American Scientist

Strangers in the Night: A Brief History of Life on Other Worlds. David Fisher and Marshall Fisher. 320 pp. Counterpoint, 1998. $25.

Worlds Without End: The Exploration of Planets Known and Unknown. John Lewis. 256 pp. Perseus Books, 1998. $24.

Life on Other Worlds: The 20th Century Extraterrestrial Life Debate. Steven Dick. 304 pp. Cambridge University Press, 1998. $24.95.

Buckminster Fuller once said: "Sometimes I think we're alone. Sometimes I think we're not." Either way, the implications are staggering. People have long been intoxicated by the idea of life beyond Earth. This age-old debate has been reinvigorated by the recent discovery of planets beyond the solar system, and by the possibility of life-supporting environments on Mars and among the moons of Jupiter. Three new books explore different aspects of the question: Are we alone?

Strangers in the Night is by the father-and-son team of David and Marshall Fisher, who wrote an eminently readable book on the invention of television. Their subjects range from martian "canals" and the wishful thinking of Percival Lowell to the possible detection of fossil life in ALH 84001—a free chunk of Mars that landed in the blue ice fields of Antarctica. They also trace the quixotic struggle to detect with radio telescopes signals from intelligent life forms.

It is rare to find a book that illuminates the scientific method while describing research on a frontier topic. Strangers in the Night succeeds in this admirably. The suspense, confusion and ultimate disappointment of the Viking experiments are clearly documented. The critique of the chemical and morphological evidence for life in ALH 84001 is thorough and balanced. Even with a dozen Mars rocks in our hands, we can be no more definitive than one eminent scientist who, in the aftermath of Lowell's observations, was asked by William Randolph Hearst to respond to the query: "Is there life on Mars? Please cable one thousand words." The scientist replied, "Nobody knows" 500 times.

It is also rare to find a book that tells the story of science so well. Strangers in the Night is rich with anecdotes and insights into the people who have struggled to make the Search for Extraterrestrial Intelligence (SETI) a respectable discipline. SETI attracts scientists who are willing to spend years sifting through radio noise on the chance of a nonrandom signal. They are also willing to risk an erratic flow of federal funding and the bemusement of their colleagues. Along the way, the authors make diverting asides. They describe the 17th-century Belgian physiologist who thought that wheat could turn into mice, the searchers for deep ocean life who risked their lives in the early bathyspheres and the scientists who vied with each other to claim discovery of the first extrasolar planets. This is an excellent read.

Worlds Without End author John Lewis, professor of planetary science at the University of Arizona, brings us a grand tour of planets, both real and hypothetical. He summarizes the diverse geology and chemistry of planetary surfaces and atmospheres and speculates as to their suitability for life. The writing is enlivened in places by wit and asides but more often tends to be dry and didactic. Occasionally, Lewis lapses into jargon; some readers may find the discussion of spin-orbit resonance, condensation sequences and eutectic melting to be rather heavy going. Patience is rewarded, however, and there is no other book that contains so much information on the diversity of planets.

Lewis starts with a brief multicultural overview of the idea of the plurality of worlds, then moves on to solar-system evolution. He describes the properties of worlds both large and small—he calls them "Earthlets" and "Earthissimos"—and makes a plea against "terrestrial chauvinism" in considering sites for life. Lewis argues that water and carbon have unique advantages for the formation of life, regardless of the planetary environment.

Worlds Without End contains some splendid examples of scientific visualization. We are introduced to Jupiter looming in the Io sky and the Earth in orbit around an M-dwarf sun, the star a mud-red point of light and our atmosphere chilled and collapsed to a 10-foot snowbank of frozen nitrogen and oxygen. The first extrasolar planets were discovered in orbit around a pulsar—a most implausible location. Our imaginations probably limit us when we consider worlds beyond ours.

Life on Other Worlds by Steven Dick updates and abridges his earlier book, The Biological Universe. Dick is a noted historian of science at the U.S. Naval Observatory. The tone of the book is authoritative, the scholarship impressive. Like Lewis, Dick writes in a textbook-like style, with a passive voice and in prose that needs a better cadence. Like the Fishers, Dick begins with a brief historical overview and a chronology of the search for life on Mars. In hindsight, it is remarkable that a series of innovations—larger telescopes throughout this century, remote analysis by the Viking landers in 1976 and lab study of samples in the 1990s—have failed to clear up this mystery.

Dick also details the many false dawns in the search for extrasolar planets. This rocky history might easily be forgotten in the triumphal progression of results from the Doppler technique in the past few years. Life on Other Worlds shows clearly how state-of-the-art observations can be misleading and how some data are only meaningful in the context of a theory. Science progresses, but it is less a stately march than the lurching progression of a drunkard.

There is an enjoyable section on aliens as imagined in the worlds of literature and film, and as represented in the popular culture by the UFO phenomenon. More extensive surveys of science fiction in print and on screen have been published elsewhere, but Dick's analysis is acute. He takes his fellow scientists to task for not engaging in the debate, thus leaving the field open to charlatans, mystics and the uncritical scrutiny of the media. Aliens are now so firmly planted in the public consciousness that polls show little support for SETI, because most people think we already know the answer! SETI is based on two great leaps in the dark. The first is the idea that intelligence is a necessary (or at least plausible) consequence of biological evolution. Life scientists tend to be skeptical because of the contingency that occurs at every stage of life's evolution on our planet. The second is the belief that radio communication is the correct strategy for a search. This assumption is rarely questioned, but the entire enterprise hangs on its plausibility.

Having covered an impressive amount of ground, Dick concludes with the cultural and religious implications of making contact. Given our present ignorance, these debates inevitably have the flavor of pure philosophy. SETI's strongest tether in the scientific method is the appeal to empiricism made by pioneers Giuseppe Cocconi and Phillip Morrison in 1959: "The probability of success is difficult to estimate; but if we never search, the chance of success is zero."

Although these books ask whether we are alone, they do not address an equally relevant question: Why are we so lonely? Life in the universe is the field where science and the popular culture meet—where biologists and engineers follow in the footsteps of mystics and dreamers. SETI has acquired the status of a modern scientific religion. Contact with a superior civilization has become a metaphor for salvation. In the absence of hard data, everyone has an opinion. Perhaps the best answer to Enrico Fermi's famous question "Where are they?" was given by his Hungarian-born colleague Leo Szilard, who said, "They are among us, but they call themselves Hungarians." It may turn out that the universe is teeming with anaerobic bacteria, but we are the only planet burdened with existential angst. Meanwhile, SETI practitioners are buoyed by an unshakeable optimism.

Perhaps when we finally get welcomed into the galactic club, optimism will prove to be humanity's most endearing quality. Nearly 2,000 years before Galileo, Epicurus was free to speculate: "There are infinite worlds both like and unlike this world of ours.… In all worlds there are living creatures and plants and other things we see in this world." For most of this century, we have known of the 40 billion stars that make up our galaxy, but there has not been a scrap of evidence that they would offer any more companionship than a glow in the night sky. Science may finally provide some answers.—Chris Impey, Steward Observatory, Tucson