‘All right, then,’ he went on, ‘that’s good for a start. Now, if you take a brown mass of matter and apply temporal translation to it – you know, send it back in time – you are, in effect, creating matter at the point in time to which you are sending it. To do that, you must use an amount of energy equivalent to the amount of matter you have created. In other words, to send a gram – or, say, an ounce – of anything back in time, you have to disintegrate an ounce of matter completely, to furnish the energy required.’

‘Hm-m-m,’ I said, ‘that’s to create the ounce of matter in the past. But aren’t you destroying an ounce of matter by removing it from the present? Doesn’t that create the equivalent amount of energy?’

And he looked just about as annoyed as a fellow sitting on a bumble-bee that wasn’t quite dead. Apparently laymen are never supposed to question scientists.

He said: ‘I was trying to simplify it so you would understand it. Actually, it’s more complicated. It would be very nice if we could use the energy of disappearance to cause it to appear, but that would be working in a circle, believe me. The requirements of entropy would forbid it. To put it more rigorously, the energy is required to overcome temporal inertia and it just works out so that the energy in ergs required to send back a mass, in grams, is equal to that mass times the square of the speed of light in centimeters per second. Which just happens to be the Einstein Mass-Energy Equivalence Equation. I can give you the mathematics, you know.’

‘I know,’ I waxed some of that misplaced eagerness back. ‘But was all this worked out experimentally? Or is it just on paper?’

Obviously, the thing was to keep him talking.

He had that queer light in his eye that every research student gets, I am told, when he is asked to discuss his problem. He’ll discuss it with anyone, even with a ‘dumb flatfoot’ – which was convenient at the moment.

‘You see,’ he said like a man slipping you the inside dope on a shady business deal, ‘what started the whole thing was this neutrino business. They’ve been trying to find that neutrino since the late thirties and they haven’t succeeded. It’s a subatomic particle which has no charge and has a mass much less than even an electron. Naturally, it’s next to impossible to spot, and hasn’t been spotted yet. But they keep looking because, without assuming that a neutrino exists, the energetics of some nuclear reactions can’t be balanced. So Pop Tywood got the idea about twenty years ago that some energy was disappearing, in the form of matter, back into time. We got working on that – or he did – and I’m the first student he’s ever had tackle it along with him.

‘Obviously, we had to work with tiny amounts of material and . . . well, it was just a stroke of genius on Pop’s part to think of using traces of artificial radioactive isotopes. You could work with just a few micrograms of it, you know, by following its activity with counters. The variation of activity with time should follow a very definite and simple law which has never been altered by any laboratory condition known.

‘Well, we’d send a speck back fifteen minutes, say, and fifteen minutes before we did that – everything was arranged automatically, you see – the count jumped to nearly double what it should be, fell off normally, and then dropped sharply at the moment it was sent back below where it would have been normally. The material overlapped itself in time, you see, and for fifteen minutes we counted the doubled material—’

I interrupted: ‘You mean you had the same atoms existing in two places at the same time.’

‘Yes,’ he said, with mild surprise, ‘why not? That’s why we use so much energy – the equivalent of creating those atoms.’ And then he rushed on, ‘Now I’ll tell you what my particular job is. If you send back the material fifteen minutes, it is apparently sent back to the same spot relative to the Earth despite the fact that in fifteen minutes, the Earth moved sixteen thousand miles around the Sun, and the Sun itself moves more thousand miles and so on. But there are certain tiny discrepancies which I’ve analyzed and which tum out to be due, possibly, to two causes.

‘First, there is a frictional effect – if you can use such a term – so that matter does drift a little with respect to the Earth, depending on how far back in time it is sent, and on the nature of material. Then, too, some of the discrepancy can only be explained by the assumption that passage through time itself takes time.’

‘How’s that?’ I said.

‘What I mean is that some of the radioactivity is evenly spread throughout the time of translation as if the material tested had been reacting during backward passage through time by a constant amount. My figures show that – well, if you were to be moved backward in time, you would age one day for every hundred years. Or, to put it another way, if you could watch a time dial which recorded the time outside a ‘time-machine,’ your watch would move forward twenty-four hours while the time dial moved back a hundred years. That’s a universal constant, I think, because the speed of light is a universal constant. Anyway, that’s my work.’

