Astrobiology : A Multi-Disciplinary Approach

Rating:
Summary: Best astrobiology textbook on the market now
Review: Astrobiology is a relatively new science. Not completely new: I've been reading astrobiology books since the 1960s. But only recently have some fairly decent astrobiology textbooks been written that picture a core of topics needed to cover the subject. These include the definition, nature, and origin of life; the development of life on Earth, the mass extinctions on Earth; possibilities of life elsewhere in the planetary system, possibilities for life to survive in outer space; changes to the Earth's environment brought about by life; the nature and evolution of consciousness and intelligent life; detection of extrasolar planets; and signatures of extraterrestrial life. They also include some astronomy: formation of galaxies, habitable galaxies and habitable portions of galaxies, formation of stars and planets in these galaxies, migration of planets, statistics on deadly collisions of big objects with potentially life-bearing planets, and the significance of risks to life such as supernovae and gamma ray bursters.

So far, no book is ideal in covering all these topics for upper division college students. But I think this one comes closest.

Since this book might be read by those who know plenty of astronomy but not much biology, or by those who know biology but not astronomy, the book begins with some needed background: fundamentals of physics, physical chemistry, and biochemistry. It then gets into the question of how the elements we're made of were synthesized in the first place. And it shows that our Universe is fairly well suited for life, even if not completely ideal.

Then we get into an important topic, the thermodynamic foundations of life. The book makes the point that one always has to be aware of the energetics of life: life needs energy, so where does that energy come from? In addition, life requires a low entropy state. Such states are not all that hard to come by, but one must know how one is achieved. And life implies a high information content. Again, one must know how to measure that content and decide where it has come from. The author makes the point that given sufficient free energy, systems not in equilibrium will exhibit self-organizing and self-complexifying properties. I found this fascinating. It was almost as though the Purpose of Life were to reduce carbon dioxide, and life were merely a side-effect of catalyzing this reaction.

Next there is a fascinating discussion of how life might have evolved. Did we start with replicators, cell boundaries, substrates, or proteins, or a little of all of them? Was there an "RNA world" before the "DNA world?" And a "TNA" or "PNA" (peptide nucleic acid) world before that? Can we have autocatalysis without replication?

After that comes a discussion of extreme environments, given that life's last common ancestor may well have been an extremophile. And then we learn about the faint early Sun, a carbon dioxide greenhouse effect on Earth, the rise of oxygen in the atmosphere, and a possible "snowball Earth." We read about possibilities of life elsewhere in our planetary system: Europa, Titan, and Mars. And we find out about techniques for discovering extraterrestrial signatures of life. There's a very good and up-to-date section on extrasolar planets.

The textbook ends with a little material on the nature of self-awareness and on future prospects for the human species and civilization. I think it is an excellent text.