A Scientific Look at Aliens

Edward Regis, Jr. (Ed.) Extraterrestrials: Science and Alien Intelligence. Cambridge University Press, 1985.

Some of the scientific and philosophical issues raised by the question of whether or not extraterrestrial intelligent life exists are discussed in this collection of papers, where the wide divergence of opinion shown demonstrates that it is very much an open question.

Ernst Mayr argues that as only one intelligent species developed on Earth after billions of years of evolution, the chances of intelligence developing elsewhere are close to zero. For this reason he believes that the SETI (Search for Extra Terrestrial Intelligence) programme is "a deplorable waste of the taxpayers' money". Although he is well aware of examples of convergent evolution, having established that "... eyes evolved independently not less than forty times in different groups of animals...", he rejects the argument that the same principle can be applied to the evolution of intelligence: as he also rejects the argument that the evolution of intelligence would necessarily lead to the establishment of a sophisticated technology.

David M. Raup also discusses convergent evolution, and argues that it does favour the development of intelligence. He also suggests that the fossil record indicates that life originated independently several times on Earth. He thus thinks that there is a good chance that ETI exists.

If ETI does exist, would alien science resemble ours, or would it be so different as to be incomprehensible to us? Nicholas Rescher thinks that the chances of an alien civilisation developing science in a manner resembling human science is extremely remote, but his arguments are somewhat abstruse and there is not enough space to discuss them here. His views are firmly opposed by Marvin Minsky who discusses the constraints which nature imposes on all conceivable intelligent beings. He uses simple mathematical arguments to show that many problems have simple solutions and that although there may be other possible solutions, these are likely to be so complicated that they are not worth the effort of discovering and applying them.

If ETI does not exist, then there is no point in spending time and money trying to detect it. In the past few years some ingenious arguments have been developed in attempts to convince us of the non-existence of the extraterrestrials. Frank J. Tipler employs what has become one of the favorites - which may be called the 'von Neumann machine argument'. If the ETI's exist, then they should be here. They are not here, therefore they do not exist. An advanced civilization could build self-replicating machines, and it has been calculated that such machines could spread through the galaxy "in less than 300 million years".

Carl Sagan and William I. Newman oppose Tipier's argument by employing the reductio ad absurdam method: "...with any plausible initial mass for such a device, and with even one copy per reproductive event, the entire mass of the Galaxy would be converted into von Neumann machines within a few million years of their invention." Also: "These implacable replicators will not stop until the the entire universe has been converted into about 1047 von Neumann machines, which then presumably cannibalise each other."

This is all good fun, but down-to-earth readers will want to see a more practical and constructive approach. This is provided by Jill Tarter, who considers that listening for artificial radio signals is the most promising method of trying to obtain evidence for ETI. She describes the techniques employed and the problems encountered in this work and gives a list of SETI observing programmes carried out from 1959 to 1984.

The diverse opinions and arguments advanced by contributors to this book show that the question of ETI is far from simple. They can be contrasted with the generally naive and simplistic remarks on the subject which appear in much of the UFO literature. Every ufologist should obtain a copy. -- John Harney. From Magonia 21, December 1985


No comments: