Hi Edwin,
I'd almost given up on you! Excellent essay again, and brave, as you know the judges will be stony ground. Still, nicely put together and argued, and of course I agree with most. I know you won't mind discussion of the bits I don't, but first, full marks for stating we CAN'T VALIDLY 'MEASURE' FROM OTHER FRAMES!
I'll re-state my own clear rationale for that as I suggest it's where your 'absolute' background needs 'completion'. We can't validly measure PROPAGATION speed from another system. But we CAN use pythagorus and lateral emission sequences to 'measue' "CO-ORDINATE" speeds, which CAN be c+v as they're only apparent, as the system itself (train) is also moving.
That then means we have the LOCAL backgrounds we know exist; a LENS in motion, then ECRF, ECI frame, Barycentric, Interstellar (ISM), IGM, etc. And the key to the whole rationale is that each is "DISCRETE", i.e. mutually exclusive spatially and 'nested' hierarchically, so 'bounded' by the LT as a real 'shock' speed change mechanism. THEN I suggest your 'absolute' can make absolute sense in ALL cases!!
Your glass window question was spot on because light does c/n in ALL glass, so light from the Bebecar changed speed o both entering and leaving the glass, by TWO factors each time! I know that's hard to grasp and retain but I also know you have the intellect.
But that's just about content (not a valid scoring matter).
Do think thet through and let me know if you struggle to rationalise it. I thought you had before but with so many essays such concepts are very hard to embed and recall!
By the way on THAT model there IS of course also an 'ultimate' absolute system frame, but at the centre of the universe, so inaccessible.
But well done. I confess I'd thought Susskind a bit brighter and braver than that. But I found his views on QM & string theory similarly limited. Do you think it may be the usual peer pressure from having to get paid by universities?
Very best,
Peter