After a few minutes, in which I chewed all this, I asked: ‘Where did you get the energy needed for your experiments?’

‘They ran out a special line from the power plant. Pop’s a big shot there, and swung the deal.’

‘Hm-m-m. What was the heaviest amount of material you sent into the past?’

‘Oh’ – he sent his eyes upwards – ’ I think we shot back one hundredth of a milligram once. That’s ten micrograms.’

‘Ever try sending anything into the future?’

‘That won’t work,’ he put in quickly. ‘Impossible. You can’t change signs like that, because the energy required becomes more than infinite. It’s a one-way proposition.’

I looked hard at my fingernails: ‘How much material could you send back in time if you fissioned about . . . oh, say, one hundred pounds of plutonium.’ Things, I thought, were becoming, if anything, too obvious.

The answer came quickly: ‘In plutonium fission,’ he said, ‘not more than one or two percent of the mass is converted into energy. Therefore, one hundred pounds of plutonium when completely used up would send a pound or two back into time.’

‘Is that all? But could you handle all that energy? I mean, a hundred pounds of plutonium can make quite an explosion.’

‘All relative,’’ he said, a bit pompously. ‘If you took all that energy and let it loose a little at a time, you could handle it. If you released it all at once, but used it just as fast as you released it, you could still handle it. In sending back material through time, energy can be used much faster than it can possibly be released even through fission. Theoretically, anyway.’

‘But how do you get rid of it?’

‘It’s spread through time, naturally. Of course, the minimum time through which material could be transferred would, therefore, depend on the mass of the material. Otherwise, you’re liable to have the energy density with time too high.’

‘All right, kid,’ I said. ‘I’m calling up headquarters, and they’ll send a man here to take you home. You’ll stay there a while.’

‘But – What for?’

‘It won’t be for long.’

It wasn’t – and it was made up to him afterwards.

I spent the evening at Headquarters. We had a library there – a very special kind of library. The very morning after the explosion, two or three operators had drifted quietly into the chemistry and physics libraries of the University. Experts in their way. They located every article Tywood had ever published in any scientific journal and had snapped each page. Nothing was disturbed otherwise.

Other men went through magazine files and through book lists. It ended with a room at Headquarters that represented a complete ‘Iywoodana. Nor was there a definite purpose in doing this. It merely represented part of the thoroughness with which a problem of this sort is met.

I went through that library. Not the scientific papers. I knew there’d be nothing there that I wanted. But he had written a series of articles for a magazine twenty years back, and I read those. And I grabbed at every piece of private correspondence they had available.

After that, I just sat and thought – and got scared.

I got to bed about four in the morning and had nightmares.

But I was in the Boss’ private office at nine in the morning just the same.

He’s a big man, the Boss, with iron-gray hair slicked down tight. He doesn’t smoke, but he keeps a box of cigars on his desk and when he doesn’t want to say anything for a few seconds, he picks one up, rolls it about a little, smells it, then sticks it right into the middle of his mouth and lights it in a very careful way. By that time, he either has something to say or doesn’t have to say anything at all. Then he puts the cigar down and lets it bum to death.

He used up a box in about three weeks, and every Christmas, half his gift-wraps held boxes of cigars.

He wasn’t reaching for any cigars now, though. He just folded his big fists together on the desk and looked up at me from under a creased forehead. ‘What’s boiling?’

I told him. Slowly, becaqse micro-temporal-translation doesn’t sit well with anybody, especially when you call it time travel, which I did. It’s a sign of how serious things were that he only asked me once if I were crazy.

Then I was finished and we stared at each other.

He said: ‘And you think he tried to send something back in time – something weighing a pound or two – and blew an entire plant doing it?’

‘It fits in,’ I said.

I let him go for a while. He was thinking and I wanted him to keep on thinking. I wanted him, if possible, to think of the same thing I was thinking, so that I wouldn’t have to tell him—

Because I hated to have to tell him—

Because it was nuts, for one thing. And too horrible, for another.

So I kept quiet and he kept on thinking and every once in a while some of his thoughts came to the surface.

After a while, he said: ‘Assuming the student, Howe, to have told the truth – and you’d better check his notebooks, by the way, which I hope you’ve impounded—’

‘The entire wing of that floor is out of bounds, sir. Edwards has the notebooks.’