Looking for explanations of what electromagnetic waves (light, etc.) are, I found apparently contradicting explanations. According to the first, which seems wrong to me, EM waves are explained using the following two facts:
- A changing electric field causes a magnetic field, and
- a changing magnetic field causes an electric field.
So, if you cause an electric field to change this will create a magnetic field (thus a change in the magnetic field), which will in turn generate an electric field, and so on. And so the EM waves self-propagate in this way, as in a "chain" reaction. This explanation seems wrong and misleading to me, for when a magnetic field is generated by a changing electric field, the former is far weaker than the latter (unless I am missing something); and the same is the case when an electric field is generated by a changing magnetic field. So according to this explanation, the EM waves should not be able to propagate very far, for at every turn (from magnetic to electric, or from electric to magnetic), it should become weaker and weaker, and die out very soon.
The second explanation has to do with the fact that when an electric field changes (or a magnetic field changes), this information cannot propagate faster than the speed of light c, and this limit in the speed of propagation of the information creates a "kink" in the EM field, a kink that propagates with the speed of light. This kink is indeed a disturbance of the electric-magnetic field - thus a disturbance in the E-field accompanied by a change in the magnetic field, but this dance between electric and magnetic field, captured by facts (1) and (2), is not really pivotal in the explanation of why and how the wave can propagate (as the first explanation implies!)
So, my question is: what role do facts (1) and (2) play in the explanation EM waves's ability to propagate? More specifically: I am right to suppose that the first explanation reported here should be dismissed?