'Scientists of the world unite! Is that the idea?'

'Not exactly. It isn't just a case of scientists versus the rest. The matter goes deeper. It's a clash between two totally different modes of thinking. Society today is based in its technology on thinking in terms of numbers. In its social organization, on the other hand, it is based on thinking in terms of words. It's here that the real clash lies, between the literary mind and the mathematical mind. You ought to meet the Home Secretary. You'd see straight away what I mean.'

'And you had an idea for altering all this?'

'I had an idea for striking a blow for the mathematical mind. But I'm not sufficient of an a.s.s to imagine that anything I could do would be of decisive importance. With luck I thought I might be able to provide a good example, a sort of locus cla.s.sicus locus cla.s.sicus, to quote the literary boys, for how we ought to set about twisting the tails of the politicians.'

'My G.o.d, Chris, you talk about numbers and words, but I never knew a man who used so many words. Can you explain what you're up to in simple terms?'

'By that I suppose you mean in terms of numbers. Well, I'll try. Let's a.s.sume that survival is possible when the Cloud gets here. Although I say survival, it's pretty certain that the conditions won't be pleasant. We shall either be freezing or sweltering. It's obviously extremely unlikely that people will be able to move about in a normal way. The most we can hope for is that by staying put, by digging our caves or cellars and staying in them, we shall be able to hang on. In other words all normal travel of people from place to place will cease. So communication and the control of human affairs must come to depend on electrical information. The signalling will have to go by radio.'

'You mean that coherence in society coherence so that we don't split up into a whole lot of disconnected individuals will depend on radio communications?'

'That's right. There'll be no newspapers, because the newspaper staffs will be in shelter.'

'Is this where you come in, Chris? Is Nortonstowe going to become a pirate radio station? Oh boy, where are my false whiskers!'

'Now listen. When radio communication becomes of overriding importance, problems of quant.i.ty of information will become vital. Control will gradually pa.s.s to those people with the ability to handle the greatest volume of information, and I planned that Nortonstowe would be able to handle at least a hundred times as much as all other transmitters on the Earth put together.'

'This is fantasy, Chris! How about power supplies for one thing?'

'We've got our own diesel generators, and plenty of fuel.'

'But surely you can't generate the tremendous amount of power that would be needed?'

'We don't need a tremendous amount of power. I didn't say we would have a hundred times the power of all other transmitters put together. I said we would have a hundred times the information-carrying capacity, which is quite a different thing. We shan't be transmitting programmes to individual people. We shall be transmitting on quite low power to Governments all over the world. We shall become a sort of international information clearing-house. Governments will pa.s.s messages one to another through us. In short we shall become the nerve centre of world communication, and that is the sense in which we shall control world affairs. If that seems a bit of an anti-climax after my build-up, well, remember I'm not a melodramatic sort of person.'

'I'm coming to realize that. But how on earth do you propose to equip yourself with this information-carrying capacity?'

'Let me give you the theory of it first. It's quite well known really. The reason it hasn't been put into operation already is partly inertia, vested interest in existing equipment, and partly inconvenience all messages have to be recorded before transmission.'

Kingsley settled himself comfortably in an armchair.

'Of course you know that, instead of transmitting radio waves continuously, as is usually done, it's possible to transmit in bursts, in pulses. Let's suppose that we can transmit three sorts of pulses: a short pulse, a medium pulse, and a long pulse. In practice the long pulse might last for perhaps twice the duration of the short pulse, and the medium pulse might be one and a half times as long. With a transmitter working in the range seven to ten metres the usual range for long-distance work and with the usual band width, it should be possible to transmit about ten thousand pulses per second. The three sorts of pulses could be arranged in any a.s.signed order ten thousand of 'em per second. Now suppose we use the medium pulses for indicating the ends of letters, words, and sentences. One medium pulse indicates the end of a letter, two medium pulses following each other indicate the end of a word, and three following each other indicate the end of a sentence. This leaves the long and the short pulses for transmitting letters. Suppose, for instance, we elect to use the Morse code. Then at an average, about three pulses are needed per letter. Reckoning on an average of five letters to a word, this means that about fifteen of the long and short pulses are required per word. Or, if we include the medium pulses for marking the letters, about twenty pulses are required per word. So at a rate of ten thousand pulses per second this gives a transmission rate of about five hundred words per second, compared with a normal transmitter which handles less than three words per second. So we should be at least a hundred times faster.'

'Five hundred words per second. My G.o.d, what a gabble!'

'Actually we will probably broaden our band width so that we can send upwards of a million pulses per second. We reckon that a hundred thousand words a second might be possible. The limitation lies in the compression and expansion of messages. Obviously no one can talk at a hundred thousand words per second, not even the politicians, thank goodness. So messages will have to be recorded on magnetic tape. The tape will then be scanned electronically at high speed. But there's a limit to the speed of the scanning, at any rate with our present equipment.'

'Isn't there one big snag in all this? What's to stop the various Governments throughout the world from building the same sort of equipment?'

'Stupidity and inertia. As usual, nothing will be done until the crisis is on us. My one fear is that the politicians will be so lethargic that they won't get single transmitters and receivers built, let alone whole batteries of stuff. We're pushing 'em as hard as we can. For one thing they want information from us, and we've refused to provide this except by radio link. Another thing is that the whole ionosphere may get altered so that shorter wave-lengths have to be used. We're preparing here to go as short as one centimetre. This is a point that we're constantly warning 'em about, but they're devilishly slow, slow in action and slow in wit.'

'Who here, by the way, is doing all this?'

'The radio astronomers. You probably know that a whole crowd came in from Manchester, Cambridge, and Sydney. There were more than enough for doing the radio astronomy so that they were jumping on each others' heels. That was until they locked us in. Everybody got mad, the silly a.s.ses as if it wasn't obvious we should be locked up. Then I pointed out, with my usual tact, that anger wouldn't help us, that the obvious thing to do was to lick the pants off the politicians by converting some of our radio astronomy stuff into communication equipment. It was, of course, discovered that we had far more electronic equipment than was necessary for radio astronomy purposes, So we soon had a veritable army of communication engineers at work. Already we could swamp the B.B.C. in the amount of information we could transmit, if we were so minded.'

'You know, Kingsley, I'm still bemused by this pulse business. It still seems to me incredible that our broadcasting system should go on pumping out two or three words a second, when they might be sending five hundred.'

'That's a very easy one, Geoff. The human mouth transmits information at some two words per second. The human ear can only receive information at rates less than about three words per second. The great brains that control our destinies therefore design their electronic equipment to comply with these limitations even though electronically no such limitation exists. Don't I keep telling everyone that our whole social system is archaic, with the real knowledge at the bottom and a whole crowd of hobbledehoys at the top?'

'Which makes a very fine exit line,' laughed Marlowe, 'Speaking for myself, I've got a feeling that you're in danger of oversimplifying things just a tiny bit!'

The Cloud Approaches

The Cloud was not visible during the following summer since it lay in the daytime sky, although it was keenly examined with the radio telescope at Nortonstowe.

The situation was better than the Prime Minister had expected. News from Nortonstowe suggested that the coming of the Cloud was not likely to lead to an impossible fuel crisis, for which he was heartily thankful. For the time being there was no fear of public alarm. With the exception of the Astronomer Royal, in whom he reposed great confidence, the threat from the scientists, particularly from Kingsley, had been safely ca.n.a.lized at Nortonstowe. True, ridiculous concessions had been made. Worst of all he had lost Parkinson. It had been necessary to send Parkinson to Nortonstowe to make sure that no hanky-panky was going on there. But apparently the reports he was receiving were quite above board, and for this reason the Prime Minister resolved to let sleeping dogs lie, in spite of urgent suggestions to the contrary by some of his Ministers. Occasionally the Prime Minister wavered in this decision, for he found it intensely difficult to swallow the frequent messages from Kingsley advising him to secrecy.

