The Black Cloud

by Fred Hoyle

  “Explosions!’ gasped Barnett.

  “That’s right, explosions, either by nuclear fission, or more probably by nuclear fusion. There’s no shortage of hydrogen in this Cloud.”

  “Are you being serious, Chris?”

  “Of course I’m being serious. If I’m right in supposing that some beast inhabits the Cloud, then why shouldn’t he be at least as intelligent as we are?”

  “There’s the slight difficulty of radioactive products. Wouldn’t these be extremely deleterious to living material?’ asked McNeil.

  “If they could get at the living material, certainly they would. But although it isn’t possible to produce explosions with magnetic fields, it is possible to prevent two samples of material mixing with each other. I imagine that the beast orders the material of the Cloud magnetically, that by means of magnetic fields he can move samples of material wherever he wants inside the Cloud. I imagine that he takes very good care to keep the radioactive gas well separated from the living material — remember I’m using the term “living” for verbal convenience. I’m not going to be drawn into a philosophical argument about it.”

  “You know, Kingsley,” said Weichart, “this is going far better than I thought it would. What I suppose you would say is that whereas basically we assemble materials with our hands, or with the aid of machines that we have made with our hands, the beast assembles materials with the aid of magnetic energy.”

  “That’s the general idea. And I must add that the beast seems to me to have far the better of it. For one thing he’s got vastly more energy to play with than we have.”

  “My God, I should think so, billions of times more, at the very least,” said Marlowe. “It’s beginning to look, Chris, as if you’re winning this argument. But we objectors over here in this corner are pinning our faith to Yvette’s question. It seems to me a very good one. What can you offer in answer to it?”

  “It is a very good question, Geoff, and I don’t know that I can give a really convincing answer. The sort of idea I’ve got is that perhaps the beast can’t stay for very long in the close proximity of a star. Perhaps he comes in periodically to some star or other, builds his molecules, which form his food supply as it were, and then pushes off again. Perhaps he does this time and time again.”

  “But why shouldn’t the beast be able to stay permanently near a star?”

  “Well, an ordinary common or garden cloud, a beastless cloud, if it were permanently near a star, would gradually condense into a compact body, or into a number of compact bodies. Indeed, as we all know, our Earth probably condensed at one time from just such a cloud. Obviously our friend the beast would find it extremely embarrassing to have his protective Cloud condense into a planet. So equally obviously he’ll decide to push off before there’s any danger of that happening. And when he pushes off he’ll take his Cloud with him.”

  “Have you any idea how long that will be?’ asked Parkinson.

  “None at all. I suggest that the beast will push off when he’s finished recharging his food supply. That might be a matter of weeks, months, years, millennia for all I know.”

  “Don’t I detect a slight smell of rat in all this?’ Barnett remarked.

  “Possibly. I don’t know how keen your sense of smell is, Bill. What’s your trouble?”

  “I’ve got lots of troubles. I should have thought that your remarks about condensing into a planet apply only to an inanimate cloud. If we grant that the Cloud is able to control the distribution of material within itself, then it could easily prevent condensation from taking place. After all, condensation must be a sort of instability process and I would have thought that quite a moderate degree of control on the part of your beast could prevent any condensation at all.”

  “There are two replies to that. One is that I believe the beast will lose his control if he stays too long near the Sun. If he stays too long, the magnetic field of the Sun will penetrate into the Cloud. Then the rotation of the Cloud round the Sun will twist up the magnetic field to blazes. All control would then be lost.”

  “My God, that’s an excellent point.”

  “It is, isn’t it? And here’s another one. However different our beast is to life here on Earth, one point he must have in common with us. We must both obey the simple biological rules of selection and development. By that I mean that we can’t suppose that the Cloud started off by containing a fully-fledged beast. It must have started with small beginnings, just as life here on Earth started with small beginnings. So, to start with, there would be no intricate control over the distribution of material in the Cloud. Hence if the Cloud had originally been situated close to a star, it could not have prevented condensation into a planet or into a number of planets.”

  “Then how do you visualize the early beginnings?”

  “As something that happened far out in interstellar space. To begin with, life in the Cloud must have depended on the general radiation field of the stars. Even that would give it more radiation for molecule-building purposes than life on the Earth gets. Then I imagine that as intelligence developed it would be discovered that food supplies — i.e. molecule-building — could be enormously increased by moving in close to a star for a comparatively brief period. As I see it, the beast must be essentially a denizen of interstellar space. Now, Bill, have you any more troubles?”

  “Well, yes, I’ve got another problem. Why can’t the Cloud manufacture its own radiation? Why bother to come in close to a star? If it understands nuclear fusion to the point of producing gigantic explosions, why not use nuclear fusion for producing its supply of radiation?”

  “To produce radiation in a controlled fashion requires a slow reactor, and of course that’s just what a star is. The Sun is just a gigantic slow nuclear fusion reactor. To produce radiation on any real scale comparable with the Sun, the Cloud would have to make itself into a star. Then the beast would get roasted. It’d be much too hot inside.”

