Cosmos (8 page)

Biology is more like history than it is like physics. You have to know the past to understand the present. And you have to know it in exquisite detail. There is as yet no predictive theory of biology, just as there is not yet a predictive theory of history. The reasons
are the same: both subjects are still too complicated for us. But we can know ourselves better by understanding other cases. The study of a single instance of extraterrestrial life, no matter how humble, will deprovincialize biology. For the first time, the biologists will know what other kinds of life are possible. When we say the search for life elsewhere is important, we are not guaranteeing that it will be easy to find—only that it is very much worth seeking.

We have heard so far the voice of life on one small world only. But we have at last begun to listen for other voices in the cosmic fugue.

If we lived on a planet where nothing ever changed, there would be little to do. There would be nothing to figure out. There would be no impetus for science. And if we lived in an unpredictable world, where things changed in random or very complex ways, we would not be able to figure things out. Again, there would be no such thing as science. But we live in an in-between universe, where things change, but according to patterns, rules, or, as we call them, laws of nature. If I throw a stick up in the air, it always falls down. If the sun sets in the west, it always rises again the next morning in the east. And so it becomes possible to figure things out. We can do science, and with it we can improve our lives.

Human beings are good at understanding the world. We always have been. We were able to hunt game or build fires only because we had figured something out. There was a time before television, before motion pictures, before radio, before books. The greatest part of human existence was spent in such a time. Over the dying embers of the campfire, on a moonless night, we watched the stars.

The night sky is interesting. There are patterns there. Without even trying, you can imagine pictures. In the northern sky, for example, there is a pattern, or constellation, that looks a little ursine. Some cultures call it the Great Bear. Others see quite different images. These pictures are not, of course,
really
in the
night sky; we put them there ourselves. We were hunter folk, and we saw hunters and dogs, bears and young women, all manner of things of interest to us. When seventeenth-century European sailors first saw the southern skies they put objects of seventeenth-century interest in the heavens—toucans and peacocks, telescopes and microscopes, compasses and the sterns of ships. If the constellations had been named in the twentieth century, I suppose we would see bicycles and refrigerators in the sky, rock-and-roll “stars” and perhaps even mushroom clouds—a new set of human hopes and fears placed among the stars.

Occasionally our ancestors would see a very bright star with a tail, glimpsed for just a moment, hurtling across the sky. They called it a falling star, but it is not a good name: the old stars are still there after the falling star falls. In some seasons there are many falling stars; in others very few. There is a kind of regularity here as well.

Like the Sun and the Moon, stars always rise in the east and set in the west, taking the whole night to cross the sky if they pass overhead. There are different constellations in different seasons. The same constellations always rise at the beginning of autumn, say. It never happens that a new constellation suddenly rises out of the east. There is an order, a predictability, a permanence about the stars. In a way, they are almost comforting.

Certain stars rise just before or set just after the Sun—and at times and positions that vary with the seasons. If you made careful observations of the stars and recorded them over many years, you could predict the seasons. You could also measure the time of year by noting where on the horizon the Sun rose each day. In the skies was a great calendar, available to anyone with dedication and ability and the means to keep records.

Our ancestors built devices to measure the passing of the seasons. In Chaco Canyon, in New Mexico, there is a great roofless ceremonial kiva or temple, dating from the eleventh century. On June 21, the longest day of the year, a shaft of sunlight enters a window at dawn and slowly moves so that it covers a special niche. But this happens only around June 21. I imagine the proud Anasazi people, who described themselves as “The Ancient Ones,” gathered in their pews every June 21, dressed in feathers and rattles and turquoise to celebrate the power of the Sun. They also monitored the apparent motion of the Moon: the twenty-eight higher niches in the kiva may represent the number of days for the Moon to return to the same position among the constellations. These people paid close attention to the Sun and the Moon and the stars.
Other devices based on similar ideas are found at Angkor Wat in Cambodia; Stonehenge in England; Abu Simbel in Egypt; Chichén Itzá in Mexico; and the Great Plains in North America.

Some alleged calendrical devices may just possibly be due to chance—an accidental alignment of window and niche on June 21, say. But there are other devices wonderfully different. At one locale in the American Southwest is a set of three upright slabs which were moved from their original position about 1,000 years ago. A spiral a little like a galaxy has been carved in the rock. On June 21, the first day of summer, a dagger of sunlight pouring through an opening between the slabs bisects the spiral; and on December 21, the first day of winter, there are two daggers of sunlight that flank the spiral, a unique application of the midday sun to read the calendar in the sky.

