Once the project had been agreed upon, Kimball acted as bombardier. Since the orbiting Discovery could track the probe only during the few seconds while it was passing directly over the slot, space capsule Alice was fitted with receiving gear. Kimball dropped the probe at the exact center of the chasm, then flew to the edge and waited on the brink, Alice’s receiving antenna jutting out over the abyss.
At first the probe fell with the lethargic slowness to be expected in Jupiter V’s gravity field. Its instruments recorded a very slight temperature rise, but nothing else of importance. There was no radioactivity, no magnetic field.
And then, five miles down, it began to accelerate. Its signals started to drop rapidly in pitch, indicating a Doppler effect of astonishing magnitude. Kimball had to continually retune the receiver in order to keep track of the signals, and the radar started to indicate impossible ranges and velocities. In a few seconds, the probe was two hundred miles away-which, taken at face value, meant that it had gone right through Jupiter V and out the other side. Thereafter, it became more and more difficult to detect, and swiftly passed beyond the tuning range of the receiver. On the last contact, it had descended nine thousand and fifty miles down a hole which under no circumstances could be more than a hundred miles deep-the diameter of the tiny moon.
The radar was working perfectly; Kimball checked it with the utmost care as soon as he got back to the ship. The trouble must lie in Jupiter V-and Hunter neatly summed up what everybody was now beginning to suspect.
“I’m afraid,” he said, “that there’s something seriously wrong with space.”
“A long time ago,” said Kaminski, “I came across a remark that I’ve never forgotten-though I can’t remember who made it. ‘Any sufficiently advanced technology is indistinguishable from magic.’ that’s what we’re up against here. Our lasers and mesotrons and nuclear reactors and neutrino telescopes would have seemed pure magic to the best scientists of the nineteenth century. But they could have understood how they worked-more or less- if we were around to explain the theory to them.”
“I’d be glad to settle without the theory,” remarked Kimball, “if I could even understand what this thing is-or what it’s supposed to do.”
“It seems to me,” said Bowman, “that there are two possibilities-both just about equally impossible. The first is that Jupiter V is hollow-and there’s some kind of micro-universe down there. A whole galaxy a hundred miles across.”
“But the probes went thousands of miles, according to the radar readings.”
“There could be some kind of distortion. Suppose the probes got smaller and smaller as they went in. Then they might seem to be thousands of miles away, when they were still really quite close.”
“And that,” said Kaminski, “reminds me of another quotation-one of Niels Bohr’s. ‘Your theory is crazy- but not crazy enough to be true.’ ”
“You have a crazier one?” asked Hunter.
“Yes, I do. I think the stars-and that sun down there- are part of our own universe, but we’re seeing them through some new direction of space.”
“I suppose you mean the fourth dimension.”
“I doubt if it’s anything as simple as that. But it probably does involve higher dimensions of some kind. Perhaps non-Euclidean ones.”
“I get the idea. If you went down that hole, you’d come out hundreds or thousands of light- years away. But how long would the journey really be?”
“How long is the journey from New York to Washington? Two hundred miles if you fly south. But twenty-four thousand if you go in the other direction, over the North Pole. Both directions are equally real.”
“I seem to remember,” said Bowman, “that back on Earth you once told me that shortcuts through space-time were scientific nonsense-pure fantasy.”
“Did I?” replied Kaminski, unabashed. “Well, I’ve changed my mind. Though I reserve the right to change it back again, if a better theory comes along.”
“I’m a simpleminded engineer,” said Hunter rather aggressively. “I see a hole going into Jupiter V, and not coming out anywhere. But you tell me that it does come out. How?’
Everyone waited hopefully for Kaminski to answer. For a moment he hemmed and hawed, then he suddenly brightened.
“I can only explain by means of analogy. Suppose you were a Flatlander, an inhabitant of a two- dimensional world like a sheet of paper-unable to move above or below it. If I drew a circle in your flat world, but left a small gap in it, you would say that the gap was the only way into the circle. Right?”
“Right.”
“If anyone went into the circle, they could only come out the same way?”
“So that’s what you’re driving at. The circle could be a cross-section of a tube passing through Flatland. If I was clever enough to crawl up the tube, by moving into the third dimension, I would leave my flat universe altogether.”
“exactly. But the tube might bend back into Flatland again, and you could come out somewhere else. To your friends, it would seem that you’d traveled from A to B without crossing the space between. You’d have disappeared down one hole and emerged from a totally different one, maybe thousands of miles away.”
“But what advantage would that be? Surely the straight line in Flatland itself would still be the shortest distance between A and B.”
“Not necessarily. It depends what you mean by a straight line. Flatland might really be wrinkled, though the Flatlanders wouldn’t be able to detect it. I’m not a topologist, but I can see how there might be lines that were straighter than straight, if some of them went through other dimensions.”
“We can argue this until kingdom come,” said Hunter. “But supposing it’s true-what shall we do about it?”
“There’s not much we can do. Even if we had an unlimited fuel and oxygen supply, it might be suicide to go into that thing. Though it may be a shortcut, it could be a damn long one. Suppose it comes out somewhere a thousand light-years away-that won’t help us, if the trip takes a century. We wouldn’t appreciate saving nine hundred years.”
That was perfectly true; and there might be other dangers, as inconceivable to the mind of man as this anomaly in space itself. Discovery had come to the end of her travels; she must remain here in an eternal orbit, just a few miles from a mystery that she could never approach.
Like Moses looking into the promised land, they must stare at marvels beyond their reach.
BALL GAME
After a while they began to call it the Star Gate; no one was quite sure who coined the name. And because the human mind can accept anything, however strange, its mystery soon ceased to haunt them. One day, perhaps, they would understand how the stars were shining down there at the bottom of that chasm; the night sky, reflected in a pool of still water, might have seemed just as great a mystery to early man.
They still had twenty days of operating time before they would have to go into hibernation, and there was enough fuel for the pods to make five more trips down to the surface. Bowman allowed three visits, at internals of a week, and then left the pods in their airlocks, fully provisioned, ready for any future emergency that might arise.
The descents taught them little more than they already knew. They watched the regular transit of those strange stars and the giant red sun, drifting with clockwork precision across the distant end of the Star Gate-still in a direction, and at a speed, that had nothing to do with the spin of Jupiter V itself.
Kaminski brooded for hours over his photographs, trying to identify the star patterns with the aid of the maps stored in Athena’s memory. His total failure neither disappointed nor surprised him. If indeed he was looking out through a window onto some remote part of the Galaxy, there was no hope of recognizing the view. One of those faint stars might even be the Sun; he could never identify it. From a few score light-years away, Type G-zeroes are as indistinguishable as peas in a pod.
The three remaining instrumented probes were dropped at intervals of a week-the last one, just before hibernation was due to commence. Each performed in an identical manner, dwindling away into impossible distances before its signals were lost. The record depth-in this hundred mile-diameter world!-was eleven thousand miles….
After that, they had done everything that was humanly possible, their stores were almost exhausted, and it was time to sleep. In one sense, their mission had been a success, they had discovered what they had been sent to find-even if they did not know what it was. But in another, the expedition had failed, since they could not report their findings to Earth. All Kimball’s attempts to re-establish communications with jury-rigged antennas and overloaded output circuits had been successful. The daily messages and news reports continued to come in, and were at once encouraging and frustrating. It was good for their morale to know that Earth, and their friends, had not forgotten them, and that the preparations for their return were going ahead at the highest priority. But it was maddening not to be able to reply, and to be the custodians of a secret that would rock human society to its foundations.