The Year's Best Science Fiction 9

WHERE IS EVERYBODY? Ben Bova

It was Enrico Fermi, the late Nobel Prize-winning physicist, who asked the question. His reasoning was basically this:

The universe is so vast that, according to mere blind chance, there must be literally billions of planetary systems. With so many planets available, it is incomprehensible that intelligent life should have evolved only on Earth. There must be many—millions, at least—of intelligent races elsewhere in space. But the universe is much older than the Earth. Therefore, the chances are that intelligent races exist who are much older than man. It is not impossible to imagine many races so far advanced that they have solved the problems of interstellar flight. If this is true, then:

Where is everybody? Why have they not established contact with us? Or is the fact that we have not received interstellar visitors proof that no intelligent life exists in space?

There are usually two reasons given for our lack of interstellar tourists. The first is the “grain of sand” argument; the second is the “postage stamp” analogy.

The first argument uses a poetic metaphor to make its point:

A man can walk across a very large beach without much difficulty. He can chart its shoreline and depths, its contour and headlands. But—can he inspect every grain of sand on the beach?

In other words, even assuming that an advanced race could develop interstellar travel, could they explore every one of the Milky Way’s 100 billion stars in an effort to find other intelligent races? Stated in this manner, the prospects for interstellar contact sound dim indeed. But let us examine this argument a little more closely. Basically, it involves two facets: the ability to achieve interstellar flight, and the ability to investigate very large numbers of stars. An intelligent race could develop the technology necessary for interstellar flight. And it need not inspect every one of the Milky Way’s 100 billion stars. Some stars are manifestly inhospitable to the evolution of life; many others are too young to have allowed intelligence time enough to develop. Moreover, our solar system is situated away from the center of the galaxy, out where the stars are relatively far apart. At the galaxy’s heart, where the oldest stars are, interstellar distances must be less than half of those in our region of space.

It is possible, then, to envision an intelligent race scouting the galaxy in a highly purposeful fashion, seeking out stars that are old and stable enough to have sponsored intelligent life. With the use of powerful radio receivers or other detection devices, interstellar explorers might be able to find inhabited planets at very great distances. So it would seem that while our planet is indeed a single grain of sand on the vast shores of space, an intelligent race might find us if it had enough energy, time and purpose.

The question of purpose brings us to the “postage stamp” analogy. You have no doubt seen this picture painted by astronomers and anthropologists alike: Consider the history of the Earth. Let the height of the Empire State Building represent the planet’s five billion years of existence. Man’s one-million-year tenure on Earth can then be represented by a one-foot ruler, standing at the very top of the building. A dime placed atop the ruler represents the entire span of man’s civilization. And, at the very top of the whole wobbly conglomerate, is glued a postage stamp— this represents the length of time since man has developed modern science.

If other intelligent races exist, what are the chances of our meeting a race at exactly our own level of development? Within the thickness of the postage stamp, that is. They will either be far below or far beyond us, technologically.

Several cosmologically-minded thinkers have arrived at the conclusion that technology may be only a passing phase in the development of an intelligent race. Perhaps it is only in the first blush of its youth that a race is interested in exploring the stars. This type of reasoning is typified by Sebastian von Hoerner, of the Astronomical Research Institute of Heidelberg, who states that an intelligent race is bound either to destroy itself or to stagnate within a few hundred, or at best, a few thousand years after reaching the modern Earthly level of technology. In other words, the postage stamp may grow as thick as a dime, but certainly no thicker. Is this a reasonable assumption? Will man destroy himself? Or will he become a passive, stagnant lotus-eater, served by his machines until his ultimate (and not-too-distant) extinction?

Let us be optimistic and assume that man (or any intelligent race) will not destroy himself. Will he become stagnant? Is the technological “state of mind” merely a passing fancy? Anthropologists have amassed some solid evidence that points entirely in the opposite direction.

Even before man was fully human he was a maker and user of tools. The wheel and the plow were invented about 10,000 b.c. The so-called modern era of science, dating roughly from Copernicus, Galileo and Newton, is not completely different from the eras that preceded it. The technology that we are so justly proud of did not spring fullblown from the minds of a few brilliant men. It was the product of generations of effort. Modern society represents not so much a break with the past as an acceleration of past trends, speeded by the gathering forces of technical methods and accumulated scientific knowledge. In short, an intelligent race is apt to be technologically oriented, and unlikely to give up its technology.

It would seem, then, that the postage stamp atop the Empire State Building is an artifact. Man’s technology may be very young, but so is man himself. As long as he has been human, he has been a tool-wielder. If and when we meet other intelligent races, the chances are that the technologies will be fully as old as they are. Thus, if we meet an older race, its technology will be far advanced over ours. And if we find a younger race, its talents will be similarly undeveloped.

