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The barber pole (early view)

🕑 Added 2023-08-30 19:55:00 +0000 UTC

Comments

Steffones kaspari

Interesting..while I am a noobie in physics, does the pattern of muticolor change with the shape of the fluid container? Why in the first place a cylinder was used?

Carsten Lechte

Hi, I can try to address it. The E and B fields are indded in phase. In the 90° shifted case, their product would be zero, and that vector product is the Poynting vector, which represents energy flux, which has to be non-zero. Both fields being 0 at some points does not matter for energy conservation. Think of it as regions of 0 or max field just moving outward in concentric circles/spheres, each taking their preserved field energy with them. The energy sloshing picture would describe a single oscillator at a fixed location. E.g. a pendulum where the energy sloshes between kinetic and potential. But moving waves are different. The energy is stored in the whole field distribution at all locations, and because of the wave characteristic, there are always many locations where the field is non-zero. That is where the energy goes. At no time are the fields 0 everywhere. Conversely, in the oscillator case, if the total energy is 0 at one point in time, it must be 0 at all times, and no sloshing can occur. HTH.

jason black

I'm excited for the part that discusses "exactly what that wiggling is, and what it is that's wiggling." In particular: I have seen many diagrams about how the E and B fields oscillate as light propagates along, but they always show those two fields oscillating _in phase_: reaching their peaks and troughs simultaneously. This always confuses me. Energy must be conserved, right? So shouldn't it be that the E and B fields oscillate _out_ of phase, with the energy sloshing back and forth between those two fields? In phase, you'd have moments where both fields were 0, in which case where did the energy go? So either a) my understanding is wrong (likely) or b) the diagrams are wrong (plausible). If you could address that, I would be super-stoked.

Tom LaFleur

Excellent investigation and presentation. Wonder if you could explain a little more about what happens with the magnetic field during polarization. I would think it should fade out with the electric field. Any idea how the electric field is selectively blocked and passed?