Science and Survival

CARL SAGAN

Here are the memorable words from the citation of the Federation of American Scientists in 1985:

Carl Sagan is certainly the most visible spokesman of the scientific community of the planet Earth. Through the device they call television, fully five percent of the planet's four and one-half billion humans have actually seen his face and heard his words describing the nature of the cosmos. His book relating these lectures is the best selling book on science in English, the planet's major language for such discussions. Professor Sagan's efforts to sensitize his fellow Earthlings to the nature of their cosmic condition, coupled with the psychological relationship inspired by television, have given him unprecedented influence. He has used this influence to catalyze and disseminate a major study warning that warfare might produce totally disastrous results.

Carl Sagan (1934-1996) delivered the following Commencemnt Address to the Senior Class of Yale College in 1981.


This article is abridged from Speak Out Against the New Right edited by Herbert F. Vetter (Boston: Beacon Press, 1982)


In East Africa, in the records of the rocks dating back to about a million years ago, you can find a sequence of worked tools that our ancestors designed and executed. Their lives depended on making and using these tools well. This was, of course, Stone Age technology. Stones were used for all sorts of activities—chipping, flaking, cutting, carving. Although there are many ways of making stone tools, what is remarkable is that in a given site for enormous periods of time the tools are prepared in the same way—which means that there must have been educational institutions hundreds of thousands of years ago. There must have been professors and students, examinations and failing grades, laboratory courses, graduating ceremonies and post-graduate education.

The education that you are receiving is part of a long and distinguished human tradition. There is a reason for it. Our ability to learn from experience and to incorporate what previous generations have uncovered for themselves is the secret of our success as a species. Unaided, we are not stronger, or faster, or better camouflaged, or better swimmers or flyers than other animals. The only things we are better at are thinking and building. For that reason we have a long childhood in which many facts and attitudes are learned, different from generation to generation. We continue our education into adulthood and, indeed, for all our lives. That sequence of learning experiences has produced the most remarkable transformation of ourselves and our planet. If you drive through Manhattan, there are vistas in which nothing of the natural landscape is left, nothing that our ancestors of a hundred thousand years ago would recognize as familiar—except the people. We're dressed and coiffed differently, some of us are clean-shaven, but we ourselves would be entirely recognizable to our forebears. However, we have changed the environment profoundly.

Our enormous powers have, as everybody recognizes, not always been used for human benefit. In the four years since you have entered Yale College, more than a thousand strategic nuclear warheads have been deployed in ballistic missiles by the United States and the Soviet Union. These, in turn, were responses to other warheads introduced in previous years. Many of these warheads have yields of one or two megatons. A megaton is the equivalent of a million tons of TNT going off all at once. If you add up the yields of all the bombs dropped by all the combatants in the Second World War, you find that it comes to two million tons of TNT, the yield of one modern nuclear weapon. A thousand World War II's have been stockpiled and targeted while you have been here at Yale College. That is something that distinguishes this class from other classes. You are not responsible for it, but you will have an opportunity to do something about it.

In the same four years, 20 new worlds have been examined close-up for the first time by the human species by means of two remarkable spacecraft called Voyager 1 and Voyager 2. They have flown by the planet Jupiter, discovered its ring system, and examined its remarkably diverse array of moons. Then they were accelerated by the gravity of that massive planet to approach Saturn where they examined that planet and its elegant system of rings and moons. Voyager 2 will then continue on and in five years (if it survives that long) will examine the planet Uranus. Both spacecraft will eventually find themselves expelled from the solar system as the human species' third and fourth interstellar spacecraft.

Until this four-year period, 1977-1981, Jupiter, its rings and its moons, and Saturn, its rings and its moons, could be seen indistinctly at best. No surface details on these moons were detectable at all from the Earth. But now we have a vast library—approaching 100,000 detailed photographs of these worlds, and their diversity is astonishing. There is a world with an underground ocean of liquid sulfur. There is one that looks like a sphere of cracked crystal. There is a moon with an atmosphere denser than that of the Earth, and an unbroken cloud layer made of organic molecules. There are worlds made of ice. There are ring systems of billions of individual orbiting snowballs. There are many worlds we have never seen before. Only one generation in the history of the human species is privileged to live during the time those great discoveries are first made; that generation is ours.

It is remarkable that these two sets of events use very much the same physics, that of Isaac Newton, which is equally good at propelling devastating warheads to Moscow and to Washington, and at sending vehicles engaged in the peaceful and benign exploration of the solar system to Jupiter and Saturn.

