Why do you insist on digging your hole even deeper!
1. We are working in flat spacetime,, with inertial frames ONLY, so the covariant derivatives coincide with the partial ones.
No, the Christoffel symbols vanish if the
coordinate system is Cartesian. You've clearly never computed the Christoffel symbols for polar coordinates. Congratulations on once again making a fool of yourself.
2. Guest254 agreed with me that the Shubert transforms do not make the classical (differential form) Maxwell laws covariant.
General coordinate transformations will not leave the form of non-tensorial equations unchanged - this should be obvious.
3. The disagreement starts over the general covariant expression (tensor notation). Guest says that the change of variable proposed by Shubert is legit, I am saying that it isn't. For two reasons:
My claim is far grander -
any coordinate transformation will leave the form of a tensor equation invariant.
-in flat spacetime the difference between 2 and 3 is indeed just a change in notation (connection coefficients are zero)
This is cringe-worthy. Polar coordinates a new thing for you then?
-it is not possible for a change in notation to change the underlying physics, i.e. both 2 and 3 are not covariant, you can't have 2 non-covariant and 3 covariant
You're still
massively confused as what general covariance means. It is a statement regarding the
form of the equations. General covariance means that you can write down the equations in such a way that their
form does not change under coordinate transformations. I.e, you can write them down in terms of objects that behave in very special ways under coordinate transformations - these special objects are called tensors.
-the transformations rules for tensors don't work with the Shubert crackpot coordinate transforms (this is why 2 fails the covariance) but the lazy bum (Guest) refuses to even try to calculate the simplest expression in order to convince himself.
And to top it off, you admit to not being able to differentiate! But because I'm in a chirpy mood: if f(x,t) = ax + bt + S(cx + dt + S(S(x))), then f_x = a + S'(cx + dt + S(S(x)))(c+S'(S(x))S'(x)). This chain rule thing is magic!