Prof Jim Al-Khalili
Jim Al-Khalili OBE is a scientist, author and broadcaster. He is the Professor of Physics at the University of Surrey, where he also holds a chair in Public Engagement in Science. He is the current president of the British Humanist Association. Jim is a leading science communicator, having written a number of bestselling popular science books and presented a huge number of science programmes for the BBC.
It’s not so much discovery as discovering there’s more to discover.
On getting interested in science
Growing up I…my brother’s two years younger than me and he was always the one with the telescope and he was into the dinosaurs and collecting stuff and I was much more interested in football and girls from an unhealthily early age, so, yeah, I was interested in science but I wasn’t the geek like my brother was. I think I was about thirteen or fourteen when, for whatever reason, I fell in love with physics. I remember doing well in a school test in physics and thinking, oh, this is fun. This is sort of common sense. And maths. And you get to ask about the really big questions. What’s out there? How far does the universe extend? What is the nature of time? I had no, um, access to books or people I could ask so it was just there, it was this excitement that I could just find out if I carried on with physics.
On the great achievements of physics in my lifetime
So over the period of time that I’ve been interested in physics – so we’re talking about some time, probably in the mid seventies until now, so it’s a long enough period – what has been the most important? Well, there’s important in the whole of science, there’s World Wide Web, there’s mapping of the Human Genome, but, for me, I guess in physics it’s the advances we’ve made in astronomy and cosmology. People don’t tend to think about this, they think astronomy is an incremental advance that we’ve made. We just build bigger telescopes, we see further and we just learn a little bit more about the universe. But I think discovering that there’s all this stuff out there, dark matter, dark energy that we had no inkling of 20, 30 years ago, ah, and that we still don’t understand, it’s opened up the universe to us and it has…it is showing us there’s so much more we don’t understand. So it’s not so much discovery as discovering there’s more to discover.
On trying to understand quantum mechanics
The book I wrote on quantum mechanics, a popular science book aimed at the lay person who’s prepared to get a headache reading through it, ah, what I say in it is, well, the book title is ‘Quantum: A Guide for the Perplexed’ but I always qualify that and say, look, I am not promising that if you read this book cover to cover you will be any less perplexed, you’ll just understand why you’re perplexed. And that sort of sums up what I feel about quantum mechanics. You become familiar with it, you know, if you really study quantum mechanics you’ll learn to use the maths to solve problems, to learn about how atoms and particles that make up atoms all fit together. But as to what it all means there isn’t…there aren’t experts out there in quantum mechanics that understand and the rest of the world who don’t. No one knows how nature does what it does at the quantum level. We have a theory that makes predictions that if we do an experiment, turns out, agree with the theory and the theory explains many of the phenomena in the sub-atomic world, and without it we wouldn’t have the whole of chemistry and so much of physics, we wouldn’t know about semiconductors and electronics and microchips and so on. But as to the underlying, you know, weirdness of quantum mechanics that everyone tends to know about, cats in boxes and atoms being in two places at once, well, that’s the way that nature works down at the sub-atomic level and here’s a theory that predicts that predicts that’s how it behaves but it doesn’t really tell us why. We don’t have a logical, common sense interpretation of the scientific theory, which is unusual because it’s the only theory in the whole of science that seems to get away without having any interpretation.
On string theory
Many physicists, probably around my generation, have spent the last two or more decades working in string theory and they would swear by it. It’s the theory of everything. It’s the forerunner theory of physics that will combine all the forces of nature in some nice simple equation, almost. But for most physicists, who don’t work in string theory, there’s a healthy scepticism towards it, for two reasons.
One, because it hasn’t really borne fruit. It hasn’t, you know, it hasn’t delivered on what it promised. We still don’t know whether it’s the theory of everything or not. It might be a load of rubbish. The other reason is because, many would argue, it’s not really a scientific theory because there’s no way yet that we know of that we can test it. A scientific theory is a hypothesis that you can put to the sword, think of some experiment to design, look for empirical evidence out there in the universe to confirm it or to at least allow it to live another day. It should be something that you can make predictions and go away and test. String theory does none of those things.
It promises a lot; it promises to combine all the four forces of nature. We think we understand how three of the four forces are combined in what’s called a Grand Unified Theory, the electromagnetic force, the strong nuclear force and the weak nuclear force. We’ve already combined electromagnetism and the weak nuclear force in something called the electroweak force, so it’s just the strong force that we think we understand how that more or less fits in because those are all forces described by particles. Gravity, the fourth force, doesn’t fit. Gravity isn’t a theory of particles, of quantum theory, it’s a theory of geometry. It’s just completely different maths, a different mindset. Gravity’s fine, Einstein’s general theory of relativity is our current best theory of gravity, but it doesn’t fit in with the other three forces.
What string theory says is, here’s a way that gravity can be brought into the fold and described also by exchange of particles, which string theory would suggest ‘pop out’ of the mathematics, ah, very elegantly and beautifully in a mathematic sort of way. But pretty maths isn’t science and increasingly I think a lot of physicists are saying, you know, maybe it’s not. Maybe it’s not the route to go. Maybe there are elements of string theory that are right, but we’re in the mid nineties when Ed Witten made…came up with what’s called the second revolution of string theory and he said, ‘Look, there are different kinds of string theory, all requiring ten dimensions, nine of space, one of time, give me one more dimension, the eleventh dimension and I’ll combine them all into one really super theory which we now call M-theory‘. And there was a lot of optimism that M-theory was it, we were almost there and theoretical physics as we know it would come to an end. That hasn’t happened yet. So we’re…I could say ‘watch this space’ but you might be watching this space a long time!