by Fred Hoyle
Fifth Planet
Fred & Geoffrey Hoyle
Preface
The very nature of the plot has forced us to set this story in the more distant future than we would otherwise have preferred. It is hardly possible to foresee the shape of society a century or more ahead of one’s own time, and we have not attempted to do so. Instead we have been content to extrapolate those social trends that can plainly be seen at the moment. The story was written in August 1962. We mention this to bring out the prediction - we take a little pride in its apparent correctness - at the foot of page 22. We do not know whether to hope or fear that other predictions of the story will turn out to possess a similar validity.
The basis of the plot is to be found on pages 208 to 210. However, to avoid too much interruption of the narrative, the ideas mentioned in these pages have been shortened as far as possible. Physics regards theworld as four dimensional. All moments of time exist together. The world can be thought of as a map, not only spatially, but also with respect to time. The map stretches away both into the past and into the future. There is no such thing as ‘waiting’ for the future. It is already there in the map.
Two problems arise out of this. The first is the so-called ‘ arrow of time ’. Events occur in the map in definite sequences. Light emerges from a torch after you press the switch. The emphasis here is not on the word ‘after’ - it would be possible to turn the map round, to count time backwards, as we do in counting years b.c. Then one would say that light emerges from the torch before one presses the switch. This is simply a trivial inversion. What is not trivial is that light does not emerge both before and after the pressing of the switch.
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Events do not occur symmetrically with respect to time. In the case of the torch there is an asymmetry whichever way we elect to read the map. It is this asymmetry that we refer to as the arrow of time. The ‘future’ part of the map is radically different from the ‘past’, and this is true whichever way we turn the map.
Physics has made a good deal of progress in understanding this problem. The arrow of time may not be completely resolved, but at any rate it is being grappled with. The same cannot be said for the second problem.
What constitutes the present? Provided one considers oneself as something apart from the physical world, the answer does not seem difficult. The present can be thought of as the particular place in the map where you happen to be. It is your subjective presence at a particular spot that defines the present. But you cannot have your cake and eat it. You cannot consider your subjective presence as being outside the physical world and in the same breath consider yourself as a part of the map.
According to science, a hiiman is an animal. He takes his place in the map along with all other physical events. In fact the events that constitute the human are confined to a fourdimensional tube, a world tube, that threads its way over a finite portion of the map. What then is the subjective present ? It is certainly not the whole collection of events inside one’s own personal tube, otherwise we should live the whole of our lives all at once, like playing a sonata simply by pressing the whole keyboard. Stated more precisely, the subjective present consists not of the complete collection of events but of a certain subset. How is the subset defined ?
Certain clear technical issues now appear. Is the subset such that one particular member has a time-like displacement to all other members ? In that case the other members could have a causal connexion to the particular member. But if so, how is the particular member of the subset chosen?
There seems to be no way of coping with issues such as these except by admitting that something else besides the
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four-dimensional world tube is needed. Something else outside what science would normally describe as the animal itself.
This approach need not be mystic. The required subset could be defined mathematically as the intersection of the world tube with a three-dimensional space-like surface. Thus a surface
for a particular value of c, and with df/dx* (i = 1,2,3,4) a time-like vector, serves to define a subset of points in the world tube. Changing c changes the subset. We could be said to live our lives through changes of c - i.e. by sweeping through a family of surfaces.
It is plausible that the subjective present has a mathematical structure of this kind. But what then are the <^> surfaces ? Could they be derived from known physical fields, for example from the electromagnetic field ? That is to say, is the subjective present really controlled by normal sensory data? An obvious way of testing this possibility would be to keep the known external fields constant and to consider whether the subjective present can be considered to change.
Our impression - no more than an impression - is that changes of the subjective present do occur under conditions where the external electromagnetic field, for example, is essentially unchanged. As a rather imprecise example of what we mean, suppose two visits separated by many years are made to a particular place - say, to a mountain - and suppose the weather and the lighting conditions are generally similar on the two occasions. Exact identity of condition is of course impossible, but we find it difficult to believe that major differences of the subjective present, such as might be felt by an individual, are determined by slight, and perhaps even unnoticed, changes in the external conditions - e.g. by the slight shift in the disposition of grass and boulders on a mountainside.