Why did people all over the world make such an effort to learn astronomy? We hunted gazelles and antelope and buffalo whose migrations ebbed and flowed with the seasons. Fruits and nuts were ready to be picked in some times but not in others. When we invented agriculture, we had to take care to plant and harvest our crops in the right season. Annual meetings of far-flung nomadic tribes were set for prescribed times. The ability to read the calendar in the skies was literally a matter of life and death. The reappearance of the crescent moon after the new moon; the return of the Sun after a total eclipse; the rising of the Sun in the morning after its troublesome absence at night were noted by people around the world: these phenomena spoke to our ancestors of the possibility of surviving death. Up there in the skies was also a metaphor of immortality.

The wind whips through the canyons of the American Southwest, and there is no one to hear it but us—a reminder of the 40,000 generations of thinking men and women who preceded us, about whom we know almost nothing, upon whom our civilization is based.

As ages passed, people learned from their ancestors. The more accurately you knew the position and movements of the Sun and Moon and stars, the more reliably you could predict when to hunt, when to sow and reap, when to gather the tribes. As precision of measurement improved, records had to be kept, so astronomy encouraged observation and mathematics and the development of writing.

But then, much later, another rather curious idea arose, an assault by mysticism and superstition into what had been largely
an empirical science. The Sun and stars controlled the seasons, food, warmth. The Moon controlled the tides, the life cycles of many animals, and perhaps the human menstrual
^*
period—of central importance for a passionate species devoted to having children. There was another kind of object in the sky, the wandering or vagabond stars called planets. Our nomadic ancestors must have felt an affinity for the planets. Not counting the Sun and the Moon, you could see only five of them. They moved against the background of more distant stars. If you followed their apparent motion over many months, they would leave one constellation, enter another, occasionally even do a kind of slow loop-the-loop in the sky. Everything else in the sky had some real effect on human life. What must the influence of the planets be?

In contemporary Western society, buying a magazine on astrology—at a newsstand, say—is easy; it is much harder to find one on astronomy. Virtually every newspaper in America has a daily column on astrology; there are hardly any that have even a weekly column on astronomy. There are ten times more astrologers in the United States than astronomers. At parties, when I meet people who do not know I am a scientist, I am sometimes asked, “Are you a Gemini?” (chances of success, one in twelve), or “What sign are you?” Much more rarely am I asked, “Have you heard that gold is made in supernova explosions?” or “When do you think Congress will approve a Mars Rover?”

Astrology contends that which constellation the planets are in at the moment of your birth profoundly influences your future. A few thousand years ago, the idea developed that the motions of the planets determined the fates of kings, dynasties, empires. Astrologers studied the motions of the planets and asked themselves what had happened the last time that, say, Venus was rising in the Constellation of the Goat; perhaps something similar would happen this time as well. It was a subtle and risky business. Astrologers came to be employed only by the State. In many countries it was a capital offense for anyone but the official astrologer to read the portents in the skies: a good way to overthrow a regime was to predict its downfall. Chinese court astrologers who made inaccurate predictions were executed. Others simply doctored the records so that afterwards they were in perfect conformity with events. Astrology developed into a strange combination of observations, mathematics and careful record-keeping with fuzzy thinking and pious fraud.

But if the planets could determine the destinies of nations, how could they avoid influencing what will happen to me tomorrow? The notion of a personal astrology developed in Alexandrian Egypt and spread through the Greek and Roman worlds about 2,000 years ago. We today can recognize the antiquity of astrology in words such as
disaster
, which is Greek for “bad star,”
influenza
, Italian for (astral) “influence”;
mazeltov
, Hebrew—and, ultimately, Babylonian—for “good constellation,” or the Yiddish word
shlamazel
, applied to someone plagued by relentless ill-fortune, which again traces to the Babylonian astronomical lexicon. According to Pliny, there were Romans considered
sideratio
, “planet-struck.” Planets were widely thought to be a direct cause of death. Or consider
consider:
it means “with the planets,” evidently a prerequisite for serious reflection. Consider the mortality statistics in the City of London in 1632. Among the terrible losses from infant and childhood diseases and such exotic illnesses as “the rising of lights” and “the King’s evil,” we find that, of 9,535 deaths, 13 people succumbed to “planet,” more than died of cancer. I wonder what the symptoms were.

And personal astrology is with us still: consider two different newspaper astrology columns published in the same city on the same day. For example, we can examine the New York
Post
and the New York
Daily News
on September 21, 1979. Suppose you are a Libra—that is, born between September 23 and October 22. According to the astrologer for the
Post
, “a compromise will help ease tension”; useful, perhaps, but somewhat vague. According to the
Daily News
’s astrologer, you must “demand more of yourself,” an admonition that is also vague but also different. These “predictions” are not predictions; rather they are pieces of advice—they tell what to do, not what will happen. Deliberately, they are phrased so generally that they could apply to anyone. And they display major mutual inconsistencies. Why are they published as unapologetically as sports statistics and stock market reports?