Professor Brian Cox is widely recognised as the foremost communicator for science, cosmology and astronomy in the world, and is Professor of Particle Physics at the University of Manchester, The Royal Society Professor for Public Engagement in Science and a Fellow of the Royal Society. In this interview, we discuss whether there is meaning in the universe, the nature of time and the rarity of life in the universe.
Brian has presented a number of highly acclaimed, award-winning science programs for the BBC watched by billions around the world including ‘Adventures in Space and Time’ (2021), ‘Universe’ (2021), ‘The Planets’ (2018), ‘Forces of Nature’ (2016), ‘Human Universe’ (2014), ‘Wonders of Life’ (2012), ‘Wonders of the Universe’ (2011) and ‘Wonders of the Solar System’ (2010). His latest series ‘Solar System’ premiered on BBC Two in October 2024 to huge viewing figures and rave reviews. Previously Brian co-hosted popular astronomy and cosmology series ‘Stargazing Live’ with Dara O’Briain, and he co-hosts award-winning BBC Radio 4 series ‘Infinite Monkey Cage’, which has gone on to become one of the UK’s most popular podcasts. As an author, Brian has sold over a million books worldwide including ‘Black Holes’, ‘Universal: A Guide to the Cosmos’, ‘Quantum Universe’ and ‘Why Does E=mc2?’.
Brian has undertaken several sell-out live world tours, setting numerous Guinness World Records, including for the biggest selling science tour – a record he himself broke with his most recent worldwide tour, ‘Horizons’, which took in venues in the UK, USA, Australia, New Zealand, Singapore, Hong Kong and across Europe and was performed to hundreds of thousands of people across the world. The Horizons tour will conclude later this year with a string of dates in the US. Accompanied by Sydney Symphonic Orchestra, Brian performed a run of sell-out shows at Sydney Opera House in December 2023, followed by up a week of sell-out shows at the Royal Opera House in London in the summer of 2024 where he was accompanied by the Britten Sinfonia.
Prior to his academic and television career, Brian was in rock bands Dare and D:Ream, famously playing the keyboard on the latter’s hit track ‘Things Can Only Get Better’. Brian has worked as a consultant on a number of film projects including Danny Boyle ‘Sunshine’, whilst his content has attracted hundreds of millions of views across social media platforms.
Q: Why do we search for meaning in the universe?
[Prof. Brian Cox]: Well, it’s worthwhile first of all, I think, trying to understand what ‘meaning’ is, because it’s a very difficult term to define—‘meaning’. In my live shows when I’m talking about this, I say to the audience: whatever you think it is, it self-evidently exists, because the universe means something to each of us. But I would argue that whatever it is, it’s an emergent property. So it exists here on Earth because there are complex biological systems. Without those complex biological systems, it doesn’t exist. There is no meaning.
So it follows that I think what we’re really saying is: what are we looking for ourselves? It’s a property of the human brain, I would argue. By the way, as an aside, I would then argue that if there are no other complex biological systems in a galaxy like the Milky Way, then there’s no meaning in that galaxy at all—so the galaxy is meaningless if there are no complex biological systems in it. We bring meaning to it, would be my statement. And I don’t think it’s a particularly controversial thing to say, because it’s hard to understand what you mean by meaning if you try to divorce it from biology.
Q: How rare is life?
[Prof. Brian Cox]: So the answer is, we don’t know. If you phrase the question as, “How far would you have to go to see another civilisation—intelligent, living things, let’s say?” the answer is, of course, we don’t know. All we can do is make a couple of rough observations and some educated guesswork.
One observation is that we haven’t seen any sign of other civilisations. That’s not entirely trivial: we have looked a bit—we’ve tried to listen with SETI, Breakthrough Listen, and so on. There’s some attempt to begin a systematic survey of the sky to see if we can detect anything, and we haven’t so far. But we haven’t been doing it for very long, and our sensitivity isn’t that great yet, so we still don’t know. But to date, we’ve seen nothing.
