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The Universe and Carl Sagan


Keay Davidson

Skeptical Inquirer Volume 23.6, November / December 1999

Few people ever extolled the wonders of science with more eloquence or were as effective in defending reason and campaigning against pseudoscience as Carl Sagan. A polymath prodigy and visionary interdisciplinary scientist with lifelong passions for planetary astronomy, the origins of life, and seeking extraterrestrial intelligence, Sagan turned his early enthusiasms about UFOs to rigorous but open-minded skepticism. An excerpt from a new biography, Carl Sagan: A Life.

All his life, Carl Sagan was troubled by grand dichotomies—between reason and irrationalism, between wonder and skepticism. The dichotomies clashed within him. He yearned to believe in marvelous things—in flying saucers, in Martians, in glistening civilizations across the Milky Way. Yet reason usually brought him back to Earth. Usually; not always. A visionary dreams of a better world than this one. He refuses to think that modern society and its trappings—money, marriage, children, a nine-to-five career, and seemingly blind obedience to a waving flag and an inscrutable God—are all that there is. Sagan was blinded, but not by these. He was blinded by the sheer glory of the new cosmos unveiled by science during the first two decades of his life. This cosmos was an ever-expanding, unbounded wonderland of billions of galaxies. And across the light-years, Sagan dreamed, random molecular jigglings had perhaps spawned creeping, crawling, thinking creatures on alien landscapes bathed in the glow of alien suns.

This vision blinded Sagan, sometimes, to the needs of the people around him. These included friends who worshipped him, although he hurt them; wives who were entranced by his passions, although enraged by his absenteeism and oft illogical “logic”; sons who were enthralled by his example, even as they struggled to escape his shadow; and colleagues who envied and honored him, even while they scorned his wilder notions and mocked his pomposities. Hardly anyone who knew Sagan intimately has an unmixed opinion of him. In the final analysis, he was the dichotomy: the prophet and the hardboiled skeptic, the boyish fantasist and the ultra-rigorous analyst, the warm companion and the brusque colleague, the oracle whose smooth exterior concealed inner fissures.

To Sagan, the rationale for his broader interests was simple: He refused to pigeonhole himself. He apparently sensed that the coming space age would be radically interdisciplinary: astronomers would have to talk to biologists and chemists and geologists and atmospheric physicists and many other experts whom they normally ignored. Hence he trained himself in subjects unrelated to astrophysics—in particular, biology, which was the topic closest to his first love, extraterrestrial life.

Rare is the scientist with world-class understanding of two broad disciplines—say, astronomy and biology. Sagan was one of the rare ones. The Hutchins program [at the University of Chicago] gave him the confidence to straddle disciplines. He traced this confidence to a biology course in which, he recalled, “there were only three topics. The first was enzyme chemistry; the second was diabetes; and the third was the physiological concomitants of the expression of emotions.” True, this selection of biological science “was unrepresentative—no Darwin, no genetics!” Yet the class explored those three topics so deeply—“we read diabetes papers published that very year”—that he evidently concluded that he could understand any topic he wished, if he worked hard enough. Millions of readers would later enjoy the results: a hyperpolymath conversant with astrophysics, biology, neuroscience, primate communication, atmospheric physics, geopolitics, nuclear strategy. . . . Sagan was the multidisciplinary scholar par excellence, the “Renaissance man” so uncommon in the age of specialization, of industrialized academia, where the divisions of labor are as real as in Henry Ford’s factories.

Why did an established scientist like H.J. Muller spend time with this impatient New Jersey teenager who had a short attention span for tedious research and was obsessed with UFOs and aliens? Muller was a generous man. For all the disappointments of his life—betrayed by a political ideology, revolted by Hitlerian perversion of the eugenic ideal—Muller clung to his socialist ethics, which cherished “ordinary” people, however unschooled and immature.

His kindness rubbed off on Sagan. Though later in life, after he had become famous, Sagan struck many colleagues as arrogant; he almost always displayed patience and good humor when addressing laypeople. After Sagan’s death, his friend Paul West published a novel, Life with Swan (1999), which featured a blatantly Saganish character, one Professor Raoul Bunsen, who, West wrote, was “as willing to answer stupid elementary questions as to formulate, almost as masochistic exercise, questions nobody could answer.” A true science popularizer must have a democratic soul; he cannot afford to feel contempt for his audience. Otherwise, why bother popularizing? As Sagan’s fame grew, he became accustomed to standing at a podium and listening as an audience member stood and asked him a question about UFOs or astrology or other silliness. Then, typically, Sagan responded firmly but politely, trying to make the questioner feel intelligent, not like an ignoramus. Any other speaker might have snapped, “That’s the dumbest thing I ever heard.” But Muller wouldn’t have said that; nor did Sagan.

Carl Sagan rejected religion from an early age. In the early twentieth century powerful forces of secularization were sweeping through American Judaism (as through all Western culture). The Holocaust caused some Jews to reject God altogether: what deity would have permitted such a horror?

