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High Profile

Joining the dots

According to the citation for his 2004 Benjamin Franklin medal, the Nobel laureate Professor Steven Weinberg is 'considered by many to be the pre-eminent theoretical physicist alive in the world today'. Third Way rang him in Austin. You are (as the Times Higher Education Supplement once put it) an 'intellectual icon' among scientists, and your books for the general public have made you a household name, certainly in scientifically literate households. Have you found your celebrity difficult to handle? You know, that's a very hard question to answer without sounding silly! That sort of thing doesn't amount to much within the scientific profession, because people judge you on the basis of whether you're doing anything interesting right now. OK. I mentioned your celebrity because it struck me that currently there is enormous public interest in 'great scientists' such as Alan Turing and Stephen Hawking. I don't think anyone would have predicted 20 or 30 years ago that an actor would win an Oscar for portraying an elementary-particle physicist. Well, on a more serious level you have authors who are among the most appreciated producers of high literature who are bringing scientific ideas into their work - not applications of science, the way science fiction has done ever since Jules Verne, but science itself, as, for ex-ample, in Ian McEwan's novel Solar or Tom Stoppard's play Arcadia.1 I think there has been a remarkable movement of scientific thought into the very best of our present literature. In part, that is a testimony to the work of you and others who have explained some of the discoveries of science in terms that can be understood even by people who don't speak the language of mathematics. Do you feel that it is part of the responsibility of being a scientist to write for the lay audience? It's hard enough to make progress in science - hard for me and hard for everyone, and there are a lot of people competing for every shred of a new idea, so I certainly wouldn't criticise people who don't write for the public; but I do have some admiration for those who do. After all, we get support from the public [finances] and we justify that by describing scientific advance as part of the advance of civilisation. We also justify it in terms of its technological applications, of course, but when we talk about science as part of the culture of our times - well, we'd better make it part of that culture by explaining what we're doing. I think it's very important not to write down to the public. You have to keep in mind that you're writing for people who are not mathematically trained but are just as smart as you are. Possibly I go too far in the direction of explaining the technicalities. In The First Three Minutes, 2 I put them in a separate section and several people who have become really very effective scientists have told me that reading those technical appendices was one of the things that stirred them into becoming scientists. That pleased me more than any other praise could possibly do. Your new book, To Explain the World,3 tells beautifully the story of the 'discovery' of modern science. What was your motive in writing it? I had been giving a course on the history of science, concentrating on physics and astronomy, which is what I know best; and as time passed I began to realise something that became the main theme of the book: that, as a novelist once said,4 'the past is a foreign country: they do things differently there.' I have always been interested in history. I find that knowing history gives life to theoretical physics, which is otherwise a very abstract and chillingly esoteric field. It also gives you perspective. You begin to understand why Einstein developed his theory the way he did, and which parts of the theory are historically contingent, rather than really called for by what we actually know. However, that was all the history of the recent past and in that period we can recognise ourselves and can still put ourselves in the shoes of an Einstein and see how the state of knowledge of that time would have driven him into the kind of theory that he was able to develop. What I learnt in teaching the course was how different things were before science became modern. People not only were ignorant of the many things we've since learnt about the world, they didn't have anything like our idea of what there was to learn about it or the shape that that learning would take. It wasn't that they were stupid: very intelligent people were thoroughly muddled about the relation between human values and natural science, muddled about how science should interact with religion, muddled (and this is in a way most extraordinary) about the role mathematics would play in science. Aristotle did not think mathematics had a place in science. It would be used by astronomers, say, who wanted to predict where some planet would be seen in the sky at any given date and time, but it had nothing to do with understanding really what a planet is. And that's so foreign to the way we think about science that I found it exhilarating in a way, because I was stepping into a different world, a world of people whose mentality was really different from ours; and that op-ened up a challenge of seeing how we got from there to where we are now. The book