  “Even then I doubt whether a cloud of this mass could produce very much radiation,” remarked Marlowe. “Its mass is much too small. According to the mass-luminosity relation it’d be down as compared with the Sun by a fantastic amount. No, you’re barking up a wrong tree there, Bill.”

  “I’ve a question that I’d like to ask,” said Parkinson. “Why do you always refer to your beast in the singular? Why shouldn’t there be lots of little beasts in the Cloud?”

  “I have a reason for that, but it’ll take quite a while to explain.”

  “Well, it looks as if we’re not going to get much sleep tonight, so you’d better carry on.”

  “Then let’s start by supposing that the Cloud contains lots of little beasts instead of one big beast. I think you’ll grant me that communication must have developed between the different individuals.”

  “Certainly.”

  “Then what form will the communication take?”

  “You’re supposed to be telling us, Chris.”

  “My question was purely rhetorical. I suggest that communication would be impossible by our methods. We communicate acoustically.”

  “You mean by talking. That’s certainly your method all right, Chris,” said Ann Halsey.

  But the point was lost on Kingsley. He went on:

  “Any attempt to use sound would be drowned by the enormous amount of background noise that must exist inside the Cloud. It would be far worse than trying to talk in a roaring gale. I think we can be pretty sure that communication would have to take place electrically.”

  “That seems fair enough.”

  “Good. Well, the next point is that by our standards the distances between the individuals would be very large, since the Cloud by our standards is enormously large. It would obviously be intolerable to rely on essentially D.C. methods over such distances.”

  “D.C. methods? Chris, will you please try to avoid jargon?”

  “Direct current.”

  “That explains it, I suppose!”

  “Oh, the sort of thing we
get on the telephone. Roughly speaking, the difference between D.C. communication and A.C. communication is the difference between the telephone and radio.”

  Marlowe grinned at Ann Halsey.

  “What Chris is trying to say in his inimitable manner is that communication must occur by radiative propagation.”

  “If you think that makes it clearer …”

  “Of course it’s clear. Stop being obstructive, Ann. Radiative propagation occurs when we emit a light signal or a radio signal. It travels across space through a vacuum at a speed of 186,000 miles per second. Even at this speed it would still take about ten minutes for a signal to travel across the Cloud.

  “My next point is that the volume of information that can be transmitted radiatively is enormously greater than the amount that we can communicate by ordinary sound. We’ve seen that with our pulsed radio transmitters. So if this Cloud contains separate individuals, the individuals must be able to communicate on a vastly more detailed scale than we can. What we can get across in an hour of talk they might get across in a hundredth of a second.”

  “Ah, I begin to see light,” broke in McNeil. “If communication occurs on such a scale then it becomes somewhat doubtful whether we should talk any more of separate individuals!”

  “You’re home, John!”

  “But I’m not home,” said Parkinson.

  “In vulgar parlance,” said McNeil amiably, “what Chris is saying is that individuals in the Cloud, if there are any, must be highly telepathic, so telepathic that it becomes rather meaningless to regard them as being really separate from each other.”

  “Then why didn’t he say so in the first place?’ — from Ann Halsey.

  “Because like most vulgar parlance, the word “telepathy” doesn’t really mean very much.”

  “Well, it certainly means a great deal more to me.”

  “And what does it mean to you, Ann?”

  “It means conveying one’s thoughts without talking, or of course without writing or winking or anything like that.”

  “In other words it means — if it means anything at all — communication by a non-acoustic medium.”

  “And that means using radiative propagation,” chipped in Leicester.

  “And radiative propagation means the use of alternating currents, not the direct currents and voltages we use in our brains.”

  “But I thought we were capable of some degree of telepathy,” suggested Parkinson.

  “Rubbish. Our brains simply don’t work the right way for telepathy. Everything is based on D.C. voltages, and radiative transmission is impossible that way.”

  “I know this is rather a red herring, but I thought these extra-sensory people had established some rather remarkable correlations,” Parkinson persisted.

  “Bloody bad science,” growled Alexandrov. “Correlations obtained after experiments done is bloody bad. Only prediction in science.”

  “I don’t follow.”

  “What Alexis means is that only predictions really count in science,” explained Weichart. “That’s the way Kingsley downed me an hour or two ago. It’s no good doing a lot of experiments first and then discovering a lot of correlations afterwards, not unless the correlations can be used for making new predictions. Otherwise it’s like betting on a race after it’s been run.”

