The Black Cloud

by Fred Hoyle

  “So while one wave-length might be completely reflected by the atmosphere, some shorter wave-length might penetrate almost completely into outer space.”

  “That’s exactly the situation. But let me go back to my particular wave-length for a moment, and to the effect of rising ionization. For convenience in talking, I’d like to call it “pattern of events A”.”

  “You’d like to call it what?’ asked Parkinson.

  “This is what I mean:

  1. A low ionization allowing almost complete penetration.

  2. A rising ionization giving a reflected signal of increased strength.

  3. An ionization so high that reflection becomes complete.

  “This is what I call “pattern A”.”

  “And what is pattern B?’ asked Ann Halsey.

  “There won’t be any pattern B.”

  “Then why bother with the A?”

  “Preserve me from the obtuseness of women! I can call it pattern A because I want to, can’t I?”

  “Of course, dear. But why do you want to?”

  “Go on, Chris. She’s only pulling your leg.”

  “Well, here’s a list of what happened this afternoon and evening. Let me read it out to you as a table.”

  Transmission wave-length

  Approximate time of switching on

  Event

  1 metre

  2.45 p.m.

  Pattern A taking approximately half an hour.

  10 centimetres

  3.15 p.m.

  Pattern A taking approximately half an hour.

  1 centimetre

  3.45 p.m.

  Complete penetration of ionosphere over a period of three hours roughly.

  10 centimetres

  7.0 p.m.

  Pattern A taking approximately half an hour.

  No transmissions from 7.30 p.m. to 9.0 p.m.

  1 metre

  9.0 p.m.

  Pattern A taking half an hour.

  10 centimetres

  9.30 p.m.

  Pattern A taking half an hour.

  ‘It certainly looks horribly systematic when it’s all put together like that,” said Leicester.

  “It does, doesn’t it?”

  “I’m afraid I’m not getting this’ — Parkinson.

  “Nor am I,” admitted McNeil.

  Kingsley spoke slowly.

  “As far as I’m aware, these events can be explained very simply on one hypothesis, but I warn you it’s an entirely preposterous hypothesis.”

  “Chris, will you please stop trying to be dramatic, and tell us in simple words what this preposterous hypothesis is?”

  “Very well. In one breath — that on any wave-length from a few centimetres upwards our own transmissions automatically produce a rise of ionization which continues to the saturation point.”

  “It simply isn’t possible.” Leicester shook his head.

  “I didn’t say it was possible,” answered Kingsley. “I said it explained the facts. And it does. It explains the whole of my table.”

  “I can half see what you’re driving at,” remarked McNeil.

  “Am I to suppose that the ionization falls as soon as you cease transmission?”

  “Yes. When we stop transmission the ionizing agent is cut off, whatever it may be — perhaps Bill’s electrical discharges. Then the ionization falls very rapidly. You see the ionization we’re dealing with is abnormally low in the atmosphere, where the gas density is large enough to give an extremely rapid rate of formation of negative oxygen ions. So the ionization dries up very quickly as soon as it isn’t being renewed.”

  “Let’s go into this in a bit more detail,” Marlowe began, speaking out of a haze of aniseed smoke. “It seems to me that this hypothetical ionizing agency must have pretty good judgement. Suppose we switch on a ten-centimetre transmission. Then according to your idea, Chris, the agency, whatever it is, drives the ionization up until the ten-centimetre waves remain trapped inside the Earth’s atmosphere. And — here’s my point — the ionization goes no higher than that. It’s all got to be very nicely adjusted. The agency has to know just how far to go and no further.”

  “Which doesn’t make it seem very plausible,” said Weichart.

  “And there are other difficulties. Why were we able to go on so long with the twenty-five centimetre communication? That lasted for quite a number of days, not for only half an hour. And why doesn’t the same thing happen — your pattern A as you call it — when we use a one-centimetre wave-length?”

  “Bloody bad philosophy,” grunted Alexandrov. “Waste of breath. Hypothesis judged by prediction. Only sound method.”

  Leicester glanced at his watch.

