escape because it will become the the conditions on the planet will not be will not support complex life like us.

[00:14:42]It'll be too hot. Um but uh you know the the the possibility is we discussed we could destroy ourselves which is um you know it would be given that it's quite possible that there is nowhere else um in a galaxy then as we said before that would be a really silly thing to do. So I think it's more likely we might not have to wait for the sun to do it because we might do it through our own stupidity. You know even very simple things like you go back to the Greeks so Aristotle and the great you know very clever people but they thought the earth was at the center of the universe. Why?

[00:15:20]Because it feels like it. It feels like we're not moving. Um and that's quite a deep point actually in physics. It's like why is it that we're flying around relative to the sun very fast at whatever speed it is 18 m a second or something like that and the whole solar system is going around the Milky Way galaxy and so on. Why is it that we don't feel it? And um the Greeks quite naturally said well because we're at the center of the universe. They also said everything falls towards the earth so therefore the earth must be at the center. It's it's natural and and actually it's quite a deep uh thought to to understand why it doesn't feel that we're moving. You have to go all the way to Einstein really for someone to take that very seriously. And he well he said actually he said well this um there's a great little explanation in Steven Hawings brief history of time about this that the idea that you can't tell whether you're moving or not demolishes the notion of absolute space. So if we think about if I say space of you or most people I suppose you'd think the way that Newton did of a big box within which things happen that's got to be that's a natural picture of space and the universe isn't it is a a thing in which all the planets and galaxies are placed but um in in the brief history of time Hawings says well imagine bouncing a ball so we bounce a ball on the table now a tennis ball so I drop it and I catch it again um so let's say I drop it and it takes a second to bounce up so in that second The Earth has moved about 18 miles or so in space around the sun. So you could ask the question, did that ball return to the same place in space or not? And the answer is you can't answer it. You it does from our perspective, but from the perspective of someone watching the Earth go all the way around the sun, it went up by caught it again, it had moved 18 miles. And then from some other perspective, it would have done something else. So the point is you can't say this is a point in space. it came back to the same place because that just depends on your perspective, depends on whether you're watching the sun, the earth go around the sun or whatever it is. So, so Einstein said that means there's no such thing as absolute space, which is kind of follows if you think about it. But that's a difficult it's it's a cool but difficult thought process in the bit we can see of the universe. Let's say a trillion and you'll see different numbers um because it's hard to measure actually. So we're making estimates based on little bits of the sky that we can observe. It's it's billions and billions and billions to paraphrase Carl Sean and it's it's something like you could say 300 billion, 500 billion, a trillion, even two trillion. So within a factor of two, three or four, we're not really sure.

[00:17:58]It's an estimate because you can't count them. It's an exercise for everybody who's listening. Count to count to a trillion and then come back to me when you've done it. And to this day, I think Cosmos is one of, if not, if not the greatest science documentary series because, and this is the thing that really connected with me, it it's not just about astronomy or the exploration of the planets or the wider universe.

