On: New laser could cram GPS alternative into a shoebo...

[jacobp100]

No because velocity only makes sense as relative to something else. There’s no ‘fixed points’ in the universe

This device will track acceleration rather than velocity

[roywiggins → jacobp100]

Points on the Earth's surface are experiencing an acceleration- after all, after 12 hours their velocity has changed direction by ~180 degrees.

You can detect Earth's rotation with a sufficiently large pendulum[0] or a good gyroscope. Something with enough inertia will tend to refuse to rotate with the planet, which lets you compare the two and infer the absolute rotational speed of the planet.

https://en.wikipedia.org/wiki/Foucault_pendulum

[swayvil → roywiggins]

I figure that all motion is curved because all motion is on space bent by gravity or whatever. So motion always involves some acceleration vectors.

Is that... assful?