So far we have tested two lines of speculation and concluded that: (1) An intelligent race could reach us if it wanted to; (2) Once a race develops technology, it is not likely to dispose of it and return to nature. But our original question remains unanswered. If intelligent races abound among the stars, why have they not visited us? Is man alone in his intelligence and technology?

One key to these questions depends on the “geography” of space. Astronomers are still not at all certain of the age of our galaxy, but we can pick 10 billion years as a convenient value. Ten billion years ago, there was no Milky Way galaxy, no stars, no planets, no life. Only a vast, distended cloud of tenuous gas—a nearly perfect vacuum by human standards, but so large that it contained more than 200 billion times the mass of our sun. (Where this gas came from is a cosmological question that will be carefully avoided here.) This tremendous cloud consisted of hydrogen atoms, simple protons and electrons. Nothing more. Much of this primordial gas is still present between the stars today; we see it in the brilliant swirls of nebulae, we hear its 21-centimeter-wavelength “song” on our radio telescopes.

In some unknown manner, the cloud began to rotate and contract. As it did so, tiny swirls and eddies began to appear, to break into still smaller whirls and ultimately to produce stars. (The first stars, evidently, were produced in large batches. We can see them today. They are very ancient globular clusters which may contain 100,000 or a million individual stars, packed together as closely as the planets of our own solar system.) As the original gas cloud continued to rotate and contract it produced many more stars. The nucleus of the Milky Way is so thick with stars that our own region of the galaxy, out toward the edge, must be classed as a stellar desert. Thus the central portions of our galaxy, according to astronomical theory, contain the oldest stars.

As the gas cloud condensed, its rotation became faster. Its shape became flattened, bulging at the center. Finally, to maintain stability, the cloud began to fling off great belts of gas from its middle. These belts—long, twisted filaments of star-producing gas—became the spiral arms of our galaxy, thousands of light-years in cross-section, tens of thousands of light-years in length. In one of these belts, known as the Carina-Cygnus Arm, is the sun and our solar system, some 25,000 light-years from the star-thronged center of the galaxy.

It would appear, then, that our sun is a latecomer to the galaxy. Indeed, astronomers refer to the sun as a “second generation” star. Of course, many of the stars in our region of the galaxy are much younger. Sirius, for example, can hardly be more than a few hundred million years old and Rigel is probably no older than man himself—one million years.

Before we go any further, we had better straighten out a bit of astronomical jargon. Astronomers frequently refer to two types of stars in the Milky Way. Stars in our own quarter of the galaxy—including the sun—are called Population I. Other stars, such as those nearer the galaxy’s center and in the globular clusters, are called Population II. The confusing thing is that the Population II stars are older, hence are “first generation” stars, while the younger Population I stars are “second generation.” In addition to their different locations in the galaxy, Population II stars apparently have rather different chemical compositions than our own neighbors of Population I. This difference is one of degree, and at first glimpse would seem trivial: Population II stars are comparatively poor in heavier elements. Now, all stars of all populations are about 99 percent hydrogen and helium; the younger the star, the higher the percentage of hydrogen compared to helium. In any case, the heavier elements—such as the metals—are restricted to about one percent of the star’s mass. But, just as in a detective story, this seemingly insignificant fact is a critical clue.

The older Population II stars are metal-poor. The younger Population I stars are relatively metal-rich. If the galaxy began with nothing but hydrogen gas where did the metals come from?

The answer to that riddle was first proposed about a dozen years ago by a group of English astronomers and mathematicians, among them Thomas Gold, Fred Hoyle and Hermann Bondi. The stars are nuclear cookers, they said. We know that the sun is fusing hydrogen into helium, and in the process converting four million tons of mass into energy every second. But, said Gold, Hoyle and Bondi, this is only the beginning of a star’s career. At a certain point in its lifetime (some five billion years from now, for the sun) a star reaches a critical stage. Its hydrogen fuel is becoming depleted. At the core of the star is a large amount of helium—”ash” from the hydrogen fires—under tremendous pressure and, consequently, at very high temperatures, perhaps 100 million degrees Kelvin.

Under these conditions, the helium will begin to fuse into heavier elements: oxygen, carbon, neon. Eventually, the star goes on to produce constantly heavier elements at constantly higher internal temperatures. Finally the star runs out of energy sources, collapses and explodes. Most of its material—from hydrogen on up through the heavier elements—is hurled out into space. This is a supernova.

