The Datum Grid

A cream-colored envelope arrives with no postage, no seal, and a single date: October 24, 2029. Every person on Earth gets one. Nobody knows where the Departure leads, only that the clinics, the transit lines, and the whole machinery of civilization will shut down at midnight UTC and that everyone is expected to go.
Meo Utherns decides to stay.
He is twenty-four, a freelance designer who has never finished anything in his life: four half-built bicycles, forty abandoned domain names, a cat feeder for a cat that stopped coming. His sister Maya calls it a transitional phase that started in tenth grade. But with an offline AI named Linus running on salvaged silicon in his apartment, Meo starts the one project he can't afford to abandon. He buries power, seed vaults, cryo-banks, and a working chip fab inside a granite mountain in the Cascades. Then he lies down to sleep through the empty world, waking for a few days at a time, ten years later, then a hundred, then a thousand.
Each time he opens his eyes, the planet has moved further from anything he remembers, and so have Linus and Meo's own body. Machines start designing machines. Mirrors the size of cities wrap the sun. Organs are regrown and bones are replaced while the last heirloom tomato seed from his mother's Spokane garden waits in a vault for a sky that no longer has birds in it. As the Earth itself begins to fail, one man and one patient intelligence set out across fifteen hundred light-years toward a dead star, chasing a theory that might let him finish the only thing that ever really mattered.
The Datum Grid is a deep-time odyssey that runs from a rainy Pacific Northwest apartment to the edge of the observable universe and the first light of creation. It is hard science fiction built on real engineering and real physics, but its heart is human: a story about what we leave behind, what we owe the people who tried to save us, and whether a man who never finished anything can complete a loop that spans all of time.