is subtitled 'The discovery of modern science', but originally you had referred to its 'invention'. Why did you change that? I wanted to emphasise something most people would take as a commonplace but it's actually a rather radical view among professional historians and philosophers of science: that science is not simply a part of our cultural milieu, the way our music and literature are, but is something that's forced on us by nature - not just scientific knowledge but 'the scientific method'. What we do when we say we are doing science is something we have learnt to do because it is sufficiently well tuned to the nature of the world that it allows us to gain reliable knowledge. In that sense, we discovered science the way we discovered making beer. This relates to what is commonly called 'the science wars' of the Nineties, doesn't it, when you and others had to defend the hard realism of science and scientific knowledge against those philosophers, sociologists and historians who said that science is a product of culture. That really firm constructivist view of science as simply an expression of our culture, something constructed the way we construct our language or our rules of etiquette, I think, has become pretty much a dead end. It didn't lead to anything interesting. You write that the history of the discovery of modern science 'serves as a warning that science may not be in its final form.' Do you think we still have a long way to go? I'm afraid so. After the success of the Standard Model, 5 which really became indisputable in the 1980s, many of us thought: The next step is to bring gravity into the picture, and soon we are going to have what I call 'the final theory'. Well, it didn't work out that way. The closest we've come to something that looks like it could be it is string theory6 - and we've had string theory now for over 30 years. It's very mathematically demanding and it's also very mathematically beautiful, and I don't know of any better opportunities we have; but it hasn't produced any predictions that allow us to confirm that it's correct. I wouldn't be surprised if we've got a long wait coming. Fundamental physics is in somewhat of a doldrum right now, in the sense that almost the only things that are going on are continual confirmations of things we thought were true all along. Cosmology is much more exciting now - but of course you can't do experiments in the early universe, you have to wait for whatever op- portunities the universe offers to observers. It is very slow and very difficult. You write about science's five 'intellectual neighbours': poetry, mathematics, philosophy, technology and religion. Could you talk a little about how science relates to poetry? You've already referred to the beauty of string theory… We use aesthetic judgement all the time in judging theories. Copernicus developed his heliocentric theory on the basis of its aesthetic superiority to what Ptolemy had done - and he was right. Aesthetics has proved a pretty good guide, at least since then. I would say that negative aesthetic judgements would justify rejecting a theory simply on the grounds that it's not the kind of theory we're trying to find. We're looking for theories that have a certain compactness and simplicity and a wide scope, and if theories don't have that, well, to hell with them. Theories can be so ugly that we just regard them as not worth investigating. There may not be anything they say that's false, they're just not what we're looking for. So, aesthetics is still bound up with physics; but we would never say, for example, of string theory - at least, I never would and I think most physicists never would - that it must be right because it's so beautiful. On the other hand, if you say, 'This is really worth working on because it's so beautiful,' yes, I would agree with that. What about the relationship with religion, which I think you would say is far more complex and more dangerous? I disagree with Stephen Jay Gould7 and others who say there can be no conflict between science and religion because they operate in different spheres - science in the sphere of fact and religion in the sphere of values or morality or something. That may be true of whatever Stephen Gould wanted to recognise as religion, but it certainly does violence to history. Religions have made all sorts of statements of fact - about the burning bush, the empty tomb, [Muhammad's] night journey to Paradise - and occasionally those statements have conflicted with what's been discovered scientifically. I would say that there has been a kind of retreat of religion - at least of Christianity, which is the religion I know best - from any area where it could come in conflict with scientific knowledge. You see this in the statements of the Vatican about its conflict with Galileo: it's not just that it acknowledges that 'Well, that time we were wrong about the solar system,' it has agreed with Galileo's famous statement that you can't use scripture as a source of scientific knowledge. Of course, the Roman Catholic Church has never put as much emphasis on scripture as some Protestant denominations, and here and there there are pockets of retrograde Protestantism that still maintain the side of religion against scientific knowledge - as, for example, in the arguments about evolution. But I don't think that's part of the mainstream of