There are some arguments, such as the famous Fermi paradox named after Enrico Fermi, which I think has a great deal of force. Essentially, Fermi asked, “Where are they?” The paradox is that in the Milky Way galaxy, with something like 400 billion stars and trillions of planets, it’s estimated there may be around 10 billion (maybe more, maybe less) potentially Earth-like worlds. And the galaxy has been around for about 13 billion years. The argument goes that if a civilisation had developed ahead of us and become a spacefaring civilisation—especially if it could build self-replicating machines (machines that travel to nearby star systems and copy themselves)—it’s very hard to see why we haven’t noticed any evidence of that. Because it’s been so long, billions and billions of years, during which a civilisation could have arisen and essentially become immortal. If you can become interstellar, or build these so-called Von Neumann machines, you’d think we’d see something. You could argue maybe they’re here already, and we don’t see them—maybe they’re the size of an iPhone, or even nanomachines too small to detect. But as far as we can tell, we don’t see anything.
That may suggest there’s simply nothing out there. Why might that be? Why would there be no civilisations ahead of us that have already written their signature across the sky? Many biologists I speak to aren’t surprised. Most astronomers are surprised, but biologists look at the history of life on Earth. As far as we know, life has been present for around 4 billion years—pretty much the entire history of the Earth—beginning more or less as soon as Earth formed. But we don’t see evidence of anything very complicated until about a billion years ago. There are some arguments about possible older fossils, but it’s roughly a billion. So it looks like life here didn’t become more complex than single cells—and certainly not as complex as animals or plants—until the last billion years. So, from cell to civilisation took about 4 billion years, which is a long time—a third of the age of the universe.
We also live in a very violent universe. Many stars don’t even live for 4 billion years. The ones that do can be like our Sun, which is relatively quiet, but many are red dwarfs that are very active. It’s difficult to see how a civilisation could arise around a red dwarf—maybe it can, but it’s hard. Big stars don’t last 4 billion years either. So if it takes billions of years to produce complex living things at our level, maybe there aren’t many places that could sustain an unbroken chain of life for that long. Many biologists I speak to would say it’s almost incomprehensible that something as complex as us has even appeared at all—we might just be very lucky. Or, in the spirit of debate, maybe it normally only takes a few hundred million years to go from life to intelligence, and we were just slow. Again, we don’t know. We have a sample size of one.
Q: How is quantum mechanics helping us understand the universe?
[Prof. Brian Cox]: Well, quantum mechanics is, as far as we can tell, the base theory. I’ve heard people describe it as the operating system on which all the other theories run. So it appears that this behaviour is fundamental. It’s interesting as a theory—odd, because the mathematical and logical structure is perfectly understandable (it’s not difficult), it’s just not the one we’re used to. Essentially, you have a probabilistic theory, but it’s not the sort of probability theory we’re familiar with. Yet it’s actually a very natural theory.
If you look at a modern textbook (rather than the historical ones), you’ll see that quantum mechanics baffled people in the 1920s and 1930s, because they were trying to figure out how atoms worked and were confronted with baffling observations. That’s often, sadly, how it’s still taught today—starting with the confusion of Niels Bohr, Einstein, Schrödinger, and Heisenberg, who were all confused because it is confusing. But if you go back and look at the theory of quantum information, for example—which underpins attempts to build quantum computers—you can see quite clearly that quantum mechanics is a consistent mathematical structure, not that difficult to understand in itself, which nature has chosen. The confusing thing is that nature chose something that doesn’t feel intuitive to us. And I think it has a reputation for being mystifying, confusing, and almost mystical—mainly because of its history rather than what it really is as a theory.
Having said that, when you try to map quantum mechanics onto our everyday experience, you come to its interpretations—things like the many-worlds interpretation, often described as there being an infinite number of universes, which is indeed very confusing and difficult to understand. But I would emphasize that quantum computers—although we don’t have them working on a large scale yet—do show, I think pretty conclusively, that the world described by quantum mechanics is the real world. If you needed more proof, you could say lasers and transistors are evidence of it, since quantum theory underpins all of that and much of modern technology. But quantum computers really highlight how strange the universe is, I think.
Q: What is time?
[Prof. Brian Cox]: We don’t know. It’s one of the deepest questions in physics. You’re right—even in Einstein’s theory of relativity, it’s counterintuitive in the sense that it’s not what Newton would have thought. Newton assumed time was universal: he basically posited a great clock in the sky, and if everyone had perfect watches and synchronized them, those watches would stay synchronized for all of time, no matter what you did. That was one of his assumptions in the Principia Mathematica, but Einstein showed in 1905—drawing on 19th-century work in electricity and magnetism—that it’s not like that at all.