[00:18:24]It's also about what that exploration means for us, for our civilization. So, it immediately connected the the stars and the the things that captured my imagination out there in space with our situation here on Earth. And that's always stayed with me and that's actually a central part of the show here at Sydney Opera House because the to me um cosmology and astronomy raise profound questions that we have as a civilization been trying to answer for centuries if not millennia. And they're questions about our existence. It's I I start the show by saying um what does it mean to live a finite fragile life in an infinite eternal universe which I I so often joke is the only interesting question in philosophy. I don't really mean that. So if any philosophers are listening I it's kind of a joke but if you think about it it probably is the question which resonates through the history of philosophy. what does it mean with and the interesting thing about for me about astronomy and cosmology is it frames that question um it places that question the arena of reality if you like it tells us that we are one planet around one star amongst 400 billion stars in the Milky Way galaxy which is itself one of two trillion galaxies in the observable universe which is itself a small patch of what exists and and and as I'll discuss in the show maybe even the the our universe itself which goes way beyond the horizon um might be one of a potentially infinite number of universes. So we we are definitely small, right? There's no doubt about that. But the question is and this is the question that we address head on in the show with with music and philosophy and art and science. The the question is does that mean that we are insignificant? and and all of them Sean go back to Oenheimer Feman they were all thinking is there something in the way that nature forces us to think and in the things that we've discovered about our place in the universe and how we came to be where we are is there something in there that can be transferred to wider society not just the facts but the the way of thinking and Sean was beautifully eloquent on that there's very famous pale blue dot which he wrote if you seen the reflections on the image of Earth taken from beyond the orbit of Neptune, just a single pixel. And if you've never read that, it's an extremely powerful piece of writing um where he says things like um you know, in its cosmic context, he says, I I can't remember exactly, but it's something like think of the rivers of blood that have been spilled by people who, you know, in their glory and their wonderful visions are fought for the momentary possession of a fraction of a dot. And it's a beautiful, beautiful piece of writing. and and so but um going back to Oppenheimer and Feman they um the and it's the same with Sean the what they came to I think the idea that they came to is that there are two mutually apparently contradictory ideas that arise when you think about our place in the universe one is that we have been over just the last 4 or 5 hundred years demoted from the center so we've gone from the center of the universe to to a type One planet around around one star in 400 billion in one galaxy amongst two trillion in a small patch of the observable universe which may be one universe amongst an infinite multiverse of bubble universes right so we've been demoted but at the same time and Sean did this in cosmos made it so clear we don't know of anywhere else where this happens so it's a reasonable assumption why don't we proceed by assuming that this is the only place where as Sean memorably said in cosmos atoms have come together that can think and feel and explore the universe. He said that you know we are what are we?

[00:22:48]We're collections of atoms that can understand atoms and that you might have to go a long way perhaps millions of light years or more before you find that and that's what Sean did. So he didn't just talk about astronomy and cosmos. He used it to try to teach us or inform us of our fragility and value. and he used it as a political it's a political film or a political series which I found very attractive >> when we contemplate the size and the scale of the universe and our place within it which you're forced to do when you think about the the distance scales and the sheer size and age of the universe then um I think it's very natural for us to tend to come to the conclusion that we don't matter at all and it's true in some sense just physically um what What are we? We're little specks of of of just a collection of atoms on one moat of dust orbiting around one little star in in 400 billion stars in one galaxy amongst two trillion galaxies in a small patch of a potentially infinite universe. So clearly it it is true we are physically insignificant.

[00:24:02]So I've tended in in in the past to focus um arguments or think about arguments of our value um in in the context of what does it mean to live these finite fragile lives in this infinite universe. And I could make a strong argument and and have many times that notwithstanding our physical insignificance, we may be remarkably valuable because the the number of civilizations on the average in a particular galaxy, any given galaxy might be less than one on the average.

[00:24:37]Many galaxies may not even have civilizations in them. If that is the case and that it it's speculative but if it's the case then we would be remarkably valuable notwithstanding our physical insignificance because we would be uh perhaps the only place in the Milky Way galaxy where collections of atoms have come together that can think and do science and have conversations like this in a very real sense bring meaning to an otherwise meaningless galaxy. So that that that has been my position for some time. I think it's a I think it's a good working hypothesis. By the way, as an aside, if you you think that uh we I think Carl Sean said it many years ago in some sense, if that's the case, we have a responsibility to the cosmos itself because, you know, we're we're we're a product of 13.8 8 billion years of cosmic evolution, but we might be a very rare and special product, but we might only be here. We'll only be here for a small amount of time. The the the sun will only be here for a small amount of time in cosmic time scales and so on. So I I've tended to make that argument. But one of the great joys about um reading other people's views about essentially being a scientist is that you can come across a point of view and you think I hadn't thought of that that I might change my mind given that that that wonderful piece of thought.

