Replies

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?

"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?"

I don't necessarily accept your premise that the field itself doesn't propagate.

A disturbance to a field may very well propagate at Light speed, but that's an entirely different action, in my opinion, than the field *itself* propagating.

"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."

That train of thought very likely misses the right track.

It's too easy to think along those lines and confuse the field itself changing or springing into existence with that of an existing field being disturbed.

When we turn ON the electromagnet, the magnetic field suddenly covers a sizeable area where it did not cover in the past when our electromagnet was OFF.

How *fast* did the field cover this new area?

Yet what you seem to be saying is that this "change" in going from "no field" to "some field" is akin to a disturbance in an existing field.

I'm not convinced that's entirely valid or useful. It might be a division by zero event.

Yes, if we have an *existing* magnetic field, then a disturbance in that field should propagate through the field itself at the speed of Light. That's well-known and not under dispute so far as I'm aware.

But what hasn't been conclusively proved or accepted is how fast the field itself covers an area when the field first forms, likewise for when the field ends as to how fast it ceases to cover an area.