POSTSCRIPT: THE OTHER COORDINATE
Beyond Time

Designing a calendar for the Solar System turns out to be surprisingly difficult.

That is probably not the last piece of civil infrastructure for which this will be true.

For most of human history, we have enjoyed an enormous hidden simplification: one inhabited planet. However different our countries, calendars, languages and institutions became, everybody ultimately occupied the same physical world. We could disagree about almost everything while remaining inside one shared geography.

A multi-world civilisation loses that convenience.

Solarian has dealt with one consequence.

If people live on Mars, Ceres, Titan, artificial habitats and worlds much farther out, the answer to when? can no longer rely on everybody sharing the same day, month or year. Local time has to mean something locally while still remaining intelligible to everyone else.

But time is only one coordinate of civilisation.

The other is space.

Where, exactly, is something?

On Earth, that question looks deceptively solved.

We have latitude and longitude, nations and regions, cities and postcodes, roads and street numbers, property boundaries, maritime zones, airspace, cadastral systems and countless layers of naming accumulated over centuries. Most people never need to understand how those systems fit together. They simply type an address into a phone and expect the world to know what they mean.

That apparent simplicity hides an extraordinary amount of infrastructure.

Take it away from Earth and the assumptions begin to loosen.

A settlement on Mars needs more than a picturesque name. Land, infrastructure, emergency services, transport, ownership and administration eventually require places to have durable identities.

An asteroid creates a different problem. There may be no familiar north, no useful street grid and very little reason for the vocabulary of terrestrial geography to survive unchanged.

A moon belongs simultaneously to its own surface geography, a planetary system and the wider Solar System.

An artificial habitat may rotate, move, expand, dock with another structure or occupy an orbit chosen by engineers rather than inherited from geology.

And eventually people will need to answer very ordinary questions inside all of them.

Where is the hospital? Which parcel of land does this contract refer to? Where does this road, tunnel or utility corridor begin? Which jurisdiction contains this structure? Where should a spacecraft actually go?

The precision systems will be excellent. Coordinates, navigation networks and orbital mechanics will describe physical position vastly more accurately than ordinary civil life requires.

But that sounds familiar.

Atomic clocks can measure time precisely too.

They do not tell somebody what next Monday means.

Perhaps civil space has the same problem as civil time.

The engineering coordinate and the human address are related, but they are not necessarily the same thing.

And perhaps the deeper challenge is again architectural: deciding what needs to be universal, what should remain local, how different scales fit together and how a system can survive the transition from empty terrain to places with history, ownership and culture.

A civilisation of many worlds will eventually need to know both: When is this?

And: Where is this?

Solarian is an attempt at the first question.

The second may turn out to be at least as interesting.

I have some ideas about that too.

But that is for some other place.