The
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closely reproducible in the sense of this example. The fantasy of the present story lies in the properties we have ascribed to these surfaces, in fact to the functional behaviour of
6 April 1963 F. H.
G. H.
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Contents
1 Night Thoughts 11
2 Tight Little Island 17
3 First Preparations 26
4 The Rocket 36
5 Personnel 45
6 The Russian Ship 54
7 The Launching 64
8 The Voyage 80
9 The Landing 95
10 Exploration 114
11 The Return 138
12 Dulce Domum 150
13 Cathy 162
14 War 178
15 The Aftermath 193
Chapter One
Night Thoughts
Hugh Conway shifted uneasily. An hour before his wife had come to him with such fervour that he knew she must have been unfaithful again. He could hear her soft breathing, a more regular rhythm than his own. It wasn’t surprising, not with Cathy’s beauty, the completely flawless beauty that you couldn’t 'take your eyes off; the sort of beauty that you had to see, that couldn’t be described, photographed, or painted. They had been married for ten years, and still Conway couldn’t keep his eyes off her even though he knew it annoyed her. Even other women, women who might spend hours in front of a mirror, acknowledged it. For compensation they shook their heads and said sharply it was a pity Cathy had not been equally blessed with brains.
For ten years Conway had been on the hook. For ten years they had staggered from one domestic crisis to another, from one social absurdity to another. Things had seemed to be going better during the last few months, but now this new affair had started. The odd thing was that in the abstract he valued intelligence more than beauty. In the last few years there had been half a dozen other women that he’d liked, that he could talk sensibly to, and that he’d have been happy with. More than once he’d made up his mind to put an end to the inane, futile life with Cathy. But then, in some unguarded moment, he’d be riveted again; the old
chemistry would start up in his blood, and that would be it. He wondered why Cathy herself didn’t break it up. She only despised him for his weakness. Probably she regarded him as a convenient base from which to conduct her operations.
Literary types had always written their own variations on
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the theme of ‘Love and War’. But only a hundred years ago they’d been talking about there being two cultures. Now the old literary culture was dead, and the scientific culture, if by that you meant physics, wasn’t in much better shape. Their places had been taken by a new culture.
What a tiger he’d have been if he’d lived in the middle of the last century, and known what he knew now. Conway allowed his thoughts to play with the prospects. It was, he decided, the confusion of the present that was the devil. Being a good scientist didn’t help. It only made you more keenly aware of the uncertainties of the future. The 1960s was the time when they’d first thought of going to the moon. He could have told them exactly what they’d find when they got there. There’d been quite a bit of argument about whether they’d find dust or lava. As it turned out they’d found both. Funny to think now that that first trip to the moon has set the whole world alight. It had been the touchstone of national prestige. Now it was just a pinpoint in the past. Today the world was alight again. Everybody said it was the biggest thing ever; and for once, Conway thought, everybody was right. Funny too to think that in i960 they hadn’t had the slightest suspicion about it
Even as recently as a hundred years ago the astronomers had known almost nothing about the proper motions of the stars. The line of sight motions were, of course, known from the Doppler shift. But the transverse motions, even of quite near-by stars, only caused them to change their directions by a few tenths of a second of an arc each year. It hadn’t been until the coming of high-quality satellite telescopes that angles as small as this could be measured in any particular year, although over twenty or thirty years it would have been possible to measure the cumulative effect from the ground. But nobody had been willing to start a programme that wouldn’t pay off results for thirty years. So, not until the nineties of the last century did the proper motions begin to be really well known. Not until then was it possible to decide just how each individual star was moving in space.
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The same sort of measurements, parallax measurements, had given accurate distances to the stars — at any rate, for distances up to a thousand light years. And with the distances and motions fully known, it was possible to build a model of how all the stars were moving in the neighbourhood of the Sun. With the solar system at the centre, you could imagine each star represented by a little dot. Attached to each dot was an arrow, the direction of the arrow showing where the star was moving, and the length of the arrow showing how fast the star was moving. That was the first stage. Then you had to make a correction. If you wanted a model of the stars as they are now at the present moment you had to allow for the fact that we do not see the direction of the stars as they are, but only as they were at the moment when the light started out on its journey to us. If you want the model as it is now you have to move each star a bit along the direction of its arrow. The amount you have to move a particular star depends on two things - its speed of motion and its distance. The distance, because there has been more delay in the light from a distant star than from a near-by one. And the speed for the obvious reason that a star moves more out of its position every year the faster it is moving.
Suppose that all this has been done and that you have a model showing the positions and motions of the stars as they are now. Then by following each star in turn along its appropriate arrow you can find out where they will all be a year from now. Or ten years from now. Or a hundred years from now. In fact, you can find out whether any two arrows will meet each other. If any two arrows do meet each other you know that some time in the future those two particular stars will come near to each other. Of course they can hardly be expected to collide, for stars are very tiny things compared to the distances between them. A direct collision is vastly improbable, but a close approach is quite another matter.
