Read Billions & Billions Online

Authors: Carl Sagan

Billions & Billions (12 page)

This advice is fully applicable to the modern oracles, the scientists and think tanks and universities, the industry-funded institutes, and the advisory committees of the National Academy of Sciences. The policymakers send, sometimes reluctantly, to ask of the oracle, and the answer comes back. These days the oracles often volunteer their prophecies even when no one asks. Their utterances are usually much more detailed than the questions—involving methyl bromide, say, or the circumpolar vortex, hydrochlorofluorocarbons or the West Antarctic Ice Sheet.
Estimates are sometimes phrased in terms of numerical probabilities. It seems almost impossible for the honest politician to elicit a simple yes or no. The policymakers must decide what, if anything, to do in response. The first thing to do is to understand. And because of the nature of the modern oracles and their prophecies, policymakers need—more than ever before—to understand science and technology. (In response to this need, the Republican Congress has foolishly abolished its own Office of Technology Assessment. And there are almost no scientists who are members of the U.S. Congress. Much the same is true of other countries.)


But there’s another story about Apollo and oracles, at least equally famous, at least equally relevant. This is the story of Cassandra, Princess of Troy. (It begins just before the Mycenaean Greeks invade Troy to start the Trojan War.) She was the smartest and the most beautiful of the daughters of King Priam. Apollo, constantly on the prowl for attractive humans (as were virtually all the Greek gods and goddesses), fell in love with her. Oddly—this almost never happens in Greek myth—she resisted his advances. So he tried to bribe her. But what could he give her? She was already a princess. She was rich and beautiful. She was happy. Still, Apollo had a thing or two to offer. He promised her the gift of prophecy. The offer was irresistible. She agreed.
Quid pro quo
. Apollo did whatever it is that gods do to create seers, oracles, and prophets out of mere mortals. But then, scandalously, Cassandra reneged. She refused the overtures of a god.

Apollo was incensed. But he couldn’t withdraw the gift of prophecy, because, after all, he was a god. (Whatever else you might say about them, gods keep their promises.) Instead, he condemned her to a cruel and ingenious fate: that no one would
believe her prophecies. (What I’m recounting here is largely from Aeschylus’s play
Agamemnon
.) Cassandra prophesies to her own people the fall of Troy. Nobody pays attention. She predicts the death of the leading Greek invader, Agamemnon. Nobody pays attention. She even foresees her own early death, and still no one pays attention. They didn’t want to hear. They made fun of her. They called her—Greeks and Trojans alike—“the lady of many sorrows.” Today perhaps they would dismiss her as a “prophet of doom and gloom.”

There’s a nice moment when she can’t understand how it is that these prophecies of impending catastrophe—some of which, if believed, could be prevented—were being ignored. She says to the Greeks, “How is it you don’t understand me? Your tongue I know only too well.” But the problem wasn’t her pronunciation of Greek. The answer (I’m paraphrasing) was, “You see, it’s like this. Even the Delphic Oracle sometimes makes mistakes. Sometimes its prophecies are ambiguous. We can’t be sure. And if we can’t be sure about Delphi, we certainly can’t be sure about you.” That’s the closest she gets to a substantive response.

The story was the same with the Trojans: “I prophesied to my countrymen,” she says, “all their disasters.” But they ignored her clairvoyances and were destroyed. Soon, so was she.

The resistance to dire prophecy that Cassandra experienced can be recognized today. If we’re faced with an ominous prediction involving powerful forces that may not be readily influenced, we have a natural tendency to reject or ignore the prophecy. Mitigating or circumventing the danger might take time, effort, money, courage. It might require us to alter the priorities of our lives. And not every prediction of disaster, even among those made by scientists, is fulfilled: Most animal life in the oceans did not perish due to insecticides; despite Ethiopia and the Sahel, worldwide famine has not been a hallmark of the
1980s; food production in South Asia was not drastically affected by the 1991 Kuwaiti oil well fires; supersonic transports do not threaten the ozone layer—although all these predictions had been made by serious scientists. So when faced with a new and uncomfortable prediction, we might be tempted to say: “Improbable.” “Doom and Gloom.” “We’ve never experienced anything remotely like it.” “Trying to frighten everyone.” “Bad for public morale.”

What’s more, if the factors precipitating the anticipated catastrophe are long-standing, then the prediction itself is an indirect or unspoken rebuke. Why have we, ordinary citizens, permitted this peril to develop? Shouldn’t we have informed ourselves about it earlier? Don’t we ourselves bear complicity, since we didn’t take steps to insure that government leaders eliminated the threat? And since these are uncomfortable ruminations—that our own inattention and inaction may have put us and our loved ones in danger—there is a natural, if maladaptive, tendency to reject the whole business. It will need much better evidence, we say, before we can take it seriously. There is a temptation to minimize, dismiss, forget. Psychiatrists are fully aware of this temptation. They call it “denial.” As the lyrics of an old rock song go: “Denial ain’t just a river in Egypt.”


The stories of Croesus and Cassandra represent the two extremes of policy response to predictions of deadly peril—Croesus himself representing one pole of credulous, uncritical acceptance (usually of the assurance that all is well), propelled by greed or other character flaws; and the Greek and Trojan response to Cassandra representing the pole of stolid, immobile rejection of the possibility of danger. The job of the policymaker is to steer a prudent course between these two shoals.

