- #1
TrickyDicky
- 3,507
- 27
Probably this has an easy answer but I can't see it just now, according to the principle of relativity we shouldn't be able to tell based on physical experiments if a body is at rest or in a uniform velocity, but in the case of charged objects we seem to be able to differentiate it simply by the fact that at rest produces an electric field as defined by electrostatics formulas and if moving follows electrodynamics and it also has a magnetic field so when in doubt it gives a hint of which object is moving and which in rest, unlike the famous example about looking at the other train by the window and not knowing which is moving or if both are moving.