[Southack]

"As I said, changes in fields propagate. Off to on is certainly a change."

Indeed you did, but you *also* claimed that fields themselves don't propagate, something that is conclusively disproved by observing a field go from covering no area to covering a sizeable area.

What I did was to show an example wherein BOTH what you said about "changes" propagating as well as what I said about the field propagating were included in the same analogy.

And that analogy is also reproducable by experiment. We *can* observe that a magnetic field goes from covering no area to covering a sizeable area as soon as our electromagnet switches states from OFF to ON.

With that fact known, it is now reasonable to ask *how fast* did that magnetic field propagate from covering no area to covering its new, sizeable area.

[Physicist]

Indeed you did, but you *also* claimed that fields themselves don't propagate, something that is conclusively disproved by observing a field go from covering no area to covering a sizeable area.

Codswallop. Going from no field to some field is a change, and that change is what is propagating. It's all that has to propagate for a complete description of what's going on.

With that fact known, it is now reasonable to ask *how fast* did that magnetic field propagate from covering no area to covering its new, sizeable area.

The change in field is an electromagnetic wave, and it propagates at the speed of light.

Now: since the changes in an electromagnetic field propagate at c, how is it possible that orbits in a central electrical potential remain stable? Does an electron "see" where the potential well is now, or where it was some time ago?