What the example shows is that you cannot explain an improbability of this magnitude by simply pointing to our presence on the scene to ponder it. There is still a massive improbability that needs to be accounted for. Remember that the anthropic principle does not say that, given the billions of stars in the universe, it’s remarkable that life turned up on our planet. Rather, it says that the entire universe with all the galaxies and stars in it had to be formed in a certain way in order for it to contain life at all. It’s hard to disagree with the conclusion drawn by philosopher Antony Flew. Long a champion of atheism—he is one of the most frequently cited figures in atheist literature—Flew finally concluded that the fine-tuning of the universe at every level is simply too perfect to be the result of chance. Flew says that in keeping with his lifelong commitment “to go where the evidence leads,” he now believes in God.”
Flew recognizes that the anthropic principle requires a better explanation than Lucky Us. So does astronomer Lee Smolin, who writes that “luck will certainly not do here. We need some rational explanation of how something this unlikely turned out to be the case.” The odds of us being here in the universe are so fantastic that some kind of a serious explanation is required. Deep down, one suspects that Weinberg and Dawkins know this.
Consequently, many atheists have fled to the second explanation for the anthropic principle: Multiple Universes. Actually, an infinity of universes. Each universe operates according to its own set of laws. Consequently one universe may have an inverse-square law ofgravity and another may have an inverse-cube law of gravity. Indeed, under conditions of true infinity, we would expect that every physical condition, every possible arrangement of matter and energy, is realized. Everything that can happen does happen. In this remarkable situation—the argument goes—we can finally account for our privileged universe. As there are an infinite number of universes, it’s entirely possible that one has developed in a way that permits observers like us.
There are several versions of the Multiple Universes theory. One is that we live in an oscillating universe that goes through an infinite number of cycles, in which big bangs are followed by big crunches. If the constants of nature vary in each cycle, at some point a particular combination will be realized by chance, like a winning number in a casino slot machine. A second version is that the Big Bang spawned multiple universes, each with its own set of laws. These universes are like separately expanding balloons that cannot relate to one another. Each has its own set of laws. A third version, sometimes called the parallel worlds theory, holds that at each act of quantum measurement the world splits into a series of parallel universes. In fact, universes are springing up even as you read this sentence. Don’t ask where; the universes are disconnected from each other and we have access only to our own universe. Another idea, presented by Smolin, is that our universe emerged from a black hole in a previous universe, and indeed the black holes in our universe are even now generating other universes. Smolin has even raised the possibility of the Darwinian principle of natural selection applying to universes, in which some universes adapt and survive and others don’t. (Not surprisingly, Darwinian hounds like Dawkins and Dennett have rushed to praise this theory.) In all these versions an infinite horizon of possibilities is invoked in order to allow for the possibility that our universe could have arisen purely by chance.
What is one to make of all this? As with all scientific theories, we begin by asking for the evidence. So what is the empirical evidence for oscillating and parallel and multiple universes? Actually, there isn’t any. As Weinberg admits, “These are very speculative ideas … without any experimental support.” Smolin is even more candid. He calls his ideas “a fantasy…. It is possible that all I have done here is cobble together a set of false clues that only seem to have something to do with each other…. There is every chance that these ideas will not succeed.” I appreciate this candor, and I am reminded of that old Ptolemaic remedy for problematic data: “just add epicycles.” Now we are in the realm of “just add universes.”
