Anno Computatri

Anno Computatri is a thought experiment exploring what a time system built without Earth as a reference point would look like. Conventional time units above the atomic second — minutes, hours, days, years — are rooted in Earth’s rotation and orbit, assumptions that break down in interplanetary or interstellar contexts.

The project examines what a universal calendar would require, including a stable atomic anchor, a fixed standard year, and a mapping to historical Earth dates. It also raises deeper questions about relativistic drift, timekeeping on vessels with no orbital period, and how human intuitions about time reflect Earth-specific conditions.

Time is deceptively local. We measure it in rotations and revolutions — one planet spinning, one planet orbiting a star — and then treat the resulting numbers as if they were facts about the universe rather than facts about where we happen to live.

Anno Computatri started as a thought experiment around the basic assumptions of time measurement. What would happen if you tried to build a time system from first principles, without assuming Earth as the reference point?

The first move is obvious: anchor to something universal. International Atomic Time (TAI) already does this — the second is defined by quantum transitions in cesium-133, independent of any planet. But every higher-level structure we use — the minute, the hour, the day, the year — inherits the Earth. They’re convenient fictions that work here and break down the moment you’re on Mars, in interplanetary transit, or reasoning about a distributed civilization that genuinely doesn’t share a sky.

Asimov’s Foundation universe sketches a “Galactic Standard Year” but never quite specifies it. That vagueness is interesting in itself: even in fiction, we haven’t worked out the calendrical infrastructure a spacefaring civilization would actually need. You need an anchor epoch, a fixed number of atomic seconds per “standard year,” and a convention for how Earth’s historical calendar maps onto it — otherwise you can’t read old records, and the whole project loses its utility.

From there, the questions multiply. How do you handle relativistic drift between reference frames at interstellar distances? What does “local time” mean on a generation ship with no fixed orbital period? How do you build a calendar that feels intuitive to humans who evolved with seasons, while remaining mathematically coherent across environments that have none?

These aren’t engineering problems yet. They’re the step before engineering: working out what we actually want, what the constraints are, and which assumptions we’ve been making without knowing it. The interesting part isn’t the solution. It’s what the problem reveals about how deeply Earth-shaped our intuitions about time really are.

→ The full project lives at annocomputatri.net.