Are We Alone in the Universe?
NORMAN J. BERRILL
Professor of Zoology, McGill University
Flying saucers? Men on Mars? in this down-to-earth tour of outer space a noted scientist explores the possibility of life beyond our planet
MAN SEEMS almost ready to leave the solid earth and go off in rockets into outer space. Also, to judge from persistent reports of flying saucers and their occupants, we appear to be expecting visitors.
The two ideas reflect the constant change in our ideas about life itself. Not so long ago only lunatics and heretics doubted that the earth was the centre of the universe, and the sun and the stars circled about us. Man was the focus of all creation, made by God in his final triumph. But within his narrow world he still had room to move around, to find adventure in distant parts, to leave congested areas and escape into solitude. Now it is difficult to travel without continually meeting someone dressed much too like oneself at every turn. Now it is recognized that our world is one of the lesser planets circling the sun in company with a few others, isolated from the nearest star by timeless space. Now, beneath the mushrooming spectre of the hydrogen bomb, the awful thought occurs that our world may some day be uninhabitable.
Naturally our thoughts fly outward as they have never done before, and we have an urge to visit other worlds than the one we know so well. We begin to feel a haunting loneliness, tinged with fear and the immemorial thirst to seek new knowledge. Above all perhaps, we’d like to see some new and more interesting faces, just so long as they seem somewhat human. We want to know whether there is anyone like us on some other planet of our solar system, or even in the universe. Or do we have to go on talking to ourselves and perhaps hiding from ourselves on this same tiny planet for evermore?
This is a serious question, deadly serious. For
upon the answer depends much of the meaning of our individual lives, of the purpose of the universe as a whole. But how on earth are we going to find the answer? The belief that there is life on Mars, for instance, or that recently we have had some visitors from some such unearthly place may be no more than wishful thinking. There is in fact no real evidence that this earth has received anything at any time from outer space except meteors and radiation. Nor is there any guarantee that we actually will ever make an interplanetary trip in person, or that we would be wise to do so even if we could. In the meantime we can best seek the answer by reflecting on how life originated and evolved upon this earth and, using this knowledge as a yardstick, by trying to determine whether suitable conditions for a similar event may exist in other places. We deal with possibilities and probabilities, rarely with certainties.
What are those conditions? To begin with, t he essential substance of all that lives upon the earth contains more water than anything else, water which is a built-in part of what is actually alive and without which there would be no life. This is true of all things that we earthlings recognize as living, whether the organism he an amoeba or a cabbage, a jellyfish or a man. The proportion varies, of course. The jellyfish is more than 98 percent water, while more substantial creatures, like mice, men and elephants are more than two thirds water.
This gives us our basic limitation. We have neither reason nor evidence to think that life of any sort can exist in an active state if water is absent. This limits our search for life within our own solar system to regions where water would neither freeze nor boil. The majority of the planets of our solar system are excluded right there. Mercury is much too close to the sun and moreover keeps one side permanently facing the sun. This side has a temperature of about 400 degrees centigrade, high enough to melt lead. The opposite side receives no heat at all, and is intensely cold.
In the other direction, working from the outermost, inward, Pluto, Neptune, Uranus, Saturn and Jupiter are all so far from the sun that even on Jupiter, the closest of them, the surface temperature is about minus 140 degrees centigrade, cold enough to freeze the night.
It doesn’t leave much chance for life on the planets we know—only Venus on the sunward side of us, Mars on the other, and the moon around us. Of these the moon can be ruled out at once. It is so small and light that whatever water and atmosphere it may once have had has disappeared long ago, for the surface of the moon lies nakedly exposed to empty space. During the long lunar day, equal to fourteen of our own, the noon temperature rises considerably above the boiling point of water. By sunset the temperature drops below zero and during the long night the surface becomes almost as cold as Jupiter. With such tremendous changes from heat to cold, without an atmosphere of any sort, we should feel no surprise that our powerful telescopes fail to reveal any sight of life, green or otherwise on the moon. The moon is dead. Even its craters are now thought to be the result of . Continued on page 32
CONTINUED FROM PAGE 12
bombardment by giant meteors fro outer space and not caused by volcan explosions from within. The dead ruis all-pervading.
