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The Planet-Girded Suns: Man's View of Other Solar Systems  by Sylvia Engdahl (1974) ~ Page 8 of 8 |
Conclusion
(Please read the Introduction
if you haven't yet seen it.)The last four chapters of The Planet-Girded Suns deal with the current state of scientific knowledge—and opinion—about extrasolar worlds as of the time of its publication in 1974, as well as the opinions of religious leaders and of the public in general. They also discuss the question of whether interstellar communication and/or interstellar travel may become possible. Since these chapters are somewhat outdated now, I don't want to post them without revision, and revising doesn’t seem worthwhile since there are many more recent books covering these subjects.
It’s worth noting here, however, that there has been a pendulum with regard to majority opinion about whether planets of other suns are inhabited, which has swung several times during the past few centuries. As the preceding chapters show, belief in the existence of life on them was almost universal among educated people from the late seventeeth century until the mid-nineteenth century, when William Whewell published a book opposing the idea; it began to decline in the late nineteenth century, but continued to prevail until the early twentieth century. Then, after a period when it was out of favor, it was on the rise again from the late 1940s until, by the 1970s, it had once again become the virtually unchallenged view of science—for at that time, radio astronomers believed that communication with extrasolar worlds might be imminent. In 1972, the U.S. National Academy of Sciences issued a report stating that our civilization is “within reach of one of the greatest steps in its evolution: knowledge of the existence, nature and activities of independent civilizations in space.”
But in recent years, the pendulum has started to swing again. Though there are still many enthusiasts for SETI, the search for extraterrestrial intelligence through radio astronomy, more and more scientists have begun to feel that there aren’t as many extrasolar civilizations as they once thought, and some say that perhaps there are none at all. Like William Whewell and Alfred Russel Wallace before them, they have challenged the widespread belief that advanced forms of life commonly exist in other solar systems. For instance, in 2000 Peter Ward and Donald Brownlee published a book titled Rare Earth in which they argue that the evolution that has occurred on our planet may be the exception rather than the rule.
Why has this happened, just at the time when we have at last obtained direct evidence that extrasolar planets themselves do exist? Of course, all qualified writers on both sides of the issue present detailed scientific arguments in accord with the knowledge of their era, just as they always have. But there is much more to it than that. We still don’t have any actual evidence concerning the existence or non-existence of extrasolar life; speculation based on scientific fact is still only speculation. And speculation depends a great deal on feelings. As I have suggested elsewhere, there are many emotional reasons why some people may, underneath, not want to believe in the existence of extrasolar civilizations, just as there are emotional reasons why other people do want to. The fact that so far there has been no success in establishing communication through SETI is only one of them; but it is, I think, a significant one. The 1972 Academy of Sciences report mentioned above stated, “More and more scientists feel that contact with other civilizations is no longer something beyond our dreams but a natural event in the history of mankind that will perhaps occur in the lifetime of many of us.” That last phrase may be an important key. As I’ve said in the introduction to Early Space Poetry, there may be a sort of “sour grapes” reaction now that it appears that personal knowledge about such civilizations is beyond the dreams of today's scientists after all.
And yet most people aware of the universe, today as in earlier eras, do tend
to believe in the existence of extraterrestrials, whether or not they feel
science supports this belief—just as they long for the stars even if
they know that according today's theories, rapid interstellar travel is not
as likely in fact as it seems in science fiction. That has not changed
since I wrote the concluding section of The Planet-Girded Suns,
which appears below.
In 1904 a reviewer of Alfred Russel Wallace’s book Man’s Place in theUniverse, referring to the belief in plurality of worlds held by great scientists of the past, wrote: “That such men entertained a theory for which they could not adduce a scientific reason indicates more on the side of its probability than any amount of scientific improbability could weigh against it. It revealed an unconscious tendency of the human mind to lean to that side of the question.” Unconscious tendencies shared by large numbers of creative people usually do prove fruitful. Today, many want to go to the stars.
One woman’s comments on Wallace’s book ended the discussion of habitable worlds this way: “Demonstrative evidence on the point is not at hand, and cannot be looked for. Arguments . . . are futile. They rest on arbitrary assumptions. Our minds are inadequate to grasp the vastness of creative design; yet common sense obliges us to admit that what is inconceivable to us may nevertheless really exist. All that we are quite certain of regarding our place in the Cosmos is that the genus Homo . . . is earthbound. No second island in space is attainable by him in his present condition. His habitation begins to seem inconveniently narrow; but there is small chance of adding to it by annexation—there are no more worlds for him to conquer.”
By “present condition” that author meant life as distinguished from life after death; she could not, in 1904, envision any kind of space travel as an actual possibility. Her words sound rather unhappy.
