Barrow and Tippler's Anthropic Cosmological Principle

One of the remarkable and mysterious facts about this world is how well designed it is for us. The temperature, atmosphere and water all seem just right for humanity to live and prosper. Of course, if our sun is amongst myriad stars in the galaxy and our galaxy amongst millions more galaxies in the universe, then it is perhaps not too surprising that one amongst the profusion can support human life. Indeed, if the Gaia hypothesis is correct, perhaps planets within quite wide environmental ranges will self-regulate to ensure conditions conducive to life.

However, there is a still more mysterious coincidence in the heart of things. If the fundamental physical constant of the universe were only a little different not only life, but molecules, and even atoms would not have formed. Not only would there be no humanity, but nothing at all but chaos. In Genesis we read that "God's spirit moved over the waters" which represented primordial chaos, and by speaking a word called forth order and life. Many, who do not hold on to the literal truth of Genesis still find in the remarkable balances of the cosmos the best evidence for a creator who has prepared a way for life and humanity.

In their book, "The Anthropic Cosmological Principle" (Clarendon Press, 1986), Barrow and Tippler cast doubt on this argument. It is like a person looking at all the generations that have gone before and all those that are to go and remarking how strange and unlikely it is that she is alive now rather than in one of those other generations. Of course she is alive now, if she weren't she wouldn't be around to wonder. Similarly, it would only be possible to argue about the wonderful coincidence of physical law if those laws were of a kind suitable to develop life. The world we live in must be tailor made for us otherwise we would not be here to argue that the world is tailor made for us!

Gott's arguments in The Grim Reckoning calculating the expected remaining duration of homo sapiens have a similar feel. He is not poised at a random point in the history of mankind, but at a particular point, namely one of the first generations with enough statistical knowledge for him to perform his calculations. The phenomenon observed (the duration of humanity) and the observation (the point Gott makes his discovery) are not independent, it is a reflexive system.

Arguments that derive from single cases and self-reflexive systems are always difficult. At 30,000 feet over the Atlantic an aircraft malfunctions, it plummets towards the sea and explodes in mid-air scattering debris over tens of square miles of ocean. Expecting no survivors a rescue ship combs the area and the crew are amazed to pull from the waters a sole survivor. Whilst floating awaiting rescue the man had first been amazed at his miraculous survival, but then, being conversant with the Anthropic Cosmological Principle had realised that if he hadn't survived then there would have been no musing. Far from a wonder that he had survived, it was inevitable, he couldn't wonder on it unless it had happened. So is it miraculous or inevitable?

The ultimate strength of the Anthropic Principle seems to be very much a matter of attitude and belief, especially as it relies heavily on counterfactual logic "if the world were different then...". Unless, as some cosmologists believe, every possible universe exists with every possible sort of physical law (in which case that is itself a form of universe!), such counterfactuals are suggestive evidence, but can neither prove or disprove the existence or necessity of a creator. However, it does give pause to some over-simplistic arguments on both sides.

Perhaps, as we approach Christmas, the exact nature of the way in which the word calls forth order out of chaos 10 billion years ago is not nearly as important as the speaking of that word in Galilee.

Alan Dix
Lancaster University
alan@hiraeth.com
alan@hcibook.com
December 1997