If we all synchronize our watches and then go off and do different things, even just going to the shops, we’ll see that our watches measure different time intervals by the time we meet again. And if someone were to travel fast in a rocket, or go near a black hole or a very massive star, then come back, the difference in elapsed times on our watches could be huge—potentially billions of years. In Einstein’s theory, the reason is straightforward: there’s this very beautiful idea called spacetime. You can picture it as a map of space and time, with every event in the universe—anything that happens—marked as a point on that map, located at some position in space and time.
A clock measures the “distance” it travels through spacetime between events. So if we all meet in a room on Earth, then go our separate ways for a year, and then come back together, the time each watch shows is effectively how far that watch (or person) travelled through spacetime between those two events. That distance can be arbitrarily small if, say, someone zooms off near the speed of light and comes back quickly—on their watch, only a second might have passed. It’s analogous to asking, “What’s the distance between London and Manchester?” It depends on which route you take. In relativity, the route length is the time that passes.
That’s fascinating, but it still doesn’t tell you what time actually is—only that a clock is measuring this spacetime distance. Einstein famously said time is what a clock measures, which was a half-joke but also the best answer he could give. Today, cutting-edge physics research looks at the smallest possible clocks, built from just a few atoms, and how they work on a quantum level. We also study “time crystals,” which have symmetries in time analogous to a crystal’s symmetries in space. All of this underscores that at a fundamental level, we still don’t know exactly what time is.
I should say that spacetime itself—often called the fabric of the universe—now seems to emerge from something deeper. Studies of black holes suggest that space and time may be built from a kind of quantum network, perhaps a network of qubits. It looks like the underlying spacetime could emerge from such a network. And by the way, that’s similar to how consciousness might emerge from a brain—a complex arrangement of atoms—even though we don’t really know how that happens. Likewise, we suspect spacetime emerges from a collection of “things in a pattern,” though we don’t yet know what those things are.
Q: How does art help us understand the science of the universe?
[Prof. Brian Cox]: I think it’s the latter—it’s really important. We began by talking about meaning, asking what is meaning to us, what is truth in some sense, what is the structure that underlies reality, and what is our place within it. In my live show, right at the start, I ask: “What does it mean to live a finite, fragile life in an infinite, eternal universe?” It’s a good question. And science alone won’t answer it—it doesn’t answer questions about meaning. It’s necessary, but not sufficient.
So, any discussion of our place in the universe and what it means to be human requires us to know the scale of the problem. You need to know that we live in a galaxy of more than a billion suns, and that it’s one galaxy among two trillion galaxies in the small patch of the universe we can see. You need that knowledge, but it’s still not sufficient.
The picture I have is of some structure you can almost visualize, and—following Plato—you see science, art, and philosophy as different lights that you shine on that thing, each casting vivid shadows. We only have access to those shadows. So surely, to construct this thing, to understand what it means to be human, you need as many lights as possible.
In my live shows, I built a whole performance around this idea using classical music, often with orchestras. We first did it at the Sydney Opera House just over a year ago with the Sydney Symphony Orchestra. The music wasn’t merely a soundtrack; it was part of a discussion between the science, the cosmology, and the music. Most of the pieces were composed around the turn of the 20th century—Sibelius’ Fifth Symphony, Mahler’s Fifth, and almost all of Richard Strauss’ Also sprach Zarathustra. People know the first minute of Zarathustra from 2001: A Space Odyssey, but not the rest.
Strauss was following Nietzsche there—the work was inspired by Nietzsche’s book. Nietzsche is asking these questions: who are we, how do we justify our existence in the face of the unlimited power of nature? At the premiere (around 1896 or 1897, I think), Strauss said that musically, nature is always in C major, and humanity is in B minor (sometimes B major)—a semitone down. So there’s this musical argument all the way through about how we can fit ourselves into nature’s power and majesty. At the end, it just fades away with those two keys clashing: the woodwind plays a B major chord and the bass plays a C, and it just disappears into infinity. It’s as eloquent an exploration of these questions as I’ve come across.
Of course, Strauss didn’t know the half of it, and Nietzsche—who was terrified—didn’t know anything like what we know today. They didn’t know about quantum mechanics or the vastness of the universe. Even the existence of galaxies beyond our own wasn’t established back then, and these ideas were already terrifying them. Now, it’s even more terrifying, but it’s also fascinating to let these perspectives—science, music, philosophy—have a conversation.
I firmly believe that when we’re talking about questions of meaning, we need to deploy every tool at our disposal.