Peering into the hazy and crazy

Physicist Robert Ehrlich would like college students to be taught how to assess controversial claims by scientists and he has suggested that this book could be used as the basis. His selection of nine controversies - from criminology, relativity, the earth sciences, cosmology, astronomy and epidemiology - avoids being too subversive as it excludes any ideas that he thinks are "inconsistent with the fundamental principles of nature" (which he classifies as "nutty").

The short introductions to each controversy cover a surprisingly wide area and are more interesting to read than accounts that fail to consider alternative views. If you want to learn about the HIV theory of Aids or the expanding universe, this could be an excellent way to start. Before you read why the solar system may have two suns, you are treated to an excellent short account of the theory of mass extinctions; afterwards there is a discussion of whether natural regularities need to have a scientific explanation or can be attributed to chance.

The main part of each of the nine sections is devoted to a critical analysis of the claims. Not only is much of the evidence unexpected, but an apparently strong case can turn out to be flawed. Here the reader discovers a variety of statistical and logical comments and is warned about some pitfalls. An appreciation of graphs is essential, but not algebra, which is relegated to some footnotes about special relativity.

Ehrlich's own "crazy idea" has been to discover a remarkable way of testing for the existence of tachyons - Jparticles that always travel faster than light. This work may have predisposed him to be more sympathetic to the scientist who tries to confront a large and powerful consensus. Although he implicitly shares the scientific view that observations must come first and theory will have to be changed if necessary, I suspect he would be very reluctant to take this approach the whole way and challenge, say, the theory of relativity. As for any theory that challenged the principle of conservation of energy, he would definitely regard it as nutty.

There could be big consequences if some of the controversial claims Ehrlich does discuss were confirmed. His coverage of these possible consequences tends to be a bit cursory and dull. For example, a deeper discussion of the issues involved in time travel or faster-than-light communication would not require much specialist knowledge and would have appealed to the non-scientist.

This book does not always present all sides of the scientific argument. For example, the consensus view that low-level nuclear radiation is almost harmless, is only contrasted with the "crazy" notion that it is beneficial. This narrow coverage disregards the work of Alice Stewart and Rosalie Bertelle, who have concluded that such radiation is quite harmful. Nevertheless, this section is worth reading for its useful advice on medical statistics.

This is an excellent, thought-provoking read for those interested in science, but it should be read for its arguments rather than for its conclusions. And it does not attempt to cover all areas of current scientific controversy. There is nothing, for example, on BSE, genetically modified foods, evolutionary psychology, global warming or the paranormal.

Geoff Wexler is a physicist formerly in the faculty of technology, the Open University.