Conway began to figure the probabilities. Assume as approach within twenty astronomical units, the distance of
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the planet Uranus from the Sun. That gives a target area of ten to the minus eight square parsecs. Taking thirty kilometres per second as the average speed of the stars relative to any particular star, and taking the mean density of the stars as one per cubic parsec, the chance of an approach to any special star was just ten to the minus eight for every thirty thousand years. So over three billion years the chance was one in a thousand. In the lifetime of the solar system there had been one chance in a thousand of just such an approach of another star, and this really wasn’t very long odds. Taking all stars together, there had been more than a hundred million approaches between pairs of them during the whole history of the Galaxy.
All this the men of the twentieth century would have followed. And they wouldn’t have been particularly surprised to learn that the Sun was going to be one of these hundred million cases. The unexpected thing was that this ^particular moment - the late twenty-first century - was the time of the encounter. It wasn’t a billion years ago, and it was unlikely to be a billion years hence. It would be now, the year 2087.
A special name had to be found for the approaching star. At an early stage, helium lines were detected in the spectrum, so it had seemed obvious to use the Greek name for the Sun, Helios. This was towards the end of the twentieth century, before the last remnants of a classical culture were lost.
Of course, it wasn’t clear to begin with just how close Helios would approach the Sun. The target area was very small, so that small errors of measurement led to big errors in the answers. The first estimates gave a distance of closest approach that exceeded ten thousand astronomical units, that is, about three hundred times the distance of the farthest planet, Pluto. Then a half century of unremitting effort showed that the approach was to be a good deal nearer than this. By the year 2025 the best estimate was a thousand astronomical units, 961 to be more precise.
The mounting interest of the public had helped to main
Night Thoughts
tain the popularity of the physical sciences at a time when nuclear physics and the study of elementary particles were steeply in decline - the latter because it had become too difficult. Fundamental astronomy was once more in vogue. As Helios came closer it became easier to make accurate measurements. During the sixties, excitement mounted furiously as it became more and more clear that Helios would actually move inside the orbits of the outer planets. By 2070, a definitive value was obtained. At its closest, Helios would be a mere twenty astronomical units from the Sun. It would be 15,000 times brighter than the full moon, although at that distance it would still have only a fortieth of the brightness of the Sun itself.
The orbit of the Earth would be disturbed, but not enormously so. After Helios had receded away again the Earth’s path around the Sun would be more elliptical than it was before. This would be the main effect. The result would be an accentuation, not enormous, but certainly perceptible, of the seasons of the year. And the year itself would certainly be changed from the immemorial 365^ days. But nobody knew yet exactly what the changes would be.
If the effects on the Earth’s motion were to be comparatively slight, this was manifestly not the case for the outer planets of the solar system. Helios would exert as big an influence on these as the Sun did. Indeed there was a likelihood that the three outer planets, Uranus, Neptune, and Pluto, would be stripped away entirely from our system.
Because Helios was to penetrate our system it was clear that we should penetrate the planets of Helios itself, if the incoming star had any planets. Astronomical theories showed that this was a marginal issue. The larger mass of Helios was a point against
the existence of a planetary system. But it was quickly pointed out that Helios was spinning around only very slowly, like the Sun, and this scarcely seemed credible unless a system of planets had indeed developed. In the event, just at the turn of the century, two planets were in fact detected observationally. They were
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large fellows, like Jupiter in our own system. Their American discoverers named them Hera and Semele.
This was before the development of quantitative social studies had changed our cultural and intellectual standards, before those philosophers of the nineteenth and twentieth centuries who had inquired into the nature of man’s thinking had attained a popular distinction exceeding Newton and Einstein. The new fashion was to have its opportunities, however. For when, forty years later, two further planets were detected, of about the size of our own Uranus, they were named Hegel and Kierkegaard.
And now a fifth planet had been found only a few months ago, by Conway himself. It was much smaller than the others and had therefore been difficult to pick up against the background glare of Helios. It was much more like the earth in size. Apart from this simple fact, little so far was known about it. Conway’s mind ranged over plans for the future. There was a tradition that whoever discovered a new planet had the honour of naming it, like the rule that had operated a century or more ago in the naming of the chemical elements. Conway smiled to himself in the darkness. Because he was British and because the British, according to the rest of the world, were still immersed in the twentieth century, he had refused widespread international pressure to adopt the name Spinoza. Instead he had called it - Achilles.
Chapter Two
Tight Little Island
Hugh Conway scraped a fragment of butter over a piece of hard half-burnt toast. Cathy made a pretence of reading The Times. The financial page too, Hugh noticed, as he cocked an eye over the top of the paper. He studied the flawless complexion and the pile of dark, soft chestnut curls, thinking, for perhaps the millionth time, that he was an ass. She put down the paper and looked at him squarely with deep-blue killer eyes.
