WE ARE THE MARTIANS?

Giovanni F. Bignami, We are the Martians: Connecting Cosmology with Biology, Springer-Verlag Italia, 2012.

This is a short book of student notes giving an interdisciplinary treatment of recent findings on the development of the universe (or at least the observable part of it) from the Big Bang to the emergence and evolution of living organisms. The account of the development of the universe leading to the formation of galaxies containing billions of stars and planets is as described in many popular books on astronomy and cosmology.
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It gets more interesting in chapter two, which describes the formation of organic molecules, which are necessary for the emergence and evolution of living organisms.

There is a discussion of the findings of space probes sent to explore the solar system, particularly Mars and the larger satellites of Jupiter and Saturn, which seem to have the possibility of supporting living organisms beneath their surfaces. A European mission to Mars, Mars Express, started orbiting the planet in 2003 and one of its instruments detected the presence of methane in the atmosphere. On Earth, most of the methane in the atmosphere is produced by bacteria. It is estimated that methane in the Martian atmosphere would not last longer than 400 years, so it would have to be replenished continuously to provide a detectable amount. This indicates the possibility of a biological origin.

We are also informed that investigations by spacecraft of the composition of comets indicate that most of them did not originate in the solar system but have arrived from other stars (just as comets are sometimes expelled from our solar system by the slingshot effect when they pass very close to the sun and are accelerated so that their orbits are changed from elliptical to parabolic).

Bignami discusses the possibility of biological material arriving on Earth in comets (perhaps as bacterial spores?), but he is a bit confusing, as he rejects what he calls panspermia, by which we find a little later that he means directed panspermia, as proposed by Fred Hoyle. Indeed, the clumsy translation from the Italian by Marialuisa Bignami (oddly, not mentioned in the acknowledgments), together with the informal style and presentation, make meanings a bit obscure in places.

Although the title mentions cosmology, Bignami is an astronomer who is evidently not very keen on cosmology and prefers to believe that the universe came into existence 13.7 billion years ago, rather than join the cosmologists in constructing elaborate mathematical models of an infinite and eternal cosmos.

This book will no doubt be of interest to students starting to learn about the topics discussed, but would benefit from being edited into a slightly more formal style and submitted to a professional translator.

• John Harney