In point of fact Kingsley's innuendos were shrewdly conceived, for Government security was not good. At each level of the political hierarchy, individuals regarded it as safe to impart information to their immediate subordinates. The outcome was that a knowledge of the approach of the Cloud filtered slowly downwards, until by the early autumn it reached almost to the parliamentary level. In short it had almost become available to the Press. But the moment was not quite ripe yet for the Cloud to become headline news.

The autumn was stormy and the skies in England were overcast. So although by October the Cloud had obscured a portion of the constellation of Lepus no alarm was given until November. It came from the clear skies of Arabia. Engineers of a large oil company were drilling in the desert. They noticed the concern with which their men were examining the sky. The Arabs pointed to the Cloud, or rather to a blackness in the sky, which by now was about seven degrees across, looking like a yawning circular pit. They said the pit should not be there, and that it was a sign in the sky. What the sign meant was not clear, but the men were frightened. Certainly none of the engineers remembered any such blackness, but none of them knew the disposition of the stars well enough to be certain. One of them had a star map back at base, however. When the drilling expedition was over he consulted the map. Sure enough, something was wrong. Letters to newspapers in England followed.

The newspapers took no immediate action. But within a week a whole series of similar stories came to hand. As often happens, one report was the signal for a host of others, rather as a single raindrop heralds the outbreak of a storm. The London papers sent special correspondents equipped with cameras and star maps to North Africa. The reporters set out in high spirits, thinking it a wonderful relief to a drab November. They returned in a chastened mood. The black hole in the sky did not encourage frivolity. No photographs were brought back. Newspaper editors had not realized that it is extremely difficult to photograph the stars with an ordinary camera.

The British Government was in some difficulty to know whether or not to prevent reports appearing in the Press. It was eventually decided that no action be taken, since any suggestion of suppression could only emphasize the gravity of the situation.

Editors were surprised at the tone of the reports submitted to them. They gave orders for a lighter and more frivolous touch, and it was in ba.n.a.l headlines such as APPARITION APPEARS IN SKY.

CELESTIAL BLACK-OUT DISCOVERED IN N. AFRICA.

NO STARS FOR CHRISTMAS, SAY ASTRONOMERS.

that the first news reached the public towards the end of November. A campaign was run. Photographs came in from several observatories, both in Great Britain and elsewhere. These appeared on front pages of the dailies (on the last page of course in the case of The Times The Times), in some cases after a generous degree of touching up. Articles by well-known scientists were featured.

The people were informed of the existence of the highly tenuous interstellar gas, the gas that occupies the vast regions of s.p.a.ce between the stars. Mixed up with this gas, it was pointed out, were myriads of fine grains, probably grains of ice, no more than about one hundred-thousandth part of an inch in their dimensions. It was these grains that produced the dozens of dark patches to be seen along the Milky Way. Photographs of such dark patches were displayed. The new apparition was simply one of these patches seen from near by. The fact that the solar system occasionally pa.s.sed close to, or even through, such acc.u.mulations had been known to astronomers for some time. Indeed encounters of this sort formed the basis of one well-known theory of the origin of comets. Photographs of comets were also displayed.

Scientific circles were not wholly soothed by this information. The Cloud became a frequent topic of conversation and speculation in laboratories everywhere. The argument given by Weichart a year earlier was rediscovered. It was soon realized that the density of the material of the Cloud was a critical factor. The general tendency was to set this much too low, but some scientists remembered Kingsley's remarks at the meeting of the British Astronomical a.s.sociation. Significance was also attached to the disappearance from the universities of the group at Nortonstowe. It was generally felt that the circ.u.mstances justified a measure of alarm. No doubt this apprehension would have grown rapidly stronger had it not been for the increasing call of the Governments, both in Britain and elsewhere, on scientists in general. They were asked to take a part in organizing the emergency preparations that were then gaining real momentum, preparations particularly concerned with food, fuel, and shelter.

The alarm did communicate itself to the public in some degree, however. During the first fortnight of December there were signs of a growing uneasiness. Well-known columnists, demanding an informed statement from the Government, used much the same trenchant terms that they had employed several years earlier concerning the BurgessMaclean episode. But this first wave of apprehension spent itself in a curious way. The third week of December was frosty and clear. In spite of the cold, people streamed by car and bus out of the towns to get a view of the night sky. But no apparition, no hole in the sky, was visible. Few stars could be seen at all because of bright moonlight. In vain did the Press point out that the Cloud was invisible except when projected against a background of stars. As an item of news the Cloud, for the time being at least, was dead. In any case Christmas was only a few days off.

