I said that F/q is not an electric field. In the primed frame there is no magnetic field by definition of the problem at hand and therefore in the primed frame there can be no magnetic force. The force is due soley to the electric field. Recall that S' is the rest frame of the particle and as such there can be no magnetic force anyway.Originally posted by quartodeciman
So where do we stand WRT your challenge:
I replied that Einstein DID know that law, and that he identified it as the electric force in the primed coordinate system. Then you said that F was NO electric force. I rejoined that Einstein thought so and must have divined his transformations from it (where else?)
Maybe someone else will climb in and I can go back to just reading this thread.
You made an error above when you wrote
This relation is not valid. Why would you think you can do this?Now use some v' = -v symmetry:
X = X'
Y = Y' - (v'/c)N' = Y' + (v/c)N'
Z = Z' + (v'/c)M' = Z' - (v/c)M'