# Julia

Germany

 2d awarded Popular Question Feb 1 revised How can one meaningfully say that one field generates the other in an EM-wave?edited tags Jan 20 comment strict local extremum of $f'$ that is neither saddle nor inflection value of $f$With extremum I mean "strict extremum", then the derivative of constant function would be constant without a strict extremum, so it doesn't match the first condition. Jan 20 asked strict local extremum of $f'$ that is neither saddle nor inflection value of $f$ Jan 19 awarded Popular Question Jan 11 comment How can one meaningfully say that one field generates the other in an EM-wave?@Anna, thanks for your edit. This gives an argument, that there is no causal relation. Jan 11 comment How can one meaningfully say that one field generates the other in an EM-wave?If you vote to close, please comment why and how to improve the question. Jan 11 comment How can one meaningfully say that one field generates the other in an EM-wave?@anna v Thanks for your post, but sorry, I don't see how this answers my question, you just rephrase the statement, my question is about, and then recall some other (well known) facts about EM-waves, but I don't see the relation to my question. Jan 11 comment How can one meaningfully say that one field generates the other in an EM-wave?@GennaroTedesco Ok, that answers the second part of my question about the causal part. So you would agree that there is no causal relation just as I wrote it above. What do you mean about the logical part? Jan 11 comment How can one meaningfully say that one field generates the other in an EM-wave?@GennaroTedesco Weaker in logical sense. Just like: "Every polynomial over $\mathbb{C}$ of degree $n > 0$ has at least one root" is (true but) weaker than "Every polynomial over $\mathbb{C}$ of degree $n > 0$ has exactly $n$ roots". Jan 11 comment How can one meaningfully say that one field generates the other in an EM-wave?@CuriousOne No this is a physical question in the realm of this formalism. If you want a covariant notation you may ask the same question about the components of $F_{\mu\nu}$ given a fixed reference system, so if you want: "The question is notation covariant" :-). Jan 11 revised How can one meaningfully say that one field generates the other in an EM-wave?edited tags Jan 11 comment How can one meaningfully say that one field generates the other in an EM-wave?@GennaroTedesco Often one hears explanations of electromagnetic waves on high school or undergraduate level, where someone says something like: "The idea is that the changing magnetic field induces a changing electric field and the other way around." This is stronger (but wrong as stated in my question). And you get the feeling that this should "explain" the occurence of the electromagnetic wave. So I expect there is some stronger (but correct) interpretation of this statement than my first interpretation in my questioni. Jan 11 comment How can one meaningfully say that one field generates the other in an EM-wave?@GennaroTedesco: As indicated in my question there are possible (but maybe wrong) stronger interpretations, so the first interpretation is the weakest one occuring in my question and the weakest one I know. Jan 11 comment How can one meaningfully say that one field generates the other in an EM-wave?@CuriousOne I don't really see how your comment relates to my question. Jan 11 revised How can one meaningfully say that one field generates the other in an EM-wave?added 1 character in body Jan 11 asked Mutual induction in electromagnetic wave theory Jan 11 revised How can one meaningfully say that one field generates the other in an EM-wave?added 341 characters in body Jan 11 comment Detailed form of light waves in vacuum and how to test it experimentally?But an LED or light bulb is not a dipole!? Jan 11 asked How can one meaningfully say that one field generates the other in an EM-wave?