[00:26:11]And I found it happened to me recently.

[00:26:13]I was reading a book, it's a very old book now by David Deutsch who's is one of the the greats, one of the founders of quantum computing. So he's a really is a a physicist and a thinker worth paying attention to. And he made a point which I had heard before actually in a book called the anthropic cosmological principle by John Barrow and Frank Tifllo which is a huge influence on me when I was an undergraduate physicist.

[00:26:39]So I couldn't believe I'd forgotten this point, but David Deutsch and Var and Tiffler pointed out that it's not necessarily the case that life will always be a speck, right? Something that's very valuable and local in the universe, but doesn't make much difference on a cosmic scale. It's not necessarily the case because you can imagine. So let's take the Earth as an example. So you might say, well, a planet is a very big thing and living things are very small, so they don't make much difference to a planet. That's wrong because if you look at the Earth, its atmosphere is the product of life.

[00:27:18]It's got oxygen in it and high concentration. It would not have that without photosynthesis. So obviously now our civilization has sculpted the surface of the earth. You see it if you look at the earth from space. You don't just see oceans. You don't just see a kind of common or garden planet on the night side of the planet. You see our civilization. So we have now transformed the earth as a civilization, but life has been transforming it for billions of years. So you could say, well, okay, so what what happens if we stay here? We become a space fairing civilization. We don't destroy ourselves or we we aren't destroyed by some impact from space.

[00:28:00]Then could you conceive of technology that could start to affect the solar system? And the the answer must be yes.

[00:28:08]We could imagine building cities on Mars. We could imagine could in physics pure physics terms terraforming Mars, turning it into a habitable world. We could imagine going to the moons of Jupiter or Saturn. We could imagine going to the edge of the solar system.

[00:28:25]You could even imag could you imagine technology in a million years let's say that would allow us to begin to affect the lifetime of the sun. Could you imagine that in physics? According to laws of physics, I suppose you could you could imagine a tremendously powerful civilization that could start to, I don't know, throw material into the sun, whatever it is. Maybe it was ridiculous thing to do, but you could at least imagine it. And then you go a million years, 2 million years, 3 million years, 10 million years, a billion years into the future. Imagine that our civilization expands to the stars and becomes an interstellar civilization. Imagine our civilization populates the entire galaxy. There's nothing in the laws of physics that prevent that. And imagine we start to understand the quantum theory of gravity. We start to understand how spaceime works. Imagine if we start to glimpse some underlying structure in reality that gives us power that we've not yet dreamed of. Who knows in a billion years? And so is it really true that in the far future of the universe then life will play no role or could it be that life could play a central role in the far future of the universe and the reason that it reminded me of Barrow and Tiflla's magnificent book the anthropic cos cosmological principle which I strongly recommend is that in there they consider a cosmology which is it sounds like science fiction and but you can you can conceive of it given the known laws of nature. It's a cosmology called the omega point cosmology. So they consider a recolapsing universe.

[00:30:08]Now at the moment our universe is accelerating in its expansion or or whether it continues to do that forever, we don't know. Um but at the moment there it is. But imag in a recolapsing universe, you can at least consider a situation where life in the far future is so powerful that it can begin to control the collapse of the universe and try to configure it presumably by moving matter and energy around in some inconceivable way. You can you can just about construct this thing such that the the the the ability of life to process information increases faster than the rate of collapse of the universe. And and so what that means, what what does it mean?

[00:30:55]Um it means that what's the what's the appropriate measure of time for a for a intelligent being? It it's really I think fundamentally it should be considered you should think of it as the time it takes to process one bit of information.

[00:31:11]And it turns out that you can at least write the equations down for a universe in which the ability to process information diverges to infinity.

[00:31:20]I think we're at the frontier of a of a very exciting time in our history as a civilization because we are now I think on the verge of becoming a space fairing civilization in in the truest sense of the word. Let's say a multilanetary civilization.

