When I was at university my friend Bruno claimed to have the ideal pickup line. He’d approach a woman in a bar and say that in a parallel universe at that very moment an identical man was asking a lady out on a date, but that she was about to refuse. Bruno would then ask her, deadpan, whether she was about to make the same mistake. He swore this worked.
Yet maybe Bruno’s real success was in beginning to grapple with the concept of a multiverse (also called a “meta-universe”) in which many universes co-exist: a concept that is now advanced in response to an argument that Christians raise when trying to prove that God exists. The first part of that argument goes like this: Against all odds, the earth’s environment is so conducive to life that God must have arranged it.
For instance, if the earth’s orbit around the sun were a tiny fraction more circular or, conversely, slightly more elliptical, life on the planet would be impossible. And if it weren’t for the moon—itself the product of a freak collision with Earth—the planet wouldn’t retain the crucial tilt of its axis. And that’s not even to mention carbon. Life is impossible without it. Yet the combination of the age of the universe, the relative youth of the sun, and well-timed supernovae has enabled the production of life-enhancing carbon in a way that surely can’t be coincidental. The anthropic coincidences are sufficiently numerous as to fill a weighty tome. Surely God must have arranged it all.
This is often called the Weak Anthropic Principle (often abbreviated as WAP) and is nowadays generally dismissed as a poor argument in favor of God’s existence. Since the first confirmed observation in 1992 of a planet orbiting a star other than the sun, it has become clear that there are countless such planets. So it is hardly surprising that at least one solar system contains a mere single planet, Earth, which enjoys a beneficial environment. In fact, this past September, astronomers announced that they discovered in a nearby solar system a potentially habitable planet they have called Gliese 581. Steven Vogt, an astronomer at the University of California, Santa Cruz, explained, “The fact that we were able to detect this planet so quickly and so nearby tells us that planets like this must be really common.”
But more recently, believers have appeared to be on stronger ground by relying on what is called the Strong Anthropic Principle (SAP). This principle is concerned with why the laws of physics are so fine-tuned as to allow life on the planet. This is much more difficult to explain away than WAP because the fine-tuning does indeed appear to be staggeringly improbable. This principle came into vogue after 1998, when it was discovered that the universe is expanding at an accelerating rate. This requires the existence of what Albert Einstein called the cosmological constant; but what is it that prevents that constant from being much larger than it is, in which case our universe would have blown itself apart?
There are plenty more anthropic coincidences, but I will mention just two. If neutrons were a fraction heavier, they couldn’t be bound within the nuclei of atoms and so life would be impossible. And if the weak nuclear force were a little weaker, all the hydrogen in the early universe would have turned to helium and no stars would have formed; yet if it were much stronger, the supernovas would have failed to discharge the heavy element planets necessary to foster life.
So what is the answer? Are the coincidences so great that God must be responsible?
Perhaps the first point to note is that the Anthropic Principle is contentious. The same phrases have been given conflicting definitions and there is debate as to whether it’s a scientific principle at all. In fact, science writer Martin Gardner was so unimpressed by one aspect, the Final Anthropic Principle (FAP), that he renamed it the Completely Ridiculous Anthropic Principle (CRAP).
A key difficulty is that cosmology is still a relatively young science and so, for the moment, all debate is being conducted with far less information than there will be in, say, 100 years. It is rather like debating evolution back in 1859. Add to the mix that much of cosmology is counter-intuitive and based primarily on mathematics, and the issue becomes all the more difficult.
Even so, are there any naturalistic explanations for fine-tuning the laws of physics? Physicist Paul Davies’ book, The Goldilocks Enigma, lists eight possible explanations. Theoretical physicist Lee Smolin has added a ninth with similarities to what I will discuss below.
Particle physicist Victor Stenger has written that too much has been made of the cosmological coincidences. He challenges the assumption that life is impossible under any other arrangement of physical laws and constants. For instance, he argues that silicon could possibly support life in the way presently performed by carbon. Similarly, and contrary to virtually unanimous previous opinion, recent research into bacteria in a California lake has raised the possibility of life that isn’t dependent on phosphorus.
Yet the main response is the multiverse theory. Stephen Hawking’s latest book explains that the positive energy of matter can be balanced by negative gravitational energy. The result is that universes are capable of creating themselves. What’s more, the number of universes out there is in the region of ten followed by 500 zeros. This is all based on M-theory, which, in turn, owes much to quantum theory in that no particle has a single history but rather has every possible history. Similarly the multiverse comprises every possible universe. And so it’s hardly a surprise that one of them—the one we inhabit—has the laws of physics that permit intelligent life.
Add to the mix that M-theory has passed every experimental test to which it has ever been put, and this solution is starting to look like the real deal. Perhaps it is little wonder that Victor Stenger concluded, “The universe looks just as it would be expected to look if it were not created by God. From this we can conclude, beyond a reasonable doubt, that such a God does not exist.”
However there are problems with this approach. Some physicists feel uncomfortable about the theory that a particle has no single history, a theory that is crucial to the concept of multiverses as presently formulated. Also M-theory is not yet perfected. It may never become the Theory of Everything that physicists have been looking for. In that case, the multiverse theory will remain vulnerable to a better theory coming along. Besides, Occam’s Razor is a key scientific principle. Crudely, it means that simple theories are the best. So which is the simpler theory, that there is an unimaginably large number of universes that we will never see, or that a celestial being created the universe?
Anthony Flew spent most of his adult life as a prominent atheist. In his last years he converted to deism and co-wrote the 2007 book, There Is a God, to explain why. The extent to which he was involved in the writing is controversial. Yet, on its face, it seems that the Anthropic Principle was possibly the key reason for his change of mind. Quite frankly, that is astounding. Science may ultimately confirm that there is a natural explanation to the cosmological coincidences or it may not. Yet this is a difficult issue on which many experts differ. And probably all of them would admit that key scientific answers—or a crucial inability to provide answers—lies ahead. For anyone to claim that he has sufficient information and expertise to believe that the principle objectively proves the existence of God is either disingenuous, misguided, or is letting his heart rule his head. And for an atheist to be converted partly because of the Anthropic Principle is utterly bizarre.
However, Flew was certainly right on one point: Even if the Anthropic Principle were to demonstrate the existence of a god, it would hardly follow that that would be the Christian god.
Most well versed physicists will probably base their own opinions about the Anthropic Principle at any particular time on whatever the latest scientific thinking happens to be at that moment. Yet it’s important for those approaching this issue within the context of the God debate to take a step back. Both Flew’s conversion along with Stenger’s bold conclusion seem particularly strong in the context of an issue that hasn’t yet been scientifically resolved.
Clearly, there is at least one highly plausible response to the fine-tuning argument. And so the Anthropic Principle can’t deliver the knock-out blow that Christians hope. But until the science behind it becomes more settled, most people trying to find the answer to whether there is a god will have to look elsewhere.
As for Bruno’s pickup line, I never tried it myself. Then again, I was always hopeless at chatting up women. Just ask my wife.