What drift is, and the line no instrument crosses

In software, the declaration and the world begin as one claim and drift into two — the same on Monday, strangers by spring — and nothing sounds an alarm as they part, because every instrument we own is pointed at the half that still holds.

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Captain Cook charted an island in the Coral Sea in 1774. A whaling ship reported it again a century later — heavy breakers, sandy islets — and from there it entered the directories.

In 1974 the French flew over the spot, found open water, and took it off their charts. The Australians took it off theirs in 1985.

It stayed on the maps. Not the ones sailors steer by — the ones everybody else looks at. National Geographic had it. Google Maps had it. So did the shoreline databases that scientific work is built on. Each had inherited it from something earlier, and each agreed with the others, which is exactly what you would want maps to do.

In November 2012 an Australian research vessel crossed the spot while surveying plate tectonics and measured the water underneath: never less than thirteen hundred metres. Google removed the island within four days. National Geographic struck it a week later.

Somebody had gone and looked in 1974. It took another thirty-eight years for the rest of the record to hear about it — and only because a ship on other business sailed over it. That is drift.

Software keeps charts, and copies them the same way. The specification, the schema, the suite of tests, the pipeline that will not let you ship until they all line up — every one of them holds the system against something you drew earlier. They are good at what they are for, and what they are for is confirming that the copies agree. Not one has been out to the water.

And software has no second chart. There is no edition the sailors keep and the rest of us only look at — the copy everybody agrees with is the one the ship is steering by.

One half of the distance can be built into an instrument: how far what is running has moved from what you drew. We built one at Ficus, and its limit is deliberate. It sees the trouble that announces itself — the thing that stops answering, the thing that reads zero — and it is nearly blind to the trouble that does not, where everything still runs and the answer has quietly stopped being true.

The other half cannot be built at all. An instrument can hold the ship against the chart. It cannot hold the chart against the sea.

This is not knowledge walking out of the door. Nobody lost anything: the correction was published in 1974 and sat there in plain sight. What keeps a system true is not a stock of knowledge held by whoever is still in the building — people drift as much as systems do. It is that a person is the one who notices it and attends to it, because a person is the only one who pays.

The system supplies the measure. Someone still has to go and look — and then go and tell everyone who copied you.

The definition first appeared on 21 July 2026, inside The number stays green. Lifted out so it has its own address.