[00:31:40]So there's been a revolution in engineering in the last 10 years or so, the last decade because now we have reusable rockets. So SpaceX now Blue Origin have reusable rockets which means that access to Earth orbit is cheap or at least cheaper than it's ever been before. So we are industrializing the space above our heads just a few hundred miles above our heads at an everinccreasing rate. Of course, it's been very important to us for many years, decades in fact. So, satellite navigation, communications, weather forecasting, earth observation, climate observation and so on. The the observation of Earth from Earth orbit has been part of our lives whether we think about it or not for quite some time. But now because we have the technology to access it cheaply, I think we are seeing a revolution. And so it will not be long before there isn't just one uh crude space station in orbit, which is the International Space Station. There will be multiple space stations in orbit. There will be scientific research at a much higher level in orbit, commercial scientific research. There'll of course be space tourism. There's an increasing demand on communications for example. So the Starlink satellites, hundreds and hundreds of them up there. There'll be there'll be multiple competing constellations of satellites that allow us to make phone calls and access highspeed internet from any point on the earth. And so that that process is accelerating and it is going to accelerate further. So what does that mean? So there's tremendous opportunity.

[00:33:26]It's incredibly exciting before we start thinking, by the way, about going out to the asteroids and mining them and building cities on Mars and building cities on the moon and so on. But let's just talk about Earth orbit first. It's tremendously exciting, huge opportunity.

[00:33:42]But of course, when you start to move outwards to a new frontier, then um the frontier can become crowded. You can have competition um for the real estate.

[00:33:55]Uh you can you need some way of managing conflicts between um by which I mean conflict physical conflict between the satellites. What happens if someone's satellite comes close to another satellite? How do you manage that? Do you allocate particular orbits? Um or or or do you say that we're going to have some framework like air traffic control where you have an avoidance system that everybody agrees on whereas if two things come close they avoid each other.

[00:34:20]that framework is not yet there. I I've attended several meetings and conferences where um there are of course many countries and international bodies that are trying to work on the management of space. I find that it's a challenge because always of course it's always a challenge when different countries and different commercial interests and so on are trying to flesh out agreements about how you manage a frontier. Um, but ultimately I find it exciting because what it means is we're now at the stage where as as the great Carl Sean said, we're beginning to take our first steps out into the cosmic ocean. And I always remember and he said the water seems inviting. So it's a tremendous opportunity.

[00:35:09]But what what what kind of opportunities are going to open up? Well, um we know for example, so already from our experience on the International Space Station that uh sort of development of new drugs for example or development of new um uh ways of building semiconductors for example, silicon wafers and so on. Lots of experiments have been done that suggest that there might be an advantage to on orbit manufacturing. So it's in a microgravity environment of certain things growing crystals and so on which might be useful. And so as we begin to get more experience operating in microgravity we begin to see that there are applications for particularly material science and biosciences.

[00:35:56]But beyond that, so when we start to move outwards beyond near Earth orbit and build the infrastructure that we need close to the planet to begin to move further out into space, then opportunities begin to open up that I find tremendously exciting. So one very well-known example would be mining asteroids. So one could argue there are people that argue that one of the biggest problems we face and have faced historically on earth is competition for resources. So not only just the pure competition which leads to conflict and war if you think those resources are limited which they are on earth but also just the stress of course that you put on the earth itself on the environment as we we our civilization grows and requires access to more resources it damages the planet it creates conflict and so on. But if you have the infrastructure to begin to move outwards, for example, to the near-earth asteroids, then what you find is that resources are no longer limited in any reasonable sense. There are vast amounts of resources out there in space that we will have access to within the next decade or so or certainly few decades. So that begins to transform the way that we think about our civilization, the way that we think about expanding our civilization, increasing the capability of our civilization and so on. I think so. So so I think there's a tremendous opportunity there to to to grow our civilization crucially without further damaging the planet that most of us will live on for the foreseeable future. And that's why for me I'm ultimately optimistic about those steps that we're making into space. I mean I would not have imagined I think if you went back 20 years that we would be we would have so many rockets flying and coming back to the earth again and then flying again. Um perhaps within my lifetime but certainly at this point in the 21st century. So I think it's exciting but the challenge is as with all new technologies and you could extend this debate by the way to artificial intelligence or quantum computing as well as space flight. The challenges come when we try to build the regulatory framework and you need a regulatory framework. One of the things I think we're very bad at on planet earth is recognizing that we all live on planet earth. Um, so we're all on the same spacecraft, let's say, making our way on our journey around the sun. And ultimately challenges about the management of space or the management of artificial intelligence or the management of the power potentially quantum computers I think ultimately are global challenges and we're very bad historically at facing global challenges together. So that would be the the my my my worry. Um, and of course just to say how you think about space. So it's it literally it's only a few hundred miles that way up there. Now there are satellites whizzing around other than the geostationary ones. So like the international space station would be a good idea.

