The Collected Stories of Arthur C. Clarke (46 page)

Dr Henderson smiled. ‘Thanks to Walt Disney, I can picture the scene rather well.’

Davis was not very encouraging. ‘It was probably only the missus banging the dinner gong,’ he said. ‘The most infuriating part of our work is the way everything can peter out when it gets most exciting. The strata have been washed away, or there’s been an earthquake—or, worse still, some silly fool has smashed up the evidence because be didn’t recognise its value.’

Henderson nodded in agreement. ‘I can sympathise with you,’ he said. ‘That’s where the physicist has the advantage. He knows he’ll get the answer eventually, if there is one.’

He paused rather diffidently, as if weighing his words with great care. ‘It would save you a lot of trouble, wouldn’t it, if you could actually
see
what took place in the past, without having to infer it by these laborious and uncertain methods. You’ve been a couple of months following these footsteps for a hundred yards, and they may lead nowhere for all your trouble.’

There was a long silence. Then Barton spoke in a very thoughtful voice.

‘Naturally, Doctor, we’re rather curious about your work,’ he began. ‘Since Professor Fowler won’t tell us anything, we’ve done a good deal of speculating. Do you really mean to say that—’

The physicist interrupted him rather hastily. ‘Don’t give it any more thought,’ he said. ‘I was only daydreaming. As for our work, it’s a very long way from completion, but you’ll hear all about it in due course. We’re not secretive—but, like everyone working in a new field, we don’t want to say anything until we’re sure of our ground. Why, if any other palaeontologists came near this place, I bet Professor Fowler would chase them away with a pick-axe!’

‘That’s not quite true,’ smiled Davis. ‘He’d be much more likely to set them to work. But I see your point of view; let’s hope we don’t have to wait too long.’

That night, much midnight oil was burned at the main camp. Barton was frankly sceptical, but Davis had already built up an elaborate superstructure of theory around their visitor’s remarks.

‘It would explain so many things,’ he said. ‘First of all, their presence in this place, which otherwise doesn’t make sense at all. We know the ground level here to within an inch for the last hundred million years, and we can date any event with an accuracy of better than one per cent. There’s not a spot on Earth that’s had its past worked out in such detail—it’s the obvious place for an experiment like this!’

‘But do you think it’s even theoretically possible to build a machine that can see into the past?’

‘I can’t imagine how it could be done. But I daren’t say it’s impossible—especially to men like Henderson and Barnes.’

‘Hmmm. Not a very convincing argument. Is there any way we can hope to test it? What about those letters to
Nature
?’

‘I’ve sent to the College Library; we should have them by the end of the week. There’s always some continuity in a scientist’s work, and they may give us some valuable clues.’

But at first they were disappointed; indeed, Henderson’s letters only increased the confusion. As Davis had remembered, most of them had been about the extraordinary properties of Helium II.

‘It’s really fantastic stuff,’ said Davis. ‘If a liquid behaved like this at normal temperatures, everyone would go mad. In the first place, it hasn’t any viscosity at all. Sir George Darwin once said that if you had an ocean of Helium II, ships could sail in it without any engines. You’d give them a push at the beginning of their voyage and let them run into buffers on the other side. There’d be one snag, though; long before that happened the stuff would have climbed straight up the hull and the whole outfit would have sunk—gurgle, gurgle, gurgle…’

‘Very amusing,’ said Barton, ‘but what the heck has this to do with your precious theory?’

‘Not much,’ admitted Davis. ‘However, there’s more to come. It’s possible to have two streams of Helium II flowing in opposite directions
in the same tube
—one stream going through the other, as it were.’

‘That must take a bit of explaining; it’s almost as bad as an object moving in two directions at once. I suppose there
is
an explanation, something to do with Relativity, I bet.’

Davis was reading carefully. ‘The explanation,’ he said slowly, ‘is very complicated and I don’t pretend to understand it fully. But it depends on the fact that liquid helium can have
negative
entropy under certain conditions.’

‘As I never understood what positive entropy is, I’m not much wiser.’

