Billions & Billions

by Carl Sagan

  I could see life in there—a network of branches, some encrusted with green filamentous algae, and six or eight small animals, mostly pink, cavorting, so it seemed, among the branches. In addition, there were hundreds of other kinds of beings, as plentiful in these waters as fish in the oceans of Earth; but they were all microbes, much too small for me to see with the naked eye. Clearly, the pink animals were shrimp of some suitably unpretentious variety. They caught your attention immediately because they were so busy. A few had alighted on branches and were walking on 10 legs and waving lots of other appendages. One of them was devoting all its attention, and a considerable number of limbs, to dining on a filament of green. Among the branches, draped with algae much as trees in Georgia and north Florida are covered with Spanish moss, other shrimp could be seen moving as if they had urgent appointments elsewhere. Sometimes they would change their colors as they swam from environment to environment. One was pale, almost transparent; another orange, with an embarrassed blush of red.

  In some ways, of course, they were different from us. They had their skeletons on the outside, they could breathe water, and a kind of anus was located disconcertingly near their mouths. (They were fastidious about appearance and cleanliness, though, possessing a pair of specialized claws with brushlike bristles. Occasionally, one would give itself a good scrub.)

  But in other ways they were like us. It was hard to miss. They had brains, hearts, blood, and eyes. That flurry of swimming appendages propelling them through the water betrayed what seemed to be an unmistakable hint of purpose. When they arrived at their destination, they addressed the algal filaments with the precision, delicacy, and industriousness of a dedicated gourmet. Two of them, more venturesome than the rest, prowled this world’s ocean, swimming high above the algae, languidly surveying their domain.

  After a while you get so you can distinguish individuals. A shrimp will molt, shedding its old skeleton to make room for a new one. Afterward, you can see the thing—transparent, shroud-like, hanging rigidly from a branch, its former occupant going about his business in a sleek new carapace. Here’s one missing a leg. Had there been some furious claw-to-claw combat, perhaps over the affections of a devastating nubile beauty?

  From certain angles, the top of the water is a mirror, and a shrimp sees its own reflection. Can it recognize itself? More probably, it just sees the reflection as one more shrimp. At other angles, the thickness of the curved glass magnifies them, and then I can make out what they really look like. I notice, for example, that they have mustaches. Two of them race to the top of the water and, unable to break through the surface tension, bounce off the meniscus. Then, upright—a little startled, I imagine—they gently sink to the bottom. Their arms are crossed casually, it almost seems, as if the exploit were routine, nothing to write home about. They’re cool.

  If I can clearly see a shrimp through the curved crystal, I figure, it must be able to see me, or at least my eye—some great looming black disk, with a corona of brown and green. Indeed, sometimes as I watch one busily fingering the algae, it seems to stiffen and look back at me. We have made eye contact. I wonder what it thinks it sees.

  After a day or two of preoccupation with work, I wake up, take a glance at the crystal world.… They all seem to be gone. I reproach myself. I’m not required to feed them or give them vitamins or change their water or take them to the vet. All I have to do is make sure that they’re not in too much light or too long in the dark and that they’re always at temperatures between 40° and 85° Fahrenheit. (Above that, I guess, they make a bisque and not an ecosystem.) Through inattention, have I killed them? But then I see one poking an antenna out from behind a branch, and I realize they’re still in good health. They’re only shrimp, but after a while you find yourself worrying about them, rooting for them.

  If you’re in charge of a little world like this, and you conscientiously concern yourself about its temperature and light levels, then—whatever you may have had in mind at the beginning—eventually you care about who’s in there. If they’re sick or dying, though, you can’t do much to save them. In certain ways, you’re much more powerful than they, but they do things—like breathing water—that you can’t. You’re limited, painfully limited. You even wonder if it’s cruel to put them in this crystal prison. But you reassure yourself that at least here they are safe from baleen whales and oil slicks and cocktail sauce.

