Socrates in the City: Conversations on Life, God and Other Small Topics

Talk

Oh, dear, what an act to follow. Let me say, I’m very pleased to be here to try to stumble along in Eric’s wake.

You gather that I am someone who wants to take science absolutely seriously, and I think that we are right to do so in this age of science. I am also someone who wants to take religion, particularly my own religion, Christianity, absolutely seriously as well. I believe that I can do that, not, of course, without puzzles occasionally, but without intellectual dishonesty and, indeed, with some degree of mutual enhancement, because it seems to me that science and religion have one extremely important thing in common— they both are concerned with the search for truth.

The question of truth is as important to religion as it is to science. Religion can do all sorts of things for you. It can comfort you in life and in death, but it cannot do any of those things unless it is actually true. Of course, science and religion are looking for different aspects of the truth.

Science has purchased its very great success by the modesty of its ambition. Science does not seek to ask and answer every sort of question. It restricts itself essentially to asking questions of process, which are “how questions” of how things come to be. It also restricts the kind of experience that it takes into account in framing and finding its answers to those questions. Science treats the world as an object, as an it, as something that you can put to the experimental test, that you can pull apart to see what it is made of, and we have learned all sorts of very significant things by doing that.

We also all know that there is a whole realm of human experience— personal experience— and, I would wish to add, the chance personal experience of encounter with the sacred reality of God, a realm of experience in which testing has to give way to trusting. If I’m always setting little traps to see if you are my friend, I would destroy the possibility of friendship between us. Religion is asking a different set of questions, deeper questions, and, in my view, more interesting questions, even than those of science— questions of meaning and purpose: “Is there something going on in what is happening in the world?”

So, there are lots of questions, it seems to me, that are necessary to ask and meaningful to ask, but which are just not scientific questions in their character and, therefore, are questions which science by itself is unable to answer. Interestingly enough, some of those questions arise from our experience of doing science but take us beyond science’s self-limited power of inquiry. You might call them meta-questions— questions that take us beyond.

I want to start by considering briefly with you two of those meta-questions, and the first one is this. It’s a very simple question, so simple, in fact, that most of the time, we don’t even stop to think about it, but I think it’s worth thinking about. It is simply this: Why is science possible at all? In other words, why can we understand the physical world in which we live?

“Well,” you might say, “that’s pretty obvious. We’ve got to survive in the world. If we don’t understand the world, we’ll soon come a cropper [British term meaning ‘run into trouble’].”

Of course, that’s true up to a point. It is true of everyday knowledge and everyday experience. If we couldn’t figure out that it’s a bad idea to step off the top of a high cliff, then we would not stay around for very long. We would stay around a bit longer in my part of the world, which is extremely flat. Nevertheless, we would obviously come to grief.

But it does not follow from that everyday practicality that somebody like Isaac Newton can come along and, in a quite astonishing, imaginative leap, see that the same force that makes the high cliff dangerous is also the force that holds the moon in its orbit around the Earth and the Earth in its orbit around the sun and discover the mathematically beautiful law of universal inverse square or gravity, and in terms of that can explain the behavior of the whole solar system. Of course, back two hundred years after Newton, Einstein comes along and discovers general relativity, which is the modern theory of gravity; then, in terms of that, he is able to explain not just our little local solar system but to frame the first genuinely scientific cosmology account of the whole universe. Incidentally, he got it wrong, but that is another story.

So, why do we have this amazing power? I worked in quantum physics, in small-particle physics, the smallest bits of matter, and the quantum world is totally different from the everyday world. In the quantum world, if you know where something is, you don’t know what it’s doing. If you know what it’s doing, you don’t know where it is. That’s the high-and-low of Heisenberg’s uncertainty principle in a nutshell. That world is totally different from the everyday world, and if we are to understand it, we have to think differently about it. But we have learned how to do that. We have powers to understand the world that greatly exceed anything that could be considered as just a survival necessity, just a mundane necessity, or, indeed, be considered as some happy additional spin-off from necessities of that kind.

I don’t know whether you are a Sherlock Holmes fan, but I hope you might be, and if you are, you will remember that when Holmes and Watson first meet each other, they’re having breakfast in a London hotel, and right from the start, Holmes is pulling Watson’s leg. He says to Watson, “I don’t know, I don’t know. Does the earth go around the sun? Or does the sun go around the earth?” The good doctor is horrified at this deplorable scientific ignorance, and Holmes just says, “Well, what does it matter for my daily work as a detective?” It doesn’t matter at all, but we all know many, many things. Science has told us many, many things that are actually intellectually satisfying to know and that are certainly not connected with the certainties of everyday life.