[00:39:29]It it it's in a country's airspace for a matter of seconds, right? So, so you clearly um you need to develop some way of managing that environment which is a way which involves international collaboration because the environment the the objects that are up there doing all the jobs that we want them to do don't stay in any one country's airspace for more than a few seconds or minutes.

[00:39:55]And so it's kind it's it's kind of obvious to me that we need a framework to manage that. When we contemplate the size and the scale of the universe and our place within it, which you're forced to do when you think about the the distance scales and the sheer size and age of the universe, then um I think it's very natural for us to tend to come to the conclusion that we don't matter at all. And it's true in some sense just physically. Um what are we? We're little specks of of of just a collection of atoms on one moat of dust orbiting around one little star in in 400 billion stars in one galaxy amongst two trillion galaxies in a small patch of a potentially infinite universe. So clearly it is true we are physically insignificant.

[00:40:46]So I've tended in in in the past to focus um arguments or think about arguments of our value um in in the context of what does it mean to live these finite fragile lives in this infinite universe. And I could make a strong argument and and have many times that notwithstanding our physical insignificance, we may be remarkably valuable because the the number of civilizations on the average in a particular galaxy, any given galaxy might be less than one on the average.

[00:41:21]Many galaxies may not even have civilizations in them. If that is the case and that it it's speculative but if it's the case then we would be remarkably valuable notwithstanding our physical insignificance because we would be uh perhaps the only place in the Milky Way galaxy where collections of atoms have come together that can think and do science and have conversations like this in a very real sense bring meaning to an otherwise meaningless galaxy. So that that that has been my position for some time. I think it's a I think it's a good working hypothesis. By the way, as an aside, if you you think that uh we I think Carl Sean said it many years ago in some sense, if that's the case, we have a responsibility to the cosmos itself because, you know, we're we're a product of 13.8 8 billion years of cosmic evolution, but we might be a very rare and special product, but we might only be here. We'll only be here for a small amount of time. The the the sun will only be here for a small amount of time in cosmic time scales and so on. So I I've tended to make that argument. But one of the great joys about um reading other people's views about essentially being a scientist is that you can come across a point of view and you think I hadn't thought of that that I might change my mind given that that that wonderful piece of thought.

[00:42:55]And I found it happened to me recently.

[00:42:57]I was reading a book, it's a very old book now by David Deutsch who's is one of the the greats, one of the founders of quantum computing. So he's a really is a a physicist and a thinker worth paying attention to. And he made a point which I had heard before actually in a book called the anthropic cosmological principle by John Barrow and Frank Tiffler which is a huge influence on me when I was an undergraduate physicist.

[00:43:22]So I couldn't believe I'd forgotten this point, but David Deutsch and Var and Tiffler pointed out that it's not necessarily the case that life will always be a speck, right? Something that's very valuable and local in the universe, but doesn't make much difference on a cosmic scale. It's not necessarily the case because you can imagine. So let's take the Earth as an example. So you might say, well, a planet is a very big thing and living things are very small, so they don't make much difference to a planet. That's wrong because if you look at the Earth, its atmosphere is the product of life.

