4 upvotes, 1 direct replies (showing 1)
View submission: Two questions about light waves
Neither is generally true. Waves in guiding structures (for example, optical fibers) can have components in the direction of propagation as a simple example. Look up TE, TM and hybrid modes. The second one is also not true, the waveform can be completely arbitrary. Also, at the end of the day what you can measure is the intensity distribution, which for a sinusoidal wave is basically constant (as long as the frequency is high enough).
Comment by Jeff-Root at 26/12/2023 at 19:32 UTC
1 upvotes, 1 direct replies
I see that the thing about "modes" specifically addresses my question about whether the E & M fields are perpendicular. I didn't read enough to understand it, though.
It sounds as though a longitudinal component to the light wave would either mean that the light is speeding up and slowing down very slightly, or that you are talking about a combination of different waves, maybe with different wavelengths, or traveling in very slightly different directions, or-- most likely-- out of phase. But those different waves that get combined together could still be purely transverse sine waves, couldn't they?
I'm not asking about what happens to waves when they combine or interfere with each other-- I'm asking about the light itself. Like an individual photon. Can an individual photon be anything other than a transverse wave? Can an individual photon have any waveform other than a sine wave?
I understand the fact that these properties of an individual photon cannot be observed or measured directly. But it should be possible to determine them by observing the behavior of many photons individually. Such as the interference pattern built up gradually on a photographic plate by individual photons in an extremely dim beam passing through narrow slits. Only a single observation of any photon can be made, so its waveform can't be observed, but I'm wondering if there is a way to observe many photons one-by-one and combining the info into a picture of the waveform. And whether that waveform is necessarily sinusoidal.