1. Nov 20, 2012

cragar

Lets say I have a uniformly charged spherical shell. that is roating with an angular
velocity w. Now machs principle says that accleration is relative to the distant stars.
If the distant stars are rotatingng with the same w as the spherical shell, there will be no B field inside the shell. This seems strange. Why should the distant stars have anything to do with the B field of the rotating shell? And lets say the stars started moving relative to the shell why would this all of a sudden create a B field to appear in the frame.

2. Nov 20, 2012

Vorde

It's not about the 'stars themselves moving', it's about being in the reference frame of equal rotation. In that reference frame, it appears as if there is no magnetic field in the shell as your said. But its not the movement of the stars than cause that, it's the fact that they are in a reference frame where this appears to be the case.

3. Nov 20, 2012

cragar

why cant accleration just be absolute

4. Nov 20, 2012

tris_d

5. Nov 20, 2012

Vorde

Good question, and it's a tricky one I don't trust myself to address.