An exuberant, provocative look at the possibility of extraterrestrial life, what it might be like, and what it might mean.
In his opening pages, Grinspoon (Astrophysics and Planetary Science/Univ. of Colorado; Venus Revealed, 1997) lays down the history of scientific interest in life beyond Earth, from the discovery that the planets are worlds like ours to the many theories that those other worlds might be inhabited. The second section summarizes scientific opinion on ET life, especially as seen by the new discipline of astrobiology. Our knowledge about life is confined to specimens from our world, Grinspoon reminds us; discovery of even one organism on another world would dramatically alter our perspective. He points out that the Drake equation, meant to estimate the prevalence of life in the universe, depends heavily on the expected lifetime of advanced civilizations. On the other side of the debate, Fermi’s Paradox states the key problem: if intelligent life is common in the universe, why can't we detect it? Grinspoon devotes some attention to possible answers, from the worst-case scenario (we are alone in the universe) to the possibility that ETs are already here, secretly making contact with selected humans. The third portion explores the far fringes of the subject, from UFO conspiracy theories and abductions to crop circles and mutilations of farm animals. The author resists the temptation to look down his nose at the true believers, pointing out that organized skepticism often has trouble recognizing truths that don’t conform to the scientific model. He concludes with the suggestion that our civilization could be a mere stepping stone to some higher form of consciousness, and that truly advanced life forms may be immortal. Wisecracks, philosophical musings, and personal anecdotes make his text as lively as it is authoritative.
The best look at this subject since Carl Sagan’s Cosmic Connection (1973).