the relation between science and religion. Indeed. Six-day creationism and even 'intelligent design' are very minority views in most of the Christian world. Sometimes Europeans think that America is just awash in religious fundamentalism. I don't think that's true. I think that in America, as in Europe, even among people who identify themselves as religious, the importance of belief - meaning belief in certain facts - has diminished. On the rare occasions when I get into discussions about religion and I express scepticism about things like the existence of an afterlife, I'm told: 'Well, it's not so im-portant what you believe; the important thing is how you live.' I've heard that so often! That bothers the life out of me, because as a physicist it's very important to me what you believe to be true. And here are all these people who claim to be religious and they believe in religion but they don't particularly believe in what any given religion teaches, for instance about the supernatural. Some people would argue that Christianity was crucial to the emergence of modern science. Would you share that point of view? Well, it certainly configured it in the sense of providing an institutional framework for it - first the cathedral schools and then the universities. Copernicus was supported as the canon of a cathedral, although I don't see that he performed any ecclesiastical functions! And the universities had Christian roots, but that's sort of trivial. I mean, you could say that the ambitions of the kings of Alexandria provided the fiscal background for the development of mathematical science in the Hellenistic period, but you wouldn't say that doctrines of kingship were important to those great Hellenistic scientists. It's just that that was where the money was coming from. Isn't there something in the argument that for modern science to develop you need to combine a belief in the regularity of the laws of nature with an emphasis on observation, rather than just using logic to work out the universe on the back of an envelope? And I credit Christianity with that, after a bad patch in the 13th century; but of course it's not special to Christianity- you find all that in Aristotle, who taught that the world is governed by laws, and even more so in the work of his Hellenistic followers, who were, as far as I can see, completely separated from religion. You don't find any real religious feeling in the surviving writings of Ptolemy and Archimedes and Aristarchus. Your new book gives us some beautiful pen portraits of a number of Muslim scientists and thinkers down the years. Do you see this as an important story to tell given the strength of Muslim fundamentalism today? Well, what I got was a sense of how complicated things are. There is a simple narrative you can tell, that there was a golden age of Arab or Muslim science that came to an end around 1100, and it ended because of the ad- vent of a sterner, more fundamentalist Islam. That may be true, I just don't know; but it is true that Muslim science reached a peak and although it continued after 1100 it was not what it had been. It certainly did not develop the way science did in Europe with the advent of the Scientific Revolution, which relied in some details on work that had been done in the Islamic world but was not impelled by any contemporary developments in Muslim science. It's also true that there were signs of a kind of Is-lamist absolutism, like the sacking of observatories by Muslim crowds and the burning of scientific and medical books in Spain. (You can make exactly the same speculations about the end of science in the Greek-speaking world around the time of the acceptance of Christianity. [Edward] Gibbon, whose Decline and Fall I have read three times now, thought that it was the advent of Christianity that spelt the doom of science in that part of the Roman Empire (it had never flourished in the Latin-speaking part). I don't know of a single scientific advance that was made during the thousand years of the Byzantine Empire. You read praise of the Byzantines' art and philosophy and so on, but never of their scientific achievements, because there simply were none.) You might argue that there was also a challenge to science in the form of 'occasionalism', the doctrine that everything that happens is a unique occasion caused by the will of God and that it's not pious to talk about laws of nature because that puts God's hands in chains. This idea was propounded particularly by al-Ghazali in the 11th century,8 but it also came up in the condemnation of Aristotle by the bishops of Paris in the 13th century, and it was Christians like Albertus Magnus and Thomas Aquinas who put that down and restored his teaching. Was religion part of your upbringing, growing up in New York in the Thirties? Not really. My parents were nominally Jewish - as it is with so many 'religious' people, not only in Judaism but in Christianity and Islam, it was not so much a set of beliefs as a loyalty to a community. They thought it was important to maintain the historical continuity of Jewishness and so they had me barmitzvah'd - something I objected to but not very strongly, because I didn't want to hurt their feelings. When I was little, entirely on my own initiative, I guess you could say I was a Deist. I believed that there must be a God, but I never believed in the stories