Excursus on Natural Theology (Part 17): Is the Fine-Tuning Explained by Chance?

Is the Fine-Tuning Explained by Chance?

Today we want to continue our discussion of the design argument for God’s existence based upon the fine-tuning of the universe. We saw that the fundamental constants and boundary conditions of the universe are fine-tuned for the existence of embodied conscious agents to a degree that is incomprehensibly delicate as well as complex. There are three explanations for this incredible fine-tuning available in the literature. One is physical necessity – that the constants and quantities have to have the values they do. The second is chance, and the third is design. We’ve already seen that the first alternative – that it is a matter of physical necessity – is highly implausible. The best evidence indicates that these constants and quantities are independent of the laws of nature, and that there is nothing physically that would determine that they should have the finely tuned values that they do.

That leads us to the second alternative, chance. Could the fine-tuning of the universe be the result of chance? According to this alternative it is just an accident that all of the constants and quantities fall into the infinitesimal life-permitting range. We just basically lucked out. The fundamental problem with this explanation is that the chances of a life-permitting universe’s existing are so remote that this alternative becomes unreasonable.

Sometimes people will object that it is meaningless to speak of the probability of a fine-tuned universe’s existing because there is, after all, only one universe. So you can’t say, for example, that one out of every ten universes is finely tuned to be life-permitting.

Cambridge University physicist John Barrow gives the following illustration of the sense in which it can be said that it is highly improbable that a finely tuned universe should exist. Barrow said, let’s imagine a sheet of paper and put on it a dot representing our universe. Now alter some of the fundamental constants and quantities by tiny amounts. That will then be a description of a new universe. If that universe is life-permitting, make it a red dot. If it is life-prohibiting, we will make it a black dot. Then do it again, do it again, and do it again until your sheet of paper is filled with dots. What you wind up with is a sea of black with only a couple of pinpricks of red. It’s in that sense that it is overwhelmingly improbable that the universe should be life-permitting. There are simply many more life-prohibiting universes than life-permitting universes in our local area of possible universes.

Sometimes people will appeal to the example of a lottery in order to justify the chance alternative. In a lottery in which all of the tickets are sold it is fantastically improbable that any one person should win the lottery. Yet, somebody has to win if all the tickets have been sold! So it would be unjustified for the winner (whoever he might be) to say something like, “Well, the odds of my winning were twenty million to one. The lottery must have been rigged to make me win!”

In the same way, these people will say, some universe out of the range of possible universes had to exist, and the winner of the “universe lottery” would also be unjustified if he thought that because his universe exists this must have been the result of design and not chance. All of the universes are equally improbable, and yet some universe had to exist. So the one that does exist would exist simply by chance alone, and it would be unwarranted to conclude that it was a result of design.

This lottery analogy is actually very helpful because I think it enables us to see where the objector has gone wrong – where he has misunderstood the argument from fine-tuning – and then to offer a better and more accurate analogy in its place. Contrary to popular impression, the argument for design is not trying to explain why this particular universe exists. Rather it is trying to explain why a life-permitting universe exists. The lottery analogy was misconceived because it focused on why a particular person won.

The correct analogy to the fine-tuning argument would be a lottery in which billions and billions of white ping pong balls were mixed together with just one orange ping pong balls, and you were told then that one ball will be randomly selected out of this horde. If it is orange, you will be allowed to live. If it is white, you will be shot. Notice that any particular ball that is chosen is equally improbable. No matter which ping pong ball rolls down the chute, the odds against that particular ping pong ball will be fantastically improbable. But some ball must roll down the chute. That is the point illustrated by the first lottery analogy. Somebody has to win. Just because that particular ball is highly, highly improbable would not justify a design inference. But that point is irrelevant because we are not trying to explain why this particular ball was picked.

The relevant point, rather, is that whichever ball rolls down the chute it is incomprehensibly more probable that it will be white rather than orange. Getting the orange ball is no more improbable than getting any particular white ball, but it is incomprehensibly more probable that whichever ball you get it will be white rather than orange. So if the orange ball does roll down the chute allowing you to live, you certainly should suspect that the lottery was rigged to let you live.

