The European: You speak about cosmology in rather philosophical terms. Can we ever completely wrap our brains around the questions posed by astronomy.
Sir Rees: I think it’s surprising that our brains have been so successful at understanding the worlds of atoms and cosmos alike. Over the last fifty years we have come to understand a great deal about the universe. We can observe that it contains billions of galaxies, each containing billions of stars and we have very good evidence that it all started in some hot dense stage about 13.7 billion years ago. The evidence for that is in my view as strong as the evidence which a geologist will give you about the early history of our earth.
The European: What is our place within this vastness?
Sir Rees: Of course we observe that the earth is a planet around an ordinary star which is one of many millions or billions of stars. But I would say that although the earth is very small, it is one of the most important places in the galaxy. It is the one place where we know that something very complicated has evolved. That process has led from simple life by Darwinian evolution to creatures like ourselves, able to understand our origins and contemplate the wonder and the mysteries of the universe. We should not be impressed by sheer size but should also admire the intricate complexity of all the things on the earth. And the most complicated things that we know about are human beings. Even though we are small we should not regard ourselves in some sense inferior to the rest of the universe. But there’s another point I’d like to make: It has taken several billion years for the evolution to progress from simple organisms to complex mammals. And so we know that we would not be here if the universe had not existed for a long time. And therefore we should not be surprised that the universe is very big because to exist for a long time and to expand for a long time the universe is going to end up very big.
The European: Is there still room for mystery within this scientific framework?
Sir Rees: Oh, very much so. Because the nature of science is that as it advances new questions come into focus. If you think about cosmology fifty years ago, people were debating whether the universe had a start and an end. Most of those debates have been settled. But we now debate a new set of questions that could not even have been posed beforehand. So the nature of science is that you settle some questions just to find yourself confronted with new questions. The horizon of knowledge expands with technological progress, but there is always room for mystery.
The European: What new questions are we now facing?
Sir Rees: One question is to understand the very beginning. Although we can with confidence trace time back to the first milliseconds of the universe, what happened right at the begining is still a mystery. The conditions were so extreme: very high density, very high energy, very high pressure. We don’t understand the relevant physics because these conditions cannot be simulated in experiments. And there are other mysteries. What is the dark matter? Is the universe infinite? My work focuses on the formation of stars out of the initial plasma. In the field of astronomy, we cannot do too many experiments. But new technologies allow us to look back further through time, and new computers allow us to run more accurate simulations. And also, as I mentioned earlier, we have discovered that our sun is not the only star with planets around it. We now believe that very many stars, perhaps even most, are orbited by systems of planets. And some of these planets may be like earth.
The European: You have said that there might have been more than just one Big Bang. How could that be?
Sir Rees: Of course it is just a speculation. But it is certainly possible, indeed likely, that there was a lot more to physical reality than the volume which we can probe with our telescopes. And almost everyone will agree that there many galaxies which are beyond the limits of what we can see with our telescopes. A few hundred years ago, nobody would have believed that our sun is not unique or that our galaxy is not the only galaxy. Thinking about the properties of the Big Bang is thus an entirely legitimate speculation.
The European: Is that like the next humiliation of man, in line with the revelations of Copernicus, Darwin and Freud?
Sir Rees: I don’t see it as an humiliation. We should not be impressed by size. What is important is complexity. Even an insect can be more impressive than a star because it is more complex. New discoveries about the universe should not take away the realization of our own complexity.
The European: But it is another step towards removing man from the center of the universe.
Sir Rees: We are not in the middle, but we may still be very special.
The European: If there are multiple universes, are we living in one that is somehow unique?
Sir Rees: I don’t think so. If there are other Big Bangs they might give rise to a cosmos that differs from ours. But we can’t say anything definite about that.
The European: So we might never be able to look beyond our reality and see what else might be out there?
Sir Rees: I think we will. We will learn a great deal more about other planets around other stars and about whether there is life on them. But as you say there are some parts of space and time which we can’t directly observe and those would only be understood indirectly if we have a fundamental theory of space and time. We believe in Einstein’s theory of relativity because we can test it in many ways. We therefore believe Einstein’s writings about the inside of black holes even though we can’t observe them. That is how we can take unobservable things seriously.
The European: Can we ever look past the Big Bang and see what was before?
Sir Rees: In a sense, yes. Because when you use the word before, you are implying that time ticks away in a particular way. And one of the posibilities is that when we extrapolate backwards in time, space and time get mixed up in a very complicated way. Perhaps we can’t talk about a certain direction of time and therefore you can’t talk about before and after. But we have to accept that we may need to get even further away from common sense concepts. The beginning of the universe is so extreme that we have to jettison our intuitions. We need new ideas which are not yet properly formulated.
The European: We still need to be able to express our findings through language, not just through numbers. Do we have the mental capacities for that?
Sir Rees: It’s a very interesting question whether there are some phenomena which are beyond human brains. In order to understand many concepts in science you need a special vocabulary or you need a mathematical notation. It is often the case that you can understand a concept well only after you have developed the appropriate language or the approrpiate notation. To give you an example: To do arithmetic using Roman numerals is a lot more difficult than to do multiplication using the Arabic numerals we use. That is an example where having the right notation allows you to do calculations that you couldn’t do before and on a more sophisticated level. You’ve got to have the right concepts in order to understand things clearly. It’s possible that there are some questions which we cannot answer, just as a a monkey cannot understand quantum theory. But we are nowhere near the limit.
The European: Is religion still a concept helping us to understand the hugeness and the variety that surrounds us?
Sir Rees: I don’t think so. I believe that religion and science coexist. But I do not believe that religion can help me with my science. It’s a different mode of thought.
The European: Man is always in need of assurance. And in religion he can rely on something. Science, in contrast, seems rather cold. How can we avoid getting lost?
Sir Rees: Again, you’re giving your subjective thoughts which many people don’t share. I think the universe revealed by modern science is a more wonderful place to live in than the rather more limited and constricted view that people had of the universe in the past. So I don’t think it does have the effect you are describing. To feel that we are part of this immensity is something which is exhilarating to many people, not depressing. You are assuming that your psychology is universal. Many people would react differently.
The European: But you still go to church on Sundays?
Sir Rees: Yes.
The European: So you are religious?
Sir Rees: If you grew up in Western culture, you are imbued with the Christian tradition, our finest buldings, our finest music. This is a part of most Western communities. I still feel connected to that. But I am not a believing Christian.
The European: How will the scientific progress of the coming century change our perceptions about ourselves and about the world we inhabit?
Sir Rees: I don’t know. Some of today’s questions will have been solved. But there will be new questions. I think the key issue for us as practical people is how to ensure that the world of the future can strive without degrading the environment, without any disasters. We will have a world which is very hard to cope with and very hard to govern. But we have to ensure that science is applied in the optimum way. And this is where scientists have a responsibility to engage with the public and politicians.
The European: Is there a chance that man can builld colonies somewhere else in the cosmos?
Sir Rees: I think, in the long run, yes. But I think it’s foolish to think that this is a way to solve the problems on earth. Overall, the universe is not a very inhabitable place for humans. And so the problems of the earth must be solved on earth.