Suppose a group of scientists claims that a major environmental catastrophe is looming. Suppose further that what is required to prevent or mitigate the catastrophe is expensive: expensive in fiscal and intellectual resources, but also in challenging our way of thinking—that is, politically expensive. At what point do the policymakers have to take the scientific prophets seriously? There are ways to assess the validity of the modern prophecies—because in the methods of science, there is an error-correcting procedure, a set of rules that have repeatedly worked well, sometimes called the scientific method. There are a number of tenets (I’ve outlined some of them in my book
The Demon-Haunted World
)
:
Arguments from authority carry little weight (“Because I said so” isn’t good enough); quantitative prediction is an extremely good way to sift useful ideas from nonsense; the methods of analysis must yield other results fully consistent with what else we know about the Universe; vigorous debate is a healthy sign; the same conclusions have to be drawn independently by competent competing scientific groups for an idea to be taken seriously; and so on. There are ways for policymakers to decide, to find a safe middle path between precipitate action and impassivity. It takes some emotional discipline, though, and most of all an aware and scientifically literate citizenry—able to judge for themselves how dire the dangers are.

CHAPTER 10
A PIECE OF THE SKY
IS MISSING

[T]his goodly frame, the earth, seems to me a sterile promontory; this most excellent canopy, the air, look you, this brave o’erhanging firmament, this majestical roof fretted with golden fire, why, it appears no other thing to me than a foul and pestilent congregation of vapors.

WILLIAM SHAKESPEARE
,
Hamlet
, II, ii, 308 (1600–1601)

I
’d always wanted a toy electric train. But it wasn’t until I was 10 that my parents could afford to buy me one. What they got me, secondhand but in good condition, wasn’t one of those bantamweight, finger-long, miniature scale models you see today, but a real clunker. The locomotive alone must have weighed five pounds. There was also a coal tender, a passenger car, and a caboose. The all-metal interlocking tracks came in three varieties: straight, curved, and one beautifully crossed mutation that permitted the construction of a figure-eight railway. I saved up to buy
a green plastic tunnel, so I could see the engine, its headlight dispelling the darkness, triumphantly chugging through.

My memories of those happy times are suffused with a smell—not unpleasant, faintly sweet, and always emanating from the transformer, a big black metal box with a sliding red lever that controlled the speed of the train. If you had asked me to describe its function, I suppose I would have said that it converted the kind of electricity in the walls of our apartment to the kind of electricity that the locomotive needed. Only much later did I learn that the smell was made by a particular chemical—generated by the electricity as it passed through air—and that the chemical had a name: ozone.

The air all around us, the stuff we breathe, is made of about 20 percent oxygen—not the atom, symbolized as O, but the molecule, symbolized as O
2
, meaning two oxygen atoms chemically bound together. This molecular oxygen is what makes us go. We breathe it in, combine it with food, and extract energy. Ozone is a much rarer way in which oxygen atoms combine. It is symbolized as O
3
, meaning three oxygen atoms chemically bound together.

My transformer had an imperfection. A tiny electric spark had been sputtering away, breaking the bonds of oxygen molecules as they happened by:

O
2
+ energy → O + O

(The arrow means
is changed into
.) But solitary oxygen atoms (O) are unhappy, chemically reactive, anxious to combine with adjacent molecules—and they do:

O + O
2
+ M → O
3
+ M

Here, M stands for any third molecule; it doesn’t get used up in the reaction but is required to help it along. M is a catalyst.
There are plenty of M molecules around, chiefly molecular nitrogen.

That’s what was going on in my transformer to make ozone. It also goes on in automobile engines and in the fires of industry, producing reactive ozone down here near the ground, contributing to smog and industrial pollution. It doesn’t smell so sweet to me anymore. The biggest ozone danger is not too much of it down here, but too little of it up there.


It was all done responsibly, carefully, with concern for the environment. By the 1920s, refrigerators were widely perceived to be a good thing. For reasons of convenience, public health, the ability of producers of fruit, vegetables, and milk products to market at sizable distances, and tasty meals combined, everyone wanted to have one. (No more lugging blocks of ice; what could be bad about that?) But the working fluid, whose heating and cooling provided the refrigeration, was either ammonia or sulfur dioxide—poisonous and evil-smelling gases. A leak was very ugly. A substitute was badly needed—one that was liquid under the right conditions, that would circulate inside the refrigerator but would not hurt anything if the refrigerator leaked or was converted into scrap metal. For these purposes it would be nice to find a material that was also neither poisonous nor flammable, that doesn’t corrode, burn your eyes, attract bugs, or even bother the cat. But in all of Nature, no such material seemed to exist.

So chemists in the United States and Weimar and Nazi Germany invented a class of molecules that had never existed on Earth before. They called them chlorofluorocarbons (CFCs), made up of one or more carbon atoms to which are attached some chlorine and/or fluorine atoms. Here’s one:

(C for carbon, Cl for chlorine, F for fluorine.) They were wildly successful, far exceeding the expectations of their inventors. Not only did they become the chief working fluid in refrigerators, but in air conditioners as well. They found widespread applications in aerosol spray cans, insulating foam, and industrial solvents and cleansing agents (especially in the microelectronics industry). The most famous brand name is Freon, a trademark of DuPont. It was used for decades and no harm seemed ever to come from it. Safe as safe could be, everyone figured. That’s why, after a while, a surprising amount of what we took for granted in industrial chemistry depended on CFCs.

By the early 1970s a million tons of the stuff were manufactured every year. So, it’s the early 1970s, let’s say, and you’re standing in your bathroom, spraying under your arms. The CFC aerosol comes out in a fine deodorant-carrying mist. The propellant CFC molecules don’t stick to you. They bounce off into the air, swirl near the mirror, careen off the walls. Eventually, some of them trickle out the window or under the door and, as time passes—it may take days or weeks—they find themselves in the great outdoors. The CFCs bump into other molecules in the air, off buildings and telephone poles, and, carried up by convection currents and by the global atmospheric circulation, are swept around the planet. With very few exceptions, they do not fall apart and do not chemically combine with any of the other molecules they encounter. They’re practically inert. After a few years, they find themselves in the high atmosphere.

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