‘Entropy is a measure of the heat distribution of the Universe. At the beginning of time, when all energy was concentrated in the suns, entropy was a minimum. It will reach its maximum when everything’s at a uniform temperature and the Universe is dead. There will still be plenty of heat around, but it won’t be usable.’

‘Whyever not?’

‘Well, all the water in a perfectly flat ocean won’t run a hydro-electric plant—but quite a little lake up in the hills will do the trick. You must have a difference in level.’

‘I get the idea. Now I come to think of it, didn’t someone once call entropy “Time’s Arrow”?’

‘Yes—Eddington, I believe. Any kind of clock you care to mention—a pendulum, for instance—might just as easily run forward as backward. But entropy is a strictly one-way affair—it’s always increasing with the passage of time. Hence the expression, “Time’s Arrow”.’

‘Then
negative
entropy—my gosh!’

For a moment the two men looked at each other. Then Barton asked in a rather subdued voice: ‘What does Henderson say about it?’

‘I’ll quote from his last letter: “The discovery of negative entropy introduces quite new and revolutionary conceptions into our picture of the physical world. Some of these will be examined in a further communication.”’

‘And are they?’

‘That’s the snag: there’s no “further communication”. From that you can guess two alternatives. First, the Editor of
Nature
may have declined to publish the letter. I think we can rule that one out. Second, the consequences may have been
so
revolutionary that Henderson never did write a further report.’

‘Negative entropy—negative time,’ mused Barton. ‘It seems fantastic; yet it might be theoretically possible to build some sort of device that could see into the past…’

‘I know what we’ll do,’ said Davis suddenly. ‘We’ll tackle the Professor about it and watch his reactions. Now I’m going to bed before I get brain fever.’

That night Davis did not sleep well. He dreamed that he was walking along a road that stretched in both directions as far as the eye could see. He had been walking for miles before he came to the signpost, and when he reached it he found that it was broken and the two arms were revolving idly in the wind. As they turned, he could read the words they carried. One said simply: To the Future; the other: To the Past.

They learned nothing from Professor Fowler, which was not surprising; next to the Dean, he was the best poker player in the College. He regarded his slightly fretful assistants with no trace of emotion while Davis trotted out his theory.

When the young man had finished, he said quietly, ‘I’m going over again tomorrow, and I’ll tell Henderson about your detective work. Maybe he’ll take pity on you; maybe he’ll tell me a bit more, for that matter. Now let’s go to work.’

Davis and Barton found it increasingly difficult to take a great deal of interest in their own work while their minds were filled with the enigma so near at hand. Nevertheless they continued conscientiously, though ever and again they paused to wonder if all their labour might not be in vain. If it were, they would be the first to rejoice. Supposing one could see into the past and watch history unfolding itself, back to the dawn of time! All the great secrets of the past would be revealed: one could watch the coming of life on the Earth, and the whole story of evolution from amoeba to man.

No; it was too good to be true. Having decided this, they would go back to their digging and scraping for another half-hour until the thought would come: but what if it
were
true? And then the whole cycle would begin all over again.

When Professor Fowler returned from his second visit, be was a subdued and obviously shaken man. The only satisfaction his assistants could get from him was the statement that Henderson had listened to their theory and complimented them on their powers of deduction.

That was all; but in Davis’s eyes it clinched the matter, though Barton was still doubtful. In the weeks that followed, he too began to waver, until at last they were both convinced that the theory was correct. For Professor Fowler was spending more and more of his time with Henderson and Barnes; so much so that they sometimes did not see him for days. He had almost lost interest in the excavations, and had delegated all responsibility to Barton, who was now able to use the big pneumatic drill to his heart’s content.

They were uncovering several yards of footprints a day, and the spacing showed that the monster had now reached its utmost speed and was advancing in great leaps as if nearing its victim. In a few days they might reveal the evidence of some eon-old tragedy, preserved by a miracle and brought down the ages for the observation of man. Yet all this seemed very unimportant now; for it was clear from the Professor’s hints and his general air of abstraction that the secret research was nearing its climax. He had told them as much, promising that in a very few days, if all went well, their wait would be ended. But beyond that he would say nothing.

