Vega— look, yon can see it's bluish—and the same kind of debris system. It's true, I can't check this out from the constellations because of the glare. I'd still give you ten-to-one odds this is Vega.”
“But then where are they?” Devi asked. Xi, whose eyesight was acute, was staring up—through the organosilicate matrix, out the transparent pentagonal panels, into the sky far above the ring plane. He said nothing, and Ellie followed his gaze. There was something there, all right, gloaming in the sunlight and with a perceptible angular size. She looked through the long lens. It was some vast irregular polyhedron, each of its faces covered with… a kind of circle? Disk? Dish? Bowl?' Here, Qiaomu, look through here. Tell us what you see.”
“Yes, I see. Your counterparts… radio telescopes. Thousands of them, I suppose, pointing in many directions. It is not a world. It is only a device.”
They took turns using the long lens. She concealed her impatience to look again. The fundamental nature of a radio telescope was more or less specified by the physics of radio waves, but she found herself disappointed that a civilization able to make, or even just use, black holes for some kind of hyperrelativistic transport would still be using radio telescopes of recognizable design, no matter how massive the scale. It seemed backward of the Vegans… unimaginative. She understood the advantage of putting the telescopes in polar orbit around the star, safe except for twice each revolution from collisions with ring plane debris.
But radio telescopes pointing all over the sky—thousands of them—suggested some comprehensive sky survey, an Argus in earnest. Innumerable candidate worlds were being watched for television transmission, military radar, and perhaps other varieties of early radio transmission unknown on Earth. Did they find such signals often, she wondered, or was the Earth their first success in a million years of looking? There was no sign of a welcoming committee. Was a delegation from the provinces so unremarkable that no one had been assigned even to note their arrival?When the lens was returned to her she took great care with focus, f/stop, and exposure time. She wanted a permanent record, to show the National Science Foundation what really serious radio astronomy was like. She wished there were a way to determine the size of the polyhedral world. The telescopes covered it like barnacles on a whaler. A radio telescope in zero g could be essentially any size. After the pictures were developed, she would be able to determine the angular size (maybe a few minutes of arc), but the linear size, the real dimensions, that was impossible to figure out unless you knew how far away the thing was. Nevertheless she sensed it was vast.
“If there are no worlds here,” Xi was saying, “then there are no Vegans. No one lives here. Vega is only a guard-house, a place for the border patrol to warm their hands.”
“Those radio telescopes”—he glanced upward—”are the watchtowers of the Great Wall. If you are limited by the speed of light, it is difficult to hold a galactic empire together. You order the garrison to put down a rebellion. Ten thousand years later you find out what happened. Not good. Too slow. So you give autonomy to the garrison commanders. Then, no more empire. But those”—and now he gestured at the receding blot covering the sky behind them—”those are imperial roads. Persia had them. Romehad them.
China had them. Then you are not restricted to the speed of light. With roads you can hold an empire together.”
But Eda, lost in thought, was shaking his bead. Something about the physics was bothering him.
The black hole, if that was what it really was, could now be seen orbiting Vega in a broad lane entirely clear of debris; both inner and outer rings gave it wide berth. It was hard to believe how black it was.
As she took short video pans of the debris ring before her, she wondered whether it would someday form its own planetary system, the particles colliding, sticking, growing ever larger, gravitational condensations taking place until at last only a few large worlds orbited the star. It was very like the picture astronomers had of the origin of the planets around the Sun four and a half billion years ago. She could now make out inhomogeneities in the rings, places with a discernible bulge where some debris had apparently accreted together.
The motion of the black hole around Vega was creating a visible ripple in the bands of debris immediately adjacent The dodecahedron was doubtless producing some more modest wake. She wondered if these gravitational perturbations, these spreading rarefactions and condensations, would have any long-term consequence, changing the pattern of subsequent planetary formation. If so, then the very existence of some planet billions of years in the future might be due to the black hole and the Machine… and therefore to the Message, and therefore to Project Argus. She knew she was overpersonalizing; bad she never lived, some other radio astronomer would surely have received the Message, but earlier, or later. The Machine would have been activated at a different moment and the dodec would have found its way here in some other time.
So some future planet in this system might still owe its existence to her. Then, by symmetry, she had snatched out of existence some other world that was destined to form bad she never lived. It was vaguely burdensome, being responsible by your innocent actions for the fates of unknown worlds.
She attempted a panning shot, beginning inside the dodecahedron, then out to the struts joining the transparent pentagonal panels, and beyond to the gap in the debris rings in which they, along with the black hole, were orbiting. She followed the gap, flanked by two bluish rings, further and further from her. There was something a little odd up ahead, a kind of bowing in the adjacent inner ring.
“Qiaomu,” she said, handing him the long lens, “look over there. Tell me what you sec.”
“Where?”
She pointed again. After a moment he had found it. She could tell because of his slight but quite unmistakable intake of breath. “Another black hole,” he said. “Much bigger.”
They were falling again. This time the tunnel was more commodious, and they were making better time.
“That's it?” Ellie found herself shouting at Devi. “They take us to Vega to show off their black holes.
They give us a look at their radio telescopes from a thousand kilometers away. We spend ten minutes there, and they pop us into another black hole and ship us back to Earth. That's why we spent two trillion dollars?”
“Maybe we're beside the point,” Lunacharsky was saying. “Maybe the only real point was to plug themselves into the Earth.”
She imagined nocturnal excavations beneath the gates of Troy.
Eda, fingers of both hands outspread, was making a calming gesture. “Wait and see,” he said. “This is a different tunnel. Why should you think it goes back to Earth?”
“Vega's not where we're intended to go?” Devi asked. “The experimental method. Let's see where we pop out next.” In this tunnel there was less scraping of the walls andfewer undulations. Eda and Vaygay were debating a space-time diagram they had drawn in Kruskal-Szekeres coordinates. Ellie had no idea what they were talking about. The deceleration stage, the part of the passage that felt uphill, was still disconcerting.
This time the light at the end of the tunnel was orange. They emerged at a considerable speed into the system of a contact binary, two suns touching. The outer layers of a swollen elderly red giant star were pouring onto the photosphere of a vigorous middle-aged yellow dwarf, something like the Sun. The zone of contact between the two stars was brilliant. She looked for debris rings or planets or orbiting radio observatories, but could find none. That doesn't mean very much, she told herself. These systems could have a fair number of planets and I'd never know it with this dinky long lens. She projected the double sun onto the piece of paper and photographed the image with a short-focal-length lens.
Because there were no rings, there was less scattered light in this system than around Vega; with the wide-angle lens she was able, after a bit of searching, to recognize a constellation that sufficiently resembled the Big Dipper. But she had difficulty recognizing the other constellations. Since the bright stars in the Big Dipper are a few hundred light-years from Earth, she concluded that they had not jumped more than a few hundred light-years. She told this to Eda and asked him what he thought. “What do I think? I think this is an Underground.”
“An Underground?”
She recalled her sensation of falling, into the depths of Hell it had seemed for a moment, just after the Machine had been activated.
“A Metro. A subway. These are the stations. The stops. Vega and this system and others. Passengers get on and off at the stops. You change trains here.”
He gestured at the contact binary, and she noticed that his hand cast two shadows, one anti-yellow and the other anti-red, like in—it was the only image that came to mind—a discotheque.
“But we, we cannot get off,” Eda continued. “We are in a closed railway car. We're headed for the terminal, the end of the line.”
Drumlin had called such speculations Fantasyland, and this was—so far as she knew—the first time Eda had