Why do men and women feel strongly about other worlds, other suns? If it were just because they thought it might be fun to go there, this emotion would indeed be childish; yet it is not confined to children. It is felt by adults in every region of this planet who know perfectly well that they have no personal chance of going anywhere in space. It was felt by Bruno in the sixteenth century and by increasing numbers in succeeding ages. The landing of Apollo 11 brought response from people of many countries, some of whom had never paid any attention to astronomy before. Not everyone shares the feeling, but no one can deny that it is widespread.
Some of those who have pondered the question believe that the desire to go to other worlds is a human instinct, related to man’s evolution. They believe it is necessary to the survival of a sentient race: ours, and that of all others inhabiting the universe.
In our time it has become evident that the population of Earth cannot continue to grow indefinitely. This problem is so frequently discussed that it needs no elaboration. Many people are convinced that the only long-range permanent solution to it is the colonization of uninhabited planets: first the suitable ones in our own solar system, but eventually, extrasolar worlds as well.
To be sure, there are also many people who disagree with this view. It has often been maintained that colonization of other worlds would not solve Earth’s population problem. Figures have been presented to show that spaceships could not possibly carry away people fast enough to keep up with the rate of increase. For example, to hold the population of Earth constant at the 1969 rate, almost 190,000 people per day would have to emigrate. It is very true that such a plan would not be practical; no one who has thought the matter through claims that it would. Population growth on Earth will have to be slowed down much sooner than colonies can be established in any case, and eventually it will have to stop. The idea of colonization is not to get rid of extra people born on Earth by sending them somewhere else. It is to provide new lands where mankind—our human race—can continue to grow and evolve.
But, some argue, if Earth’s population were stabilized, why would there still be a problem? What difference would colonization make if the terrestrial birth rate has to be controlled anyway? Those who consider colonies essential see a big difference; they believe it is contrary to nature for the population of a progressive species to be completely stabilized. Some feel that it is impossible—that the biological instinct toward growth is stronger than conscious reasoning based on man’s limited knowledge, and that without colonies, despite controls there would ultimately be overpopulation, followed by a sharp drop caused by starvation or war. Others think that it is possible to achieve stabilization, but that if this should happen all types of progress would stop, and man would slip backward into decadence. Either way, they believe continued evolution of man demands ceaseless expansion.
People who feel this way are not confined to followers of any particular philosophy. On the contrary, they are found among those whose opinions conflict sharply in other respects. To give two extremes, some Christians believe that the Bible’s command, “Be fruitful and multiply,” is a law of God that must be obeyed literally; while dialectical materialists have traditionally held that infinity of the universe, and a corresponding infinite potential for growth and development in man, is a law of nature. A Russian scientist, Igor Zabelin, has suggested that the population explosion is man’s instinctive preparation for resettlement on other planets. One does not have to agree with any of these specific ideas to believe that unlimited expansion of our human race (and also, of course, of whatever other sentient races there may be) is a basic cosmic principle.
Social scientists and others, including some of widely assorted viewpoints, have observed that the exploration of space is the only outlet left for man’s pioneering and aggressive impulses. That the conquest of space might serve as a substitute for war is a common argument for exploring our solar system. Speculatively, it is also possible to argue that man’s aggressive impulses are an instinctive preparation for conquering space. The length of his recorded history is only a tiny fraction of the evolutionary time scale, compared to what came before and what, in the judgment of scientists, may be yet to come. Two things are sure: man has entered space, and he does not want any more conquering of territory to be done on his home world.
At present there is no evidence for the arguments in favor of expansion; only time can show whether they are valid. But if they do prove to be true, travel within our solar system will not be enough to ensure mankind’s survival. In due course, it will be necessary to travel to other suns.
A further argument for interstellar migration is that without it, our whole species could be wiped out by a single catastrophe. Or, in the very distant future, man’s extinction would inevitably occur when our sun becomes unstable. This will not happen for billions of years; it is not an immediate danger, and people therefore feel that it has little significance here and now. The idea, however, does affect one’s outlook toward the universe. Do all sentient species ultimately die? Scientists calculating the number in the galaxy often assume that they do. The life-span of stars is known to be finite. If interstellar travel is impossible, the life-span of a civilization cannot exceed that of its mother star. Perhaps that does not matter; yet many people care deeply about the fate of their remote descendants.
Considerations like these raise questions that are unanswerable. Philosophers ponder them, but they cannot resolve them—at least not in this era, and probably not for many eras to come. One such question concerns the relationship between individual people and mankind as a whole. Some people believe that mankind is like an organism: that in a further stage of evolution, it will be a single organism. Just as single-cell life forms evolved into multicellular forms, they argue, species composed of sentient individuals evolve into larger entities. Others believe that individual beings always remain of primary importance, and that in highly evolved civilizations they cooperate without becoming mere parts of some “group mind.” This issue is not as clear-cut as it sometimes seems to be. People who are convinced of the importance of individuals nevertheless usually consider the future of mankind more important than their personal affairs, and often choose to make sacrifices for mankind’s benefit. Neither they nor advocates of the other hypothesis can explain why.