[00:44:02]It's got oxygen in it and high concentration. It would not have that without photosynthesis. So obviously now our civilization has sculpted the surface of the Earth. You see it if you look at the Earth from space. You don't just see oceans. You don't just see a kind of common or garden planet on the night side of the planet. You see our civilization. So we have now transformed the earth as a civilization but life has been transforming it for billions of years. So you could say well okay so what happens if we stay here? We become a space fairing civilization. We don't destroy ourselves or we we aren't destroyed by some impact from space.

[00:44:43]Then could you conceive of technology that could start to affect the solar system? And the the answer must be yes.

[00:44:52]We could imagine building cities on Mars. We could imagine could in physics pure physics terms terraforming Mars, turning it into a habitable world. We could imagine going to the moons of Jupiter or Saturn. We could imagine going to the edge of the solar system.

[00:45:09]You could even imag could you imagine technology in a million years let's say that would allow us to begin to affect the lifetime of the sun. Could you imagine that in physics terms according to laws of physics? I suppose you could you could imagine a tremendously powerful civilization that could start to I don't know throw material into some whatever it is. Maybe it was ridiculous thing to do but you could at least imagine it. And then you go a million years, two million years, three million years, 10 million years, a billion years into the future. Imagine that our civilization expands to the stars and becomes an interstellar civilization.

[00:45:50]Imagine our civilization populates the entire galaxy. There's nothing in the laws of physics that prevent that. And imagine we start to understand the quantum theory of gravity. We start to understand how spacetime works. Imagine if we start to glimpse some underlying structure in reality that gives us power that we've not yet dreamed of, who knows in a billion years. And so, is it really true that in the far future of the universe, then life will play no role?

[00:46:19]Or could it be that life could play a central role in the far future of the universe? And the reason that it reminded me of Barrow and Tiffler's magnificent book, the anthropic cosm cosmological principle, which I strongly recommend, is that in there they consider a cosmology, which is it sounds like science fiction, and but you can you can conceive of it given the known laws of nature. It's a cosmology called the omega point cosmology. So they consider a recolapsing universe. Now at the moment our universe is accelerating in its expansion or or whether it continues to do that forever we don't know um but at the moment there it is but imag in a recolapsing universe you can at least consider a situation where life in the far future is so powerful that it can begin to control the collapse of the universe and try to configure it presumably by moving matter and energy around in some inconceivable Okay. You can you can just about construct this thing such that the the the the ability of life to process information increases faster than the rate of collapse of the universe. And and so what that means what what does it mean?

[00:47:39]Um it means that what's the what's the appropriate measure of time for a for a intelligent being? It it's really I think fundamentally it should be considered you should think of it as the time it takes to process one bit of information.

[00:47:54]And it turns out that you can at least write the equations down for a universe in which the ability to process information diverges to infinity before the universe collapses. So you you in that case you almost say that life manipulates the universe such that it becomes immortal right in the far future. Now I emphasize this is complete, you know, it's beyond speculative. So I'm not advocating for this that the for this position that that's the way that nature is. But it's really interesting. It was really interesting to me to just think about it. the the the the point I think the key point which is interesting is that it's not necessarily the case that life remains insignificant on a cosmic scale.

[00:48:45]You shouldn't assume that because if if life persists sufficiently long and becomes sufficiently knowledgeable and powerful, there is a question. So there is a cosmological horizon. And there are different kinds of cosmological horizons. And it is a a a very good question that but people don't really even know how to phrase it that but could it be that you can describe the whole universe in terms of a quantum theory living on a boundary of some description.

[00:49:17]And I think the guess is yes the the guess but we don't even know what we mean by the boundary.

[00:49:24]>> Yeah.

[00:49:24]>> Right. um it's one of the problems here.

