Broca's Brain: The Romance of Science

by Carl Sagan

  One numerical coincidence of this sort, which is of deep significance, was well known to the Babylonians, contemporaries of the ancient Hebrews. It is called the Saros. It is the period between two successive similar cycles of eclipses. In a solar eclipse the Moon, which appears from the Earth just as large (1/2°) as the Sun, must pass in front of it. For a lunar eclipse, the Earth’s shadow in space must intercept the Moon. For either kind of eclipse to occur, the Moon must, first of all, be either new or full-so that the Earth, the Moon and the Sun are in a straight line. Therefore the synodic month is obviously involved in the periodicity of eclipses. But for an eclipse to occur, the Moon must also be near one of the nodes of its orbit. Therefore the nodical month is involved. It turns out that 233 synodic months is equal to 241.9989 (or very close to 242) nodical months. This is the equivalent of a little over eighteen years and ten or eleven days (depending on the number of intervening leap days), and comprises the Saros. Coincidence?

  Similar numerical coincidences are in fact common throughout the solar system. The ratio of spin period to orbital period on Mercury is 3 to 2. Venus manages to turn the same face to the Earth at its closest approach on each of its revolutions around the Sun. A particle in the gap between the two principal rings of Saturn, called the Cassini Division, would orbit Saturn in a period just half that of Mimas, its second satellite. Likewise, in the asteroid belt there are empty regions, known as the Kirkwood Gaps, which correspond to nonexistent asteroids with periods half that of Jupiter, one-third, two-fifths, three-fifths, and so on.

  None of these numerical coincidences proves the existence of God-or if it does, the argument is subtle, because these effects are due to resonances. For example, an asteroid that strays into one of the Kirkwood Gaps experiences a periodic gravitational pumping by Jupiter. Every two times around the Sun for the asteroid, Jupiter makes exactly one circuit. There it is, tugging away at the same point in the asteroid’s orbit every revolution. Soon the asteroid is persuaded to vacate the gap. Such incommensurable ratios of whole numbers are a general consequence of gravitational resonance in the solar system. It is a kind of perturbational natural selection. Given enough time-and time is what the solar system has a great deal of-such resonances will arise inevitably.

  That the general result of planetary perturbations is stable resonances and not catastrophic collisions was first shown from Newtonian gravitational theory by Pierre Simon, Marquis de Laplace, who described the solar system as “a great pendulum of eternity, which beats ages as a pendulum beats seconds.” Now, the elegance and simplicity of Newtonian gravitation might be used as an argument for the existence of God. We could imagine universes with other gravitational laws and much more chaotic planetary interactions. But in many of those universes we would not have evolved-precisely because of the chaos. Such gravitational resonances do not prove the existence of God, but if he does exist, they show, in the words of Einstein, that, while he may be subtle, he is not malicious.

  BLOOM CONTINUES his work. He has, for example, demonstrated the preordination of the United States of America by the prominence of the number 13 in major league baseball scores on July 4, 1976. He has accepted my challenge and made an interesting attempt to derive some of Bosnian history from numerology-at least the assassination of Archduke Ferdinand at Sarajevo, the event that precipitated World War I. One of his arguments involves the date on which Sir Arthur Stanley Eddington presented a talk on his mystical number 136 at Cornell University, where I teach. And he has even performed some numerical manipulations using my birth date to demonstrate that I also am part of the cosmic plan. These and similar cases convince me that Bloom can prove anything.

  Norman Bloom is, in fact, a kind of genius. If enough independent phenomena are studied and correlations sought, some will of course be found. If we know only the coincidences and not the enormous effort and many unsuccessful trials that preceded their discovery, we might believe that an important finding has been made. Actually, it is only what statisticians call “the fallacy of the enumeration of favorable circumstances.” But to find as many coincidences as Norman Bloom has requires great skill and dedication. It is in a way a forlorn and perhaps even hopeless objective-to demonstrate the existence of God by numerical coincidences to an uninterested, to say nothing of a mathematically unenlightened public. It is easy to imagine the contributions Bloom’s talents might have made in another field. But there is something a little glorious, I find, in his fierce dedication and very considerable arithmetic intuition. It is a combination of talents which is, one might almost say, God-given.