Once or twice Henderson had paid them a visit, and they could see that he was now labouring under a considerable strain. He obviously wanted to talk about his work, but was not going to do so until the final tests had been completed. They could only admire his self-control and wish that it would break down. Davis had a distinct impression that the elusive Barnes was mainly responsible for his secrecy; he had something of a reputation for not publishing work until it had been checked and double-checked. If these experiments were as important as they believed, his caution was understandable, however infuriating.

Henderson had come over early that morning to collect the Professor, and as luck would have it, his car had broken down on the primitive road. This was unfortunate for Davis and Barton, who would have to walk to camp for lunch, since Professor Fowler was driving Henderson back in the jeep. They were quite prepared to put up with this if their wait was indeed coming to an end, as the others had more than half-hinted.

They had stood talking by the side of the jeep for some time before the two older scientists had driven away. It was a rather strained parting, for each side knew what the other was thinking. Finally Barton, as usual the most outspoken, remarked:

‘Well, Doc, if this
is
Der Tag, I hope everything works properly. I’d like a photograph of a brontosaurus as a souvenir.’

This sort of banter had been thrown at Henderson so often that he now took it for granted. He smiled without much mirth and replied, ‘I don’t promise anything. It may be the biggest flop ever.’

Davis moodily checked the tyre pressure with the toe of his boot. It was a new set, he noticed, with an odd zigzag pattern he hadn’t seen before.

‘Whatever happens, we hope you’ll tell us. Otherwise, we’re going to break in one night and find out just what you’re up to.’

Henderson laughed. ‘You’ll be a pair of geniuses if you can learn anything from our present lash-up. But, if all goes well, we may be having a little celebration by nightfall.’

‘What time do you expect to be back, Chief?’

‘Somewhere around four. I don’t want you to have to walk back for tea.’

‘OK—here’s hoping!’

The machine disappeared in a cloud of dust, leaving two very thoughtful geologists standing by the roadside. Then Barton shrugged his shoulders.

‘The harder we work,’ he said, ‘the quicker the time will go. Come along!’

The end of the trench, where Barton was working with the power drill, was now more than a hundred yards from the main excavation. Davis was putting the final touches to the last prints to be uncovered. They were now very deep and widely spaced, and looking along them, one could see quite clearly where the great reptile had changed its course and started, first to run, and then to hop like an enormous kangaroo. Barton wondered what it must have felt like to see such a creature bearing down upon one with the speed of an express; then he realised that if their guess was true this was exactly what they might soon be seeing.

By mid-afternoon they had uncovered a record length of track. The ground had become softer, and Barton was roaring ahead so rapidly that he had almost forgotten his other preoccupations. He had left Davis yards behind, and both men were so busy that only the pangs of hunger reminded them when it was time to finish. Davis was the first to notice that it was later than they had expected, and he walked over to speak to his friend.

‘It’s nearly half-past four!’ he said when the noise of the drill had died away. ‘The Chief’s late—I’ll be mad if he’s had tea before collecting us.’

‘Give him another half-hour,’ said Barton. ‘I can guess what’s happened. They’ve blown a fuse or something and it’s upset their schedule.’

Davis refused to be placated. ‘I’ll be darned annoyed if we’ve got to walk back to camp again. Anyway, I’m going up the hill to see if there’s any sign of him.’

He left Barton blasting his way through the soft rock, and climbed the low hill at the side of the old riverbed. From here one could see far down the valley, and the twin stacks of the Henderson-Barnes laboratory were clearly visible against the drab landscape. But there was no sign of the moving dust-cloud that would be following the jeep: the Professor had not yet started for home.

Davis gave a snort of disgust. There was a two-mile walk ahead of them, after a particularly tiring day, and to make matters worse they’d now be late for tea. He decided not to wait any longer, and was already walking down the hill to rejoin Barton when something caught his eye and he stopped to look down the valley.