[00:49:27]So the the reason that Maldina was able to show this is this works for this very specific thing called ads space is because there's a boundary you can identify in that particular geometry whereas our universe is dissa right there isn't it's not obvious what you mean by a boundary it's not really obvious what question you know as you said it's hard to find the words it is we don't really know what question we're asking But that rough picture that there could be a a theory of a quantum theory somehow this network of cubits that gives rise to geometry, space, time is accepted broadly, right? So we but when you try to get into the detail of it, it's only been fully realized for a very specific model which is kind of a toy model. It's not our universe. So it could be that our universe does not admit that description could be could be that but it's certainly beyond us the moment technically but it's a wonderful thought and actually there's a paper uh recently that so people are beginning to use the the Google chip the willow chip >> um which is a a very powerful it's not a quantum computer it's a proto quantum computer kind of thing so and people have started to use it because what it is is a load of cubits that you can entangle and you can set it up and it's very well controlled. So whilst we don't know how to do quantum calculations on the thing really what you can do is try to say well could I set them up so that it's like space emerges from them and there was a paper recently where something that was described in the paper as a one-dimensional wormhole was made it wouldn't be in our universe this thing it would be but it kind of emerged from this structure and that's the kind of picture we're trying to get to it's a it's a good paper. It's been peer- reviewviewed. It's a controversial paper. You'll see loads of stuff online but it's worth looking at those papers and by the time this is uh sent out there might be some other paper a lot of people are working on it. So also actually building little clocks little quantum clocks or tiny clocks and because we don't even know what a clock is right at the most fundamental level because we don't know what time is. So, so we we're talking about very fundamental questions about reality in this research. Um, so it's very counterintuitive, but it's about polarity that there's a property of particles called spin where this is realized. So they're like quantum coins really and and we use it now in quantum cryptography for example. So this is becoming technology now. this this idea of using entanglement and also in quantum computing extremely exciting. So so we're now this is not just wishy-washy wild stuff. It's it's fundamental. We use it we use it in laboratories as it's people think of entanglement as an information resource now a resource that we can use to build computers. Um, but it's profound because it it really does seem to be the case that entanglement builds up spaceime. So that it's almost like it's the underpinning structure. I mean, imagine a world where at the fundamental level space, which is this thing we take it for granted. It's the room that we're in. We talk about things being one mile apart or something. We think we know what we mean by distance.

[00:53:09]actually know underpinning that it does seem is a is a world of quantum entanglement in which there is no concept of distance or separation or space it emerges it's like it's like saying um you know you I talk about us right we you right what are you you're a human being and you're thinking and feeling and we're having this conversation but actually there's another level which you could call a deeper level where you're just atoms so you're just protons and neutrons and electrons and the protons and neutrons are made of quarks and they're all stuck together and that's a description of you. But it isn't you. It isn't it feels like it isn't all there is to you, right? There's also you a human being with thoughts and feelings and you know the the most wonderful structure in the universe which is what human beings are.

[00:54:00]In the same way we're saying that um that space and time are like that and and it's it's as incomprehensible but then again no less incomprehensible is that the fact that a human being can be made of atoms what we're saying is space and time can be made of something else which seems to be quantum entanglement.