  CHAPTER 9

  SCIENCE FICTION – A PERSONAL VIEW

  The poet’s eye, in a fine frenzy rolling,

  Doth glance from heaven to earth, from

  earth to heaven;

  And as imagination bodies forth

  The forms of things unknown, the poet’s pen

  Turns them to shapes, and gives to airy nothing

  A local habitation and a name.

  WILLIAM SHAKESPEARE,

  A Midsummer Night’s Dream, Act V, Scene 1

  BY THE TIME I was ten I had decided-in almost total ignorance of the difficulty of the problem-that the universe was full up. There were too many places for this to be the only inhabited planet. And judging from the variety of life on Earth (trees looked pretty different from most of my friends), I figured life elsewhere would look very strange. I tried hard to imagine what that life would be like, but despite my best efforts I always produced a kind of terrestrial chimaera, a blend of existing plants and animals.

  About this time a friend introduced me to the Mars novels of Edgar Rice Burroughs. I had not thought much about Mars before, but here, presented before me in the adventures of John Carter, was an inhabited extraterrestrial world breathtakingly fleshed out: ancient sea bottoms, great canal-pumping stations and a variety of beings, some of them exotic. There were, for example, the eight-legged beasts of burden, the thoats.

  These novels were exhilarating to read. At first. Then slowly doubts began to gnaw. The plot surprise in the first John Carter novel I read hinged on him forgetting that the year is longer on Mars than on Earth. But it seemed to me that if you go to another planet, one of the first things you check into is the length of the day and the year. (Incidentally, I can recall no mention by Carter of the remarkable fact that the Martian day is almost as long as the terrestrial day. It was as if he expected the familiar features of his home planet somewhere else.) Then there were incidental remarks made which were at first stunning but on sober reflection disappointing. For example, Burroughs casually comments that on Mars there are two more primary colors than on Earth. I spent many long minutes with my eyes tightly closed, fiercely concentrating on a new primary color. But it would always be a murky brown or a plum. How could there be another primary color on Mars, much less two? What was a primary color? Was it something to do with physics or something to do with physiology? I decided that Burroughs might not have known what he was talking about, but he certainly made his readers think. And in those many chapters where there was not much to think about, there were satisfyingly malignant enemies and rousing swordsmanship-more than enough to maintain the interest of a citybound ten-year-old in a Brooklyn summer.

  A year later, by sheerest accident, I stumbled across a magazine called Astounding Science Fiction in the neighborhood candy store. A glance at the cover and a quick riffle through the interior showed me it was what I had been looking for. With some effort I managed to scrape together the purchase price, opened it at random, sat down on a bench not twenty feet from the candy store and read my first modern science-fiction short story, “Pete Can Fix It,” by Raymond F. Jones, a gentle time-travel story of post-nuclear-war holocaust. I knew about the atom bomb-I remember an excited friend explaining to me that it was made of atoms-but this was the first I had seen about the social implications of the development of nuclear weapons. It got you thinking. The little device, though, that Pete the garage mechanic put o
n automobiles so passers-by might make brief cautionary trips into the wasteland of the future-what was that little device? How was it made? How could you get into the future and then come back? If Raymond F. Jones knew, he wasn’t telling.

  I found I was hooked. Each month I eagerly awaited the arrival of Astounding. I read Jules Verne and H. G. Wells, read from cover to cover the first two science-fiction anthologies that I was able to find, made scorecards, similar to those I was fond of making for baseball, on the quality of the stories I read. Many of the stories ranked high in asking interesting questions but low in answering them.

