3 ms·

But doesn’t > If you turn the solenoid on and off you would think it would make no difference because no matter what you do, the magnetic field the particle en

But doesn’t > If you turn the solenoid on and off you would think it would make no difference because no matter what you do, the magnetic field the particle encounters is zero. The key, though, is that the magnetic potential is not zero along the particle's path, and the magnetic potential affects the particle's phase in measurable way when the two states recombine. Imply that you can measure the potential somehow? That the particles phase is affected by the potential being non-zero, and therefore the gauge is at least somewhat fixed?

antognini 4y ago
The issue is that the choice of gauge changes the equation between the value of the potential and all the observable quantities. So you can go ahead and measure the phase difference, the charge of the particle, and the value of the magnetic flux within the solenoid, but in order to turn that into a value of the magnetic potential, you need an equation relating them all. And different choices of gauges give you different equations. So there's no unique way to go from the quantities you've observed to a value of the magnetic potential.