The Government had good reason to be heartily thankful for this early demise of the Cloud, for they received in December an alarming report from Nortonstowe. The circ.u.mstances underlying this report are worth mentioning.

During the summer the organization at Nortonstowe settled down into a smooth pattern. The scientists divided into two groups, those concerned with 'Cloud investigations' and those concerned with the communication problems that Kingsley had explained to Marlowe. The non-scientists dealt with the business of the estate and with the building of the shelter. It was the practice for each of the three sections to hold a weekly meeting which everyone might attend. In this way it was possible to know how all affairs were developing without the necessity of going into details concerning the problems of other groups.

Marlowe worked on the 'Cloud investigations', using the Schmidt telescope taken from Cambridge. By October he and Roger Emerson had solved the problem of the direction of motion of the Cloud. Marlowe explained the matter in rather more detail than was perhaps necessary to the meeting that had been called to hear the latest results. He concluded: 'So it seems as if the Cloud must have practically zero angular momentum about the Sun.'

'And what in practical terms does that mean?' asked McNeil.

'It means that both the Sun and the Earth are certain to be engulfed. If there had been any appreciable angular momentum, the Cloud would have swung aside at the last moment. But now it's quite clear that this won't happen. The Cloud is moving straight in at the Sun.'

'Isn't that a bit odd, that it should just happen to be lined up so accurately on the Sun?' persisted McNeil.

'Well, it's got to be moving somehow,' answered Bill Barnett. 'And it's quite as likely to be moving one way as another.'

'But I can't help feeling that it's queer that the Cloud should just happen to be going straight for the Sun,' continued the tenacious Irishman.

Alexandrov stopped trying to persuade one of the secretaries to sit on his knee.

'd.a.m.n queer,' he announced. 'But lots of things d.a.m.n queer. d.a.m.n queer that Moon looks just same size as Sun. d.a.m.n queer that I'm here, isn't it so?'

'd.a.m.ned unfortunate,' muttered the secretary.

After a few minutes of further somewhat inconsequential discussion, Yvette Hedelfort stood up and addressed the meeting.

'I'm in trouble,' she announced.

There were grins and a voice was heard to remark: 'd.a.m.n queer, isn't it so?'

'I don't mean that sort of trouble,' the girl continued. 'I mean a proper kind of trouble. Dr Marlowe says the Cloud is made of hydrogen. Measurements give a density inside the Cloud a little greater than 1010 gm. per cm gm. per cm3. I estimate that if the Earth moves through such a cloud for about one month the amount of hydrogen that will be added to our atmosphere will exceed a hundred grams for each square centimetre of the earth's surface. Is this right, please?'

There was a silence as the implication of these remarks dawned on the meeting, or at any rate on some of the scientists.

'We'd better check that right away,' muttered Weichart. He figured on a pad of paper for perhaps five minutes.

'It's right, I guess,' he announced.

Almost without comment the meeting broke up. Parkinson came up to Marlowe.

'But, Dr Marlowe, what does all this mean?'

'My G.o.d, isn't it obvious? It means that enough hydrogen is going to come into the Earth's atmosphere to combine with all the oxygen. Hydrogen and oxygen are a violently unstable chemical mixture. The whole atmosphere will blow sky-high. Trust a woman to spot that.'

Kingsley, Alexandrov, and Weichart spent the afternoon arguing. In the evening they collected Marlowe and Yvette Hedelfort and went to Parkinson's room.

'Look, Parkinson,' began Kingsley, after drinks had been poured, 'I think it's up to you to decide what London, Washington, and all the other cities of sin are to be told. Things aren't quite as simple as they seemed this morning. I'm afraid the hydrogen isn't really as important as you thought, Yvette.'

'I didn't say it was important, Chris. I simply asked a question.'