  The ghostly molting shrouds and the rare dead body of an expired shrimp do not linger long. They are eaten, partly by the other shrimp, partly by invisible microorganisms that teem through this world’s ocean. And so you are reminded that these creatures don’t work by themselves. They need one another. They look after one another—in a way that I’m unable to do for them. The shrimp take oxygen from the water and exhale carbon dioxide. The algae (a plural word; singular: alga) take carbon dioxide from the water and exhale oxygen. They breathe each other’s waste gases. Their solid wastes cycle also, among plants and animals and microorganisms. In this small Eden, the inhabitants have an extremely intimate relationship.

  The shrimps’ existence is much more tenuous and precarious than that of the other beings. The algae can live without the shrimp far longer than the shrimp can live without the algae. The shrimp eat the algae, but the algae mainly eat light. Eventually—to this day I don’t know why—the shrimp started dying, one by one. The time came when only one was left, morosely—it seemed—nibbling a sprig of algae until it too died. A little to my surprise, I found I was mourning them all. I suppose it was in part because I had gotten to know them a little. But in part, I knew, it was because I feared a parallelism between their world and ours.

  Unlike an aquarium, this little world is a closed ecological system. Light gets in, but nothing else—no food, no water, no nutrients. Everything must be recycled. Just like the Earth. In our larger world, we also—plants and animals and microorganisms—live off each other, breathe and eat each other’s wastes, depend on one another. Life on our world, too, is powered by light. Light from the Sun, which passes through the clear air, is harvested by plants and powers them to combine carbon dioxide and water into carbohydrates and other foodstuffs, which in turn provide the staple diet of the animals.

  Our big world is very like this little one, and we are very like the shrimp. But there is at least one major difference: Unlike the shrimp, we are able to change our environment. We can do to ourselves what a careless owner of such a crystal sphere can do to the shrimp. If we are not careful, we can heat our planet through the atmospheric greenhouse effect or cool and darken it in the aftermath of a nuclear war or the massive burning of an oil field (or by ignoring the danger of an asteroid or cometary impact). With acid rain, ozone depletion, chemical pollution, radioactivity, the razing of tropical forests, and a dozen other assaults on the environment, we are pushing and pulling our little world in poorly understood directions. Our purportedly advanced civilization may be changing the delicate ecological balance that has tortuously evolved over the 4-billion-year period of life on Earth.

  Crustacea, such as shrimp, are much older than people or primates or even mammals. Algae go back 3 billion years, long before animals, most of the way back to the origin of life on Earth. They’ve all been working together—plants, animals, microbes—for a very long time. The arrangement of organisms in my crystal sphere is ancient, vastly older than any cultural institution we know. The inclination to cooperate has been painfully extracted through the evolutionary process. Those organisms that did not cooperate, that did not work with one another, died. Cooperation is encoded in the survivors’ genes. It’s their nature to cooperate. It’s a key to their survival.

  But we humans are newcomers, arising only a few million years ago. Our present technical civilization is just a few hundred years old. We have not had much recent experience in voluntary interspecies (or even intraspecies) cooperation. We are very devoted to the short-term and hardly ever think about the long-term. There is no guarantee that we will be wise en
ough to understand our planetwide closed ecological system, or to modify our behavior in accord with that understanding.

  Our planet is indivisible. In North America, we breathe oxygen generated in the Brazilian rain forest. Acid rain from polluting industries in the American Midwest destroys Canadian forests. Radioactivity from a Ukrainian nuclear accident compromises the economy and culture of Lapland. The burning of coal in China warms Argentina. Chlorofluorocarbons released from an air conditioner in Newfoundland help cause skin cancer in New Zealand. Diseases rapidly spread to the farthest reaches of the planet and require a global medical effort to be eradicated. And, of course, nuclear war and asteroid impact imperil everyone. Like it or not, we humans are bound up with our fellows, and with the other plants and animals all over the world. Our lives are intertwined.

