Life in the Universe

Rating:
Summary: A good college text for non-science majors
Review: This book seems to have two goals. One is to teach the reader something about astrobiology. The other is to be a text for a science course for college undergraduates (in most cases, underclassmen majoring in something other than science).

The book begins by discussing how stars and planets are formed. And then comes a major point: biology may be common in the universe given evidence that organic molecules form fairly easily, life appears to have originated early in the Earth's history, and there's evidence that Earth life can survive under a wide range of conditions.

Next, there's a section on the nature of science and the scientific method. And then some material on the definition and nature of life. From there we go to the Earth's geological record. And there's a useful discussion of greenhouse gases, possible high surface temperatures on Earth when life first developed, and a possible "Snowball Earth" much later.

Now comes a key chapter: how did life get started? And when. The text shows that it was not all that long after the Earth emerged from forming and being heavily bombarded. And that hyperthermophiles may well have been the common ancestor of life on Earth today. The book speculates that the process was: synthesis of organic precursor molecules, development of replicators (RNA), development of protocells (enclosing membranes), primitive cells (the RNA world), and then DNA-based cells. It also addresses the question of whether life could have migrated to Earth from Mars or elsewhere. There's a discussion of the rise of oxygen in the atmosphere. And how primitive life evolved into the intelligent life that now exists.

These are certainly the right topics to start with. But I wish this book, even with the constraint of being for non-science majors, had gone into just a little more detail on all of them. It does just that on the rest of the topics.

The book continues with an excellent section about possibilities of life elsewhere in our planetary system, including the environmental requirements. We look at Mars (including evidence from Martian meteorites), Jovian moons, and Titan. And we see why Venus is too close to the Sun to be in the "habitable zone."

After that, there is a discussion of extrasolar planets and the serach for extraterrestrial intelligence. If anything, there is an excess of material here, including speculations about the possible technology levels of an intelligent society and interstellar travel. But this does lead to a worthwhile discussion of the Fermi paradox: if there are relatively nearby extraterrestrials, why aren't they here by now?

Writing an overview of this field for non-science majors is a daunting task, and I think the authors did a really good job. After reading such a book, I think one will find it much easier to understand any advances made in this field in the future.