Sagan celebrated his bar mitzvah at age thirteen. “But in exactly that period when I was sort of seriously reading the Bible,” he recalled, “I found all sorts of obvious contradictions with reality. [For example], two different, contradictory accounts of the origin of the world in Genesis. . . . That propelled me away” from religion. Previously, he had soured on Edgar Rice Burroughs’s Mars novels because they contained logical inconsistencies. Now he started looking for similar inconsistencies in the ancient texts that had given hope to billions. Were they just old wives’ tales? He learned the Bible well. As an adult, debating preachers about religion, Sagan often startled them with his ability to cite passages by chapter and verse.

Sagan’s religious doubts upset his mother Rachel. Despite her flinty skepticism about most matters, she trusted in the unseen world. Her faith gave her a sense of stability. Now her only son—her future genius!—was rejecting the faith of his fathers? Their religious quarrels, Sagan later admitted, were “traumatic” because for Rachel “there were a lot of emotional, traditional connections” at stake. “There was a time,” he recalled, “when my mother and I would have, I guess, ‘fights,’ on this issue. It only lasted a year.” Then Rachel realized it was “hopeless” for her to try to change Sagan’s mind, and they stopped fighting.

Sagan’s loss of faith intersected neatly with his growing fascination with extraterrestrial life. He had rejected a supernatural explanation of the origin of life (and everything else); therefore he needed to find a scientific one. A great deal was at stake: If life emerged easily by mechanistic means on Earth, then it might be very common in the heavens; if it emerged with difficulty, then very rare. This stirred his interest in the scientific study of the origin of life. Until the early 1950s, such study was almost nonexistent; there had been theoretical papers published here and there, and a book or two, but not much else. While his teenage peers read Mickey Spillane and J.D. Salinger, Sagan turned to physicist Erwin Schrodinger’s What Is Life? (1946) and chemist A.I. Oparin’s Origin of Life (written in the 1920s and published in English in 1938).

In late 1951, when Sagan entered the University of Chicago, another entrant was Stanley Miller, a 21-year-old first-year graduate student fresh from the University of California at Berkeley. That autumn, Miller attended one of Harold Urey’s lectures. The chemist explained his theory that early Earth had a hydrogen atmosphere, in which the chemical building blocks of life could have easily formed. Perhaps (Urey noted) lightning bolts provided the energy that caused the early hydrogen-rich molecules, methane and ammonia, to assemble into organics. It’d be interesting, Urey added, if someone would demonstrate this experimentally—that is, by simulating the atmosphere of the primitive Earth in a flask. (Melvin Calvin of Berkeley had tried to, but used the wrong atmosphere, one too rich in carbon dioxide and water vapor.)

Miller was intrigued. He had been looking for a subject for his doctoral thesis, and this one sounded exciting. He approached Urey and asked for permission to do the experiment. Urey reacted cautiously, warning Miller that this was a risky project for a dissertation. But Miller persisted, and Urey finally went along—on one condition. If Miller failed to obtain interesting results within a year, then he had to find a different thesis topic. Miller agreed.

In Miller’s experiment, carbon (C) was available from methane (CH4), nitrogen (N) from ammonia (NH3), oxygen (O) from water (H2O), and hydrogen (H) from all three. An electrical discharge would break the molecules apart, possibly causing them to rearrange into organics.

About this time, H.J. Muller had written a letter to Urey, his fellow Nobelist, and urged him to meet Sagan. They did meet, and during their chat Urey mentioned Miller’s experiment. Intrigued, Sagan visited Miller in his dungeon-like basement lab. In the “dungeon,” Miller filled a flask with methane, ammonia and water. Miller then switched on the “sparking” device and left for the night. The next morning Miller examined the flask: The water within had turned “noticeably pink.” Inside were hydrocarbons—chains of carbon and hydrogen atoms. He let the sparking device run for another two days. The result: a scummy layer that, upon analysis, proved to contain an amino acid called glycine. Finally Miller let the experiment spark for a week, after which he found many more types of amino acids, including unknown types. This was a startling result. Previously, skeptics had argued that the building blocks of life could no more self-assemble into complex organics than a windstorm could turn a forest into wooden homes. Yet that is exactly what Miller appeared to have done, in an experiment mimicking presumed conditions on the primordial Earth.

News media jumped on the story. The experiment delighted that tough old Marxist, Haldane, who reportedly said he could “die happy now.” Some reporters interpreted the experiment as a latter-day version of the creation of the Frankenstein monster. Of course, Miller hadn’t created life—only its molecular building blocks. Still, a 1953 Gallup Poll asked Americans if they thought scientists would eventually create living creatures in the laboratory. Seventy-nine percent replied “No.”

Miller described his results in a seminar at the University of Chicago, with Urey present. Sagan sat in the audience. During the question period, Sagan later recalled, other professors didn’t seem to appreciate the importance of Miller’s experiment, and his results were “roundly condemned by nearly every faculty member that made a comment.” As he watched Urey try to defend Miller, and saw how nervous Miller was and how heated the discussion got, Sagan realized for the first time just how emotionally intense research could be.

Miller recalls the scene differently. Now in his late sixties, bustling, bespectacled and ebullient, he remains active in origin-of-life work at the University of California at San Diego. “What Carl didn’t realize” Miller says, “was, it wasn’t that they didn’t understand the importance, it’s just that they couldn’t believe the results!” All those amino acids! Thick coats of them! It seemed almost too easy. Almost a century after Pasteur claimed to shut the door for good on mechanistic explanations for life’s origin, young Stanley Miller had reopened it.

