A Hole In Space

I remember we stared at each other along the zigzag mess table. Then we drew lots... and I lost.

The day Lear left his waste spigot open, Childrey had put a restriction on him. Lear was not to leave the base without an escort.

Lear had treasured the aloneness of those walks. But it was worse than that. Childrey had given him a list of possible escorts: half a dozen men Childrey could trust to see to it that Lear did nothing dangerous to himself or others. Inevitably they were the men most thoroughly trained in space survival routines, most addicted to Childrey's own compulsive neatness, least likely to sympathize with Lear's way of living. Lear was as likely to ask Childrey himself to go walking with him.

He almost never went out any more. I knew exactly where to find him.

I stood beneath him, looking up through the gridwork floor.

He'd almost finished dismantling the protective panels around the gravity communicator. What showed inside looked like parts of a computer in one spot, electromagnetic coils in most places, and a square array of pushbuttons that might have been the aliens' idea of a typewriter. Lear was using a magnetic induction sensor to try to trace wiring without actually tearing off the insulation.

I called, "How you making out?"

"No good," he said. "The insulation seems to be one hundred per cent perfect. Now I'm afraid to open it up. No telling how much power is ru

"What?"

He flipped a toggle above a dull gray circular plate. "This thing is a microphone. It took me a while to find it. I am Andrew Lear, speaking to whoever may be listening." He switched it off, then ripped paper from the Mass Indicator and showed me squiggles interrupting smooth sine waves. "There. The sound of my voice in gravity radiation. It won't disappear until it's reached the edges of the universe."

"Lear, you mentioned quantum black holes there. What's a quantum black hole?"

"Um. You know what a black hole is."

"I ought to." Lear had educated us on the subject, at length, during the months aboard Lowell.

When a not too massive star has used up its nuclear fuel, it collapses into a white dwarf. A heavier star—say, 1.44 times the mass of the sun and larger—can burn out its fuel, then collapse into itself until it is ten kilometers across and composed solely of neutrons packed edge to edge: the densest matter in this universe.

But a big star goes further than that. When a really massive star runs its course

when the radiation pressure within is no longer strong enough to hold the outer layers against the star's own ferocious gravity... then it can fall into itself entirely, until gravity is stronger than any other force, until it is compressed past the Schwarzchild radius and effectively leaves the universe. What happens to it then is problematical. The Schwarzchild radius is the boundary beyond which nothing can climb out of the gravity well, not even light.

The star is gone then, but the mass remains: a lightless hole in space, perhaps a hole into another universe.

"A collapsing star can leave a black hole," said Lear. "There may be bigger black holes, whole galaxies that have fallen into themselves. But there's no other way a black hole can form, now."

"So?"

"There was a time when black holes of all sizes could form. That was during the Big Bang, the explosion that started the expanding universe. The forces in that blast could have compressed little local vortices of matter past the Schwarzchild radius. What that left behind—the smallest ones, anyway—we call quantum black holes."

I heard a distinctive laugh behind me as Captain Childrey walked into view. The bulk of the communicator would have hidden him from Lear, and I hadn't heard him come up. He called, "Just how big a thing are you talking about? Could I pick one up and throw it at you?"

"You'd disappear into one that size," Lear said seriously. "A black hole the mass of the Earth would only be a centimeter across. No, I'm talking about things from ten-to-the-minus-fifth grams on up. There could be one at the center of the sun—"

"Eek!"

Lear was trying. He didn't like being kidded, but he didn't know how to stop it. Keeping it serious wasn't the way, but he didn't know that either. "Say ten-to-the-seventeenth grams in mass and ten-to-the-minus-eleven centimeters across. It would be swallowing a few atoms a day."

"Well, at least you know where to find it," said Childrey. "Now all you have to do is go after it."

Lear nodded, still serious. "There could be quantum black holes in asteroids. A small asteroid could capture a quantum black hole easily enough, especially if it was charged; a black hole can hold a charge, you know—"

"Ri-ight."

"All we'd have to do is check out a small asteroid with the Mass Detector. If it masses more than it should, we push it aside and see if it leaves a black hole behind."

"You'd need little teeny eyes to see something that small. Anyway, what would you do with it?"

"You put a charge on it, if it hasn't got one already, and electromagnetic fields. You can vibrate it to make gravity; then you manipulate it with radiation. I think I've got one in here," he said, patting the alien communicator.

"Ri-ight," said Childrey, and he went away laughing.

Within a week the whole base was referring to Lear as the Hole Man, the man with the black hole between his ears.

It hadn't sounded fu

Please note: Childrey did not misunderstand anything Lear had said. Childrey wasn't stupid. He merely thought Lear was crazy. He could not have gotten away with making fun of Lear, not among educated men, without knowing exactly what he was doing.

Meanwhile the work went on.

There were pools of Marsdust, fascinating stuff, fine enough to behave like viscous oil, and knee-deep. Wading through it wasn't dangerous, but it was very hard work, and we avoided it. One day Brace waded out into the nearest of the pools and started feeling around under the dust. Hunch, he said. He came up with some eroded plastic-like containers. The aliens had used the pool as a garbage dump.

We were having little luck with chemical analysis of the base materials. They were virtually indestructible. We learned more about the chemistry of the alien visitors themselves. They had left traces of themselves on the benches and on the communal waterbed. The traces had most of the chemical components of protoplasm, but Arsvey found no sign of DNA. Not surprising, he said, There must be other giant organic molecules suitable for gene coding.

The aliens had left volumes of notes behind. The script was a mystery, of course, but we studied the photographs and diagrams. A lot of them were notes on anthropology!

The aliens had been studying Earth during the first Ice Age.

None of us were anthropologists, and that was a damn shame. We never learned if we'd found anything new. All we could do was photograph the stuff and beam it up to Lowell. One thing was sure: the aliens had left very long ago, and they had left the lighting and air systems ru

For us? Who else?

The alternative was that the base had been switched off for some six hundred thousand years, then come back on when something detected Lowell approaching Mars. Lear didn't believe it. "If the power had been off in the communicator," he said, "the mass wouldn't be in there any more. The fields have to be going to hold it in place. It's smaller than an atom; it'd fall through anything solid."