Perhaps this question sounds too abstract to worry about. So far it has been of interest mainly to philosophers—yet before the time of Giordano Bruno the question of whether there could be more than one world was discussed only by philosophers, too. Shortly after his time the invention of the telescope changed things. The invention of starships would bring about an even greater change. Theories about the future evolution of man would no longer be just abstractions.
The only kinds of interstellar travel scientists can now foresee involve one-way travel, at least from the standpoint of people remaining on Earth. Colonists of each new extrasolar world would be completely independent, and any messages they sent back would not be received until long years after their departure. Members of crews kept young by “time dilation” could return themselves, but only to a society they would scarcely recognize. The generation that built a starship might never hear of its fate. Under those conditions, what would “mankind as a whole” mean? Our species would spread from star to star, but there would be no real communication. Earth’s society would not be entirely “closed” because adventurous people, and people who wanted large families, could leave; still there would be no interaction between the new worlds and the old. What would happen to Earth? Would the idea of expansion alone save it, or would the home solar system’s civilization decline, to be replaced by the separate ones of countless colonies that could never unite?
There are no answers now. Science fiction often speculates about such problems, and there is also speculation in nonfiction; but our century has no data to work with. Some scientists think answers could come through contact with civilizations more advanced than ours. Barring that, mankind will have to learn through experience. It is clear, however, that a means of two-way travel—faster-than-light travel—would be more than a mere convenience. This is one reason why authors of stories so frequently assume it exists, and why some people maintain their faith that it does indeed exist despite apparent mathematical proof to the contrary . . .
With or without faster-than-light travel, if man can go to the stars he undoubtedly will. The dream of doing so is too powerful, too closely tied to the basic drives of human nature, to be abandoned by everyone, though some may call it foolish. The establishment of extrasolar colonies should not in itself be difficult, for there will first be colonies in our own solar system. Suitable planets in other systems are likely to be plentiful. Dr. Stephen Dole, in his book Habitable Planets for Man, estimated that there may be about fifty within a hundred light-years of Earth, and he was counting only those where people could live in the natural environment.
Some of those planets, however, may be already occupied. It goes without saying that people who favor the colonization of other solar systems do not suggest that man should establish outposts in inhabited systems. This is more than a matter of not taking over the home planet of a sentient species that has evolved there. If expansion from world to world is the normal course of evolution, an intelligent race that has not already colonized its entire solar system will someday need to do so; alien colonists must leave all its planets alone. Moreover, it is likely that sooner or later man will encounter colonists of other starfaring races, and their new worlds must not be touched either.
This seems to be a quite serious restriction, especially since biologists feel that life will evolve wherever the right conditions exist. But actually, according to statistics, it should not be. If present theories are right, there are millions of worlds. Life on many of them has not yet evolved into intelligent life. On some of them it never can. To be sure, most such worlds are not as desirable as ones that look just like Earth; they do not have environments in which man could live without the support of advanced technology. By the time Mars and Venus have been colonized, and starships have been developed, the technology will be available. People who dislike artificial environments, and are expecting to find a primeval paradise in some other solar system where they can “live off the land,” may have to decide whether they would rather use technology or wipe out another sentient race. It is to be hoped that it will not be a very hard choice.
In the nineteenth century people resisted the thought of planets without native sentient life because they assumed those planets would be “wasted.” Thomas Dick, in 1838, expressed the typical view as follows: “Now, can we for a moment imagine that the vast extent of surface on such magnificent globes is a scene of barrenness and desolation; where eternal silence and solitude have prevailed, and will for ever prevail . . . where nothing appears but interminable deserts, diversified with frightful precipices and gloomy caverns; where no vegetable or mineral beauties adorn the landscape; where no trace of rational intelligences is to be found throughout all their wastes and wilds . . . ?”
To suppose that this was the case would, in his eyes, require a “most gloomy and distorted” concept of reality. But Dr. Dick’s view was narrow. He had ideas he did not know how to deal with. “Some,” he admitted, “may be disposed to insinuate that the Deity may have designs in view, in the creation of matter, of which we are altogether ignorant.” On the same page he said, “It is the ultimate design . . . that this world shall, ere long, be fully peopled with inhabitants . . . and this extension of population and of cultivation is evidently going forward with rapid progress at the present time in different quarters of the globe.” He did not guess, in 1838, the implications of rapid progress in the extension of population, much less the connection with “empty and useless” planets.
