- #36
Paul Colby
Gold Member
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Ibix said:Paul - freedom to change coordinates is a gauge freedom. It's fundamentally no different from the notion that you can set the zero of potential anywhere you like. It can make the maths harder or easier, and it changes how you interpret things. But it doesn't ever change your measurements.
It must work out because the theory asserts that all direct observables are Lorentz scalars and invariant under coordinate transform. Unless there's something fundamentally wrong with the idea that physics should be coordinate independent.
After the morning shower I've adopted the view that the capacitor test is to this (Edwards) symmetry as MML is to Lorentz symmetry. The only difference is no one seriously expects an anisotropy of this type.