The Anthropic Cosmological Principle

by John D. Barrow and Frank J. Tipler, with a foreword by John A. Wheeler
Oxford University Press (Clarendon Press), 706 pp., $29.95

It has been observed that cosmologists are often wrong but seldom uncertain, and the authors of this long, fascinating, exasperating book are no exceptions. They are John Barrow, astronomer at the University of Sussex, and Frank Tipler, Tulane University mathematical physicist. Physicist John Wheeler provides an enthusiastic foreword. No one can plow through this well-written, painstakingly researched tome without absorbing vast chunks of information about QM (quantum mechanics), the latest cosmic models, and the history of philosophical views that bear on the book’s main arguments.

Just what is this “anthropic principle” that has become so fashionable among a minority of cosmologists, and is arousing such passionate controversy? As the authors make clear in their introduction, there is not one principle but four. Each is more speculative than the previous one, with the fourth blasting the authors out of science altogether into clouds of metaphysics and fantasy.

The simplest of the four is called (the authors are fond of acronyms) WAP, or the Weak Anthropic Principle. Although it goes back to Protagoras’s famous declaration that “man is the measure of all things,” its modern cosmological form seems first to have been stated by the physicist Robert Dicke in the late 1950s. As Barrow and Tipler readily admit, it is a trivial tautology, totally noncontroversial. It merely proclaims that because we exist the universe must be so constructed as to allow us to have evolved. The laws of nature clearly must be such as to permit, if not actually force, the formation of CHON (carbon, hydrogen, oxygen, and nitrogen), the four elements essential to life as we know it.

Does this mean that all life must be carbon based? Although the authors believe this, it does not follow from WAP. Even if there is noncarbon life elsewhere in the universe, the fact that we are carbon imposes a variety of tight restraints on the universe and its past. For example, the cosmos has to be about 15 billion years old. Why? Because, the authors argue, elements necessary to organic molecules are cooked inside stars. If the universe were much younger, those elements would not be available and we wouldn’t be here. If the universe were much older, all the suns would have burned out, and we wouldn’t be here either.

WAP was invoked over and over again in earlier centuries by proponents of the design argument for God. It was WAPish to point out that if the earth were slightly closer to the sun, like Venus, water would boil away and carbon life would be impossible. If the earth were slightly farther from the sun, water would freeze and Earth would have the barren deserts of Mars. Theists liked to note that when water freezes it expands and floats on water, otherwise lakes and rivers would freeze to the bottom in winter and all their life be destroyed. If Earth did not have an ozone atmosphere, animals could not survive ultraviolet radiation. And so on. Hundreds of similar arguments, most of…

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