So the wave moves like. a wave, it moves up and down, up and down. But how do photons move? Do they follow the same path or do they just go straight forward without oscillating?

  • $\begingroup$ Lubos in his blog has an article on how the classical electromagnetic wave is built up by photons.motls.blogspot.gr/2011/11/… . simple , it ain't. $\endgroup$
    – anna v
    Jan 31 '13 at 16:10
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    $\begingroup$ To speak simply of the classic diagram of a wavy line travelling left to right, the wavy line represents the strength and direction of the electric field vector. The path of the wave may be considered to travel along the zero point on this axis. $\endgroup$
    – Nic
    Jan 31 '13 at 16:25
  • $\begingroup$ @Nic, since Brazz answered pretty the same, I commented his post, could you take a look? $\endgroup$ Feb 1 '13 at 14:34

The question is a bit tricky. Actually, a photon is the electromagnetic wave. Photons are quanta of the field. You can imagine a photon as the fact that there is an oscillation in the field.

However, if you are in an approximation that allows you to treat photons as particles, then I would say that the don't oscillate, they just move on at light speed.

I know, the answer is not complete, I should explain better how photons can be defined, but perhaps someone can do it better than me.

  • $\begingroup$ How do they pass over other small particles then if they don't oscillate themselves? Like light wave can jump over some obstacle which looks impossible if photon just goes straight.. $\endgroup$ Feb 1 '13 at 14:32
  • $\begingroup$ Two possible answers: they are particles, they don't pass over other particles, they strike them; or: they are waves, so they can diffract around. Notice that the same holds for electrons: it's wave-particle duality. $\endgroup$
    – Martino
    Feb 1 '13 at 15:00
  • $\begingroup$ Found this on why light goes through things like glass: youtube.com/watch?feature=endscreen&NR=1&v=Omr0JNyDBI0 $\endgroup$ Feb 13 '13 at 16:15

According to the QM, a photon leaves an atom and reaches after some time another atom. The QM makes no statement how the photon bridges the gap and therefore QM can not explain Doppler effect and interference. A variant of QM, the "De Broglie-Bohm theory", tried to describe the path of a photon, but is considered to be refuted.

  • $\begingroup$ QM in the spatial representation includes the full-fledged wave dynamics, so it explains Doppler effect and interference as well. De Broglie-Bohm theory is not part of modern QM while the Feynman path integral formulation is. $\endgroup$
    – firtree
    Aug 24 '14 at 13:33
  • $\begingroup$ When was de Broglie-Bohm theory refuted? Last I checked, it's still a valid interpretation that makes all the same predictions the Copenhagen interpretation makes. $\endgroup$
    – Kyle Kanos
    Aug 24 '14 at 14:58

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