Sagan’s persistent interest in life’s origins was matched only by his persistent interest in UFOs. At least as late as mid-1954, when he was a college junior, he suspected they might be extraterrestrial vehicles, and he tried to persuade Muller of this. The Nobelist countered (perhaps tongue in cheek) by citing one “saucer” report that suggested UFOs were Soviet-built. Sagan replied, in a letter dated January 27, 1954, that there was no reason to believe that all UFOs were of Soviet making. In defense of his position, he pointed out that legitimate sightings had occurred much earlier than when the Soviets came to power. He also argued that the Soviets would not take the risk of flying their saucers over U.S. territory, where many sightings had happened, because if one crashed or was shot down and its origin was discovered, that might start a war. In addition, some of the saucers had been observed making flying maneuvers that would require materials much stronger than anything on Earth and which a human being would not be able to survive.

That letter was Sagan’s last known defense of UFOs. Thereafter, his faith was shaken by two books—Fads and Fallacies in the Name of Science (1952) by Martin Gardner (another University of Chicago graduate, and later the mathematics editor of Scientific American) and Extraordinary Popular Delusions and the Madness of Crowds (1841) by Charles Mackay.

Fads and Fallacies was a founding tract of the modern “skeptics” movement. Breezily and wittily, Gardner details the pseudoscientific beliefs of anti-Einstein theorists, pyramidologists, medical quacks, psychic researchers, “orgone” therapists, L. Ron Hubbard (founder of Dianetics and its far more profitable descendant, Scientology), and crank cosmologist Immanuel Velikovsky, among others. While enjoying Gardner’s account, Sagan was startled to find that it included a devastating chapter on UFOs.

Mackay’s book didn’t deal with UFOs—it was written a century before the saucer craze. Still, Sagan drew major lessons from Mackay’s accounts of the repeated instances in which humans have been gulled by false notions, ranging from get-rich-quick schemes to fortune telling. Gradually, Sagan began to recognize what flying saucers really are: not a physical phenomenon, but a psychological and a sociological one. “It was stunning,” Sagan later reflected, “how many passionately argued and defended claims to knowledge had amounted to nothing. It slowly dawned on me that, human fallibility being what it is, there might be other explanations for flying saucers.”

In time, Sagan would become a devastatingly effective critic of the UFO cult—indeed, of the flood of pseudoscience and superstition engulfing America in the second half of the twentieth century.

At Harvard, Sagan would become a nationally known scientific figure—not famous, exactly, but getting there. With James Pollack, he would study the atmosphere and surface changes of Mars and propose a radical new view of their nature. They would also elaborate and defend Sagan’s embattled theory of the Venusian greenhouse effect. In time, these two men—with remarkably similar backgrounds, yet remarkably different personalities—would be one of the great “duos” of modern space science.

Also in the mid-1960s, the mass media began exploiting Sagan. He was not a complete unknown to journalists; his name had appeared in national newspapers and magazines at least as far back as 1956, late in the first term of the Eisenhower Administration. He had even appeared on a television broadcast about Venus, where he impressed viewers with his dualistic lecturing style: darkly serious, contagiously enthusiastic. But his real publicity breakthrough came in 1966, with the publication of his book Intelligent Life in the Universe (coauthored with the Russian astronomer I.S. Shklovskii). About this time, Sagan served briefly as an adviser on the film 2001. Dining with the film’s creators, he acquired his first taste of Hollywood.

Simultaneously, he rediscovered an old love: UFOs. In 1965–66, a wave of UFO sightings swept the nation. The resulting media hoopla sparked congressional and scientific investigations. Reporters called Sagan for the scoop on saucers. A Walter Cronkite television special on UFOs included a clip of Sagan, a dulcet-toned oracle of scientific wisdom. He offered journalists an amiably skeptical stance on UFOs—an engaging alternative to the harrumphy finger-wagging of astronomer Donald Menzel, the era’s only other well-known saucer skeptic. (By that time J. Allen Hynek had ceased to be very skeptical!)

When it came to extraterrestrial life, Sagan didn’t follow a dogmatic “party line.” Sometimes he argued that it was possible (as when he espoused lunar life, balloon animals in the skies of Venus and Jupiter, and polar bear-sized creatures on Mars). Other times he shot down arguments for exobiology (as when he showed that Venus is too hot for life). An example of the latter is his explanation for the Martian “wave of darkening.” Until the mid-1960s, many astronomers regarded the wave of darkening as evidence for Martian vegetation change. Yet Sagan and Pollack discovered its true nature, which was nonbiological. It’s ironic: Sagan blew away the last indirect evidence for Martian life even as he struggled to convince Americans to support Mars missions. He was a complicated man.

The Sagan-Pollack theory of Mars surface changes should also interest scholars who study how scientific ideas evolve. In recent decades, many historians and philosophers of science have claimed that scientific “objectivity” is a myth. They argue that scientists—like most of us—follow their hearts, not their minds; their desires, not the data. And this is certainly true, much of the time. Still, when it came to the nature of Martian surface change, Sagan followed his mind, not his heart.

