Black holes, like the one seen in this visualization, present a host of possibly unknowable questions about physics and the nature of the universe.

Black holes, like the one seen in this visualization, present a host of possibly unknowable questions about physics and the nature of the universe.

The trouble with answers is that they create new questions. The more we learn, the more we realize we don’t know.

But the things that really terrify us are the things that will always remain unknown.

That’s what Marcus du Sautoy, the Professor for the Public Understanding of Science at Oxford and professor of mathematics, says in his new book “The Great Unknown.” He explores the boundaries of human knowledge, from chaos theory to the concept of infinity, to find out whether some mysteries of the universe can ever be solved.


  • Marcus du Sautoy Simonyi Professor for the Public Understanding of Science, Oxford

Marcus du Sautoy's TED Talk

Interview Highlights

On being the professor for the public understanding of science at Oxford

It’s a very multifaceted job actually – so I’m still a research mathematician, so I’m still practicing doing science. But I’m also trying to tell people about different scientific stories. Not just in mathematics but in physics, biology, neuroscience – and also, as you say, encouraging other scientists to step up to the plate. I think that’s part of the job of being a scientist, is discovery – but also communication. Not just to our fellow scientists but to the rest of the world in general.

On knowledge

The idea of knowledge is a really challenging one. It isn’t simple, it isn’t possible to sum it up in a little soundbite – and that’s why I’ve sort of gone on the journey of this book. We gain our knowledge through our interaction with our senses, with the environment around us – that’s how we seem to know, by looking, by listening. We use our analytic mind to extend those senses beyond what we can see, hear, feel, touch. But therefore there’s a kind of challenge – are there things that we can’t know because we don’t have the equipment to engage with them?

Interestingly, the word ‘to know’ is one of only I think a hundred words that have a translation across all languages. Even the word “to eat” does not easily translate into every language across the world. So we seem to know what ‘to know’ means, but actually defining it philosophically is still an ongoing challenge. What I was after was to take one step back from that and saying “Okay, yeah, we might be living in the Matrix. But what can we tell about this simulation?”

On science, certainty and politics

I think very often when politicians engage with scientists they want very definitive answers. They want black and white, yes/no answers – and we just can’t give them those in all circumstances. There’s gradations of certainty, and that’s quite subtle to communicate. That doesn’t mean we can’t use these equations to know about something like climate change. I don’t know when a wave is going to break on a beach – that’s quite chaotic – but I do know about the tides.

On quantum physics

Quantum physics really says that unknowability is at the heart of how we must do science. I mean, post-Newton, we thought that we were living in a kind of deterministic clockwork universe controlled by equations. Quantum physics says, “Oh no! Actually, something very different.” You can run an experiment the same each time and get a different result, regardless of the fact that you’ve set it up in exactly the same way. This isn’t chaos theory — it seems to be that the universe is probabilistic in nature, random in nature. And that really goes against what I thought science was about.

If you believe the universe is deterministic, as Newton did, then doesn’t that take free will out of the equation? Doesn’t that mean everything that’s gonna happen tomorrow is already determined by what you’re doing today? And quantum physics allows back into science the possibility that no, actually what you’re doing today does not determine exactly what happens tomorrow. Maybe you don’t have free will but at least that little electron flying through the air, that does have free will.

On consciousness and self-awareness

Is that cat aware of itself such as when it looks in the mirror it doesn’t think that’s another cat it thinks that’s itself? If you look at the cat videos online (of which there are many) you’ll realize most of the time it thinks it’s another cat. But if you put an orangutan in front of a mirror and you put a little yellow dot on the forehead of the orangutan and it suddenly sees the image in the mirror, it knows that’s itself because the reaction is, it doesn’t put its hand up to the mirror, it puts its hand up to its forehead to investigate. And you can do that with children too – when do children suddenly recognize themselves in the mirror? Something changes in the brain at 18 to 24 months where suddenly they don’t touch the mirror, they touch their own forehead.

On science and the role of scientists

I think the unknown is really the lifeblood of the scientist. The thing which gets me up in the morning is the things I don’t know, and I think that’s true of every scientist. We love talking about the stories we do know cuz they’re such amazing stories – that’s partially what this book is about. But I think that we all love the unknown because that’s where we’re going to make our mark, the new things that come up. The things that really terrify us are the things that might always remain unknown.

On religion

This term “God” is so complicated. I mean, I got into this discussion with a journalist when I first took over this job and it was a Sunday morning in Northern Ireland when God is not far from people’s minds and he asked me, “Do you believe in God?” And as a mathematician I spend a lot of time proving the existence of things and using my tools to prove things cannot exist … But I need a very good definition of what it is that I’m trying to prove exists or not. And if you push people on their definition of God it’ll be very different for different people. And this journalist, when I pushed him, said, “Well, it’s something that transcends definition! It’s beyond our human understanding.”

On the future of science

I love going on marches, I love shouting slogans – I spent my whole student life doing it. It was great going on the march here in Washington – the heart of the marches across the whole world! But that must be the beginning of a movement. That must be the beginning of a movement of scientists to engage with the public and show why we believe what we do – the evidence, the facts, the ways of thinking. And that’s a long debate.”

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