  If we are not graced with an instinctive knowledge of how to make our technologized world a safe and balanced ecosystem, we must figure out how to do it. We need more scientific research and more technological restraint. It is probably too much to hope that some great Ecosystem Keeper in the sky will reach down and put right our environmental abuses. It is up to us.

  It should not be impossibly difficult. Birds—whose intelligence we tend to malign—know not to foul the nest. Shrimps with brains the size of lint particles know it. Algae know it. One-celled microorganisms know it. It is time for us to know it too.

  CHAPTER 8

  THE ENVIRONMENT:

  WHERE DOES

  PRUDENCE LIE?

  This new world may be safer, being told

  The dangers of diseases of the old

  JOHN DONNE,

  “An Anatomie of the World—The First Anniversary” (1611)

  There’s a certain moment at twilight when the aircraft contrails are pink. And if the sky is clear, their contrast with the surrounding blue is unexpectedly lovely. The Sun has already set and there’s a roseate glow at the horizon, a reminder of where the Sun is hiding. But the jet aircraft are so high up that they can still see the Sun—quite red, just before setting. The water blown out from their engines instantly condenses. At the frigid temperatures of high altitude, each engine trails a small, linear cloud, illuminated by the red rays of the setting Sun.

  Sometimes there are several contrails from different aircraft, and they cross, making a kind of sky writing. When the winds are high, the contrails quickly spread laterally, and instead of an elegant line tracing its way across the sky, there’s a long, irregular, diffuse, vaguely linear tracery that dissipates as you watch. If you catch the trail as it’s being generated, you can often make out the tiny object from which it emanates. For many people, no wings or engines are visible; it’s just a moving spot separated a little from the contrail, somehow its source.

  As it gets darker you can often see that the spot is self-luminous. There’s a bright white light there. Sometimes there’s also a flashing red or green light, or both.

  Occasionally I imagine myself a hunter-gatherer—or even my grandparents when they were children—looking up at the sky and seeing these bewildering and awesome wonders from the future. For all the days of humans on Earth, it is only in the twentieth century that we have become a presence in the sky. While the air traffic in upstate New York, where I live, is doubtless heavier than in many places on Earth, there is hardly anywhere on the planet where you can’t, at least occasionally, look up and see our machines writing out their mysterious messages on the very sky that we had so long thought of as the exclusive provenance of the gods. Our technology has reached astonishing proportions for which, in our heart of hearts, we are inadequately prepared, mentally or emotionally.

  A little later, when the stars begin to come out, I can make out among them an occasional moving bright light, sometimes quite bright. Its glow may be steady, or it may be blinking at me, often two lights in tandem. No longer are there cometlike tails trailing behind them. There are moments when 10 or 20 percent of the “stars” I can see are nearby artifacts of humanity, which can for a moment be confused with immensely distant, blazing suns. More rarely, well after sunset, I can see a point of light, usually quite dim, very slowly and subtly moving. I have to be sure that first it passes this star, and then that—because the eye has a penchant for thinking that any isolated point of light surrounded only by blackness is moving. These are not aircraft. They are spacecraft. We have made machines that circle the Earth once every hour and a half. If they’re especially big or reflective, we can see them with the naked eye. They are far above the atmosphere, in the blackness of nearby space. They are so high up that they can see the Sun even when it is nearly pitch-dark down here. Unlike the airplanes, they have no lights of their own. Like the Moon and the planets, they shine merely by reflected sunlight.

  The sky begins not too far above our heads. It encompasses both the Earth’s thin atmosphere and all the vastness of the Cosmos beyond. We have built machines that fly in these realms. We are so accustomed to this, so acclimatized, that we often fail to recognize what a mythic accomplishment it is. More than any other feature of our technical civilization, these now prosaic flights are emblematic of what powers are now ours.

  But with great powers come great responsibilities.

  —

  Our technology has become so powerful that—not only consciously, but also inadvertently—we are becoming a danger to ourselves. Science and technology have saved billions of lives, improved the well-being of many more, bound up the planet in a slowly anastomosing unity—and at the same time changed the world so much that many people no longer feel at home in it. We’ve created a range of new evils: hard to see, hard to understand, problems that cannot readily be cured—certainly not without challenging those already in power.

