Billions and Billions: Thoughts on Life and Death at the Brink of the Millenium. - book reviews

Reason, July, 1997 by Kenneth Silber

For nearly two decades before his death in December 1996, Carl Sagan was arguably the most famous scientist in America. Author of numerous books and articles aimed at a general audience, host of the public-television series Cosmos, and frequent guest on The Tonight Show, Sagan addressed subjects ranging from human prehistory to the search for extraterrestrial intelligence to the consequences of nuclear war. He became virtually an all-purpose explainer of and spokesman for the scientific enterprise. His own research in planetary astronomy, respectable though it was, was distinctly secondary to his skills as a popularizer in ensuring his fame.

In many respects, Sagan was well-suited for the role of scientist-as-celebrity. His writing style was lucid, elegant, and often dramatic. At its best, it conveyed a sense of the epic quality of cosmic and biological evolution. He was an adroit public speaker who garnered attention through minor eccentricities such as the plosive "b" with which he pronounced "billions." (Yet, claims Sagan in Billions and Billions, he never mouthed the title's redundant phrase; rather, it was Johnny Carson who did so, in skits caricaturing his favorite astronomer.) Self-promotion was an obvious, and oddly appealing, feature of Sagan's public persona, as when the camera in Cosmos lingered endlessly on the host's awestruck heavenward gaze.

Sagan was an advocate as much as an expositor. He was a persuasive proponent of space exploration; unlike many astronomers, he envisioned a grand human future in space, not just a series of ever-more sophisticated data-gathering probes. He was a passionate debunker of astrology, alien abductions, channeling, and other forms of pseudoscience and irrationalism. Sagan pointed out repeatedly that widespread scientific illiteracy is a dangerous thing in a society heavily dependent on science and technology. He did more than his share to combat that danger

To be sure, at times he succumbed to the occupational hazards of the science popularizer: the oversimplification of esoteric ideas, the blurring of distinctions between speculation and established fact, and the dressing-up of personal or political views in the mantle of scientific authority. Sagan overstated the certainty of climate models showing a possible "nuclear winter," and erroneously predicted a spate of cold weather and darkened skies resulting from the oil fires of the Persian Gulf War. He also gave undue credence to the highly speculative notion, little-accepted among neuroscientists, of a "triune brain," in which the human cerebrum coexists uneasily with distinct vestiges of reptilian and early mammalian anatomy. The triune brain theory enabled Sagan to denounce behaviors of which he disapproved - such as Cold War-era defense spending - as emanations of primitive brain parts.

Billions and Billions, a posthumously published collection of essays, reflects Sagan's diversity of interests - as well as his tendency to combine brilliant scientific exposition with less-than-convincing political argument. The book is divided into three sections. The first, titled "The Power and Beauty of Quantification," contains largely apolitical essays on science and mathematics. The second, "What are Conservatives Conserving?," is a set of warnings of environmental dangers, with particular emphasis on the thinning ozone layer and global warming. The final part, "Where Hearts and Minds Collide," covers a range of topics at the intersection of science and politics, and ends with Sagan's reflections on the illness that eventually would take his life.

The book opens with its title essay, in which Sagan discusses the public's growing but imperfect familiarity with the large numbers used in astronomy, economics, and other fields. His own association with "billions" came at a time when "millions" had become a bit passe, he notes, and soon "trillions" will be commonly evoked in reports of national debts, distances to nearby stars, and more. This leads to an explanation of the workings and benefits of exponential notation in describing very large numbers. A subsequent essay elucidates the concept of exponential growth, drawing upon examples that involve chessboards, bacteria colonies, world population, and radioactive decay.

A discussion of wave phenomena, ranging from splashes in a bathtub to gamma rays in space, displays a similar inventiveness in the use of examples and analogies. Less successful is "Monday-Night Hunters," which draws links between modern sports and prehistoric survival tactics; this essay includes an odd, first-person vignette of life in the Pleistocene era. The book's first section closes with a tour of astronomy's fast-moving frontiers. Sagan sketches out current scientific evidence and speculation regarding planets in other solar systems; possible past, or present, life on Mars and Saturn's moon Titan; and the origin and fate of the universe. Sticking closely to his formal discipline, Sagan is at his most precise and authoritative.