So, why is science possible? Why can we understand the world so thoroughly and so profoundly? In fact, the mystery is greater than that even, because it turns out that mathematics is the key to unlocking the secrets of the physical universe. It’s an actual technique in fundamental physics to look for theories whose mathematical expression is in terms of beautiful equations. Some of you will know about mathematical beauty, possibly not all of you. It’s a rather austere form of aesthetic pleasure but something that those of us who speak the language of mathematics can recognize and agree upon. This is the experience of three hundred years of doing theoretical physics in which the theories that fundamentally describe the world always turn out to be framed in terms of beautiful equations. It’s an actual technique of discovery to look for equations of that sort.

The greatest theoretical physicist I’ve known personally was Paul Dirac, one of the founding figures of quantum theory and a professor in Cambridge for many years. He was not a religious man, nor a man of many words. He once said, “It is more important to have beauty in your equations than to have a fit experiment.”

Of course, by that, he didn’t mean it didn’t matter, or [that] empirical adequacy is a dispensable thing in science. No scientist could possibly mean that, but if you had a theory and it didn’t look as though, at first sight, your equations were going to fit the experiment, there were just possibly some ways out of it. Almost certainly you would have had to solve the equations in some sort of approximation. Maybe you made the wrong approximation or you hadn’t gotten the right solution or maybe the experiments were wrong. We’ve learned that more than once, I have to say, in the history of science. But if your equations were ugly, there was no hope for you. They could not possibly be right.

Dirac was, undoubtedly, the greatest British theoretical physicist of the twentieth century. He made those discoveries due to a relentless and highly successful lifelong pursuit of beautiful equations.

Now, something funny is happening there. We’re using mathematics, which, after all, is a very abstract form of human activity, to find out about the structure of the world around us. In other words, there seems to be some deep-seated connection between the reason within— the mathematical thoughts in our minds, in this case— and the reason without, which is the path and order of the physical world.

Dirac’s brother-in-law, Dr. Eugene Wigner, who also won a Nobel Prize in physics, once asked, “Why is mathematics so unreasonably effective?”

Why does the “reason within” apparently perfectly match the “reason without,” that is, the wonderful order of the world in which we live? That’s a deep question, a meta-question, and those sorts of questions do not have simple knocked-out answers. They are too, too profound for that, but for me, a highly intellectually satisfying answer is the following: The reason within and the reason without fit together because, in fact, they have a common origin in the rational mind of the Creator, whose will is the ground both of our mental experience and the physical world of which we are a part.

You could summarize what I have been trying to say so far by saying that as physicists study the world, they study a world of wonderful order, a world shot through, as you might say, with signs of mind. If that’s so, then it seems to me it’s, at least, a hypothesis worth considering, because, in fact, the capital-M Mind of the Creator lies behind that wonderful order. I, in fact, believe that science is possible, that the world is deeply intelligible, precisely because it is a creation. To use ancient and powerful language, we human beings are creatures made in the image of our Creator. The power to do theoretical physics is a small part— a small part, no doubt— of the imago Dei [image of God].

So, that is one sort of meta-question, and it illustrates the way our religious belief and understanding does not tell science what to think in its own domain. We have every reason to believe that scientifically presentable questions will receive scientifically articulated answers, even though some of those answers may prove very difficult to find. But the meta-questions take us beyond science, and it seems to me that religion can provide intellectually satisfying and coherent responses, enabling science to be set within a wider and more profound setting of intellectual intelligibility.

I would like to ask a second meta-question: Why is the universe so special? Scientists do not like things to be special. Our instinct is to like things to be general, and our natural assumption would be that the universe is just a common-variety garden specimen of what our universe might be like— nothing very special about it. But as we’ve studied and understood the history of the universe, we’ve come to realize we live in a very remarkable universe, indeed, and if it was not as remarkable as, in fact, it is, we would not be here to be struck at the wonder of it.

