“What?” Denison turned sharply on his heel, nearly overbalancing himself and sending out a spurt of dust.
All three were facing the Pionizer now, and above it, just about five feet above it, light shone like a fat star. Selene said, “I raised the intensity of the magnetic field, and the nuclear field remained stable in being—then eased further and further and—”
“Leaked!” Denison said. “Damn it. I didn’t see it happen.”
Selene said, “I’m sorry, Ben. First you were lost in your own thoughts, then the Commissioner arrived, and I couldn’t resist the chance of trying on my own.”
Gottstein said, “But just what is it that I see there?”
Denison said, “Energy being spontaneously given off by matter leaking from another Universe into ours.”
And even as he said that the light blinked out and many yards away, a farther, dimmer star came into simultaneous being.
Denison lunged toward the Pionizer, but Selene, all Lunar grace, propelled herself across the surface more efficiently and was there first. She killed the field structure and the distant star went out.
She said, “The leak-point isn’t stable, you see.”
“Not on a small scale,” said Denison, “but considering that a shift of a light-year is as theoretically possible as a shift of a hundred yards, one of a hundred yards only is miraculous stability.”
“Not miraculous enough,” said Selene, flatly.
Gottstein interrupted. “Let me guess what you’re talking about You mean that the matter can leak through here, or there, or anywhere in our Universe—at random.”
“Not quite at random, Commissioner,” said Denison. “The probability of leakage drops with distance from the Pionizer, and rather sharply I should say. The sharpness depends on a variety of factors and I think we’ve tightened the situation remarkably. Even so, a flip of a few hundred yards is quite probable and, as a matter of fact, you saw it happen.”
“And it might have shifted to somewhere within the city or within our own helmets, perhaps.”
Denison said, impatiently, “No, no. The leak, at least by the techniques we use, is heavily dependent on the density of matter already present in this Universe. The chances are virtually nil that the leak-position would shift from a place of essential vacuum to one where an atmosphere even a hundredth as dense as that within the city or within our helmets would exist. It would be impractical to expect to arrange the leak anywhere but into a vacuum in the first place, which is why we had to make the attempt up here on the surface.”
“Then this is not like the Electron Pump?”
“Not at all,” said Denison. “In the Electron Pump there is a two-way transfer of matter, here a one-way leak. Nor are the Universes involved the same.”
Gottstein said, “I wonder if you would have dinner with me this evening, Dr. Denison?”
Denison hesitated. “Myself only?”
Gottstein attempted a bow in the direction of Selene but could accomplish only a grotesque parody of it in his spacesuit. “I would be charmed to have Miss Lindstrom’s company on another occasion, but on this one I must speak with you alone, Dr. Denison.”
“Oh, go ahead,” said Selene, crisply, as Denison still hesitated. “I have a heavy schedule tomorrow anyway and you’ll need time to worry about the leak-point instability.”
Denison said, uncertainly, “Well, then—-Selene, will you let me know when your next free day is?”
“I always do, don’t I? And we’ll be in touch before then anyway.... Why don’t you two go on? I’ll take care of the equipment.”
15
Barren Neville shifted from foot to foot in the fashion made necessary by the restricted quarters and by the Moon’s gravity. In a larger room under a world’s stronger pull, he would have walked hastily up and back. Here, he tilted from side to side, in a repetitive back-and-forth glide.
“Then you’re positive it works. Right, Selene? You’re positive?”
“I’m positive,” said Selene. “I’ve told you five times by actual count.”
Neville didn’t seem to be listening. He said in a low, rapid voice, “It doesn’t matter that Gottstein was there, then? He didn’t try to stop the experiment?”
“No. Of course not.”
“There was no indication that he would try to exert authority—”
“Now, Barron, what kind of authority could he exert? Will Earth send a police force? Besides—oh, you know they can’t stop us.”
Neville stopped moving, stood motionless for a while. “They don’t know? They still don’t know?”
“Of course they don’t. Ben was looking at the stars and then Gottstein came. So I tried for the field-leak, got it, and I had already gotten the other. Ben’s setup—”
“Don’t call it his setup. It was your idea, wasn’t it?”
Selene shook her head. “I made vague suggestions. The details were Ben’s.”
“But you can reproduce it now. For Luna’s sake, we don’t have to go to the Earthie for it, do we?”
“I think I can reproduce enough of it now so that our people can fill it in.”
“All right, then. Let’s get started.”
“Not yet. Oh, damn it, Barron, not yet.”
“Why not yet?”
“We need the energy, too.”
“But we have that.”
“Not quite. The leak-point is unstable; pretty badly unstable.”
“But that can be fixed up. You said so.”
“I said I thought it could.”
“That’s good enough for me.”
“Just the same, it would be better to have Ben work out the details and stabilize it.”
There was a silence between them. Neville’s’ thin face slowly twisted into something approaching hostility. “You don’t think I can do it? Is that it?”
Selene said, “Will you come out on the surface with me and work on it?”
There was another silence. Neville said, unsteadily, “I don’t appreciate your sarcasm. And I don’t want to have to wait long.”
“I can’t command the laws of nature. But I think it won’t be long.... Now if you don’t mind, I need my sleep. I’ve got my tourists tomorrow.”
For a moment, Neville seemed on the point of gesturing to his own bed-alcove as though offering hospitality, but the gesture, if that was what it was, did not really come to birth and Selene made no sign of understanding or even anticipating. She nodded wearily, and left.
16
“I had hoped, to be frank,” said Gottstein, smiling over what passed for dessert—a sticky, sweet concoction— “that we would have seen each other more often.”
Denison said, “It is kind of you to take such an interest in my work. If the leak-instability can be corrected, I think my achievement—and that of Miss Lindstrom—will have been a most significant one.”
“You speak carefully, like a scientist. ... I won’t insult you by offering the Lunar equivalent of a liqueur; that is the one approximation to Earth’s cuisine I have simply made up my mind not to tolerate. Can you tell me, in lay language, what makes the achievement significant?”
“I can try,” said Denison, cautiously. “Suppose we start with the para-Universe. It has a more intense strong nuclear interaction than our Universe has so that relatively small masses of protons in the para-Universe can undergo the fusion reaction capable of supporting a star. Masses equivalent to our stars would explode violently in the para-Universe which has many more, but much smaller, stars than ours does.
“Suppose, now, that we had a much less intense strong nuclear interaction than that which prevails in our Universe. In that case, huge masses of protons would have so little tendency to fuse that a very large mass of hydrogen would be needed to support a star. Such an anti-para-Uni-verse—one that was the opposite of the para-Universe, in other words—would consist of considerably fewer but of far larger stars than our Universe does. In fact, if the strong nuclear interaction were made sufficiently weak, a Universe would exist which consisted of a single star containing all the mass in that Universe. It would be a very dense star, but relatively non-reactive and giving off no more radiation than our single Sun does, perhaps.”