John Barrow and the anthropic cosmological principle

Author: Carlos A. Marmelada

Physicist John D. Barrow is the 2006 winner of the substantial award Templeton Prize of 1.15 million euros. Sir John Templeton established the foundation that bears his name surname to promote the knowledge of spiritual realities. In fact, in recent years the award has been awarded to individuals who have contributed to the dialogue between science and religion. In 2004, for example, it was awarded to cosmologist George Ellis for his Christian anthropic principle, according to which God created the universe so that there would be intelligent, responsible and free beings capable of love, and thus make some creatures share in his highest qualities (an idea which, moreover, has centuries of history in the Christian tradition).

John Barrow, born in London in 1952, received his PhD from Oxford in 1977. He then collaborated with the Departments of Physics and Astrophysics at the University of Oxford and the University of California at Berkeley. In 1999 he became Full Professor of mathematics and theoretical physics at the University of Cambridge. In the same year he was awarded the Kelvin Medal of the Royal Glasgow Philosophical Society. He has also received other awards.

The author of 17 books and 400 articles, Barrow has made a great effort to disseminate scientific ideas, trying to make the most complex theories of current cosmology accessible to a wide audience. His books include The Left Hand of Creation (1983), The Anthropic Cosmological Principle (1986; with Frank Tipler), Theory of Everything (1991), The Universe as a Work of Art (1995), The Book of Nothing (2000) and The Constants of Nature (2002).

Before earning his doctorate in astrophysics, Barrow graduated in mathematics, which is reflected in his works. One of them is entitled Why Is the World Mathematical? (1992), a question that is not trivial: after all, numbers are a construct of the human mind and not objects among the material things in the universe. With a Pythagorean optimism, Barrow closes The Constants of Nature by affirming precisely that numbers are the mould with which the universe is shaped, the barcodes of an ultimate reality that will allow us to unveil the secret of the universe... one day.

Constants with appropriate values

One of the reasons why Barrow has received the award Templeton is his contribution to the development of the anthropic cosmological principle. Although Robert W. Dicke suggested some ideas in this direction as early as 1961, it was the astrophysicist Brandon Carter who, in 1974, proposed one of the first formulations of this principle when he spoke about it in Kraków, during a lecture he gave at the framework celebration of the 500th anniversary of the birth of Nicolaus Copernicus.

The anthropic principle is based on reflection on how delicate the conditions necessary for life to exist in the universe are, and on admiration for the fact that life would not have been able to appear if any of the constants of nature had a slightly different value (see Aceprensa 162/03). For example: if gravity were a little more intense, stars would burn out sooner and could not have planets that could support life, nor would there have been time to synthesise carbon (so essential for life as we know it today); and if it were weaker, the universe would have expanded even more rapidly and neither galaxies nor stars could have formed, so life would also be impossible. Examples along these lines could be multiplied.

Thus, some cosmologists wonder whether the universe is not made for us to live in. In principle, scientists are of the opinion that the constants of nature must have the same value at all times and in all places. But it is becoming clear that there are constants that could have different values than they do today. However, we also know that "very small changes in many of our constants would make life impossible", says Barrow in The Constants of Nature. The question then arises: why is the universe the way it is; why, given infinite possibilities, does the universe take the exact shape that allows us to exist? This thought leads some cosmologists, like Barrow, to the idea of an anthropic universe; that is: the universe is the way it is so that it can harbour observers, intelligent life.

Four formulations

There are various formulations of this principle. According to the so-called strong anthropic principle, the universe (and with it, the value of all constants of nature) must be such that it admits the existence of intelligent observers within it at some stage of its development. That is: the universe exists so that, at some place and time, there are intelligent beings who wonder about it. This formulation does not usually please most cosmologists, who argue that it is too compromising: they claim that it is a teleological argument that explains phenomena by their ends, rather than a deductive argument that would explain them by their causes, as is more proper to natural science.

The weak anthropic principle holds that the initial conditions of the universe, as well as its laws, must be compatible with the existence of intelligent observers. Some scientists have called this proposition tautological; others, like Stephen Hawking, acknowledge "the usefulness of some weak anthropic arguments". Be that as it may, the question remains: why are we here? In other words: can the universe only exist with these laws of nature? Whether the answer is yes or no, from a scientific point of view we do not know why. This is why Barrow insists that the anthropic principle is not a scientific theory, but a methodological principle.

But there are two more formulations: one is the anthropic participatory principle, suggested by John A. Wheeler, the scientist who coined the term "black hole". His proposal is one of the most speculative formulations of the principle. Wheeler wonders whether observers are not necessary beings for the existence of the universe. The other formulation is the final anthropic principle, proposal by Barrow and Frank J. Tipler, who suggest that once life has arisen in the universe it will never disappear, although it must be as small a form of life as the laws of physics allow.

While these proposals are subject to various criticisms, they do show that there are a handful of cosmologists (of widely varying intellectual disposition) who, in one way or another, emphasise the important role of man in the cosmos. Among them is Barrow who, although it is true that as a scientist he is "theologically" neutral, shows a certain sympathy for a theistic reading of the cosmos in the framework of the intelligent design , one of the factors that have earned him the award Templeton.