If you don’t see the point of this analogy, then imagine that the orange ball had to be randomly picked five times in a row in order for you to live. If the odds against the orange ball’s being picked even once are great enough, having it happen five times in a row won’t materially affect the probabilities. But obviously if such a thing happened – if five times in a row the orange ball came down the chute – everyone would recognize that it did not happen by chance. Somehow this was rigged.

So in the correct analogy you are not interested in why you got the particular ball that you did; rather, we are puzzled by why, against overwhelming odds, you got a life-permitting ball rather than a life-prohibiting ball. That question just isn’t addressed by saying, “Some ball had to be picked, and any particular ball is equally improbable.” In exactly the same way, some universe has to exist, but whichever universe exists it is incomprehensibly more probable that it will be life-prohibiting rather than life-permitting. We still need some explanation as to why a life-permitting universe exists.

Some people have argued that no explanation is needed for why we observe a life-permitting universe because that is the only kind of universe we could observe. If the universe were not life-permitting, then we wouldn’t be here to ask about it. This is the so-called Anthropic Principle, which says that one can observe only properties of the universe which are compatible with our existence. Obviously, it would be impossible for us to observe properties of the universe incompatible with our existence because we wouldn’t be there. So the Anthropic Principle says you can only observe properties of the universe which are compatible with our existence, and therefore since you observe those kinds of properties, you shouldn’t be surprised about it. There is no explanation necessary.

This reasoning is fallacious. The fact that we can observe only life-permitting universes does nothing to explain why a life-permitting universe exists. The fact that that is the only kind that we can observe doesn’t remove the need for an explanation of why such a universe does exist.

Again, an illustration can help here. Suppose you are traveling abroad and you are arrested on trumped-up drug charges and dragged in front of a firing squad of one hundred trained marksmen at point-blank range, all of them with rifles aimed at your heart. You hear the command given, “Ready! Aim! Fire!” And you hear the deafening roar of the guns. And then you observe that you are still alive! That all of the one hundred marksmen missed! Now, what would you conclude? “Well, I guess I really shouldn’t be surprised that they all missed. After all, if they hadn’t all missed, I wouldn’t be here to be surprised about it. Given that I am here, I should expect them all to miss!” Of course not. It is true you shouldn’t be surprised that you don’t observe that you are dead, because if you were dead you wouldn’t be able to observe it. But you should still be surprised that you do observe that you are alive, in light of the enormous improbability of all one hundred marksmen missing. In fact, if this happened, you’d probably conclude that they all missed on purpose, that the whole thing was a set-up, engineered for some reason by someone.

Therefore, theorists have come to recognize that the Anthropic Principle will not eliminate the need of an explanation of the fine-tuning unless it is conjoined with a so-called Many Worlds Hypothesis or multiverse hypothesis. According to the Many Worlds Hypothesis our universe is just one member of a World Ensemble of parallel universes, randomly ordered and preferably infinite in number. Often this ensemble is called the multiverse. If all of these other universes really exist and they are randomly ordered in their constants and quantities then by chance alone life-permitting worlds will appear in the ensemble. Since only finely tuned universes have observers in them, any observers existing in the World Ensemble will naturally look out and observe their worlds to be finely tuned. So the claim is no appeal to design is necessary in order to explain fine-tuning.

So the conjunction of the Anthropic Principle with the Many Worlds Hypothesis or multiverse is said to eliminate the surprise that we have at observing a finely tuned universe and any need of an explanation beyond sheer chance. Given that there is an infinite number of parallel universes, and that they are randomly ordered in their constants and quantities, life-permitting worlds will exist in the Ensemble and only such worlds will have observers in them. So of course the observers see their world to be finely tuned.

Before I comment on the World Ensemble hypothesis, I think it is worth pausing for a moment here to reflect on what is going on. The current debate over the fine-tuning of the universe has now become a debate over the Many Worlds Hypothesis. I am not exaggerating. This hypothesis is at the heart of the discussion today. In order to explain fine-tuning, we are being asked to believe not only that there are other unobservable universes but that there are an infinite number of these universes, and moreover that they randomly vary in their constants and quantities. All of this is needed in order to guarantee that life-permitting universes like ours will appear by chance in the ensemble.

