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Speed of light should depend on the amplitude of the waveform?

  1. Apr 26, 2009 #1
    I guess I am just bored, but I was wondering why we assume light travels in a straight line and not treat it like a waveform as I was taught in school. As far as I can remember light waves each have a frequency. Why do we not take into calculation that it actually travels over a longer path than what we give it credit for? I do understand that in the end it has very little bearing on where the light ends up, but this just seems a bit odd to me for some reason.

    I mean overall a light wave with an amplitude of 500nm and say a wave length of 650nm since I like red... to simplify the calculation if we use say the formula for a eclipse for a total movement we would get something like:

    Circ = pi * sqrt(2*(.000000250^2 + .000000325^2)
    Circ = 0.00000182171745359 meters

    take the speed of light and get how many waves there are in it...

    google this and they will do the math: ((299792458/.000000650)*0.00000182171745359)

    299792458(m/s) / .000000650 = X
    X * Circ = 840211005(m/s) Which is actually how far light moves if it has an amplitude of 500nm and a wavelength of 650nm.

    Although in the end it is constantly negating the sinusoidal movement shouldn't this be taken into consideration when looking at the speed of light and our limitations concerning the speed of light?

    To explain why I choose the formula for an eclipse to calculate with if it is a waveform be it sin or cos it seems logical an eclipse is a reasonable model for which to infer circumferance from.

    I also don't mean this to be against the TOS with a "crackpot theory" this just came to me and I couldn't think of a reasonable explanation as to why we do not take this into account.
  2. jcsd
  3. Apr 26, 2009 #2


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    Maybe you need to spend some time and effort and understand the meanings of "phase velocity" and "group velocity", and figure out what is meant when we talk about the "speed of light" in the context of wave mechanics.

  4. Apr 27, 2009 #3


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    The wave effects of light only really manifest itself when we are dealing with scatterers and length scales on the order of the light's wavelength. So for all intents and purposes, most objects that we see in our day to day life are magnitudes larger than the wavelengths of the visible regime. If you were to start looking at maybe polarizers or move down to the low frequencies of the microwave and RF ranges then you would see that most of the time the behavior of light is treated using full wave solutions.

    There is a hierarchy in modeling light. The simplest to more complex is geometric optics, physical optics, unified theory of diffraction, shooting and bouncing rays, and then a full wave solve like method of moments, finite-difference time-domain, or finite element. the first four methods are all high-frequency solvers that take into account more and more the wave nature of light.

    If you want to get more technical, look at Feynmann's ideas about quantum electrodynamics. There are some formulations of QED that can be equated to taking into account all possible paths that light can travel from point A to point B.
  5. Apr 27, 2009 #4
    the amplitude is a measure of the electric field or the magnetic field that make up the light, so its not a physical distance up and down, so u can't use arc length to say it has traveled that far.
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