John Polkinghorne on Natural Theology, Part 3
As part of the H. Orton Wiley Lecture series in Theology on the campus of Point Loma Nazarene University, Reverend Dr. John Polkinghorne inspired students and faculty alike in thinking about the interaction between science and the Christian faith. The first lecture, entitled, "Natural Theology," was delivered on November 15th, 2010. The entire MP3 is available for download here. Follow the links to see the first, second, and fourth posts in this series.
In Part 2 of this series, Dr. Polkinghorne looked at the first of two meta-questions. In today’s post, he looks at the second of these meta-questions: “Why is the universe so special?”
We've provided a written transcript of the talk to make it easier to mull over Dr. Polkinghorne’s ideas while you listen.
Fine-tuning and the “Fruitful Universe”
Now my second meta-question is a little bit more specific. I ask the question, “Why is the universe so special?” Now scientists don’t like things to be special; we like things to be general, and our natural anticipation would have been that the universe is just a common or garden specimen of what a universe might be like.
But we’ve come to understand a lot about the history of the universe. We know that our universe started 13.7 billion years ago, and it started extremely simple, just an almost uniformly expanding ball of energy, about the simplest physical system you could possibly think about. But a world that started so simple has of course become rich and complex. With you and me, in fact, the most remarkable and complex consequences are its history, at least of which we are aware. The human brain is far and away the most complicated physical system we have ever encountered anywhere in our exploration of the universe.
That fact itself might suggest that something has been going on in cosmic history rather than just one thing after another. But we’ve also come to understand many of the processes by which this rich fruitfulness has come to birth. As we’ve come to understand these, we’ve come to see that though these processes are of course evolving processes, they took long periods of time – the universe was 10 billion years old before any form of life appeared in it, at least as far as we know anyway – and life of our complexity only appeared yesterday.
Nevertheless, the universe is pregnant with life, pregnant with the possibility of life, essentially from the beginning onwards. By which I mean the given laws of nature had to take a very specific, very finely tuned form, if the universe was to have so fruitful a history.
That’s a very remarkable discovery, and let me give you some examples of why we believe that. If you’re going to have a fruitful universe, one of the first things you have to get right is that you have to have the right stars in the universe. The stars are going to have a very important role to play. First of all, you must have some stars that are going to be very long lived, live for billions of years, steadily burning, steadily producing energy which will enable the development of life on one of the encircling planets. We understand what makes stars burn in that sort of way very well, and it depends on a delicate balance between the strength of gravity and the strength of electromagnetism. Electromagnetism is the force that holds matter together. The seats on which you are sitting are held together by electromagnetism and in fact you are held together by electromagnetism.
If you alter that balance a little bit in one direction the stars will begin to burn intensely, furiously, just pouring out energy and they will only live a few million years rather than a few billion years. If you move it a little bit in the other direction they will burn so slowly they will be brown stars and they will not produce enough energy to fuel the development of life. So you have to have a very delicate finely tuned balance between the strength of gravity and the strength of electromagnetic forces in a fruitful universe.
Remember, science takes the laws of nature, takes the given strengths of gravity, the given strength of electromagnetism, uses that to explain processes in the world, how things happen, but it doesn’t explain where those laws of nature come from. They are just brute facts as far as science is concerned.
And the stars have another absolutely indispensible role to play. The stars are the place where the heavier elements essential for life are made in the interior nuclear furnaces. There are many elements that are necessary for life, of which carbon is perhaps the most essential. Carbon is the basis of the long chain molecules, which are the biochemical basis of life. The early universe only makes the simplest elements; it makes hydrogen and helium and it makes no carbon at all. Carbon only begins to be made when the universe, which started uniform, begins to condense and become lumpy and grainy with stars and galaxies. As the stars condense they heat up, nuclear processes begin again in their interiors. And it’s those nuclear processes in the stars that make carbon and the heavier elements. Every atom of carbon in your body was once inside a star. We are people of stardust made in the ashes of dead stars.
And that’s a very beautiful process that takes place in that sort of way. And one of the great triumphs of astrophysics and the second half of the 20th century was to unravel that process. One of the people who did some of the most important work on that was a senior colleague of mine in Cambridge called Fred Hoyle. And they were trying to figure out how to make carbon. They got helium, and if you can make three helium nuclei stick together that will produce carbon, but when you have something as small as a nucleus it is impossible to get three to stick together at one time, they’re just too small.