Venus and Mars are another matt* Venus, the earth’s twin sister, so alii are they in size, is only 26 million mil away when at its closest. No oth planet comes so near, if we except t! moon. Mars at its nearest approach about 35 million miles away and is litt more than half the size of the earfi Mars rotates at much the same ratet the earth, Venus probably much mo, slowly, but the temperature conditio) for sustaining water in a usable for are marginal for each of them. At not on Mars, in the equatorial region, t! temperature rises well above freezii but drops well below that every nigh Venus, on the other hand, heats up I 130 degrees Fahrenheit (or 55 degra centigrade) on the sunny side, 3 though because t he nights are very lot the temperature drops to sub-zej levels on the dark side. Water a cordingly could exist on either plane though in a much more changeai} state than we have on earth. Simp! from the point of view of water at prevailing temperatures, the earth 0 cupies the most favored position mil way between t he two extremes. Mai and Venus lie within the temperatu limits, but with little margin to spaj one way or the other. Neither is ( suitable for life as this earth of ours arf ast ronomical observations bear out tn conclusion. J
Tough on Mosquitoes
Venus in certain ways is the mu intriguing, though we know less aboi it. Through the telescope the surfa) appears devoid of markings and at t| same time reflects sunlight to a mu) greater extent than the naked airlei surfaces of the moon and Mercury. ! thick blanket of clouds prevents ( from seeing through to the plane) solid surface, and while this is aí gravating to an astronomer, the me presence of a thick atmosphere pu Venus more or less in the same categof as the earth. The force of gravity al the atmospheric pressure would I very much what we are accustomed t and every so often we hear the su gestion that on some distant day Ven may be colonized by earthlings. It i.c fascinating thought, but there is catch in it : the atmosphere of Venus not the kind a man or even a mosqui could tolerate for a minute. Our ov clouds are condensations of wat vapor, while we breathe air for the sal of the oxygen it contains. Neither these can be detected in the air Venus. Without oxygen, of course, ' and all other animals would die. Moi over there seem to be huge quantities hydrogen and carbon dioxide in t heo of Venus which would cause us strangle and suffocate even if oxyg was present. The heavy clouds are al carbon dioxide, dry-ice crystals ino
The apparent absence of water vap in its air indicates that the surface Venus must be entirely desert. Tht can be no oceans, lakes or rivers; there were, the high surface tempel tures would give rise to extensi evaporation and we would be able detect the vapor. Here, in fact, is t key to the haziness of the atmosphe The atmospheric circulation must much more violent than on the ear and great dust storms swirl to tremf dous heights. Furthermore, the hi
concentration of carbon dioxide exerts a strong greenhouse effect, trapping the heat waves from the sun and so raising the surface temperatures far above what they otherwise would be—higher than that of boiling water, on the sunny side at least. Overheated, without either water or oxygen, there can be no life on Venus—at least as we define life.
Mars, therefore, becomes our last hope for finding living company in our solar system. It, too, has an atmosphere, but we can see through to the planet ’s surface and observe a seasonal change. When conditions are favorable the telescope reveals Mars as a beautiful object with a deep orange color and misty markings. And even as long ago as 1661. in the early days of telescopes, the Martian poles were seen to be white-capped like our own. During the northern summer the northern polar cap shrinks, while the southern cap grows. As the seasons change the process is reversed. Superficially at least the similarity of Mars and the earth is striking.
In contrast, however, to the changing polar caps there are dark markings on the Martian surface which appear to be more or less permanent. They rotate with the planet and at first it was thought that they were seas and that the ruddy background was dry land. Then later, during the last half of the nineteenth century, an Italian astronomer described the markings as channels which occasionally appeared to bi> double. This led to the idea that they were canals made by intelligent beings and primarily for irrigation purposes to conduct the water melting from polar ice caps across the arid wastes of the planet. If only it were true! Those busy Martian engineers must be somewhat like ourselves no matter what they looked like. Just the thought that someone else in the solar system is digging ditches brings tremendous excitement.
Unfortunately, as the years have gone by and our knowledge has advanced, this interpretation of the dark markings has become more and more implausible. For one thing Mars is so distant and the markings are so faint that imagination has been more powerful than vision. None of what we know about Mars—and we know a great deal —suggests that we would find our counterpart there if ever we should succeed in paying a visit.
Mars has an atmosphere. So much is certain. At the Martian surface it is about as thin as it is here at the height of Mt. Everest. Carbon dioxide is present to about the same extent as in the earth’s atmosphere. Water vapor has been detected, although so far there has been no indication of atmospheric oxygen. But neither is there any sign of poisonous gases like the ammonia and methane that form the atmospheres of Saturn and Jupiter. The white polar caps are almost certainly ice or frost. Whatever they are, they must be very thin since they shrink and expand so rapidly with change of season. The large orange-colored areas are undoubtedly similar to our great earthly deserts, not entirely devoid of what may be some kind of vegetation, for there is a seasonal change of color,
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from greenish to reddish and back.