of the Bible. I think it was a religion of fear more than anything else, you know: I was afraid not to believe in God because if I didn't he would punish me by hurting my parents. And then at the age of 10 or thereabouts I said, 'Oh, this is just silly!' and I identified myself from then on as not religious. Was that when you became interested in science? Well, perhaps there was a connection - in a way, it was recapitulating something that's happened historically: when you begin to understand the nature of the rules that govern the world, the religious view of it begins to look a little threadbare - and certainly not demonstrable, the way that the rules of science are. I got interested in science, so far as I can remember, because I was given a chemistry set that an older cousin didn't want any more, which came with test tubes and an alcohol lamp and so on, all in a beautiful wooden box. I used to love playing with it, making gunpowder, and producing oxygen by electrolysis of water and then burning magnesium ribbon in the oxygen and producing a fantastic white light. I began to read a bit and it became clear that chemistry is what it is because of the properties of atoms, and so I read some popular scientific books about that; and then you get into quantum mechanics - way beyond anything I could understand, but you got a powerful sense that the world is governed by fundamental mathematical principles that are very esoteric and you have to be very grown-up to understand them but they've been fully verified in all kinds of ways. And I thought: 'Wow! This is really great stuff!' I went to a high school that supposedly specialised in science, though it actually wasn't very good in that and so the group of students I was in taught ourselves calculus; and the power of that kind of mathematics to solve physical problems was just stunning. I thought there must be other branches of knowledge that had tools of similar power and I read some books on sem-antics and philosophy, but nothing had the kind of in-tellectual pizzazz that mathematical science did. Have you ever reconsidered your rejection of theism? I certainly haven't become even slightly more religious as I've gotten older, despite the predictions of my stepmother, who 30 or 40 years ago said to me: 'When you get closer to the end of things, you're going to become a lot more religious.' I've been sort of watching since then and she has been wrong so far. But I have become a little mellower, in that I don't feel that it's my business to try to talk people out of being religious. You've always been very clear about your own position, but you have never shown the aggression of some other high-profile atheists. Is there any particular reason? Well, it's not that I disapprove of them. In fact, I rather admire someone like Richard Dawkins, but it's just not me. I feel how necessary belief - especially belief in an afterlife - is to many people, and I don't know why it should be my business to take that away from them. Perhaps I envy them believing that we're going to see the people we love after death. I mean, I wish I could believe that, and I don't know why I should get in the way of their believing it. On the other hand, I put great value on discovering and proclaiming truth, and I tend to agree with Dawkins about what is true and I certainly don't condemn him for proclaiming it. Is there anything that might convince you of the existence of God? I was in a public debate with [the theoretical physicist, theologian and priest] John Polkinghorne in New York and someone said, 'Isn't your atheism an unfalsifiable belief?' I said: 'No, it's not unfalsifiable at all. If a bolt of lightning were suddenly to come through the ceiling of this hall and strike me because of the irreligious things I've been saying, I think that would be pretty firm evidence that there's a God!' John said, 'That would raise all sorts of theological problems if that happened!' and I said: 'It would raise janitorial problems!' In To Explain the Universe, you say that the apparent fine-tuning of the universe 'is like a cry of distress from nature, complaining that something needs to be better explained'. Do you think there might be a deeper story to the universe, one that physics might not be able to explain? Or do you believe that one day we'll understand even the mystery of why its laws are so beautiful and intelligible - and unreasonable in lots of ways? I don't know that in the end the laws of nature are in-telligible to us. We assume they are and we go on making progress, but we may come to a dead end. (I once said in a talk I gave that you can't teach a dog Newtonian mechanics: they're just not smart enough to understand it. And Isaac Asimov, who was in the audience, interrupted: 'Have you ever seen a dog catch a frisbee?' So, I changed it to quantum mechanics!) As for beauty, I think that's not the hardest thing to imagine explaining. In Dreams of a Final Theory,9 I gave the analogy of a breeder of racehorses, who can tell by looking at a horse, in a way that he would not be able necessarily to put into words, that it's the kind that wins races. It's not that we have an innate aesthetic sense that allows us to predict which horses will win races, it's just that long experience has given us that facility. When it comes to science, it's not the experience of just one person, it's the