What does electromagnetic wave literally look like? Some people on the Internet called electromagnetic wave as something that has literally only two dimensions, I think it is because of this over-publicized picture http://hyperphysics.phy-astr.gsu.edu/hbase/emwav.html. Is it true? Personally, I don't think electromagnetic wave is two-dimensional despite most pictures depicted it as a two-dimensional wave. What do you think?


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I disagree with such statements. Electromagnetic waves are four-dimensional phenomena. They also have quite a few degrees of freedom. The k-vector has three dimensions, there are two polarisation and two independent phases.

  • $\begingroup$ I see. I think some people called EM wave as something two dimensional because of this over-publicized picture of EM wave hyperphysics.phy-astr.gsu.edu/hbase/emwav.html So, in reality EM wave doesn't even look like that? $\endgroup$ – Mohamed Obeidallah Dec 11 '18 at 15:12
  • $\begingroup$ That picture clearly is three dimensional. It shows a linearly polarised infinite plane wave, for which E and B always point in the same direction, but the wave pervades all of space. Obviously, a wave can only be plane in a finite volume of space-time. $\endgroup$ – my2cts Dec 11 '18 at 16:46
  • $\begingroup$ Sorry for my ignorance but can you show me which part is three dimensional? What I'm seeing is just two dimensional plane. Why E and B always point in the same direction? Is it impossible for E and B pointing to multi different directions? $\endgroup$ – Mohamed Obeidallah Dec 11 '18 at 19:38
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    $\begingroup$ There are 3 mutually orthogonal axes in the figure. $\endgroup$ – my2cts Dec 12 '18 at 0:11
  • $\begingroup$ The arrows show the direction and intensity of the electric field on the axis indicated by the line. It is easy to misinterpret the figure. $\endgroup$ – my2cts Dec 12 '18 at 0:17

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