  “It’s well over an hour since our last transmission. If Chris is right we ought to get his pattern A, if we switch on again at ten centimetres, that is to say, and possibly at one metre also. Let’s try.”

  Leicester and about half a dozen others went off to the lab. Half an hour later they were back.

  “Still complete reflection at one metre. Pattern A on ten centimetres,” Leicester announced.

  “Which looks as if it supports Chris.”

  “I’m not sure that it does,” remarked Weichart. “Why didn’t the one metre give pattern A?”

  “I might make some suggestions, but in a way they’re even more fantastic, so I won’t bother with ’em just for the moment. The fact is, and I insist it is a fact, that whenever we have switched on our ten-centimetre transmitter there has always been a sharp rise of atmospheric ionization, and whenever we switched off there has been a decline of ionization. Does anyone deny that?”

  “I don’t deny that what has happened so far agrees with what you say,” Weichart argued. “I agree that no denial is possible there. It’s when it comes to inferring a causal connexion between our transmissions and the fluctuations of ionization that I dig my toes in.”

  “You mean, Dave, that what we found this afternoon and this evening was coincidence?’ asked Marlowe.

  “That’s what I mean. I grant you that the odds against such a series of coincidences are pretty big, but Kingsley’s causal connexion seems to me an out-and-out impossibility. What I feel is that the improbable can happen but the impossible cannot.”

  “Impossible is too strong,” insisted Kingsley. “And I’m sure that Weichart couldn’t really defend his use of the word. What we’re faced with is a choice between two improbabilities — I said that my hypothesis seemed improbable when I first trotted it out. Moreover I agree with what Alexis said earlier on, that the only way to test a hypothesis is by its predictions. It’s about three-quarters of an hour since Harry Leicester did his last transmission. I’m going to suggest that he goes right now and does another ten-centimetre transmission.”

  Leicester groaned. “Not again!”

  “I predict,” went on Kingsley, “that my pattern A will be repeated. What I’d like to know is what Weichart predicts.”

  Weichart didn’t quite like the turn of the argument, and he attempted to hedge. Marlowe laughed.

  “He’s pinching you, Dave! You’ve got to stand up and take it. If you’re right about it being coincidence before, you’ve got to agree that Kingsley’s present prediction is very unlikely to be right.”

  “Of course it’s unlikely, but it might happen that way all the same.”

  “Come off it, Dave! What do you predict? Where d’you put your money?”

  And Weichart was forced to admit that he put his money on Kingsley’s prediction being wrong.

  “All right. Let’s go and see,” said Leicester.

  While the company were filing out, Ann Halsey said to Parkinson:

  “Will you help me to make more coffee, Mr Parkinson? They’ll be wanting some when they get back.”

  As they busied themselves, she went on:

  “Did you ever hear such a lot of talk? I used to think that scientists were of the strong silent type, but never did I hear such a gibble-gabble. What is it th
at Omar Khayyám says about the doctors and saints?”

  “I believe it goes something like this,” answered Parkinson:

  “Myself when young did eagerly frequent

  Doctor and Saint, and heard great argument

  About it and about, but evermore

  Came out by the same door as in I went.”

  “It isn’t so much the volume of talk that surprises me,” he laughed. “We get plenty of that in politics. It’s the number of mistakes they’ve made, how often things have turned out differently to what they’ve expected.”

  When the party reassembled it was obvious at a glance how things had gone. Marlowe took a cup of coffee from Parkinson.

  “Thanks. Well, that’s that. Chris was right and Dave was wrong. Now I suppose we must get down to trying to decide what it means.”

  “Your move, Chris,” said Leicester.

  “Let’s suppose then that my hypothesis is right, that our own transmissions are producing a marked effect on the atmospheric ionization.”

  Ann Halsey handed Kingsley a mug of coffee.

  “I’d be a lot happier if I knew what ionization meant. Here, drink this.”

  “Oh, it means that the outer parts of the atoms are stripped away from the inner parts.”

  “And how does this happen?”

