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‘It’s the perfect place’: London Underground hosts tests for ‘quantum compass’ that could replace GPS
(www.theguardian.com)
This is a most excellent place for technology news and articles.
"Fixed" ground points move a surprising amount. The local ground can shift, and of course whole continents are constantly drifting.
surely these are things that should be considered, but they move in relation to what? And is this surprising amount of any significance for tens or hundreds of miles of rail?
In relation to all other points of interest, which are themselves all moving.
It's not really relevant for rail, no, but not because of inaccuracy and drift, but because the trains are on fixed paths already. Inertial navigation and dead reckoning are accurate enough to get from station to station, and each station can have local markers, even something as simple as a reflector at the end of the platform.
But they're not developing it just for rail. It would be incredibly valuable for submarines and mining, for example.