[00:54:18]It's a theory that isn't it? I mean so there's a theory there and so you can get the little things and we will analyze them and have a look. I mean, I wouldn't I it's funny because on you mentioned social media, I think you occasionally on social media, I I'll quite often I'll tweet something and and there'll be quite a few people who disagree reasonably strongly with what I said. And one of them is is the the UFO thing, you know, that I mean, there are people who really believe that there are UFOs visiting the Earth. And I always say, you know, I haven't seen any evidence of that that I think is strong evidence. It's a huge claim that there are other civilizations out there that are visiting us. But I wouldn't be surprised in a in a sense in a strict sense that if I said to someone the other day, you know, if if a big UFO came now, we walk outside and over Westminster there's a spaceship hovering. I wouldn't have been the least bit surprised because I know that there are trillions of planets in the Milky Way galaxy alone and hundreds of billions of stars and there's been a lot of time and one of the great mysteries actually in physics is why we don't seem to see much out there anything we haven't you know there's strong there's strong evidence of nothing out there at all at the moment we we have no strong evidence of any life beyond Earth and that's a puzzle and a paradox So, it's a it's about with with those claims, you don't rule them out. If someone says, "Well, I've got this I found this thing at the bottom of the sea and I think it's really weird." Um, then the correct thing to do is go, "Okay, we'll put it in a lab and get an electron microscope and pro it around and find out just how weird it is." And nature, fineman again said, "The thing to remember is nature does not care at all what you think. Nature just doesn't it doesn't matter who you are or how famous you are, how many letters you've got before or after your name, whatever.

[00:56:10]It doesn't matter. Nature just is. So if indeed an alien spacecraft crashed into wherever it was that they found these things a billion years ago and left all the fragments there and we've dug them up, then that's interesting. So when we're falling in, we might as well be, this is the Einstein's equivalence principle, in action. we might as well be in flat space because the distortion it's like saying uh on the surface of the earth um if you look at a mile a square mile of the surface of the earth you don't feel the you don't see the curvature right you have to go some bigger distances to see that you're on a curved surface kind of like that so so the the distortion the difference in gravitational pull as you said or the distortion you don't feel it until it becomes very distorted or there's a big gravitational pull when you get very close to this And then you start to see that and actually it works. It's not only stretching, it's also a squashing. So the way the tidal gravity works is to squash in one direction and pull in the other direction.

[00:57:09]>> So we are getting >> so you feel it. So you start to feel this strange sort of sensation of being stretched and squashed and and and as you go closer and closer to the singularity, those effects become much more extreme until this so extreme for a perfectly spherical non-spinning ball of matter. It's the simplest thing you could do which tells you how space and time are distorted by it. And that's a model for a star. It's the simplest thing you could do. So he solved the equations. It's a remarkable thing. In those equations there is a description of a black hole although it wasn't realized at the time. It's a remarkable piece simple piece of mathematics actually. Um so essentially what's the idea behind a black hole? One way to think about it is that you could remove could you remove the star from from this fabric but leave the distortion behind.

[00:58:03]So if you if you do that you get the description of a black hole. But you might say what what do you mean that how can that be formed in nature? So you think about what a star is then a star is a balancing act. So it's a it's a mainly hydrogen and helium collapsing under its own gravity. That's how our sun formed 4 and a half billion years ago. So it's collapsing. So what stops it collapsing? Well, as it collapses, the core heats up and that initiates nuclear fusion reactions in the core. In in the case of our sun, it's hydrogen being fused into helium that releases energy which creates a pressure which holds the thing up. So it's balancing but it needs the fuel and and it's not infinitely big of course. So at some point it runs out of nuclear fuel and ultimately no more fusion reactions can occur in any star and so the star will resume its collapse. So the question is well is there something that stops it?

[00:59:00]Because if there isn't something that stops the collapse, then it will collapse without limit. And and so actually if you look at the history of physics in the 20s and 30s, people were saying, well, we'd like to avoid this idea that the thing will collapse without limit because if it does, then Schwarzel's equation predicts some very strange things indeed. And so people kind of try to avoid it. It was really actually Oppenheimer and uh his student Schneider in the late 30s just before the Second World War that showed that really with some assumptions it looks like a massive enough star could actually collapse without limit. So what does that mean?

[00:59:40]Collapses without limit. It means that essentially it does what I said. You essentially remove the star from the fabric of the universe leaving the distortion behind. And the black hole, the idea behind the black hole is let's say you take, let's say you take the sun, a star, the mass of the sun, and you just collapse it and you keep on collapsing it. You get to a point when the the radius of the sun is not 700,000 km, which is what is in miles, half a million miles.