During Sagan’s first decade at Cornell, he would show up all the snobs and green-eyed detractors at Harvard. He became the preeminent voice of American space science, a national (later international) celebrity visible enough to attract his first nonscientific critics. Meanwhile, he continued doing science as he liked to do it: by flitting, butterflylike, from flower to flower. Not for him was the life of the pigeon-holed academic who becomes a world-class expert on T-Tauri stars but knows nothing about the Big Bang. Nor for him was the stoic seclusion of the scholar, who takes bitter pride in refusing to popularize his life’s toil on the reproductive strategies of carp. Sagan liked talking to reporters. He had liked being on stage, in the spotlight, ever since high school, when he delivered Thurber’s bons mots to an audience of proud parents.

True, Sagan worked too hard. He did too much. His scientific accomplishments might have been less arguable had he restricted himself to one or two main fields and diligently plowed them until it was time to abandon all hope and become chair of the department. He bit off more than he could chew—and thus enjoyed one wonderful banquet after another, while his colleagues picked at their beets and parsley. In the process, Sagan befriended many fascinating fellow diners. His scientific lone-wolf days (for example, when he taught himself greenhouse theory) were over. Increasingly, he relied on collaborations, usually transient ones. The results were sometimes scientifically significant, or at least headline-grabbing. They ranged from his work with George Mullen on the role of ammonia in the early atmosphere to his Astrophysical Journal article with E. E. Salpeter on the hypothetical “balloon animals” of Jupiter. He maintained close collaborations with a chosen few, particularly Jim Pollack and Bishun Khare. With Pollack, Sagan would erect an impressive edifice of research on the Venusian atmosphere. And with Khare, he would develop an iconoclastic view of cosmic organic chemistry, one centered on inexplicable brownish smears that he dubbed “tholins.”

Also in the 1968–78 decade, Sagan cultivated his nonscientific side. He had just married an artist; she helped him tap his inner feelings, instincts, intuitions. Though he felt awkward in social situations at Harvard, his social skills blossomed after he moved to Cornell. Perhaps in this less stuffy setting, he felt free to let his idiosyncratic conversational style out of the box. Eventually, he would become a Noel Coward of science, a man for whom bold articulation and quickness of wit were absolute virtues. His eyes shone as he dominated a conversation, and deservedly so, for he typically knew more about the topic at hand—and discussed it more suavely—than anyone else present. At the same time, he listened as well as he talked. During intense conversation, his dark eyes gazed at you as if you were the sole other sentience in the cosmos. If you anxiously described the sorry state of your own research, he generously offered tips and suggestions—often crazy ones, but occasionally brilliant ones, too. History does not record how many intellectual Gordian knots were cut by Sagan’s razor-sharp tongue at wine and cheese faculty gatherings; there were more than a few. And he remembered what you said with almost photographic precision; months later, he recalled your statements as accurately as if he had tape-recorded them. When he entered a room, the conversational level noticeably improved, as it must have in Oscar Wilde’s day when he sauntered into a salon. Through conferences jammed with colleagues Sagan floated, beaming and chatting and joking; he was a six-foot-two gravity well toward whom everyone naturally gravitated. He was fun. “Hey, Carl is here!” It would be an overstatement to say that everyone loved him, for his bluntness upset many and his talent many more; in any case, he rarely failed to cause excitement.

Sagan flexed his new-found artistic muscles in his breakthrough bestseller, The Cosmic Connection. He became a TV star, the upbeat educator of sleepy-eyed millions viewing The Tonight Show. During the Viking mission, he was the TV networks’ favorite “talking head,” whose playful speculations about an inhabited Mars maddened his colleagues but titillated viewers. And like a performance artist with a NASA-sized budget, he engaged in grand forms of self-expression: he sent “messages” to aliens aboard star-bound space probes, the Pioneers 10 and 11 and the Voyagers 1 and 2.

Sagan was a contradiction. To critics like Urey, the young astronomer was a reckless speculator. But to laypeople absorbed by pseudosciences and occultism, Sagan was the Dark Prince of skepticism—the party pooper who coldly shot down their ideas about UFOs, psychic phenomena, and other silliness.

By the 1960s, Sagan had long since rejected the thesis that UFOs are extraterrestrial spaceships. Yet he could not quite put the subject out of his mind. Like a disappointed lover, he continued to hang around this subject. He discussed it with reporters, testified about saucers before Congress, served on an Air Force UFO panel, personally investigated lurid UFO reports, and starred in the first scientific “debate” on the subject. Sentimental journeys, all.

Sagan served on an Air Force UFO advisory panel, the O’Brien committee. The committee (named for its chief, scientist Brian O’Brien) evaluated the Air Force’s official saucer project, Blue Book. Although depicted in a subsequent TV series as an expensive, computerized outfit, Blue Book was in fact a backwater operation, with a few staffers and filing cabinets crammed into an office at Wright-Patterson Air Force Base. Blue Book was primarily for show. The Air Force had not taken UFOs seriously for years but felt it had to keep up appearances to deal with inquiries from UFO-titillated members of Congress and their constituents. If UFOs represented an unknown physical phenomenon, Blue Book would never figure it out. So Sagan and the rest of the O’Brien committee advised the Air Force to commission an independent, full-scale scientific study. The result was the controversial Condon Commission, chaired by noted physicist E.U. Condon.