The universe started extremely simply; 13.7 billion years ago is the rather accurate figure that cosmologists say. It started as almost a uniform expanding ball of energy, which is about the simplest possible physical system you could ever think about. One of the reasons why cosmologists talk with a certain justified boldness about the fairly early universe is because it is a fairly easy thing to think about. But our world is not so simple; it has become rich and complex, and after almost fourteen billion years, it has become the home of saints and mathematicians. We’ve come to realize, as we understood the steps by which that has happened, that though it took a long time— as far as we know, ten billion years for any form of life to appear and fourteen billion years for self-conscious life of our complexity to appear— nevertheless, the universe, in a very real sense, was pregnant with life from the very beginning. It is, in this sense, that the physical fabric of the world— that is, the given laws of nature that science uses as the basis of its exploration of what is going on, but whose origin science itself is unable to explain, which are the unexplained given, in terms of which science frames all its subsequent explanations— had to take a very precise, very finely tuned form, if the evolution of any form of carbon-based life, like ourselves, was to be a possibility in cosmic history.

Of course, the evolution of life, the evolution of the universe, was an ongoing process, but evolution by itself has to have the right material to act upon. Unless the physical fabric of the world was finely tuned for the possibility of carbon-based life, the universe could have evolved away forever, and nothing interesting would have happened. This history would have been boring and sterile in the extreme. So, we live in a very special world.

Let me just give you a couple of illustrations of why we think that is so. There are many, many arguments that point in that direction. I could spend all evening trying to list them, but I won’t do that. I’ll just give you a couple of examples. The first example is this: The very early universe is very simple, and so, it does only very simple things. For the first three minutes of the universe’s life, the whole universe is immensely hot, immensely energetic. It is a sort of cosmic hydrogen bomb with nuclear reactions going on all the time.

As the universe expanded, it cooled. After just about three minutes, the universe was so sufficiently cooled that nuclear reactions on a universe-wide scale, on a cosmic scale, ceased, and the gross nuclear structure of the world was frozen out as, in fact, what we see it to be today, which is three-quarters hydrogen and a quarter helium. The early universe was very simple and made only very simple things. It made only the two simplest chemical elements, hydrogen and helium, and those two elements have a very boring chemistry. There is nothing very much that you can do with them.

The chemistry of life actually requires about thirty elements, of which possibly the most important is carbon. We call ourselves, when we think about it, carbon-based life. The reason for that is that carbon is the basis of those very long-chain molecules, and the chemical properties of carbon seem to be necessary for living entities. But the early universe has no carbon at all. So, where did carbon come from?

As the universe began to get a bit clumpy and lumpy as gravity began to condense things, stars and galaxies began to form. Then, as the stars formed, the matter inside the stars began to heat up, and nuclear reactions began again, no longer on a cosmic scale, no longer universe-wide, but in the interior nuclear furnaces of the stars. It is here in the interior nuclear furnaces of the stars that all heavy elements— there are ninety of them altogether and about thirty of them necessary for life— were made beyond hydrogen and helium.

One of the great triumphs of the second half of the twentieth century in astrophysics was working out how those elements were made by the nuclear reactions inside the stars. One of the persons who played an absolutely leading role in that was a senior colleague of mine in Cambridge called Fred Hoyle. Fred was with Willy Fowler from Caltech— they were thinking together about how these things might happen, and they were absolutely stuck at the start.

The first element they really wanted to make was carbon, and they could not for the life of them see how to make it. They had helium nuclei— we call them alpha particles— around. To make carbon, you have to take three alpha particles and make them stick together. That turns helium-4 into carbon-12, and that is a very, very difficult thing to do. The only way to do it is to get two of them and make them stick together. First of all, that makes beryllium, and then you hope that beryllium stays around for a bit. A third alpha particle comes wandering along and eventually sticks on and makes carbon-12. Unfortunately, it does not work in a straightforward way, because beryllium is unstable and does not oblige you by staying around to acquire that extra alpha particle.

So, Fred and Willy really could not figure out how to do it. On the other hand, there they were, carbon-based life, thinking about these things: It must be possible to make carbon. And then Fred had a very good idea. He realized it would be possible to make some carbon out of even this very transient beryllium if there was an enhancement— what, in the trade, we call a resonance— present in carbon that would produce an enhanced effect. That is, it would make things go much, much more quickly than you would expect. However, you not only had to have a resonance but also had to have it at the right place; it had to be at the right energy for this process to be possible. If it were anywhere else, it would not affect the rate at which things happen.

So, Fred is convinced that there must be a resonance in carbon at precisely this energy and writes down what the energy is. The next thing, he goes to the nuclear data tables to see if carbon had such resonance, and it is not in the nuclear data tables. Fred is so sure it must be there that he rings up his friends the Laurences, who are very clever experimentalists at Caltech, and says to them, “You look. You missed the resonancy in carbon-12, and I’ll tell you exactly where to look for it. Look at this energy, and you’ll find it.” And they did— a very staggering scientific achievement. It was a very, very great thing, but the point is this: That resonance would not be there at that absolutely unique and vital energy if the laws of nuclear physics were in the smallest degree different from what they actually are in our universe.