The faint tracks that were thought to be canals appear to be several scores of miles wide and they run for hundreds of miles over the surface in a way that suggests there are no mountains or valleys. In the end, therefore, we are left with a picture of a dry planet with a limited amount of water, and with a seasonally changing vegetation which at the present time is considered to be somewhat like the lichens that cover j our rocks. Yet without oxygen it is ; difficult to see how anything com} parable to animal life as we know it could possibly exist.
So it appears that we are on our own. at least within the solar system. And after all it is not surprising. Starting with our basic condition that life ¡ depends both for its nature and for its survival upon water, no matter what other chemicals may be present, it follows that as we travel outward from the sun we pass through a region where temperatures permit liquid water to exist. And within this band there is a narrower middle region which is the most favorable in the sense that conditions are ideally balanced between the greater extremes of warm and cold. This is the region in which the earth revolves in its course around the sun. Venus is a little too close to the sun and what water it may have had has j left it long ago. Mars is chilly and has j a little water, but on balance the ! evidence suggests it lacks either enough water or oxygen to sustain animal life of what we would call a higher order.
How Did We Get Here?
In a sense man can climb back onto his pinnacle as something unique to the universe. There is virtually no doubt that within the solar system we represent the peak of creation, inasmuch as man is the most recent novelty to evolve on the earth and is also in certain definite ways the most complex.
If man is lord of our solar system as he undoubtedly is at the moment— although he is playing with deadly fire and may cut short his career—we still have several questions to answer before we can be sure there is or is not a higher species within some other solar system. Two of the most outstanding are: what have been the circumstances that have led to our existence? Is there any likelihood or possibility that such conditions may exist somewhere in the universe outside our own particular solar system, now that it is all too clear that our neighboring planets do not supply them?
The evolution of man on this earth, in the sense we are considering here, embraces the whole period of the origin and evolution of life, a time out of mind lasting more than 2,000 million years. Of this we have fossil records for the last 500 million years only.
The present belief is that life in its earliest and most primitive state came into existence surely and inevitably as the result of interactions between solar radiation and the water, with its dissolved minerals and gases, of the young planet; that the first and simplest forms of living matter evolved in the seas of those distant times. Our blood and tissues are heavy with sea salts to this very day.
Many primitive sea creatures, however, penetrated the fresh-water systems of rivers and lakes of the early Cambrian period, almost 500 million years ago, and it is in the rocks of this period that we begin to pick up the trail of actual fossils. Our own ancestral forms are among them, for the oldest remains of backboned animals of any kind come from deposits laid down under fresh water. Backbones, propulsive muscles, and a streamlined
form evolved in response to flowing streams. Fins evolved for stabilizing motion, the labyrinth of the ear for sensing motion, and the eyes for navigation.
Inland waters later on became stagnant and increasingly shallow. Lungs evolved for gulping air to make up for lack of oxygen in the water, and fins became pushing legs as bodies began to drag on the swampy mud. Before long, before the age of the coal forests ended, what had once been fish were crawling about as the first of the fourfooted creatures of the land. Reptiles began their thundering occupation of the earth.
An ice age, more severe than the one from which we are now emerging, interrupted the reptilian career, and it was followed at once by overheated conditions. During this period of tremendously varying temperatures, bodies became adjusted to greater warmth and eventually became able to control body heat at a high level. In doing so scales were discarded to make way for insulating hair, and skin glands evolved for both sweat and oil. Primitive, hairy, warm-blooded mammals started on their way.
Mammals at first were small, meek, nocturnal creatures that had to run and hide» from the larger reptiles. For the greater security of both parent and offspring the developing young were retained within the maternal body, and skin glands evolved into milk glands to ease the shock of being launched upon the world. The combination of the womb and the breast brought families into being.
When the greater reptiles disappeared the mammals in general grew larger and fiercer, and some of the meeker ones took to the trees for safety. Climbing trees took noses away from the ground and put a premium on sight. The sense of smell degenerated, and binocular vision evolved for judging distance. Feet became hands for climbing, posture became more and more erect. Eyes and hands combined in useful application, and the brain enlarged.
The land across Asia heaved and raised the Himalayas. Africa grew drier. Heavy forests gave way to scattered trees and the runways in the forest tops more or less disappeared. Treetop apes became partly grounded, and had to run to save their lives. The hinder pair of climbing hands changed into feet, brains became more and more important. Speech evolved for communicating warnings and experience, and mankind took on its recognizable form.