Meanwhile, Sagan conducted private investigations of the UFO mania. In 1966, the first UFO “abduction” was described in journalist John G. Fuller’s book The Interrupted Journey. Fuller (who also wrote about “ghosts” seen on airplanes) said that one night in the early 1960s, when Betty and Barney Hill were driving through New Hampshire, they noticed a distant UFO. The next thing they knew, several hours had passed and they couldn’t recall what had happened. They consulted a Boston psychiatrist, Dr. Benjamin Simon. He hypnotized them. Under hypnosis, they claimed that UFOnauts had stopped their car and taken them aboard a saucer, then subjected them to medical examinations.

Sagan spent a “fair amount of time” with the Hills and Simon. The psychiatrist suspected that the Hills’ story was an innocent dual hallucination, perhaps related to the stresses of their marriage, which was interracial—an extreme novelty at that time. (Decades later, Sagan was baffled to watch as his Harvard friend Dr. John Mack, a noted psychiatrist and author, became a leading defender of the validity of UFO abduction claims.) In the mid-1960s, at least one respectable American scientist, James McDonald, a professor of atmospheric physics at the University of Arizona, claimed that UFOs were alien spaceships. McDonald met with Sagan and his fellow member of the Order of the Dolphin (a SETI group), MIT physicist Phil Morrison. “I spent many hours with Jim McDonald,” Sagan later wrote to UFO investigator Walter N. Webb, adding that he saw no reason to believe that there were any sightings that were credible evidence of extraterrestrial visits.

McDonald’s data was “pitiful,” Morrison recalls. McDonald showed them “pounds and pounds” of data, including news clippings and tape recordings, about a UFO sighting on Long Island. The witness—a naval architect—drew a sketch of the “saucer.” One thing puzzled Sagan and Morrison: the saucer had rivets on its side. “Are we really to believe this?” they asked McDonald. “Look at the rivets that cross the plates here. Do you suppose [aliens] use rivets? Don’t you think [the witness] is drawing on his long experience in the Navy yard?” In retrospect, Morrison says of McDonald, “it was distressing that a serious scientist, a good man, would get involved in such research.” Like Brian O’Leary, John Lilly, Timothy Leary, J. Allen Hynek and a few other renegade scientists of the 1960s and 1970s, McDonald had heard the siren call of the unknown and would pursue it to the end—in his case, to suicide.

There are celebrities, and then there are Celebrities. Before The Tonight Show, Sagan was slightly known to a small percentage of Americans who had caught his sound bites on TV or read Intelligent Life in the Universe. After The Tonight Show, he became America’s best-known scientist. Sitting in bed at 12:45 a.m., insomniacs watched Sagan with growing excitement. This was no tweedy Mr. Science, filling beakers with smelly chemicals on a black-and-white TV image from the 1950s. Rather, this was a Mr. Science for the hip, disillusioned early 1970s, a boy-man with a startling basso profundo voice, one who kept his cool yet laughed merrily (sometimes at a startling high pitch). Sagan was, simply speaking, sexy, in a sense that transcends mere sexuality.

The young went on alert. Until that moment, the space program offered no convincing heroes for disaffected, anti-establishment, long-haired, pot-smoking college students. To them, astronauts were cornball patriots in crewcuts, blood brothers of the militarists then napalming Vietnam. But Sagan was different: he was youthful-looking (like the class president, but in a fun way). Perhaps he was a secret would-be hipster—the kind of guy who, if handed a joint, might look surprised, then accept it with a laugh and politely try it, coughing afterwards. (In fact, he was secretly an enthusiastic smoker of marijuana.) In college dorms from coast to coast, students (like this writer) didn’t stay up until 1:00 a.m. to watch Dinah Shore plug her golf tournament. They stayed up to see Carl Sagan.

On Sagan’s first appearance—November 30, 1973—he and Carson discussed what we might want to say to an alien civilization if we ever did contact one, and also the far-out pseudoscientific theories of writer Erich Von Däniken, who had been on the show the previous night. Carson and Sagan were perfect together: Carson bubbled with enthusiastic questions, and Sagan had all the answers.

Over the next thirteen years, Sagan appeared on the Carson show twenty-six times—an average of twice a year. He once explained why he made every effort to fulfill an invitation to appear on the show—because it gave him the biggest classroom in the country.

In Other Worlds, Sagan lit into pseudoscientists such as Erich Von Däniken, whom he had criticized before, and Immanuel Velikovsky. Von Däniken wanted to rewrite the history of humanity: He claimed that aliens were responsible for the pyramids and other historic artifacts. Velikovsky was even more ambitious: he wanted to rewrite the history of the whole solar system.

In 1950, Velikovsky had published a sensational book, Worlds in Collision. It argued that thousands of years ago, Venus was a comet. This comet was somehow ejected from Jupiter, as a tennis ball is shot from an ejector. After its ejection, Venus then barreled around the inner solar system like the ball in a pinball machine. It careened past Earth, triggering apocalyptic events and inspiring scary legends of doom, disaster, locusts, and so forth. While Moses was leading his people out of Egypt, Velikovsky asserted, the comet flew by and exerted mysterious forces on Earth, with the result that the Red Sea parted. Eventually—like teenage hoodlums in the B-movies of that era—Venus calmed down and settled into its present middle-class, predictable orbit.