  “It can happen in many ways, by an electrical discharge, as in a flash of lightning, or in a neon tube — the sort of strip lighting we’ve got here. The gas in these tubes is being partially ionized.”

  “I suppose energy is the real difficulty? That your transmissions have far too little power to produce this rise of ionization?’ said McNeil.

  “That’s right,” answered Marlowe. “It’s completely impossible that our transmissions should be the primary cause of the fluctuations in the atmosphere. My God, they’d need a fantastic amount of power.”

  “Then how can Kingsley’s hypothesis be right?”

  “Our transmissions are not the primary cause, as Geoff says. That’s wholly impossible. I agree with Weichart there. My hypothesis is that our transmissions are acting as a trigger, whereby some very large source of power is released.”

  “And where, Chris, do you suppose this source of power is to be located?’ asked Marlowe.

  “In the Cloud, of course.”

  “But surely it’s quite fantastic to imagine that we can cause the Cloud to react in such a fashion, and to do it with such reproducibility? You’d have to suppose that the Cloud was equipped with a sort of feedback mechanism,” argued Leicester.

  “On the basis of my hypothesis that’s certainly a correct inference.”

  “But don’t you see, Kingsley, that it’s utterly mad?’ Weichart exclaimed.

  Kingsley looked at his watch.

  “It’s almost time to go and try again, if anyone wants to. Does anyone want to?”

  “In heaven’s name, no!’said Leicester.

  “Either we go or we stay. And if we stay it means that we accept Kingsley’s hypothesis. Well, boys, do we go or do we stay?’ remarked Marlowe.

  “We stay,” said Barnett. “And we see how the argument goes. We’ve got as far as some sort of a feedback mechanism in the Cloud, a mechanism set to churn out an enormous amount of power as soon as it receives a trickle of radio emission from outside itself. The next step, I suppose, is to speculate on how the feedback mechanism works, and why it works as it does. Anybody got any ideas?”

  Alexandrov cleared his throat. Everybody waited to catch one of his rare remarks.

  “Bastard in Cloud. Said so before.”

  There were wide grins and a giggle from Yvette Hedelfort. Kingsley, however, remarked quite seriously:

  “I remember you did. Were you serious about it, Alexis?”

  “Always serious, damn it,” said the Russian.

  “Without frills, what exactly do you mean, Chris?’ someone asked.

  “I mean that the Cloud contains an intelligence. Before anybody starts criticizing, let me say that I know it’s a preposterous idea and I wouldn’t suggest it for a moment if the alternative weren’t even more outrageously preposterous. Doesn’t it strike you how often we’ve been wrong about the behaviour of the Cloud?”

  Parkinson and Ann Halsey exchanged an amused glance.

  “All our mistakes have a certain hallmark about them. They’re just the sort of mistake that it’d be natural to make if, instead of the Cloud being inanimate, it were alive.”

  Close Reasoning

  It is curious in how great a degree human progress depends on the individual. Humans, numbered in thousands of millions, seem organized into an ant-like society. Yet this is not so. New ideas, the impetus of all development, come from individual people, not from corporations or states. New ideas, fragile as spring flowers, easily bruised by the tread of the multitude, may yet be cherished by the solitary wanderer.

  Among the vast host that experienced the coming of the Cloud, none except Kingsley arrived at a coherent understanding of its real nature, none except Kingsley gave the reason for the visit of the Cloud to the solar system. His first bald statement was greeted with outright disbelief even by his fellow scientists — Alexandrov excepted.

  Weichart was frank in his opinion.

  “The whole idea is quite ridiculous,” he said.

  Marlowe shook his head.

  “This comes of reading science fiction.”

  “No bloody fiction about Cloud coming straight for dam’ Sun. No bloody fiction about Cloud stopping. No bloody fiction about ionization,” growled Alexandrov.

  McNeil, the physician, was intrigued. The new development was more in his line than transmitters and aerials.

  “I’d like to know, Chris, what you mean in this context by the word “alive”.”

