UNTIL WHEN Humanity did not conquer the stars. It optimized them. In the year 2400, interstellar travel is routine, cryosleep is reliable, and uncertainty is treated as a flaw to be eliminated. Swen Adler is a pilot trained to exist where time fractures—awake while centuries pass, trusted to intervene only if perfection fails. When a flawless colonial mission to Ross 128 b begins to feel too perfect, Swen discovers that humanity may not be expanding into the universe—but simplifying itself for it. Until When is a quiet, cerebral science fiction novel about optimization, control, and the cost of removing error from the future. There are no heroes to save the world, no wars to win—only a single question that grows harder to ignore: How long can humanity remain human… until when ?