# Charge moves relative to charge: one thing two aspects?

#### neila9876

1. Two neutral balls move relative to each other (one thing). When the frame of reference is established on the left ball, the right ball is moving (one aspect). When the frame of reference is established on the right ball , the left ball is moving (another aspect). In respect of electromagnetism, these two aspects are the same, results are both nothing.
2. Because conservation of charges, here construct a simplest system: a proton on the left side and an electron on the right side. Two charges move relative to each other (one thing). When the frame of reference is established on the proton, the electron is moving (one aspect). When the frame of reference is established on the eletron, the the proton is moving (another aspect). In respect of electromagnetism, are these two aspects different? In another word: an electron moving relative to a proton or a proton moving relative to an electon are different events logically? What's the result?

#### HallsofIvy

"Gallilean relativity", due to Gallileo, says that the result of calculations of moving objects do not depend upon the frame of reference- no mechanical experiment can determine an "absolute" velocity. Maxwell's equations, in particular that a moving charge has a magnetic field, seemed to imply that electro-magnetic experiments could determine an "absolute" velocity. Einstein's theory of relativity solved that problem- no such experiment can determine an "absolute" velocity.

So the answer to your question is "no". There is no difference between the two scenarios.

2 people

#### neila9876

Suppose the distance between the two charges is increasing. Then, what the electron experiences is electric potential decreasing, what the proton experiences is electric potential increasing. Logically, they seem to be different events?

#### topsquark

Forum Staff
Suppose the distance between the two charges is increasing. Then, what the electron experiences is electric potential decreasing, what the proton experiences is electric potential increasing. Logically, they seem to be different events?
I suppose it might seem reasonable to suggest that the two particles would experience different changes to the electric potential, but in actuality the magnitudes of the potentials are the same so the two particles react the same.

-Dan

#### neila9876

Actually, what you are talking about seems to be "one thing two aspects"?