Velikovsky based his hypothesis on ancient manuscripts and legends that, he said, recorded these apocalyptic events. He claimed that very old astronomical records did not mention the planet Venus—and naturally not, because Jupiter hadn’t ejected it yet! He also insisted that his hypothesis predicted certain celestial phenomena, including the great heat of Venus (a result of its violent ejection from Jupiter), which had been observed by Mariner 2. Velikovsky’s claims led to his showdown with Sagan, who, of course, had his own ideas about the Venusian hothouse.

Worlds in Collision blatantly violated the laws of physics. Although Velikovsky had certain scholarly credentials (he was a Russian-born psychoanalyst), he “had only the vaguest understanding of such basic physical principles as conservation of angular momentum, gravity, and entropy,” wrote the physicist Lloyd Motz, who was on friendly terms with him. Velikovsky described celestial objects behaving in ways that they simply cannot behave—unless something is terribly wrong with modem physics textbooks. For example, Motz noted, to expel Venus, Jupiter would have had to “release or expend in a matter of seconds or minutes as much energy as our Sun emits in more than a year.” Such an eruption would have expelled enough energy in those few seconds to have vaporized most of the planets, including Earth.

When physicists cited these huge discrepancies between Velikovsky’s hypothesis and physics doctrine, he shrugged and replied that his historical research showed that celestial objects behave in previously unknown ways, and that therefore it was physics that would have to change to accommodate his findings. Throughout history, of course, scientists have proposed radical new theories that violated the commonsense physics of their time, yet proved (on the whole, despite some technical errors) to be correct. Copernicus’s heliocentric hypothesis is one example; another is Alfred Wegener’s concept of continental drift. In both cases, physics was modified to accommodate the heretical idea.

Velikovsky’s theories, however, do not even fall into the category of science. Archaeologists and ancient historians have totally repudiated his interpretations of ancient records. Even if the records backed him, his predictions and calculations are not of the rigor that true science requires.

How does one distinguish a bona fide scientific hypothesis from a pseudoscientific one? The classic response is that of philosopher Karl Popper, that no hypothesis can be considered “scientific” (which is not necessarily the same thing as saying it is “true”) unless it generates predictions that are conceivably disprovable (“falsifiable,” in Popper’s term).

Velikovsky’s work raises two key questions: Were his original hypotheses conceivably falsifiable? And have they subsequently been falsified or verified by astronomical observations? If falsifiable but verified, then our knowledge of astrophysics must be seriously incomplete. If not falsifiable, we can confidently toss his notions into the historical wastebin along with dusty tracts on phrenology, spiritualism, sea monsters and other flummery.

A hallmark of pseudoscientific hypotheses is their vagueness and malleability: their proponents always manage to think up ad hoc ideas to “explain away” discrepant data (for example, the “Mars face” enthusiast who claims NASA hides photos of the “face,” the parapsychologist who blames negative results on “bad vibes” from skeptical observers, and so forth). Occasionally ad hoc explanations turn out to be correct, but the burden of proving them must rest on their proponents. Orthodox scientists are simply too busy wrestling with acknowledged mysteries to waste time chasing will-o’-the-wisps (especially those proposed by scientific ignoramuses that brazenly transgress well-established scientific principles). Yet Velikovsky—despite his obvious ignorance of physics—angrily insisted that the burden of proof lay on his critics. It was not his job to prove his theory; it was their job to disprove him.

Velikovsky and his reverential fans presented Sagan with a challenge that, in his newly emerging role as defender of the scientific faith, he simply could not refuse. Sagan decided to combat Velikovsky in something of a scientific duel—a public debate in which Velikovsky could make his case, while a panel of scientists, Sagan included, could critique them.

This was a radically different way to confront pseudoscience. True, the UFO symposium at the AAAS symposium of 1969 had pitted UFO advocates against detractors, but all were bona fide physical scientists. Velikovsky, by contrast, had no significant training in the physical sciences; his books implied that the “expertise” of his critics was a sham, that his historical scholarship was just as valid a source of knowledge about the natural world as their professional training in physics and astronomy. In other words, the Sagan versus Velikovsky debate promised to be a particularly extreme form of “turf battle”—a fight over who deserves recognition as an “authority” in a given subject. The history of science is full of such turf battles; they often decide the fate of fundamental ideas.

The Velikovsky debate certainly differed from the usual old-fashioned scientific responses to pseudoscience: ignore it or suppress it. Sagan—a fierce devotee of free speech—believed that astronomer Harlow Shapley’s boycott of Velikovsky’s initial publisher had been unjustified. The AAAS public debate would constitute, in effect, an apology to Velikovsky, giving him the opportunity to submit ideas to direct scientific scrutiny. The debate’s ultimate goal was not to reassess Velikovsky’s ideas (hardly any scientist took these seriously) but, rather, to reassure the public of science’s basic fairmindedness, at a time when a growing number of leftists and academics were depicting it as intellectual camouflage for ideological and social prejudices.