  Here, if anywhere, public understanding of science is essential. Many scientists claim that there are real dangers consequent to our continuing to do things the way we’ve done, that our industrial civilization is a booby trap. But if we were to take such dire warnings seriously, it would be expensive. The affected industries would lose profits. Our own anxiety would increase. There are natural enough reasons to try to reject the warnings. Maybe the large number of scientists who caution about impending catastrophes are worrywarts. Maybe they get a perverse pleasure out of scaring the rest of us. Maybe it’s just a way to pry research money out of the government. After all, there are other scientists who say there’s nothing to worry about, that the contentions are unproved, that the environment will heal itself. Naturally we long to believe them; who wouldn’t? If they’re right, it relieves our burden immensely. So let’s not jump into things. Let’s be cautious. Let’s go slow. Let’s be really sure.

  On the other hand, maybe those who are reassuring about the environment are Pollyannas, or are afraid to affront those in power, or are supported by those who profit by despoiling the environment. So let’s hurry up. Let’s fix things before they become unfixable.

  How do we decide?

  There are arguments and counterarguments concerning abstractions, invisibilities, unfamiliar concepts and terms. Sometimes even words like “fraud” or “hoax” are uttered about the dire scenarios. How good is the science here? How can the average person be informed on what the issues are? Can’t we maintain a dispassionate but open neutrality and let the contending parties fight it out, or wait until the evidence is absolutely unambiguous? After all, extraordinary claims require extraordinary evidence. In short, why should those who, like myself, teach skepticism and caution about some extraordinary claims argue that other extraordinary claims must be taken seriously and considered urgent?

  Every generation thinks its problems are unique and potentially fatal. And yet every generation has survived to the next. Chicken Little, it is suggested, is alive and well.

  Whatever merit this argument may once have had—and certainly it provides a useful counterbalance to hysteria—its cogency is much diminished today. We sometimes hear about the “ocean” of air surrounding the Earth. But the thickness of most o
f the atmosphere—including all of it involved in the greenhouse effect—is only 0.1 percent of the diameter of the Earth. Even if we include the high stratosphere, the atmosphere isn’t as much as 1 percent of the Earth’s diameter. “Ocean” sounds massive, imperturbable. Compared with the size of the Earth, though, the thickness of the air is something like the thickness of the coat of shellac on a large schoolroom globe compared with the globe itself. If the protective ozone layer were brought down from the stratosphere to the surface of the Earth, its thickness compared with the diameter of the Earth would be one part in four billion. It would be utterly invisible. Many astronauts have reported seeing that delicate, thin, blue aura at the horizon of the daylit hemisphere—that represents the thickness of the entire atmosphere—and immediately, unbidden, contemplating its fragility and vulnerability. They worry about it. They have reason to worry.

  Today we face an absolutely new circumstance, unprecedented in all of human history. When we started out, hundreds of thousands of years ago, say, with an average population density of a hundredth of a person per square kilometer or less, the triumphs of our technology were hand axes and fire; we were unable to make major changes in the global environment. The idea would never have occurred to us. We were too few and our powers too feeble. But as time went on, as technology improved, our numbers increased exponentially, and now here we are with an average of some ten people per square kilometer, our numbers concentrated in cities, and an awesome technological armory at hand—the powers of which we understand and control only incompletely.

  Because our lives depend on minuscule amounts of such gases as ozone, major environmental disruption can be brought about—even on a planetary scale—by the engines of industry. The inhibitions placed on the irresponsible use of technology are weak, often half-hearted, and almost always, worldwide, subordinated to short-term national or corporate interest. We are now able, intentionally or inadvertently, to alter the global environment. Just how far along we are in working the various prophesied planetary catastrophes is still a matter of scholarly debate. But that we are able to do so is now beyond question.