When Fred saw that and realized that— Fred has always been powerfully inclined toward atheism— he said, in a Yorkshire accent, which, I am afraid, is beyond my powers to imitate, “The universe is a put-up job.” In other words, this cannot be just a haphazard accident. There must be something lying behind this. And, of course, Fred does not like the word God; he said there must be some capital-I Intelligence behind what is going on in the world. So, there we are; we are all creatures of stardust. Every atom of our bodies was once inside a star, and that is possible because the laws of nuclear physics are what they are and not anything else.

Let me give you just one more example of fine-tuning. This is the most exacting example of all. It is possible to think of there being a sort of energy present in the universe, which is associated simply with space itself, and that energy these days is usually called dark energy. It used to be called the cosmological constant, but it has come to be called dark energy, because just recently astronomers believe they have measured the presence of this dark energy. In fact, it is driving the expansion of the universe.

What is striking about that expansion is that this energy is very, very small, compared to what you would expect its natural value to be. You can figure out— now, I won’t go into the details— what you would expect the natural value of this energy to be. If you’re in the trade, it is due to vacuum effects and things of that nature, but it turns out that the observed dark energy— if the observations are correct— is ten to the minus-120 times the natural expected value (10-120); that’s one over one followed by 120 zeroes.

Even if you’re not a mathematician, I am sure that you can see that is a very small number indeed. If that number were not actually as small as it is, we would not be here to be astonished at it, because anything bigger than that would have blown the universe apart so quickly that no interesting things could have happened. You would have become too diluted for anything as interesting as life to be possible.

So, there are all these sorts of fine-tunings present in the world. All scientists would agree about those facts. Where the disagreements come, of course, is in answering the meta-question: What do we make of that? What do we think about the remarkable character of the world, the specific character of the world? Was Fred right to think that the universe is, indeed, a put-up job and that there is some sort of Intelligence behind it all?

I am sure you all know that these considerations about the fine-tuning of the universe are called the anthropic principle— not meaning that the world is tuned to produce literally Homo sapiens, but anthropoi, meaning beings of our self-conscious complexity. I have a friend who thinks about these things and has written, I think, the best book about the anthropic principle, Universes. His name is John Leslie. He’s an interesting chap because he does his philosophy by telling stories, which is very nice. He’s a parabolic philosopher. That is very nice for chaps like me who are not trained in philosophy, because everybody can appreciate a story, and he tells the following story:

You’re about to be executed. You are tied to the stake, your eyes are bandaged, and the rifles of ten highly trained marksmen are leveled at your chest. The officer gives the order to fire, the shots ring out, and you find that you have survived. So, what do you do? Do you just walk away and say, “Gee, that was a close one”? I don’t think so. So remarkable an occurrence demands some sort of explanation, and Leslie suggests that there are really only two rational explanations for your good fortune.

One is this: Maybe there are many, many, many executions taking place today. Even the best of marksmen occasionally miss, and you happen to be in the one where they all miss. There have to be an awful lot of executions taking place today for that to be a workable explanation, but if there are enough, then it is a rational possibility. There is, of course, another possible explanation: Maybe there is only one execution scheduled for today, namely yours, but more was going on in that event than you are aware of. The marksmen are on your side, and they missed by design.

You see how that charming story translates into thinking about the anthropic fine-tuning— the special character of the universe in which we live. First of all, we should look for an explanation of it. Now, of course, obviously, if the universe was not finely tuned for carbon-based life, we, carbon-based life, would not be here to think about it. But the coincidence is that the fine-tunings required are so specific and so remarkable that it is no more sensible for us to say, “We’re here because we’re here, and there’s nothing more to talk about it,” than it would be for that chap who missed being executed to say, “Gee, that was a close one.” So, we should look for an explanation.

Basically, there are two possible explanations. One is that maybe there are just many, many, many different universes— all with different laws of nature, different kinds of forces, different strengths of forces, and so on. If there are enough of those universes— and there would have to be a lot of them, an enormous number of them— but if there are enough of them, then, of course, by chance, one of them will be suitable for carbon-based life. It will be the winning ticket in the cosmic lottery, as you might say, and that, of course, is the one in which we live, because we are carbon-based life. That would be a many-universes explanation.