He lifted his head. The event horizon was like a monstrous planet, so vast it was a plain beneath him that cut the universe in two. Everywhere redshifted plasma writhed and crawled, raining into the hole, and immense auroras flapped. But at its straight-line horizon he saw bands of light; one, two, perhaps three stripes, running parallel with the edge. The rings were another product of the hole’s huge gravity field, as light was not simply deflected but pulled through one orbit, two, before being flung away.

But now he was falling ever more rapidly toward that fatal surface. Telltales warned him that his signal lock to Arches was being lost: the increasing redshift he must be suffering was affecting the frequency control. It was a secondary effect of the distortion of time itself by the black hole’s gravity. He tried to divert some of his processing power to adjusting the signal, to keep the lock as long as possible.

Time, time: from the point of view of his own younger self in the outside universe, time would pass more and more slowly for Blue as he approached the event horizon, until at last duration ceased altogether, and he was pinned against the horizon like a fly embedded in glass. It wouldn’t be long, he thought, before relativity played a final trick on his tangled lifeline, and Pirius Red became the older twin after all.

Blue would know nothing of that. He probably wouldn’t feel anything when he passed through the event horizon itself. This far out from such a massive object, tidal forces had not yet begun to pluck at a body as small as his. Once inside the horizon, though, his fate would be determined.

Inside a black hole space and time pivoted about the constancy of lightspeed, and exchanged roles. Outside, time proceeded inexorably forward, but you could move back and forth in space. But inside a hole it was space that was one-directional. No matter how hard he struggled, his progress would be one way, toward the singularity at the geometric center of the hole—the singularity was now his only future. And there, long after the tides had torn his body apart, the strings and membranes that underlay the very particles of his body would be stretched and torn, before being crushed out of existence altogether.

The telltale acknowledgment signal from Arches turned to a high-frequency chirp that disappeared into inaudibility. He turned the comm system off; it was no use now.

He glanced back the way he had come. Though the crowded sky directly above him seemed unaffected, toward the hole’s horizon his view was blueshifted and muddled. It was as if he was looking out through a shallow, mirrored cone: even light was being pulled into the hole’s gravity field, and was starting to rain down on him. As he fell further the light would fold up behind him, and eventually all the light in the universe would be pulled tight into a pencil-thin cone, spearing down after him as he fell into darkness.