  “Kingsley’s ideas have many very interesting neurological implications,” McNeil remarked. “Communication for us is a matter of extreme difficulty. We ourselves have to make a translation of the electrical activity — essentially D.C. activity — in our brains. To do this, quite a bit of the brain is given over to the control of the lip muscles and of the vocal chords. Even so our translation is very incomplete. We don’t do too badly perhaps in conveying simple ideas, but the conveying of emotions is very difficult. Kingsley’s little beasts could, I suppose, convey emotions too, and that’s another reason why it’s rather meaningless to talk of separate individuals. It’s rather terrifying to realize that everything we’ve been talking about tonight and conveying so inadequately from one to another could be communicated with vastly greater precision and understanding among Kingsley’s little beasts in about a hundredth of a second.”

  “I’d like to follow the idea of separate individuals a little further,” said Barnett, turning to Kingsley. “Would you think of each individual in the Cloud as building a radiative transmitter of some sort?”

  “Not as building a transmitter. Let me describe how I see biological evolution taking place within the Cloud. At an early stage I think there would be a whole lot of more or less separate disconnected individuals. Then communication would develop, not by a deliberate inorganic building of a means of radiative transmission, but through a slow biological development. The individuals would develop a means of radiative transmission as a biological organ, rather as we have developed a mouth, tongue, lips, and vocal chords. Communication would improve to a degree that we can scarcely contemplate. A thought would no sooner be thought than it would be communicated. An emotion would no sooner be experienced than it would be shared. With this would come a submergence of the individual and an evolution into a coherent whole. The beast, as I visualize it, need not be located in a particular place in the Cloud. Its different parts may be spread through the Cloud, but I regard it as a neurological unity, interlocked by a communication system in which signals are transmitted back and forth at a speed of 186,000 miles a second.”

  “We ought to get down to considering those signals more closely. I suppose they’d have to have a longish wave-length. Ordinary light presumably would be useless since the Cloud is opaque to it,” said Leicester.

  “My guess is that the signals are radio waves,” went on Kingsley. “There’s a good reason why it should be so. To be really efficient one must have complete phase control in a communication system. This can be done with radio waves, but not, so far as we know, with shorter wave-lengths.”

  McNeil was excited.

  “Our radio transmissions!’ he exclaimed. “They’d have interfered with the beast’s neurological control.”

  “They would if they’d been allowed to.”

  “What d’you mean, Chris?”

  “Well, the beast hasn’t only to contend with our transmissions, but with the whole welter of cosmic radio waves. From all quarters of the Universe there’d be radio waves interfering with its neurological activity unless it had developed some form of protection.”

  “What sort of protection have you in mind?”

  “Electrical discharges in the outer part of the Cloud causing sufficient ionization to prevent the entry of external radio waves. Such a protection would be as essential as the skull is to the human brain.”

  Aniseed smoke was rapidly filling the room. Marlowe suddenly found his pipe too hot to hold and put it down gingerly.

  “My God, you think this explains the rise of ionization in the atmosphere, when we switch on our transmitters?”

  “That’s the general idea. We were talking earlier on about a feedback mechanism. That, I imagine, is just what the beast has got. If any external waves get in too deeply, then up go the voltages and away go the discharges until the waves can get in no farther.”

  “But the ionization takes place in our own atmosphere.”

  “For this purpose I think we can regard our atmosphere as a part of the Cloud. We know from the shimmering of the night sky that gas extends all the way from the Earth to the denser parts of the Cloud, the disk-like parts. In short we’re inside the Cloud, electronically speaking. That, I think, explains our communication troubles. At an earlier stage, when we were outside the Cloud, the beast didn’t protect itself by ionizing our atmosphere, but through its outer electronic shield. But once we got inside the shield the discharges began to occur in our own atmosphere. The beast has been boxing-in our transmissions.”

  “Very fine reasoning, Chris,” said Marlowe.

  “Hellish fine,” nodded Alexandrov.

  “How about the one-centimet
re transmissions? They went through all right,” Weichart objected.

  “Although the chain of reasoning is getting rather long there’s a suggestion that one can make on that. I think it’s worth making because it suggests the next action we might take. It seems to me most unlikely that this Cloud is unique. Nature doesn’t work in unique examples. So let’s suppose there are lots of these beasts inhabiting the Galaxy. Then I would expect communication to occur between one cloud and another. This would imply that some wave-lengths would be required for external communication purposes, wave-lengths that could penetrate into the Cloud and would do no neurological harm.”

  “And you think one centimetre may be such a wave-length?”

  “That’s the general idea.”

  “But then why was there no reply to our one-centimetre transmission?’ asked Parkinson.

  “Perhaps because we sent no message. There’d be no point in replying to a perfectly blank transmission.”

  “Then we ought to start sending pulsed messages on the one centimetre,” exclaimed Leicester. “But how can we expect the Cloud to decipher them?”

  “That’s not an urgent problem to begin with. It will be obvious that our transmissions contain information — that will be clear from the frequent repetition of various patterns. As soon as the Cloud realizes that our transmissions have intelligent control behind them I think we can expect some sort of reply. How long will it take to get started, Harry? You’re not in a position to modulate the one centimetre yet, are you?”