In theory could coax be used to make a fiber optic type gyro?

Seems like it should work; the physics is the same. The practical problem is that coax has a lot of attenuation, and a gyro needs a lot of path length to make a decent signal. Fiber is also pretty good as regards prop delay vs temperature, way better than the usual coax.

Fiber gyros can also use interferance to detect the rotational Dopplerish thing, which is awfully sensitive.

The numbers don't look promising for coax.

You mean like this?

I don't see why not. (how much loss do you get it ~1km of coax?)

George H.

You can think of storing information in a transmission line, in units of, say, bits per kilometer. Single-mode fiber will beat coax by at least 3 orders of magnitude, maybe 6.

I think that if you had lots and lots of really low-loss coax, the answer would be yes. Work out the loss per wavelength for fiber vs. coax, and I think you'll be disappointed though.

However, if you go to

Has been done, similar things also happen

(10 seconds of Googling)

w.

That's interesting Helmut. But I think it is a copy of Fizeau's experiment with moving water.

And not a gyroscope... which needs a large turns x area.

Still it's interesting, it seems to imply that one can detect absolute motion with a dielectric... but I'm probably making a mistake.

George H.

That paper sounds bogus to me, especially the part about gravity waves.

If the electrons were moving without coming into thermal equilibrium with the wire, it'd be possible. Drift velocities (and phonon scattering) give rise to Ohm's law, and also cause an electron's momentum to be closely coupled to the wire it's in. It's a MUCH more random motion than the photons in a singlemode optical fiber.

So, a storage ring (electrons circulating in vacuum) or a superconductor (with noninteracting electrons) might be practical. Coaxial wiring, not so much.

And, I'm not sure how one would make up losses. With optical, you can get laser amplification, which preserves phase: with electrons, the spin is wrong, there ARE NO AMPLIFIERS that can keep the loop phase-coherent.