This is really extraordinary when you think about it. It is a sort of back-handed compliment, if you will, to the design hypothesis. Otherwise sober scientists would not be flocking to adopt so speculative and extravagant a view as the Many Worlds Hypothesis unless they felt absolutely compelled to do so. The fact that many theorists are turning to the Many Worlds Hypothesis to rescue the alternative of chance is perhaps the best evidence that the appeal to chance is in trouble. The odds against the existence of a life-permitting universe are just too great to be faced unless you embrace the hypothesis of a World Ensemble.

In fact, when I was teaching a seminar on fine-tuning at St. Thomas University, one of the other professors in the seminar was Neil Manson, a professor of philosophy. Neil had commissioned an extraordinary sociological survey of contemporary cosmologists about issues like fine-tuning. I think this is the first and only such sociological survey done by a reputable organization published in a peer-reviewed journal. What Manson asked the cosmologists was, “Do you think that other theorists who adopt the multiverse hypothesis do so in order to avoid the design hypothesis?” He was very clever to ask it that way. He didn’t ask “Do you adopt it for that reason?” That would make them have to confess, “Yes, I as a scientist am really trying to avoid design, and that is why I believe in the World Ensemble.” No, he said, “Do you think your colleagues who believe in the multiverse are motivated by a desire to get away from design?” He didn’t mention God; he mentioned design. What he found was that over 50% of the respondents said that they did believe that in fact a large part of the motivation among contemporary cosmologists for belief in the World Ensemble or multiverse hypothesis was because they wanted to avoid the idea of a cosmic designer.

So the next time somebody says to you, “Oh, well, it could have happened by chance!” or “The improbable happens!” or “It was just dumb luck!” then ask them, “If that is the case, why do the detractors of design feel compelled to embrace an extravagance like the World Ensemble hypothesis in order to avoid design?” The fact that they would resort to such a metaphysical hypothesis, I think, is, as I say, the best evidence that the chance hypothesis is in deep trouble.

How might one respond to the Many Worlds Hypothesis? Prima facie, one might think that this is a metaphysical view that would not be susceptible to scientific testing. You just have a standoff between two metaphysical hypotheses: divine design and multiverse or World Ensemble hypothesis. But, in fact, I think that there are some scientific problems with the World Ensemble hypothesis that make it less preferable to the design hypothesis.

One way to respond to the Many Worlds Hypothesis would be to show that the multiverse itself also requires fine-tuning. In order to be scientifically credible, some plausible mechanism has to be suggested for generating the many worlds in the ensemble. But if the Many Worlds Hypothesis is to be successful in attributing fine-tuning to chance alone, then the mechanism that generates the many worlds had better not be fine-tuned itself. Otherwise, you’ve just kicked the problem upstairs, and the whole debate arises all over again on the level of the multiverse.

But the proposed mechanisms for generating a World Ensemble are so vague that it is far from evident that the physics governing the multiverse will be free of any fine-tuning. For example, if M-Theory, or superstring theory, which we briefly talked about the other day, is the physics generating the World Ensemble then it remains unexplained, as we’ve seen, why exactly 11 dimensions exist. The mechanism that actualizes all of the possibilities in the so-called cosmic landscape may also involve fine-tuning. So just postulating a World Ensemble isn’t sufficient to get rid of the alternative of design. You’d have to provide a scientifically credible model of the multiverse that doesn’t involve fine-tuning itself. And nobody has been able to do that.

A second response to the Many Worlds Hypothesis is that many theorists are skeptical that these many worlds even exist. Why should we think that a World Ensemble of other invisible universes actually exists? There really isn’t any evidence that the sort of World Ensemble required by the multiverse hypothesis is actually real. Even if there were other universes, there is no reason to think that they are randomly ordered or that they are infinite in number. So, as George Ellis, who is perhaps the most famous cosmologist in the world today, has emphasized, the Many Worlds Hypothesis as it stands today is not a hypothesis that is capable of scientific proof. By contrast with this, we have good independent reasons for believing in a designer of the universe; namely, Leibniz’s cosmological argument, al-Ghazali’s kalam cosmological argument, and Wigner’s argument from the applicability of mathematics. The design hypothesis enjoys independent reasons for thinking that such a being exists whereas there is no independent reason for thinking that the World Ensemble exists. It is simply postulated to explain the fine-tuning without any independent evidence for thinking that there is such a thing.

