- #1
Saw
Gold Member
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- 18
I see everywhere the explanation that electromagnetic radiation self-propagates this way: a changing magnetic field induces a changing electric field, which in turn induces a changing magnetic field and so on and so on.
I do not understand that. I do not have a problem with saying (it is a legitimate conceptual model, a way of expressing what happens) that wherever an electromagnetic wave is present, there is an electric field and a magnetic field. However, I do not see how that can “explain” why the radiation propagates through vacuum.
After reading this month about the subject, I come to the conclusion that all the chapters about the subject can be summarised, simplifying a little, as follows:
a) There is a basic principle: a charge attracts/repels (depending on sign) another charge.
b) Hence a set of moving charges, i.e. a current attracts/repels (depending on the sense of motion) another current (including in the concept of “current” both motion of free charges inside a conductor and aligned motion of bound charges inside a magnet).
c) An oscillation of charges, i.e. an alternate current induces (by way of attraction/repulsion) another alternate current (including in this concept also a moving magnet).
In a) and b) the phenomenon happens at a distance and I have not read that authors resort to self-replicating fields to account for that fact. Why do they do in the case of c)?
After all, the three things are manifestations of the same phenomenon and one of the findings of SR is to make that clear, isn’t it?
It seems simpler and more honest to accept that in the three cases, a), b) and c), the “influence” (attraction or repulsion or an alternative series of both things) just propagates, we do not know how. Would you agree to that?
I do not understand that. I do not have a problem with saying (it is a legitimate conceptual model, a way of expressing what happens) that wherever an electromagnetic wave is present, there is an electric field and a magnetic field. However, I do not see how that can “explain” why the radiation propagates through vacuum.
After reading this month about the subject, I come to the conclusion that all the chapters about the subject can be summarised, simplifying a little, as follows:
a) There is a basic principle: a charge attracts/repels (depending on sign) another charge.
b) Hence a set of moving charges, i.e. a current attracts/repels (depending on the sense of motion) another current (including in the concept of “current” both motion of free charges inside a conductor and aligned motion of bound charges inside a magnet).
c) An oscillation of charges, i.e. an alternate current induces (by way of attraction/repulsion) another alternate current (including in this concept also a moving magnet).
In a) and b) the phenomenon happens at a distance and I have not read that authors resort to self-replicating fields to account for that fact. Why do they do in the case of c)?
After all, the three things are manifestations of the same phenomenon and one of the findings of SR is to make that clear, isn’t it?
It seems simpler and more honest to accept that in the three cases, a), b) and c), the “influence” (attraction or repulsion or an alternative series of both things) just propagates, we do not know how. Would you agree to that?