Titans of Science: Martin Rees

Chris Smith asked Martin Rees about his endeavours bringing astronomy to a general audience...

Martin - Well of course astronomy is a subject which does lend itself to popularisation. There's a natural interest. Young kids are fascinated most of all by space and dinosaurs - both blazingly irrelevant, but both fascinating. I think if you look back over history, many of the leading astronomers have also been popularisers. I think of Eddington and Hoyle. There's a huge market now, and Patrick Moore and all the rest have amplified that market. I'm not such a fluent writer as some of them, but I would get less satisfaction if I could only talk about my work to a few fellow specialists. I think it's an extra gratification that one does get a response to these ideas and these discoveries from a wider public. But of course, if you are sitting next to someone on a plane or something like that, if you don't want to talk at all, you say you're a mathematician, that'll shut them up. But if you do want to talk, you say you're an astronomer. But then the first question they ask is probably, 'Are we alone? Life in the universe?' As I'm sure you find in your experience of popularising science, and understandably so. That's a subject which has become a serious branch of astronomy with the James Webb Telescope and even more, I think, with the world's biggest ground-based telescope, which is being built in Chile, called the Extremely Large Telescope. This will have a major mirror, which is 39 metres across - not one big sheet of glass but a mosaic of about 800 bits of glass - and this will detect enough light to actually be able to get a spectrum of some of these planets. It has much more area than the James Webb, although James Webb can go into infrared and see cooler things than you can see from the ground.

Chris - Did you not have a hand in making sure James Webb happened?

Martin - Well, only very indirectly. I was, at the time it was being discussed, chairman of the European Space Agency Science Advisory Committee, and there was an issue of whether Europe would have some fraction of it, about 10%. I was involved in those discussions. I think the European Space Agency has overall been a very successful organisation. It's far less visible in the public eye than NASA, but if you look at the straight science it does, it's comparable because it has some big projects, the best projects. You look at the background cosmic radiation called Planck, there's now a probe going to study the moons of Jupiter, and an amazing project called Gaia to study the stars in the Milky Way has studied 2 billion stars. That just indicates how, in our subject, we have changed from being a subject where we are starved of data, to one where you need computers to analyse all the data. Incidentally, in the kind of work I do, I used to develop simple ideas about gas falling into galaxies and black holes and all that - just hand waving and simple arguments. But now, computer simulations, the kind of simulations that they use in weather forecasting, etc., they can do detailed modelling of how gas falls into galaxies and how gas swirls down into a black hole. One is doing, as it were, experiments in the virtual world of a computer. Because in astronomy you can't do real experiments. You can't really crash stars and galaxies together. But in the virtual world you can, and then you can make different assumptions and then see if you see something up in the sky which resembles the output from your computer. That's how we've made huge progress in the last 20 years.

Chris - I read a very interesting quote from yourself. It was one of those things that makes you really think. You said some of the 'Aha!' insights that scientists strive for may have to wait for the emergence of post-human intellects. Are you getting at this sort of thing where we have to invent something that can think more deep thoughts than we can? Like AI type approaches that will get at problems that are currently intractable for a human brain?

What I was referring to in that context was that perhaps if you want to have the kind of theory which will be needed to understand the very beginning of the universe and what happens deep inside black holes where we have to have a unified theory that links together gravity, the force that governs the large scale universe, with the quantum world, a so-called Grand Unified Theory, then it could be that the mathematics is so hard we can't grasp it. You may know that there's a theory called string theory, which is being developed by people who want to understand the particles the world is made of and link gravity together. This is a theory which you can write down, and there are lots of variants of it. It Involves not just three dimensions of space, but about ten dimensions of space. It's very complicated. I think the quote you read out is something where I've said that it could be that a machine can work through the very elaborate mathematics and geometry involved among these theories. After churning away, it may come up with the right value for the strength of gravity, the mass of the electron, or something like that and, if it does, then we know that theory has something in it and we can confidently then apply that theory to other problems like the early universe, etc., but we may not really have an insight. That's what I meant, that what we like is to have a theory which, once we've got the idea, we say, 'Aha, why didn't I think of that before?' That's true in many cases: something in retrospect seems quite obvious. There may be this class of theories for which we never have the insight in any human brain.

Martin - But that leads to another point which I often emphasise in general talks, which is that we shouldn't think of our brains as the culmination. We are the outcome of nearly 4 billion years of biological evolution from the first life to the wonderful biosphere here on Earth, of which we are a part. But many people who accept all that somehow tend to think that we are the culmination, the top of the tree. But no astronomer can believe that because we know that the sun's been around for four and a half billion years, but it's got about 6 billion more before it flares up and dies. The universe can go on much longer, still. We could be nearer the beginning than the end of the emergence of complexity in the universe. But of course, what will post-human evolution be like? The key question then is, have we got nearly to the limits of what flesh and blood brains can do?

So will it be that future evolution will be dominated by electronic entities of some kind, which will be our sort of progeny, our descendants, and then that evolution will be not Darwinian, it'll be what I like to call secular intelligent design - machines designing better machines. That's a possibility. Then those machines would have far greater capabilities. Whether they would have consciousness and comprehension, we don't know. That's a very important question, a philosophical question. I think we are perhaps as humans at a pivotal transition stage in evolution when there may be a change from Darwinian selection to something new. These electronic entities will have no particular reason to stay on a planet. They may prefer zero gravity where they could build big structures, so they will go there. This leads to another question, which is, will we detect evidence for alien intelligence?

And of course there are searches for this. In fact, I chair a committee bankrolled by a Russian American billionaire called Yuri Milner, who's putting money into an improved search for telescopes to detect any artificial looking transmission. I think this is very worthwhile although the chances of success are small. I think if we ask, 'What are we expecting to find,' I think we might not find anything that resembles us. Intelligence may be something which is entirely electronic and therefore not expansionist and not familiar at all. This argument called the Fermi paradox, which is often used to say that if there were lots of aliens, why wouldn't they have come here already? There were some stars older than the sun which would've had planets with a head start in the evolution over ours. I think if one argues that posthuman and more technically advanced entities are not flesh and blood, they may not have instincts flesh and blood creatures do and therefore not be expansionist. So the fact that we haven't seen evidence for these entities doesn't mean they're not there.

Chris - Is it also not the case that the problems one would have to surmount in physics and technology and engineering to get here would mean that presumably these people would know far more than they could possibly learn by coming here? So is it worth their while?

Martin - Well indeed, I think that's true. The only counter argument to that is that if they're electronic, they're probably near immortal and therefore they would not be deterred by a voyage that may be 10,000 years. They may have these very long time scales. But I think you're quite right that, if they're out there, they may know that we are here and they'll be watching us, or they may not be interested.