'And you were quite right to do so, Miss Hedelfort,' broke in Weichart. 'We've been giving far too much attention to the temperature problem and overlooking the effect of the Cloud on the Earth's atmosphere.'

'Not clear until Dr Marlowe finished work that Earth would be in Cloud,' grunted Alexandrov.

'That's true enough,' agreed Weichart. 'But now the decks are cleared we can get into action. The first point is one of energy. Each gram of hydrogen that enters the atmosphere can liberate energy in two ways, first by its impact with the atmosphere and second by combination with oxygen. Of these the first yields more energy and is therefore more important.'

'My G.o.d, this only makes it worse,' exclaimed Marlowe.

'Not necessarily. Think what'll happen when the gas of the Cloud hits the atmosphere. The very outside of the atmosphere'll become extremely hot, because it's on the outside where the impact will take place. We've calculated that the temperature of the outer parts of the atmosphere'll go racing up to hundreds of thousands of degrees, perhaps even to millions of degrees. The next point is that the Earth and the atmosphere are spinning round and that the Cloud will be hitting the atmosphere from one side only.'

'From what side?' asked Parkinson.

'The Earth's position in its...o...b..t will be such that the Cloud will come at us from the approximate direction of the Sun,' explained Yvette Hedelfort.

'Although the Sun itself won't be visible,' added Marlowe.

'So the Cloud will be hitting the atmosphere during what would normally be the daytime?'

'That's right. And it will not be hitting the atmosphere during the night.'

'And that's the crux of the matter,' continued Weichart.

'Because of the very high temperature I was talking about, the outer parts of the atmosphere will tend to blow outwards. This won't happen during the "daytime" because the impact of the Cloud will hold it in, but at "night" the upper atmosphere will stream outwards into s.p.a.ce.'

'Oh, I see what you're meaning,' said Yvette Hedelfort. 'Hydrogen will come into the atmosphere during the "daytime" but it will blow out again during the "night". So there will not be any c.u.mulative addition of hydrogen from day to day.'

'That's exactly right.'

'But can we be sure that all the hydrogen will be evaporated off in this way, Dave?' asked Marlowe. 'If even a small proportion of it were retained, say one per cent or a tenth per cent, the effect would be disastrous. We've got to keep in mind how very small a disturbance small from the astronomical point of view could still wipe us out of existence.'

'I'd feel confident in predicting that effectively all the hydrogen will be evaporated away. The danger is rather the other way, that too much of the other gases of the atmosphere will also get evaporated into s.p.a.ce.'

'How can that be? You said only the outer parts of the atmosphere would be heated.'

Kingsley took up the argument.

'The situation is this. To begin with, the top of the atmosphere will be hot, extremely hot. The bottom of the atmosphere, the part where we live, will be cool to start with. But there'll be a gradual downward transfer of energy, tending to heat up the lower parts.'

Kingsley put down his gla.s.s of whisky.

'The whole point is to decide how fast the downward transference of energy will be. As you say, Geoff, only a very slight effect would be utterly disastrous. The lower atmosphere might be heated sufficiently to cook us, quite literally to cook us, all done to a turn quite slowly, politicians included, Parkinson!'

'You're forgetting that we shall survive longest, because our skins are thickest.'

'Excellent, a point to you! Of course the downward transfer of energy might be fast enough to cause the whole of the atmosphere to be blown off into s.p.a.ce.'

'Can this be decided?'

'Well, there are three ways of transferring energy, they're just our old friends, conduction, convection, and radiation. We can be pretty sure already that conduction isn't going to be important.'

'Nor convection either,' broke in Weichart. 'There'll be a stable atmosphere with a rising temperature as you go outwards. So there can be no convection.'

'So that leaves radiation,' concluded Marlowe.

'And what will the effect of radiation be?'

'We don't know,' said Weichart. 'It'll have to be calculated.'

'You can do that?' queried the persistent Parkinson.

Kingsley nodded.

'Can calculate,' affirmed Alexandrov. 'Will be b.l.o.o.d.y great calculation.'

Three weeks later Kingsley asked Parkinson to see him.