Finally, thirdly, the Many Worlds Hypothesis faces what may be a truly devastating objection. Do you remember when we talked about the thermodynamic properties of the universe, we discussed Boltzmann’s Many Worlds Hypothesis? You will remember that the Austrian physicist Ludwig Boltzmann tried to explain away the current disequilibrium of the universe by a kind of Many Worlds Hypothesis. He said that the universe as a whole really is in a state of equilibrium but there are little pockets of disequilibrium throughout the universe, and these are different worlds. We are one of these worlds. You will recall what sank Boltzmann’s hypothesis was that if our world is just a random member of a World Ensemble like this, then it’s vastly more probable that we should be observing a much smaller region of order than the vast universe that we do. In order for us to exist, all you would need would be a small fluctuation from equilibrium, say, enough to produce our solar system, not an entire universe which exists in such a state. It turns out that a parallel problem faces the Many Worlds Hypothesis as an explanation of cosmic fine-tuning.

The Oxford University physicist Roger Penrose has pressed this objection with great force. Penrose points out that the odds of our universe’s initial low entropy condition existing by chance alone are somewhere on the order of one chance out of 10^10(123). A truly incomprehensible number. By contrast the odds of our solar system’s forming by just a random collision of particles, Penrose calculates to be about one chance out of 10¹⁰⁽⁶⁰⁾, a number which is so tiny in comparison to 10^10(123) that Penrose calls this number “utter chicken feed” in comparison with 10^10(123). What that implies is that it is far more likely, incomprehensibly more likely, that we should be observing an orderly universe no larger than our solar system, since a world like that would be unfathomably more probable than a finely tuned universe like ours.

In fact, we wind up with the same sort of illusionism that attended Boltzmann’s hypothesis. A small world with the illusion of a wider universe is more probable than a real fine-tuned universe. It would be more probable that we really do inhabit a little tiny universe and that the stars and the planets we observe are just illusions, pictures as it were, on the heavens and not real stellar extra-nebular bodies that exist out there in the universe. Carried to its logical extreme, this has led to what has been called among physicists “the invasion of the Boltzmann brains” - reminiscent of a 1950s grade-B horror movie. For the most probable observable universe that could exist would consist of a single brain which fluctuates into existence out of the quantum vacuum by a random quantum process with illusory perceptions of an external world around it! So if you accept the Many Worlds Hypothesis, you would be obligated to believe that you are the only thing that exists and that this class, the people around you, your family, your own body, all of these things are simply illusions that you project. In fact, you are really a Boltzmann brain. Minimally, on atheism there’s no way to know that you are not a Boltzmann brain, so that the Many Worlds Hypothesis lands its proponent in radical and self-defeating scepticism.

No sane person believes that he is a Boltzmann brain. On atheism, therefore, it’s highly improbable that there exists a randomly ordered World Ensemble. In fact, here is the irony: the best hope for the multiverse or World Ensemble Hypothesis is theism. The best hope for this hypothesis is to say that God has created the World Ensemble and he has ordered its worlds so that they’re not randomly ordered. God could give a preference to observable worlds which are cosmically fine-tuned. To be rationally acceptable, the Many Worlds Hypothesis really needs God because if there is no God on naturalism alone it would be highly, highly improbable that we should be observing this fine-tuned universe. It would be far more probable that you are a Boltzmann brain.

With the failure of the Many Worlds Hypothesis, the last ring of defense for the alternative of chance collapses. It seems that neither physical necessity nor chance provides a good explanation of the fine-tuning of the universe.

So what about design? Is design any better an explanation of the fine-tuning of the universe? Or is it equally implausible? That will be the question that we take up next week.