It was a watery world, laced with island chains where the tectonic plates of the planet’s mantle ground against one another. It had once hosted a benign and relatively peaceful human society, occupying both the available dry land and a number of artificial archipelagos. Most of Cloud Harbor’s polities had been cortical democracies, with a few settlements of radically bionormative Martians. But thousands of years had passed since then. We had to assume that any or all of this might have changed.

Allison asked me in a small voice whether I could tell anything about the planet as it was now.

In fact I had been trolling for stray signals. There had been none, or none that I could identify. But that might only mean that the resident civilization had adopted highly lossless modes of communication. Certainly the Hypotheticals were still active here. The icy planetesimals in the far reaches of the system swarmed with busily breeding machine entities.

I was with Allison and Turk as the time differential between Vox Core and the external environment counted down to 1:1. I had created a viewscreen which filled an entire wall of the largest room of their home—in effect, a window to the world beyond Vox. It had been blank. Suddenly it filled with stars.

Cloud Harbor swam into view, an amplified image; we were still light-minutes away.

“It’s beautiful,” Allison said. She had never seen a world like this from space—the people of Vox had never been very interested in space travel. But Cloud Harbor would have been beautiful even to a jaded eye. It was a swirled crescent of cobalt and turquoise, its icy white moon standing half a degree off the sunlit horizon.

“A lot like the way Earth used to be,” Turk said.

He looked at me for a response. When I didn’t speak he said, “Isaac? Are you all right?”

But I couldn’t answer.

No, I wasn’t all right. My body was numb. My mind was full of inexplicable lights and motion. I tried to stand and toppled over.

Before my senses faded I heard the wail of a distant siren—it was the old autonomic defense system built into the city’s deep infrastructure, warning of an invasion I couldn’t see.

*   *   *

The people of Cloud Harbor had seen us coming. The warped spacetime around our temporal bubble, bleeding energy as it decelerated into the system, had broadcast easily detected bursts of Cherenkov radiation. So they had come to meet us.