  There is still a part of me that is ten years old. But by and large I’m older. My critical faculties and perhaps even my literary tastes have improved. In rereading L. Ron Hubbard’s The End Is Not Yet, which I had first read at age fourteen, I was so amazed at how much worse it was than I had remembered that I seriously considered the possibility that there were two novels of the same name and by the same author but of vastly differing quality. I can no longer manage credulous acceptance as well as I used to. In Larry Niven’s Neutron Star the plot hinges on the astonishing tidal forces exerted by a strong gravitational field. But we are asked to believe that hundreds or thousands of years from now, at a time of casual interstellar spaceflight, such tidal forces have been forgotten. We are asked to believe that the first probe of a neutron star is done by a manned rather than by an unmanned spacecraft. We are asked too much. In a novel of ideas, the ideas have to work.

  I had the same kind of disquieting feelings many years earlier on reading Verne’s description that weightlessness on a lunar voyage occurred only at the point in space where the Earth’s and the Moon’s gravitational pulls canceled, and in Wells’s invention of the antigravity mineral cavorite: Why should a vein of cavorite still be on Earth? Shouldn’t it have flung itself into space long ago? In Douglas Trumbull’s technically proficient science-fiction film Silent Running, the trees in vast closed spaceborne ecological systems are dying. After weeks of painstaking study and agonizing searches through botany texts, the solution is found: plants, it turns out, need sunlight. Trumbull’s characters are able to build interplanetary cities but have forgotten the inverse square law. I was willing to overlook the portrayal of the rings of Saturn as pastel-colored gases, but not this.

  I have the same trouble with Star Trek, which I know has a wide following and which some thoughtful friends tell me I should view allegorically and not literally. But when astronauts from Earth set down on some fardistant planet and find the human beings there in the midst of a conflict between two nuclear superpowers-which call themselves the Yangs and the Coms, or their phonetic equivalents-the suspension of disbelief crumbles. In a global terrestrial society centuries in the future, the ship’s officers are embarrassingly Anglo-American. Only two of twelve or fifteen interstellar vessels are given non-English names, Kongo and Potemkin. (Potemkin and not Aurora?) And the idea of a successful cross between a “Vulcan” and a terrestrial simply ignores what we know of molecular biology. (As I have remarked elsewhere, such a cross is about as likely as the successful mating of a man and a petunia.) According to Harlan Ellison, even such sedate biological novelties as Mr. Spock’s pointy ears and permanently querulous eyebrows were considered by network executives far too daring; such enormous differences between Vulcans and humans would only confuse the audience, they thought, and a move was made to have all physiologically distinguishing Vulcanian features effaced. I have similar problems with films in which familiar creatures, slightly changed-spiders thirty feet tall-are menacing the cities of the Earth: since insects and arachnids breathe by diffusion, such marauders would asphyxiate before they could savage their first city.

  I believe that the same thirst for wonder is inside me that was there when I was ten. But I have learned since then a little bit about how the world is really put together. I find that science fiction has led me to science. I find science more subtle, more intricate and more awesome than much of science fiction. Think of some of the scientific findings of the last few decades: that Mars is covered with ancient dry rivers; that apes can learn languages of many hundreds of words, understand abstract concepts and construct new grammatical usages; that there are particles that pass effortlessly through the entire Earth so that we see as many of them coming up through our feet as down from the sky; that in the constellation Cygnus there is a double star, one of whose components has such a high gravitational acceleration that light cannot escape from it: it may be blazing with radiation on the inside but it is invisible from the outside. In the face of all this, many of the standard ideas of science fiction seem to me to pale by comparison. I see the relative absence of these things and the distortions of scientific thinking often encountered in science fiction as terrible wasted opportunities. Real science is as amenable to exciting and engrossing fiction as fake science, and I think it is important to exploit every opportunity to convey scientific ideas in a civilization which is both based upon science and does almost nothing to ensure that science is understood.