Some AAAS members, of course, opposed holding the debate. “Certain powers in the AAAS didn’t want the symposium to happen,” recalls Sagan’s friend Don Goldsmith, an astronomer who helped organize the debate. “They felt, ‘We’ve had enough bullshit from this guy [Velikovsky]. AAAS is for science, this is non-science.’” However, the AAAS president at the time, Margaret Mead, thought the symposium would be worthwhile. She was an anthropologist famous for her affectionate studies of non-Western culture, and she apparently viewed the pseudosciences as many social scientists do—as generally harmless alternative perceptions of reality, which should be tolerated (if not accepted) as one might tolerate, say, Azande cosmology or Eskimo marriage rituals. Besides, Mead was quietly interested in fringe science. In 1969 she had pushed the AAAS to accept the Parapsychological Association as an institutional member; late in life, she served on the board of J. Allen Hynek’s Center for UFO Studies. Says Goldsmith: “Whereas physical scientists thought, ‘why should we give this bullshit a hearing?’, Margaret Mead was of the anthropological bent. . . . She felt this might be interesting whether it’s true or not.”

The symposium was held on February 25, 1974, in the Grand Ballroom of San Francisco’s St. Francis Hotel. There were seven speakers, two of them pro-Velikovsky—Velikovsky himself and the Illinois scientist Irving Michelson. (There were only these because no other pro-Velikovsky scientists could be found.) The room was packed. As Don Goldsmith recalled, “It is hard to outdo the spectacle of a seventy-seven-year-old gentleman rising to confront the critics who had rejected him for scores of years, with his supporters in the audience cheering his wit and hissing at his opponents, while his detractors sat applauding and protesting in opposite phase.”

The astronomer Dale Cruikshank attended the debate to see what he calls the “clash of the titans”—Sagan versus Velikovsky. And indeed it was Sagan who dominated on the anti-Velikovsky side. “I’m not sure who won on the arrogance side, but they were both in top form,” Cruikshank recalls wryly. Velikovsky “was an elderly man, tall and slender, big head of gray hair, and he sort of swept in with two or three people in his entourage, each of them carrying a big bundle of papers. And whenever he would snap his fingers somebody would run up with another document to support the point he had just made.” During his address, Velikovsky presented the full set of his so-called “predictions” and then declared defiantly that “Nobody can change a single sentence in my books.” His supporters in the audience stood and applauded.

Sagan was coolly composed by comparison. In the view of many present, his talk was a blend of intense analysis and amiable wit, with imaginative arguments so compelling that they seemed unanswerable. One of his key points was that Velikovsky’s most heralded “prediction,” that Venus was hot, was not a prediction in any meaningful sense of the word. Velikovsky claimed that he had anticipated Venus’s great heat long before the Mariner 2 space probe flew by the planet in 1962 and gathered data to that effect. The trouble with this claim is multifold. First, Sagan pointed out, Velikovsky never defined precisely what he meant by “heat.” To say Venus is “hot” is like saying the Sun is “big.” How hot? A specific temperature is not needed—just a range will do: say, 600 to 800 degrees Kelvin? Yet Velikovsky never provided this. Second, Sagan highlighted, Velikovsky never provided a convincing explanation of why Venus would be hot. He implied it was because of the heat experienced by Venus on being ejected from Jupiter, although (as Motz previously explained) in fact this would have vaporized it instead. Finally, such a prediction is of questionable meaningfulness, Sagan argued. People before Velikovsky had known that Venus is hot, partly based on its closeness to the Sun and partly on its atmosphere (Rupert Wildt’s 1940 suggestion of a greenhouse-driven high surface temperature). So Velikovsky’s “prediction” was not a true prediction—not even a lucky guess. His overall theory was so maddeningly vague, Sagan concluded, that it was impossible to use it to make any meaningful predictions at all. Hence Velikovsky’s theory was classic pseudoscience.

Opinions of Sagan’s performance vary. Staff writer Robert Gillette of Science magazine later described Sagan as “Velikovsky’s bete noire . . . An articulate man with a switchblade wit. . . .” A reporter from Science News, however, observed: “Sagan’s 56 pages of criticism would ordinarily be sufficient to lay to rest for all time such a picked-apart theory, but Velikovsky’s supporters are not easily dissuaded, and the controversy is sure to continue.” In fact, Sagan’s speech trounced Velikovsky. Nowadays, the pseudoscientific psychoanalyst is largely forgotten, save by a handful of devotees who haunt the World Wide Web. Sagan remains their leading bete noire.

Was Sagan’s campaign against the forces of pseudoscience really worth his time? After all, Von Däniken and Velikovsky were just the latest variations on old themes. Pseudoscientific and occult ideas are as old as the hills. Yet in the 1970s, their growing popularity—coincident with the rise of various cults (from the silly “pyramid power” to the scary Scientology) and the decline of student interest in science—alarmed many. In response, philosophy professor Paul Kurtz, a controversial figure within the American Humanist Association, formed the Committee for the Scientific Investigation of Claims of the Paranormal (CSICOP, pronounced “sigh-cop”), with the goal of challenging the intellectual merits of pseudoscientific and occult notions.

