Eckard
You asked of; "a single (thus 'local') frame"? I responded on the long string on my blog as follows;
"I agree it does need more explanation. I'm now so familiar with the new simple logic I forget how relatively confusing the previous understanding was.
Perhaps a simple interpretation of Tejunders 'continuous spontaneous localization' will help. That is confusingly 'CSL', so I'll use 'instantaneous', for 'CIL'.
Envisage a space, say a 10 metre cube, with say five 0.5 metre 'particles' in it, all made up of gluons, protons, electron shells etc. and all moving with respect to (wrt) each other. We'll slow down some light waves passing through the space, to a constant 5kph wrt the cube, which we'll call 'c', so we can see what's going on.
As a part of each plane wavefront interacts with each particle the speed of propagation is instantly changed, or 'localised', to c', which is c wrt the particle NOT the cube. Most of the wave carries on at c, and another 0.5m bit may interact with a different particle, and then be localised to c", which is yet another c, wrt THAT particle. After a very short delay (PMD) each particle re-emits the charge (wave) at c wrt itself, that is; c' or c". So each of those speeds is different when viewed from the cube (background) frame, but is always c from the frame of each particle. That is 'local c' in the 'local frame' of each particle.
Now if all the particles are at rest wrt the cube, but the PMD delay gives refractive index n = in excess of 1, then all the re-emissions will have the same speed and axis c'. The process is equivalent to 'extinction' of the old wavefront and speed c. The effect of two axis during extinction is a form of birefringence, precisely as first found by Raman Chandraseckara pre his 1930 Nobel. (He also confirmed the new emission speed c' is wrt the particle not any bound electron orbital speed). In this case the word 'local' then refers to the cube, which may of course be in motion wrt it's own background.
Maxwell's 'domains' are only valid for each of those local frames. As soon as a 'transformation' (LT or GT) between frame is required they are invalid.
The big difference here is that we can now assign a frame' the mutually exclusive 'space' envisioned conceptually by Einstein (1952) to finally complete his quest for a 'Local Reality' derived from a quantum mechanism. That mechanism is simply Raman scattering, co-incidentally found the year of his Leiden speech 1921.
Does that help clarify the meaning assigned to 'local frame? The word 'single' may be almost irrelevant, but importantly reminds us that there are others, indeed "infinitely many spaces in motion relatively"; (AE 1952)"
Do let me know if the mists of confusion are yet lifting.
Peter