by astronomers. But this is not something bright, it’s something dark, and that’s not so easy to pick up — a dark patch is pretty well camouflaged against the sky. Of course if one of the stars that has been hidden by the cloud had happened to be a bright fellow it would have been spotted. The disappearance of a bright star is not so easy to detect as the appearance of a new bright star, but it would nevertheless have been noticed by thousands of professional and amateur astronomers. It happened, however, that all the stars near the cloud are telescopic, none brighter than eighth magnitude. That’s the first mischance. Then you must know that in order to get good seeing conditions we prefer to work on objects near the zenith, whereas this cloud lies rather low in our sky. So we would naturally tend to avoid that part of the sky unless it happened to contain some particularly interesting material, which by a second mischance (if we exclude the case of the cloud) it does not. It is true that to observatories in the southern hemisphere the cloud would be high in the sky, but observatories in the southern hemisphere are hard put to it with their small staffs to get through a host of important problems connected with the Magellanic Clouds and the nucleus of the Galaxy. The cloud had to be detected sooner or later. It turned out to be later, but it might have been sooner. That’s all I can say.”
“It’s too late to worry about that now,” said the Director. “Our next step must be to measure the speed with which the cloud is moving towards us. Marlowe and I have had a long talk about it, and we think it should be possible. Stars on the fringe of the cloud are partially obscured, as the plates taken by Marlowe last night show. Their spectrum should show absorption lines due to the cloud, and the Doppler shift will give us the speed.”
“Then it should be possible to calculate how long the cloud will be before it reaches us,” joined in Barnett. “I must say I don’t like the look of things. The way the cloud has increased its angular diameter during the last twenty years makes it look as if it’ll be on top of us within fifty or sixty years. How long do you think it’ll take to get a Doppler shift?”
“Perhaps about a week. It shouldn’t be a difficult job.”
“Sorry I don’t understand all this,” broke in Weichart. “I don’t see why you need the speed of the cloud. You can calculate straight away how long the cloud is going to take to reach us. Here, let me do it. My guess is that the answer will turn out at much less than fifty years.”
For the second time Weichart left his seat, went to the blackboard, and cleaned off his previous drawings.
“Could we have Jensen’s two slides again please?”
When Emerson had flashed them up, first one and then the other, Weichart asked: ‘Could you estimate how much larger the cloud is in the second slide?”
“I would say about five per cent larger. It may be a little more or a little less, but certainly not very far away from that,” answered Marlowe.
“Right,” Weichart continued, “let’s begin by defining a few symbols.”
Then followed a somewhat lengthy calculation at the end of which Weichart announced:
“And so you see that the black cloud will be here by August 1965, or possibly sooner if some of the present estimates have to be corrected.”
Then he stood back from the blackboard, checking through his mathematical argument.
“It certainly looks all right — very straightforward in fact,” said Marlowe, putting out great volumes of smoke.[1]
“Yes, it seems unimpeachably correct,” answered Weichart.
At the end of Weichart’s astonishing calculation, the Director had thought it wise to caution the whole meeting to secrecy. Whether they were right or wrong, no good could come of talking outside the Observatory, not even at home. Once the spark was struck the story would spread like wildfire, and would be in the papers in next to no time. The Director had never had any cause to think highly of newspaper reporters, particularly of their scientific accuracy.
From midday to two o’clock he sat alone in his office, wrestling with the most difficult situation he had ever experienced. It was utterly antipathetic to his nature to announce any result or to take steps on the basis of a result until it had been repeatedly checked and cross-checked. Yet would it be right for him to maintain silence for a fortnight or more? It would be two or three weeks at least before every facet of the matter were fully investigated. Could he afford the time? For perhaps the tenth time he worked through Weichart’s argument. He could see no flaw in it.
At length he called in his secretary.
“Please will you ask Caltech to fix me a seat on the night plane to Washington, the one that leaves about nine o’clock? Then get Dr Ferguson on the phone.”
James Ferguson was a big noise in the National Science Foundation, controlling all the activities of the Foundation in physics, astronomy, and mathematics. He had been much surprised at Herrick’s phone call of the previous day. It was quite unlike Herrick to fix appointments at one day’s notice.
“I can’t imagine what can have bitten Herrick,” he told his wife at breakfast, “to come chasing over to Washington like this. He was quite insistent about it. Sounded agitated, so I said I’d pick him up at the airport.”
“Well, an occasional mystery is good for the system,” said his wife. “You’ll know soon enough.”
On the way from the airport to the city, Herrick would commit himself to nothing but conventional trivialities. It was not until he was in Ferguson’s office that he came to the issue.
“There’s no danger of us being overheard, I suppose?”
“Goodness, man, is it as serious as that? Wait a minute.”
Ferguson lifted the phone.
“Amy, will you please see that I’m not interrupted — no, no phone calls — well, perhaps for an hour, perhaps two, I don’t know.”
Quietly and logically Herrick then explained the situation. When Ferguson had spent some time looking at the photographs, Herrick said:
“You see the predicament. If we announce the business and we turn out to be wrong, then we shall look awful fools. If we spend a month testing all the details and it turns out that we are right, then we should be blamed for procrastination and delay.”
“You certainly would, like an old hen sitting on a bad egg.”
“Well, James, I thought you have had a great deal of experience in dealing with people. I felt you were someone I could turn to for advice. What do you suggest I should do?”
Ferguson was silent for a little while. Then he said:
“I can see that this may turn out to be a grave matter. And I don’t like taking grave decisions any more than you do, Dick, certainly not on the spur of the moment. What I suggest is this. Go back to your hotel and sleep through the afternoon — I don’t expect you had much sleep last night. We can meet again for an early dinner, and by then I’ll have had an opportunity to think things over. I’ll try to reach some conclusion.”
Ferguson was as good as his word. When he and Herrick had started their evening meal, in a quiet restaurant of his choice, Ferguson began:
“I think I’ve got things sorted out fairly well. It doesn’t seem to me to make sense wasting another month in making sure of your position. The case seems to be very sound as it is, and you can never be quite certain — it would be a matter of converting a ninety-nine per cent certainty into a ninety-nine point nine per cent certainty. And that isn’t worth the loss of time. On the other hand you are ill-prepared to go to the White House just at the moment. According to your own account you and your men have spent less than a day on the job so far. Surely there are a good many other things you might get ideas about. More exactly, how long is it going to take the cloud to get here? What will its effects be when it does get here? That sort of question.
“My advice is to go straight back to Pasadena, get your team together, and aim to write a report within a week, setting out the situation as you see it. Get all your men to sign it — so that there’s no question of the tale getting around of a mad Director. And then come back to Washington.
“In the meantime I’ll get things moving at this end. It isn’t a bit of good in a case like this starting at the bottom by whispering into the ear of some Congressman. The only thing to do is to go straight to the President. I’ll try to smooth your path there.”