Sagan was a founding member of CSICOP. Certainly he was attracted to the skeptics movement by his scorn for pseudoscience, and by his desire to educate the public about real science. He might also, however, have joined the skeptics movement partly to reassure his colleagues—the Donald Menzel types who suspected his loyalty to orthodox science—that he really was a loyal (if highly speculative) member of the epistemological mainstream, and not a budding Lilly or Hynek about to saunter off to fairyland.

At the same time, Sagan would always feel ambivalence about certain elements of the skeptics movement. Some of its members were too fanatical, too lacking in “compassion” (as Sagan complained) for those deluded by foolish ideas. He refused to sign astronomer Bart Bok’s anti-astrology petition because, in Sagan’s view, its tone was too authoritarian; in an age when the public increasingly distrusted “experts,” astrology buffs would not be converted to reason by an elitist-sounding petition signed by a band of astronomers. More subtle means were required to combat pseudoscience. One must not talk to the people as if they are children babbling about Santa Claus; they must be educated, patiently and respectfully so. And for that educational mission, Carl Sagan was ideally suited.

The Cosmos television series is the achievement that finally fixed Carl Sagan’s place in the celebrity firmament. With assistance from Ann Druyan and a team of others, Sagan told the saga of our universe—“all that is, ever has been and ever will be.” The thirteen-part series was eventually seen by more than four hundred million people and became a spectacularly successful book (still in print today). It inspired countless teenagers to consider science careers. Most significantly for Sagan, Cosmos gave him the celebrity status that later allowed him to challenge the revival of cold war militarism, which he and many others believed threatened terrestrial life. The series was the climax of his ascent into fame, even into iconic status in American culture. From the broadcast of the series on, his face was immediately recognizable to the generations of Americans who huddled in their living rooms raptly glued to their TV sets for each episode.

With Sagan’s striking, strangely halting and melodic voice and his emphatic gestures, he was the perfect scientific sage on screen, the entrancing visionary who could reveal the marvels of the universe, from the smallest grain of sand to the most distant stars. One journalist who wrote about the series described his unusual appeal by commenting that Sagan’s “face combines hauteur, sensuality, and a winning boyishness—a pleasing amalgam of Rudolph Nureyev and George Plimpton.”

The bad news started coming in batches. NASA’s SETI project did not long survive the Cold War; its sudden death—only months after its birth—unhappily vindicated one of Carl’s oldest worries: that the public’s inability to distinguish between UFO claptrap and SETI science would doom the latter.

In early 1993, Senator Richard Bryan, a Republican from Nevada, stood on the floor of the Senate and asked his colleagues to kill SETI. Showing no ability to distinguish between SETI and UFO-chasing, he referred to SETI as a “great Martian hunt.” The Senate went along; all SETI funding was ended.

After it all ended, SETI scientist Jill Tarter flew home, crushed. “I literally asked my husband to stay around over the weekend and not go into his office and not leave me alone with any sharp objects,” she recalls with a laugh. “It was pretty grim. How could we have screwed up so badly? How could we have let this happen?” Fortunately, the SETI program was privatized and has since survived with support from Silicon Valley industrialists and other sugar daddies. Based at the SETI Institute in a tree-shaded office park in Mountain View, California, the search is conducted under the name Project Phoenix—after the mythical bird that ascended from its own ashes.

It was the same scenario that Carl had envisioned in his book Contact, where Ellie Arroway, abandoned by a federal scientific agency, seeks support for her SETI project from a private donor. The whole episode illustrated one of Carl’s oldest fears—that poor science education would create a society unable to distinguish between scientific exploration and pseudoscientific flummery.

What is a visionary? Carl Sagan measured time in eons and space in light-years; he maintained an interplanetary perspective. To such a person, the petty bigotries and tyrannies of terrestrial life are provincialism in the extreme, utterly absurd. That was the core theme of another book, Pale Blue Dot: Ours is one planet in a vast cosmos—who are we to subdivide it into the privileged and the oppressed? “He took science so seriously, so deeply to heart,” Ann Druyan says, “he understood the human species to be precisely what it is—part of the fabric of nature, obviously related to the non-human primates in ways that were very striking. So to him racism was completely appalling. And sexism, too. Since there was no scientific basis for any kind of inferiority for women or non-white people, he couldn’t bear it. . . .

“That was true in our relationship, personally, in terms of arguments we would have,” says Druyan. “[There were] no arguments ‘from authority,’ no ‘Because I say so’ or ‘Because I want it this way.’ He was really concerned about the truth. So you had a sense that not only would every problem ultimately be solved—because it was a process of getting at the truth—but that this guy wanted to keep on growing for the rest of his life! He didn’t want to settle for the boring rituals and repetitions that most people are happy with. For him what mattered was what was true, not what would affirm his cherished belief. That’s what the real dream of science is: not the universe is as I want it to be, to make myself less afraid of the vastness, but the universe as it really is.”

Keay Davidson

Keay Davidson is a science reporter for the San Francisco Examiner. He is also a recipient of CSICOP's Responsibility in Journalism Award. This article is excerpted from Carl Sagan: A Life. Copyright ©1999 by Keay Davidson. Excerpted with permission of the publisher John Wiley & Sons, Inc. This book is available at all bookstores, online booksellers, and from the Wiley Web site.