Today, though most religious leaders see nothing contrary to religion in the concept of other intelligent beings, they are more divided on the question of space travel. Many favor it, but some are opposed. Those who oppose it may, like C. S. Lewis, be thinking of what man might do to alien races. Certainly is a valid reason for opposition if one assumes that mankind will not gain in maturity before reaching the stars. It may be, however, that starships are too advanced an invention for a people not ready to make good use of them. That is something no one yet knows. But it is worth asking what lifeless solar systems are good for, if no sentient species colonizes beyond its own.
Such questions need not necessarily be answered in religious terms, at least not “religion” of the kind involving faith in a Deity. Most human beings feel that there is a reality larger than the realities of Earth, and that somehow, man fits into this universal reality. Commentators on Soviet space achievements have remarked that the people of Russia show what one writer has called “a deep and in some ways spiritual conviction that man has a significant destiny away from his home planet.” That conviction is common to people everywhere, whether they believe in formal religion or not. It is in itself a form of faith: faith in mankind’s future.
Our human race is, in the opinion of most scientists, younger than average. It is thought that our galaxy contains many that are thousands or even millions of years more advanced. Have these races already colonized most of the empty planets? Or if not, will there nevertheless come a time when all the countless worlds of other stars have been settled? Perhaps, if there are supercivilizations, or even a single galaxy-wide association, it does not matter who possesses which world. Yet unless the different sentient species can intermarry and have children—which is unlikely when they have evolved separately—there can never be actual merging; each human race must have its own destiny, however closely they may unite in friendship. And if expansion is necessary to evolution, a supercivilization too would have to expand. Could the entire galaxy become overpopulated?
That does not seem likely if, as some scientists have speculated, civilizations learn to thrive in the depths of space itself, no longer depending on planets any more than land animals now depend on the sea in which they first evolved. Perhaps vast cities orbit certain suns; perhaps the most highly evolved beings tap other energies, and do not need sunlight at all. Expansion, however, is more than a matter of room to live in. It demands new frontiers. Can they be found through intergalactic travel, maybe? There are billions of galaxies, but the distances between them are awesome, and the others might be as fully settled as ours.
Still, the entire universe is expanding. The galaxies are receding from each other. Some astronomers believe more are continuously coming into being. There is much not yet known about cosmology: questions of beginnings and endings, in space and in time—science has barely begun to probe the mysteries of them. They are questions for the future. There will always be more questions.
For now, people of today, like those of earlier ages, can only look up at the other suns and wonder. What is happening there? To scientists that question is pointless, for starlight spans time as well as space; a star three hundred seventy-four light-years away is seen in 1974 as it actually was in the year of Giordano Bruno’s death. A radio message from its solar system would tell what its civilization was like then, and no doubt that civilization has since changed as much as Earth’s. It is hard to think of past centuries as real; yet stars appear only as they were in the past. Can man learn to communicate across years as well as distance?
It has been suggested (and not only in science fiction) that the one thing that can travel faster than light is thought—that telepathic communication might be instantaneous. This is too speculative an idea to consider seriously at present. But the implications of it are interesting to imagine when equally unknowable areas are considered; it is no more speculative than ideas about civilizations that have had interstellar contacts for millenia.
Thoughts may not reach from one solar system to another, but thoughts about extrasolar worlds are the sole form of contact mankind has had, so far, with whatever life may exist beyond Earth. The ability to think such thoughts distinguishes man from other terrestrial species; it is in itself a step toward the stars, perhaps the most crucial step. About fifty years ago the author of an article about astronomy wrote: “The knowledge that we inhabit, not this green earth alone, set in shining seas, but the wide universe, is a rightful part of the heritage of man ... Beasts and birds rejoice in the sunlight . . . but none of them, save man alone, looks beyond this earth to the outer immensities. Beasts and birds inhabit the world. Only man inhabits the universe.”
Man—and elsewhere, beings who live under the light of other suns, yet look upon ours with longing. The nineteenth-century poet and novelist George Meredith expressed this feeling about the stars:
The great life they hold,Science cannot say it that well. But science may someday prove it to be true.
In them to come, or vaster intervolved,
The issues known in us, our unsolved solved . . .
We who reflect those rays, though low our place,
To them are lastingly allied.
So may we read, and little find them cold:
Not frosty lamps illumining dead space,
Not distant aliens, not senseless Powers.
The fire is in them whereof we are born;
The music of their motion may be ours.
Spirit shall deem them beckoning Earth and voiced
Sisterly to her, in her beams rejoiced.
For a list of books about views toward extraterrestrial life before the 20th century, see my Listmania List at Amazon.com.>
Lots more that I have written, or collected, about space! |
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