  But the best of science fiction remains very good indeed. There are stories so tautly constructed, so rich in accommodating details of an unfamiliar society that they sweep me along before I even have a chance to be critical. Such stories include Robert Heinlein’s The Door into Summer, Alfred Bester’s The Stars My Destination and The Demolished Man, Jack Finney’s Time and Again, Frank Herbert’s Dune and Walter M. Miller’s A Canticle for Leibowitz. You can ruminate over the ideas in these books. Heinlein’s asides on the feasibility and social utility of household robots wear exceedingly well over the years. The insights into terrestrial ecology provided by hypothetical extraterrestrial ecologies as in Dune perform, I think, an important social service. He Who Shrank, by Harry Hasse, presents an entrancing cosmological speculation which is being seriously revived today, the idea of an infinite regress of universes-in which each of our elementary particles is a universe one level down, and in which we are an elementary particle in the next universe up.

  A rare few science-fiction novels combine extraordinarily well a deep human sensitivity with a standard science-fiction theme. I am thinking, for example, of Algis Budrys’ Rogue Moon, and of many of the works of Ray Bradbury and Theodore Sturgeon-for example, the latter’s To Here and the Easel, a stunning portrayal of schizophrenia as perceived from the inside, as well as a provocative introduction to Ariosto’s Orlando Furioso.

  There was once a subtle science-fiction story by the astronomer Robert S. Richardson on the continuous-creation origin of cosmic rays. Isaac Asimov’s story Breathes There a Man provided a poignant insight into the emotional stress and sense of isolation of some of the best theoretical scientists. Arthur C. Clarke’s The Nine Billion Names of God introduced many Western readers to an intriguing speculation in Oriental religions.

  One of the great benefits of science fiction is that it can convey bits and pieces, hints and phrases, of knowledge unknown or inaccessible to the reader. Heinlein’s And He Built a Crooked House was for many readers probably the first introduction they had ever encountered to four-dimensional geometry that held any promise of being comprehensible. One science-fiction work actually presents the mathematics of Einstein’s last attempt at a unified field theory; another presents an important equation in population genetics. Asimov’s robots were “positronic,” because the positron had recently been discovered. Asimov never provided any explanation of how positrons run robots, but his readers had now heard of positrons. Jack Williamson’s rhodomagnetic robots were run off ruthenium, rhodium and palladium, the next Group VIII metals after iron, nickel and cobalt in the periodic table. An analogue with ferromagnetism was suggested. I suppose that there are science-fiction robots today that are quark-ish or charming and will provide some brief verbal entrée into the excitement of contemporary elementary particle physics. L. Sprague de Camp’s Lest Darkness Fall is an excellent introduction to Rome at the time of the Gothic invasion, and Asimov’s Foundation series, although
this is not explained in the books, offers a very useful summary of some of the dynamics of the far-flung imperial Roman Empire. Time-travel stories-for example, the three remarkable efforts by Heinlein, All You Zombies, By His Bootstraps and The Door into Summer-force the reader into contemplations of the nature of causality and the arrow of time. They are books you ponder over as the water is running out of the bathtub or as you walk through the woods in an early winter snowfall.

  Another great value of modern science fiction is some of the art forms it elicits. A fuzzy imagining in the mind’s eye of what the surface of another planet might look like is one thing, but examining a meticulous painting of the same scene by Chesley Bonestell in his prime is quite another. The sense of astronomical wonder is splendidly conveyed by the best of such contemporary artists-Don Davis, Jon Lomberg, Rick Sternbach, Robert McCall. And in the verse of Diane Ackerman can be glimpsed the prospect of a mature astronomical poetry, fully conversant with standard science-fiction themes.

  Science-fiction ideas are widespread today in somewhat different guises. We have science-fiction writers such as Isaac Asimov and Arthur C. Clarke providing cogent and brilliant summaries in nonfictional form of many aspects of science and society. Some contemporary scientists are introduced to a vaster public by science fiction. For example, in the thoughtful novel The Listeners, by James Gunn, we find the following comment made fifty years from now about my colleague, the astronomer Frank Drake: “Drake! What did he know?” A great deal, it turns out. We also find straight science fiction disguised as fact in a vast proliferation of pseudoscientific writings, belief systems and organizations.