cumulative experience of the human race that has beaten into us that certain kinds of theory are more likely to work than others. Your dictum from The First Three Minutes is often quoted: 'The more the universe seems comprehensible, the more it also seems pointless.' Do you still perceive (as you later elucidated it) that 'the universe itself suggests no point'? Yes - even more so, because of my reading of history since then. I think that one of the essential elements in the discovery of a modern approach to science is the divorce of purpose from science. Socrates, as quoted by Plato, said that he had to put down a book by Anaxagoras because it described the heavens in purely naturalistic ways, without any concern about 'what is better'. I think the verdict of history has been overwhelming that Anaxagoras was right and Plato (speaking through his mouthpiece, Socrates) was wrong. We have to not look for purpose in the natural world. But that doesn't mean that there's no purpose in our lives. I once wrote that we are like actors who have come onto a stage and there is no play written for us, so we start improvising and we do a little comedy, a little drama - and we make it up as we go along. It is a tragic view of human life, but the tragedy is not in the script written for us, the tragedy is that there is no script. But there is a certain nobility in not finding purpose in the objective world when in fact there isn't any but instead living purposeful lives, loving each other - at least, loving some people! - doing the world's work, doing science. There is a nobility in proceeding as if there were a purpose prescribed for us but knowing that there isn't. In the new book, you say: 'Science has emerged as it gives us joy along the way.' Can you sum up what has been the joy of science for you? Well, it isn't too frequent. Every once in a while, some idea you're fooling around with turns out to work and sometimes you know it's working because everything you already knew about what had been discovered ex- perimentally falls into place. Sometimes you only learn later that experiment has verified what you have done. Either way, it's a joy. 1 Respectively, published by Jonathan Cape in 2010 and first staged by the National Theatre in 1993 2 The First Three Minutes: A modern view of the origin of the universe (Andre Deutsch, 1977) 3 To Explain the World: The discovery of modern science, published by Allen Lane on February 17 4 LP Hartley in The Go-Between (1953) 5 The theory that explains the fundamental structure of matter and shows how three of the four fundamental forces that govern it - the electromagnetic, weak and strong nuclear interactions - are related to each other. It was finalised in the mid 1970s. 6 String theory proposes that the most basic components of matter are not so much like particles as like vibrating strings. It requires at least six extra dimensions of space-time, most of them too small to be detectable. 7 Notably in his book Rocks of Ages: Science and religion in the fullness of life (Ballantine Books, 1999) 8 Abu Hamid al-Ghazali (c1058-1111) was a Muslim theologian, jurist, philosopher and mystic of Persian descent. His seminal book The Incoherence of the Philosophers strongly rejected the thought of both Aristotle and Plato. Steven Weinberg was born in 1933 in New York, where he was educated at the Bronx High School of Science. He studied theoretical physics at Cornell, graduating in 1954, and then pursued further studies for a year at the Institute for Theoretical Physics (now the Niels Bohr Institute) in Copenhagen, before earning his PhD in physics at Princeton in 1957. He worked as a researcher at Columbia University from 1957 to '59, and in 1960 joined the physics faculty at Berkeley. In 1966/67, he was the Loeb Lecturer at Harvard. He was subsequently a visiting professor at MIT, where he became professor of physics in 1969. In 1973, he was appointed Higgins Professor of Physics at Harvard and senior scientist at the Smithsonian Astrophysical Observatory. Since 1982, he has been Josey Regental Professor of Science at the University of Texas at Austin. In 1979, he was awarded the Nobel Prize in Physics (which he shared with Sheldon Glashow and Abdus Salam). He received the prize for his theory that unified the weak force and electromagnetic interaction between elementary particles. His many other honours include the National Medal of Science in 1991 and the Benjamin Franklin Medal of the American Philosophical Society in 2004. He has been elected to both the US National Academy of Sciences and the Royal Society, as well as the APS and the American Academy of Arts and Sciences. His books include Gravitation and Cosmology (1972); The First Three Minutes (1977, 1993), which won the Steel Foundation Science Writing Award; The Discovery of Subatomic Particles (1983); Elementary Particles and the Laws of Physics (1987), with Richard Feynman; Dreams of a Final Theory (1993); three volumes of The Quantum Theory of Fields (1995, 1996, 2000); Facing Up: Science and its cultural adversaries (2001, 2003); Glory and Terror: The coming nuclear danger (2004); Cosmology (2008); Lake Views: This world and the universe (2010); Lectures on Quantum Mechanics (2012); and To Explain the World (2015). He has been married since 1954 and has one daughter. This interview was conducted on January 23, 2015.