Again came the sequence. Line, oval, circle, oval, line. Then it struck him. “It’s the galaxy.”

“What?” Nikka had just arrived. “What is all this?”

“Watch.” He pointed. “See the broad line of tiny lights? That’s the galaxy as it looks from the side. That’s the way we see it from Earth, a plane seen edge-on. Now watch.” His lined hands carved the air.

The line thickened, winking with a cascade of lights. It swelled into an oval as other data sped across the image, like clouds rushing over the face of a slumbering continent. Fires lit in the oval. Traceries shot through it. It grew into a circle. Strands within it flexed and spilled with light.

Nigel said, “Catch the spiral arms? There. Faint out-lines against those bright points.”

“Well …” she looked doubtful. “Maybe.”

“See those blue points?” Dabs of blue light stood out against the other tiny glows. Evidently they were all stars. But … “I wonder what those stand for?”

“Other Watchers?” Nikka asked.

“Could be. But think. This is a map of the whole damn galaxy.” He said it quietly but it had an effect on the others now crowding into the cramped room. “Seen from every angle. Which means somebody—some-thing—has done that. Sailed far up above the whole disk and looked down on it. Charted the inlets of gas and dust and old dead suns. Seen it all.”

In the silence of the strange room they watched the galaxy spin. It moved with stately slowness. Grave and ghostly movements changed it. Sparks came and vanished. Dim gray presences passed across its face. Lingered. Were gone.

Then a specialist Nigel knew slightly, a wiry astronomer, said, “I think I recognize some of the pattern.”

“Where?” Nigel asked.

“See that quadrant? I think it’s ours.”

A segment of the galaxy did seem to Nigel, now that the astronomer pointed it out, slightly more crowded and luminous that the rest. He frowned as thin mists seemed to spill liquidly through the pie-slice segment. “You recognize stars?”

“In a way,” the astronomer said with a certain prim precision. “Not optical stars, no. Pulsars.”

“Where?”

“See the deep blue ones?”

“Yes, I was wondering—”

“They’re where pulsars should be.”

Nigel remembered vaguely that rapidly spinning neutron stars accounted for the pulsar phenomenon. As the compacted cores of these dense stars spun, they released streams of plasma. These luminous swarms flapped like flags as they left the star. They emitted gouts of radio noise. As a star spun, it directed these beams of radio emission outward, like a lighthouse sweeping its lamp across a distant ship. When the beam chanced to intersect the Earth, astronomers saw it, measured its frequency of sweep.

The astronomer went on, “They’re so prominent in this map. Far more luminous than they are in reality.”

“Perhaps they are important?” Nikka asked.

“Umm.” The astronomer frowned. His face was lined with fatigue but the fascination of this place washed away the past. Even amid tragedy, curiosity was an itch that needed scratching. “Could be. As navigation beacons, maybe?”

Nigel thought of his lighthouse analogy. Beeping signals across the blind abyss?

But there were easier ways to find your way among the stars. He pointed again. “Why is there that big blue patch at the center, then?”

The astronomer looked more puzzled. “There aren’t any pulsars at the galactic center.”

Nikka asked, “What is there? Just stars?”

“Well, it’s got a lot of gas, turbulent motions, maybe a black hole. It’s the most active region of the whole galaxy, sure, but …”

Nikka asked, “Could it be that the galactic center and pulsars have something in common?”

The astronomer pursed his lips, as if he disliked making such leaps. “Well … there’s a lot of plasma.”

Nigel asked slowly, “What kind?”

“All kinds,” the astronomer said with a touch of condescension. “Hot gas made still hotter. Until the electrons separate from the ions and the whole system becomes electrically active.”

Nigel shook his head, not knowing himself where he was headed. You just skated, and went where the ice took you. “Not around pulsars. I remember that much.”

The astronomer blinked. In his concentration the weight of the last few days slipped from him and his face smoothed. “Oh. Oh, you’re right. Pulsars put out really relativistic plasma. The stuff comes whipping off the neutron star surface close to the speed of light.”

Nigel wasn’t in the mood for a lecture. Still, something tugged at him. “What kind of plasma?”

“There aren’t any heavy ions, no protons to speak of. It’s all electrons and their antiparticles.”

“Positrons,” Nigel said.

“Right, positrons. The electrons interact with the positrons in some fashion and make the radio emission. We—”

“And at galactic center?” Nigel persisted.

The astronomer blinked. “Well, yeah … There was report a while back. … A detection of positrons at the galactic center.” His voice caught and then a wondering enthusiasm crept into it. Nigel watched the man’s face fill with a wan yet growing delight. “Positrons. If they slow down, meet electrons, the two annihilate. Give off gamma rays. A gamma-ray telescope Earthside, Jacobson’s group I think it was, saw the annihilation line.”

Nigel felt a slow, gathering certainty. “Those blue dots …”

Nikka said softly, “The Watcher keeps track of where positrons appeared naturally in the galaxy.”

The fact sank into them. The Watcher’s main job was to stamp out organic life, that was clear. But something had told the ancient craft to notice pulsars and the positron plasmas they spewed out into the galaxy. A phenomenon that occurred also at galactic center—but on a hugely larger scale, apparently, judging by the large blue zone at the very hub of the rotating swirl.

The astronomer said, puzzled, “But there can’t be so many pulsars at the center of the galaxy …”

“Still, there is that blue globe,” Nigel said.

Something was happening at galactic center. Something important.

And the machine civilization thought it was vital, perhaps as important as the obliteration of the organic yeast they so hated.

Nigel said softly, with a gathering certainty, “If we are ever to deal with these things, with their Watchers and Snarks and the whole damn mechanical zoo of them … we’ve got to confront them.”

Nikka saw what he meant. “But—Earth! We can return now. There is so much to be done.”

He shook his head. Looking around the room, with its myriad sliding sheets of alien thought and strange design, he watched the luminescence play upon the haggard faces.

Faces pursued by a voracious and unyielding intelligence. Faces lined and worn by the silent anxiety they all felt, just being here.

The Watcher would give them no rest. They had to get out. Move on.

But not simply run back home. Earth was no haven. There was no blithe sanctuary now. Not anywhere in the whole swarming galaxy.

“No. We’ve got the means. That little ship we found. It must be a fast craft. I’ll bet it came here and supervised the building of this Watcher.”

“Nigel …” Nikka began a protest, then stopped.

“That ship still works. It could go back. Back where it came from. Where we must go.”

They began to murmur and protest.

A small band of humans, their incessant crosstalk rebounding from the alien surfaces. Nigel smiled.

Their dreams lay Earthward. They would have to be convinced.

le’s all slide out of here one of these nights

But he knew he could convince them. The rest of humanity was reeling under war and a vast, brute yoke. If this small knot did not seize this opportunity, humanity would dwell forever in the dimness of ignorance. Victims. Prey.

and go for howling adventures amongst the Injuns

There was no turning back now. Maybe there never had been any possibility of turning away from what lay out here. He had felt it for a long time, since the first vague pricklings of understanding at the sunny, long lost Jet Propulsion Laboratory. Odd, he felt almost nostalgic for the place now.