Such is the road that we have taken. Circumstances have pushed or constrained us at every turn. And if any of the circumstances had been different at any critical period, the path would have taken another way, and man in the form that we see ourselves to be would never have existed. No other course would have channeled life to run in human shape, for the course and its product are unique. But, lest we feel that all events have been created for the sole purpose of our creation, the whale and the bat, if they could think and speak, could say the same about themselves. Each kind stands alone at the head of its own particular trail through time. All are the outcome of a planet of a certain size revolving at a certain distance from a sun of a particular strength. The recipe for man, however, includes fresh water as well as salt, stagnant water, land above the surface, alternating cold and heat but not too much of each, humidity and dryness, alternating oppression and escape from oppression, too many trees and not enough of them. It is a peculiar concoction as the outcome shows.
So here we stand, at present mask of the only planet in the solar systet bearing life wort hy of the name. Whi are the chances that beings like ou> selves may exist somewhere in the moi distant reaches of the universe?
Direct observation no longer help No matter how far we look across spat to the remoter galaxies, we see only th light of stars or of incandescent gasa Planets are too small to be detected an shine only by reflection. If other stai besides our sun have planets circlip around them, we will probably nevt see them. Yet this is the question tha means the most, if there are no otht planetary systems like our own, then can be no other life in our meaning o the word. If a group of planets circlip around a star is an infinitely rare cot dition, life becomes an almost accidet tal happening in the strict scientib sense. And until a few years ago thi is what it seemed to be.
For it comes to this, that the onl; way we can calculate the chances of lit outside our own solar system is b figure out how our own solar system ha come into existence. Most of the olde^ and not-so-old theories have require the near-collision of a pair of stars, th one whirling around the other air
What my family wants to see On TV is ignored;
Choice of channels rests in me As chairman of the bored.
IVAN J. COLLIN
dragging off matter which became thi planets. This type of theory account; for much that is peculiar in our system If it were true, however, planetar; systems and the life they might suppor would be extremely rare events in th universe, for the chances of two star coming together in such a way are ver; small.
But new theories are still displacing the older ones, theories which an better inasmuch as they account foi more of the strange qualities of thi solar system than did their predecessors. These relatively new theorie account for the birth of planets around a sun without involving a second star And they make it likely that planetary systems are commonplace throughoui the universe, that a large percentage o: the sun stars have planets encircling them. If these newer theories are any; where near the truth, the univers itself becomes alive, with solar systems countless beyond imagination. Foi within each system one or possibly two planets will lie within the life-forminf zone where water can exist. Could sue! planets produce another man?
Before we can give even a tentative reply we need to look once again at oui own planet, our own solar system, oui own sun. And we can counter also by asking whether there is any other mac or woman on this earth who is exactly like yourself, not merely a spit tiny image, but you down to your inmos! fibre and emotion? Unless you have ar identical twin the answer to this i¡ decidedly no! The chances of the same individual happening twice are so infinitely small they can be ignored entirely. Novelty is the essence of the universe we inhabit.
By the same token there may be millions of stars very much like our sun but none exactly the same in size and intensity. There may be millions ol planets more or less like our own whitl
lie within an all-important water zone, hut none will lie in exactly the same position relative to its own star, none will revolve about its own axis and around its sun at just t in» same rates as the earth, and none will be of' exactly the same size or have exactly osame ingredients in exactly the same proportions. There are so many variables that it is almost inconceivable that dice of such complexity could throw t he same number twice.
Each life-bearing planet throughout the universe must be unique, no matter how ideally placed it may be in relation
to its sun. It will be larger or smaller than the earth, have a somewhat different atmosphere, more or less water in its oceans, different fluctuations in temperature, perhaps more land in proportion to its seas than we have or maybe no land at all. Every particular circumstance so vital to our own peculiar human course of evolution would be changed to some extent. Human beings, with our shape and size, walking on two legs upon a pair of converted hands, with all our special advantages and disabilities, are to be found only upon this earth, never on
any other planet from here to eternity. Other planets will have their own evolutionary creations the appearance of which we cannot imagine. Yet of this we can be sure: well-placed planets evolve life, and life sooner or later evolves mind. There may not be anything that looks like a man elsewhere in the universe, but there almost certainly will be beings, of kinds uncountable, that possess intelligence and power, deep emotion, beauty in essence, and wisdom grown perhaps far beyond our own. In all that really matters we are almost certainly not alone. +