We have instruments of mythic power at our command. The question clearly is: Are we wise enough to use them properly? Science and technology are ancient tools, the distinction of our species. They are also a kind of seed-corn. They are the means for our future survival. They provide solutions to many problems, some of which we are not yet wise enough even to identify. Eating the seed-corn can get you through one more winter. But the following winter you are in desperate trouble.

At the same time that these and hundreds of other remarkable scientific accomplishments have been happening, there have been some interesting pushes and pulls: conflicting trends in opposite directions. One trend is illustrated by the recent request by the Reagan administration in the United States to cut essentially to zero all of the budget of the National Science Foundation devoted to science education, particularly in keeping science teachers up-to-date. That is clearly eating the seed-corn. The budgetary savings are trivial, the potential damage enormous.

In many areas of science the great accomplishments are made by young people, people in their twenties and early thirties. I think it likely that a number of science graduates in this class will make such significant contributions. But because this tends to happen at early ages the generation time for scientific progress is short. Abandoning scientific education for a decade turns out to be something not easily repaired. It can produce an enormous gap in our scientific expertise, one extremely difficult to remedy later on, when we come to our senses.

Any attempt to back away from understanding the world, any attempt to obscure what science is about is dangerous. One of the reasons that there is unease about science in certain quarters is because it challenges the prevailing wisdom. It sometimes is counterintuitive. It requires a certain intellectual effort. It occasionally leads us along a road that jars our predispositions.

We can understand the world because there has been a match made by natural selection between how our brains work and how the world works. For example, how is it that the laws of falling bodies are so simple? Why is the distance that an object falls proportional to the square of the time? Why is the velocity linearly proportional to the time? Why such a simple relationship? Why not the Chebyshev polynomial of the time? Why not a full spherical harmonic expansion of the time? Why just proportional to the time?

Let us imagine some of our ancestors of five or ten million years ago brachiating from branch to branch. Those who had to compute the Chebyshev polynomials of the trajectory never made it to the next branch; they left few descendants. The guys who could figure it out left descendants. We come from them. We spring from the creatures who could figure it out. And that figuring out is what we must continue to do.

In Newtonian physics, in relativity, in quantum mechanics, there are many results which seem counterintuitive, which we are not prepared for. Even the idea that an object in motion tends to stay in motion does not conform in a ready way to everyday experience because there is so much friction and atmospheric resistance down here on Earth. The prediction of special relativity that time slows down as you go close to the speed of light does not correspond to everyday experience. That's because we are not in the habit of traveling close to the speed of light. The prediction from quantum mechanics that a particle can ooze through a barrier and find itself on the other side of a wall without having made a hole, sounds absurd. But, in fact, natural radioactivity depends exactly on that process. The idea in evolutionary biology that creatures change slowly from one species to another is not in perfect conformity with everyday experience because it is rare that we find a creature that has transmogrified before our eyes into another species: we have not stuck around long enough.

In many such areas, but especially in the last, you can find today a kind of resurgent know-nothingism, a reactionary response to the findings of human beings objectively addressing the world around them. There is something called "scientific creationism" which claims that the school system should teach the supposed evidence in favor of the cosmology in the first chapter of Genesis on an equal level with the evolutionary findings that Charles Darwin initiated. I believe that this is exceptionally dangerous.

Let me give just one example of how the argument goes. By adding up all the begets in the Book of Genesis you can get the age of the Earth. It turns out to be about six thousand years old—A begat B, B begat C, C begat D. A's lifetime is stated, B's, C's and so on. Then you get up to historical times. Add it all up: 4004 B.C. according to Archbishop Usher. Now, if that is the case, then an interesting question arises. How is it that there are astronomical objects more than 6000 light-years away? It takes light a year to travel a light-year, so if we see an object that is a million light-years away or two million light-years away, we are seeing it as it was one or two million years ago in the past. If the entire universe is only 6,000 years old, what must we deduce from this? I think the only possible conclusion is that 6,000 years ago God made all the photons of light coming to the Earth in a coherent format so as to deceive astronomers into thinking there are such things as galaxies, that the universe is vast and old.

Since most of the matter and energy in the universe is in external galaxies farther away than a million light-years, God must have created most of the matter and energy in the universe to deceive human beings. That is such a malevolent theology as well as such an arrogant pretension that I cannot believe anyone, no matter how devoted to the literal interpretation of this or that religious book, could seriously consider it.

Nevertheless, this sort of doctrine is being urged upon us. Already there are trends essentially to prevent the teaching of Darwinian evolution in schools. Since evolution is one of the major insights in the biological sciences, this restriction can only be understood as a serious and major attack on the teaching of science itself.


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