The theory that results is that the older Population II stars “cooked” the heavier elements within their cores and then spewed them out in supernova explosions. (Supernovas occur about once every five hundred years in the Milky Way, on the average.) The remnants flung into interstellar space mix with the primeval hydrogen and thus provide new raw material for “second generation” stars. But notice that these newer stars have a much richer raw material to build with—it contains helium, oxygen, neon, iron and many other elements. Even rare, short-lived radioactive elements, such as californium (an “artificial” element on Earth) have been observed in the spectra of old Population II stars.

Now then, what has all this stellar cookery to do with the possibilities of intelligent life throughout the galaxy? Simply this:

The oldest stars in the Milky Way were built on hydrogen alone. They could not have planetary systems like ours because the heavier elements were not yet available. There might be a few spheres of frozen hydrogen circling these stars at great distances, but they would be sterile worlds.

The sun is a Population I star, a “second generation” luminary. It possesses a relatively large amount of heavy elements; it also possesses a planetary system that harbors life and intelligence. But the sun is a rather old Population I star—age, five billion years, about half as old as the entire Milky Way galaxy. Can it be that the first five billion years of the galaxy’s existence were spent mainly in building up heavier elements so that “second generation” stars like the sun could arise and produce planets, life and intelligence? If so, then we might well be one of the first intelligent races in the Milky Way. The teeming center of the galaxy might be devoid of life and intelligence.

Although this kind of astronomical evidence might lend support to the speculation that we are among the galaxy’s elder citizens, we should be very careful about reaching conclusions from an admittedly oversimplified paste-up of assumptions and theories. The idea has a certain satisfaction to it from an egocentric point of view, and it goes a long way toward explaining why They have not visited Earth. There might not be any of Them. Or, if there are, They might not yet have attained the advanced technology necessary for interstellar flight.

But to assume that we are in first place in the galaxy’s IQ rating is rash indeed. If astronomy has taught man anything it is the painful fact that we are not special creatures in any sense of the term. Our star is an average one, and the conditions that led to the formation of our planet and ourselves are probably not very extraordinary. Even granting that we might be among the elder citizens of the Milky Way, we must assume that among the galaxy’s 100 billion stars there are some that harbor much more intelligent species.

Then the question returns again: Where is everybody?

Imagine a race of intelligent creatures, human beings, living in their own world. They have developed in isolation, and have split into many local cultures, some have advanced to high civilizations, others have remained struggling in the Stone Age. But all of them are members of a fully human species, and as intelligent as we are. Suddenly, their world is visited by a vastly superior race. To simplify matters, we will assume that the visitors are also human in form. The first contacts are friendly enough. Soon, though, it becomes clear that the visitors have measured the natives and found them lacking. The visitors begin to take over the natives’ world.

Fighting begins. The natives lack the advanced technology of their opponents. Within a few generations the natives cease to exist, except for scattered tribes in the back country. The natives have not merely been beaten in a war. They have been virtually extinguished by a superior culture. Through intermarriage, through susceptibility to new diseases, through an emotional response that can only be described as “racial shock,” the natives either die away or are genetically engulfed by the newcomers. This actually happened to the American Indians.

What would happen if a vastly superior race suddenly dropped out of the blue, straightened out our political squabbles, handed us a child’s primer of fusion reactors, and generally took over the planet? Could our deep-grained pride stand such a shock, or would we go into a racial decline?

Look at it another way. Anthropologists are interested in studying man’s nearest relative, the primate apes. A good deal has been learned by observing chimpanzees and other apes in captivity. But the basic question of why we live in cities while our closest relatives live in trees can only be answered by studying the primates in their natural habitat. This is not easy to do because the key to the entire scheme is that the animals under scrutiny must never know they are being watched. Only by remaining “invisible” can the scientists learn how apes behave naturally.

Now let us consider the reactions of an advanced race that discovers intelligent life on the planet Earth. It seems reasonable to assume that the ethics of an intelligent race will advance together with its technology, even if the ethics advance more slowly. Any race capable of developing interstellar travel, it would seem, should also be intelligent and ethical enough to observe a relatively primitive race like our own without interfering with us. Why should they contact us? They have far more to learn by keeping us under surveillance. Thus, they might well have a “closed door” policy about contacting us, but an “open window” attitude about observing us.

Where is everybody? If you assume that: (1) an intelligent race can develop interstellar travel; (2) such a race can detect signs of intelligence at great distances in space; and (3) one or more such races have indeed evolved on “second generation” stars—then the answer may be this: They may be watching us right now, using us to learn more about the phenomenon called intelligence, and waiting for us to reach the maturity necessary before we can join them as galactic equals.