Ok, so let’s do it step by step. Stick two together gives you berylium. Helium 4 gives you beryllium-8, hope it stays around for a bit, another helium comes along, attaches itself, and bingo, you’ve got carbon-12. That’s the obvious thing to think about but it doesn’t work in the obvious way, and the reason it doesn’t work in the obvious way is that beryllium-8 is terribly unstable. It doesn’t oblige you by staying around long enough to catch that third helium, at least in an ordinary, straightforward way.
But Fred realized that it would be just possible for this to happen if there was a very large enhancement effect, in the trade we call it resonance, occurring in carbon at just the right energy, it has to be the right energy, which would enable that attachment process to catch that third helium much much more quickly that you might have thought, in fact so quickly that some of them would get caught before the beryllium-8 disappeared. It was a very good idea, and he must have felt pretty pleased with himself and he went off to just check in the nuclear data tables of this particular resonance’s energy levels, and it wasn’t in the tables, but he knew it must be there, he’s carbon based life like you and me.
So he rang up some friends in the States, a father and son team who were good experimentalists and he said, “Look, you missed something. There’s a resonance and energy level in carbon that you haven’t spotted, and I’ll tell you exactly where to look for it. I know exactly where this energy has got to be. You go look for it.” And they said, “No, no, we don’t want to do that, we have more interesting things to do.” But Fred was very determined and he bullied them into looking for it and they found it.
Now that’s a wonderful achievement, to predict an energy level in carbon on the basis of how it might have been made in the stars is a fantastic scientific achievement. But it’s more than that. Fred had a lifetime conviction of atheism, realized of course that if the laws of physics had been just a little bit different that resonance wouldn’t have been there, and the possibility of carbon-based life is too significant for it just to be a happy accident in his view, so he says in a Yorkshire accent that is beyond my power to imitate, he said that the universe is a put-up job. Fred didn’t like the word God, and so he said some Intelligent, capital “I” Intelligence, must have monkied with the laws of nature to make carbon production possible. What that could possibly be I don’t know, but the more sensible thing to say is that creation is ordained, that the laws of nature would be such, as to enable the fruitfulness of carbon-based life.
We’ll come back to evaluating that possibility in a minute, but before we do, let me give you two other examples of how specific, how special, our universe has to be for us to be able to be here today to think about. We live in a universe that is immensely big, beyond our powers to imagine really. There are a hundred thousand million stars in our galaxy in the Milky Way, of which our sun is just a common or garden specimen, and there are about a hundred thousand million galaxies in the observable universe, of which our Milky Way is a pretty common or garden specimen. So we live in a world that is unimaginably vast, and sometimes we might feel upset by that and think, “What could be the significance of us who are simply inhabitants of a speck of cosmic dust, as you might say, in this vast, vast universe?”
Nevertheless, if all those stars were not there, we would not be here to be upset at the thought of them. Because there is a direct connection between how big a universe is and how long it lasts, and a universe that is significantly smaller than our universe would not have been able to last the 14 billion years, which is the necessary time to produce beings of our complexity. So that’s another condition of the world that has to be right for human beings, or something like human beings, to be a possibility.
One final example, which is the finest tuning of all: quantum theory suggests that there should be an energy attached to space itself. In quantum theory the vacuum, so called empty space, is not just a void. There are things called vacuum fluctuations which occur in a continual sort of seething mass of things coming into being and going out of being all the time. So while there is nothing there that doesn’t mean there is nothing happening. That may sound strange and paradoxical but believe me that’s what quantum theory implies. And of course these happenings, these fluctuations, generate a certain amount of energy, we call it “zero point energy”, and that energy is spread out over the whole of space. So we expect there to be energy associated with space.
And just recently the astronomers have discovered something called dark energy which is driving the expansion of the universe, which is just such an energy associated with space. Well that’s very good, you might say. However, when we estimate, just from thinking about quantum theory, how much energy there should be in space it turns out to be a fantastically large amount, and when we see the amount of energy there actually is per volume in space, it turns out to be very, very small in relation to that expected size. In fact, it turns out to be smaller by a factor of 10-120. That means by a factor of 1 over 1 followed by 120 zeros. You don’t have to be a great mathematician to see that’s a fantastically small number. So some fantastic cancellation has taken place to turn that big number into the tiny number that we actually observe, and if it hadn’t taken place we wouldn’t be here to observe it because significantly higher energy would simply have blown the whole show apart too fast for anything interesting to happen. That’s the finest tuning that we know in the universe: one part in 10120.
So we live in a world that is very remarkably finely tuned, and we have to consider that. And all scientists would agree about what I have been telling you; this is non-contentious. Where the contention comes in is what we might make of that, what is the further significance of it.