  “Well, John, you know better than I do that the distinction between animate and inanimate is more a matter of verbal convenience than anything else. By and large, inanimate matter has a simple structure and comparatively simple properties. Animate or living matter on the other hand has a highly complicated structure and is capable of very involved behaviour. When I said the Cloud may be alive I meant that the material inside it may be organized in an intricate fashion, so that its behaviour and consequently the behaviour of the whole Cloud is far more complex than we previously supposed.”

  “Isn’t there an element of tautology there?’ — from Weichart.

  “I said that words such as “animate” and “inanimate” are only verbal conveniences. If they’re pushed too far they do appear tautological. In more scientific terms I expect the chemistry of the interior of the Cloud to be extremely complicated — complicated molecules, complicated structures built out of molecules, complicated nervous activity. In short I think the Cloud has a brain.”

  “A dam’ straightforward conclusion,” nodded Alexandrov.

  When the laugh had subsided, Marlowe turned to Kingsley.

  “Well, Chris, we know what you mean, at any rate we know near enough. Now let’s have your argument. Take your time. Let’s have it point by point, and it’d better be good.”

  “Very well then, here goes. Point number one, the temperature inside the Cloud is suited to the formation of highly complicated molecules.”

  “Right! First point to you. In fact, the temperature is perhaps a little more favourable than it is here on the Earth.”

  “Second point, conditions are favourable to the formation of extensive structures built out of complicated molecules.”

  “Why should that be so?’ asked Yvette Hedelfort.

  “Adhesion on the surface of solid particles. The density inside the Cloud is so high that quite large lumps of solid material — probably mostly ordinary ice — are almost certainly to be found inside it. I suggest that the complicated molecules get together when they happen to stick to the surfaces of these lumps.”

  “A very good point, Chris,” agreed Marlowe.

  “Sorry, I don’t pass this round.” McNeil was shaking his head. “Yo
u talk of complicated molecules being built up by sticking together on the surface of solid bodies. Well, it won’t do. The molecules out of which living material is made contain large stores of internal energy. Indeed the processes of life depend on this internal energy. The trouble with your sticking together is that you don’t get energy into the molecules that way.”

  Kingsley seemed unperturbed.

  “And from what source do the molecules of living creatures here on the Earth get their internal supplies of energy?’ he asked McNeil.

  “Plants get it from sunlight, and animals get it from plants, or from other animals of course. So in the last analysis the energy always comes from the Sun.”

  “And where is the Cloud getting energy from now?”

  The tables were turned. And as neither McNeil nor anyone else seemed disposed to argue, Kingsley went on:

  “Let’s accept John’s argument. Let’s suppose that my beast in the Cloud is built out of the same sort of molecules that we are. Then the light from some star is required in order that the molecules be formed. Well, of course starlight is available far out in the space between the stars, but it’s very feeble. So to get a really strong supply of light the beast would need to approach close to some star. And that’s just what the beast has done!”

  Marlowe became excited.

  “My God, that ties three things together, straight away. The need for sunlight, number one. The Cloud making a bee-line for the Sun, number two. The Cloud stopping when it reached the Sun, number three. Very good, Chris.”

  “It is a very good beginning, yes, but it leaves some things obscure,” Yvette Hedelfort remarked. “I do not see,” she went on, “how it was that the Cloud came to be out in space. If it has need of sunlight or starlight, surely it would stay always around one star. Do you suppose that this beast of yours has just been born somewhere out in space and has now come to attach itself to our Sun?”

  “And while you’re about it, Chris, will you explain how your friend the beast controls its supplies of energy? How did it manage to fire off those blobs of gas with such fantastic speed when it was slowing down?’ asked Leicester.

  “One question at a time! I’ll take Harry’s first, because its probably easier. We tried to explain the expulsion of those blobs of gas in terms of magnetic fields, and the explanation simply didn’t work. The trouble was that the required fields would be so intense that they’d simply burst the whole Cloud apart. Stated somewhat differently, we couldn’t find any way in which large quantities of energy could be localized through a magnetic agency in comparatively small regions. But let’s now look at the problem from this new point of view. Let’s begin by asking what method we ourselves would use to produce intense local concentrations of energy.”