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The wave model of light

  1. Jul 23, 2004 #1
    Im doing some research on the historical development of the wave model of light. does any one have any usefull information?, e.g. scientists that were involved, a time line would be very usefull and websites.

    thanks for the help :smile:
     
  2. jcsd
  3. Jul 23, 2004 #2

    selfAdjoint

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    Huygens was the first creator of an explicit wave theory of light, in the late 17th century. Newton criticised this theory which had longitudinal vibrations of an ether, by pointing out that the double refraction from iceland spar showed that longitudinal vibrations "couldn't exist" (modern expression: must be too small to show up in the phenomenon). This falsification pretty much killed interest in the wave theory during the 18th century, although the great mathematician Euler was a fan of it.

    During the early 19th century two physicists, Young in England and Fresnel in France, worked out the principles of diffraction and did experiments showing the diffraction of light. This, together with the introduction of transverse waves, revived the wave theory and it soon overtook and surpassed the old corpuscle theory.

    As the 19th century wore on, the simple ether theory began to show strain. Michelson and Morley did their famous interferometer experiment showing that the Earth had no detectible velocity through the ether. Mathematicians showed that in order to suppress longitudinal vibration the ether would have to be millions of times stiffer than steel, and yet astronomers could detect no drag from the suipposed ether on the planets, which by this time had been precisely observed for 400 years.

    Fitzgerald showed that the Michelson-Morley result could be explained by the shortening of lengths in moving objects. Maxwell produced his theory of electromagnetism in which light was seen as a wave of mutually reinforcing electric and magnetic fields. This led some, but not Maxwell himself, to abandon the ether. Herz did experiments showing that the electromagnetic radiation was real. The younger physicists at the turn of the century were enthusiasts for the electromagnetic waves.

    Lorentz, at the end of the 19th century worked on a paradox of electromagnetism, that the electromagnetic results in two systems moving with respect to each other could not be compared using Maxwell's equations. The math blew up. Lorentz found that the space and time of the two systems would have to be linear transformations of each other to make the math consistent.

    Einstein, in 1905, sought to find an operational explanation of Lorentz's mathematical result. In doing so he invented the special theory of relativity. He also published an explanation of the photoelectric effect using Planck's idea of the quantum of radiation. Planck had said that radiation was emitted and absorbed in discrete chunks or quanta; now Einstein posited that it travelled as quanta too. This eventually led to the idea of the wave-particle duality of light.
     
  4. Jul 23, 2004 #3

    reilly

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    Superb History of E&M

    Sir. E.T. Whittaker wrote a two volume work: History of Aether and Electricity which covers the subject from antiquity to first half of the last century -- does the wave thing and the particle thing, brilliantly and in full mathematical detail. Whittaker was a major player at the turn of the 20th century. As a graduate student I found this history to be of great comfort as it goes through the mistakes, as well as successes, of many of the great physicists of the past -- E&M was difficult, even for the best.

    Certainly you will find these books in a library, and, I suspect they might be available used. Well worth the effort.

    Regards,
    Reilly Atkinson
     
  5. Jul 23, 2004 #4

    selfAdjoint

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    Yes, Whittaker's book is first rate. He is only unsound on the authorship of relativity.
     
  6. Jul 23, 2004 #5
    thanks alot

    BTW, whats the "ether" theory.

    "selfAdjoint", i wish that u was my phys. teacher :biggrin: , thanx.

    "reilly" thank you very much for the book info, i'm headding to a library to find it, i hope its there. :smile:
     
  7. Jul 24, 2004 #6
    what's the current state of the theory of light? what are they using now?
     
  8. Jul 24, 2004 #7

    selfAdjoint

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    Light is described by the electroweak sector of the standard model. For most practical application engineers still use the Maxwell electromagnetic theory, although that has small errors when it comes to atomic physics.
     
  9. Jul 25, 2004 #8

    Ether is a made up medium that light must travel through. As you know, waves need a medium to travel through. This medum was proposed by Michelson and Morley, in their speed of light experiment. They said that light is a wave, and that it prpagates throughout the universe at the speed of light through the medium of 'ether' (which is supposed to be everywhere). This theory was later disproved since if there was an 'ether', the speed of light shoud not be constant in all directions. It should change since the earth is moving through this 'ether'. It kind of like a smimmer swimming upstream and downstream. The light should propagate faster in one direction than the other.
     
  10. Jul 25, 2004 #9

    mee

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    It would seem to me that this did not disprove an ether, just a particular sort of ether.
     
  11. Jul 27, 2004 #10
    the only way that this ether idea can still be used is if you stink that the universe revolves around us, and we are the centre of the universe.
     
  12. Jul 27, 2004 #11
    oh ok isee
     
  13. Jul 27, 2004 #12

    FZ+

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    Yes, it only disprove a particular sort of ether. But, if ether did not behave in this way, it is pretty pointless invoking the existence of a luminiferous ether at all. Modern spacetime has more or less supplanted it, and in the scientific mainstream, aetheric theories have mostly suffered the death of a thousand cuts. (aka Occarum's razor)

    The current theory is not to think too hard about it, if you can get away with it... One interpretation is that light is made up of particles, which move according to a probability wave, and that the photons themselves are packets of EM waves.
     
  14. Jul 28, 2004 #13
    Actually, the ether theory was not disproved by the Michelson - Morley experiment. Lorentz showed that a contraction in the direction of travel can account for the inability to detect our motion through the ether.
    Further, while QM theory ostensibly holds that an ether does not exist, it invariably invokes the "curvature" of "spacetime" in order to explain various phenomena. If "spacetime" has some property called "curvature" (the exact nature of what is meant by "curvature" is unimportant) then "spacetime" has some sort of physical reality and is therefore an ether itself (although not necessarily one of discrete particles).
     
  15. Jul 28, 2004 #14

    selfAdjoint

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    Einstein believed that spacetime was nothing but the gravity field, and it was that which had the curvature. The gravity field, or spacetime, does not support waves constituting light. It might support gravity waves; experiments are ongoing. Therefore spacetime cannot be an ether in the sense of the cause of light.

    Finally, curved space is a general relativity thing. Quantum theory doesn't use it.
     
  16. Jul 29, 2004 #15

    dlgoff

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    Do you mean, there is no medium that "vibrates" like say, light propogating in a crystal latttice?

    BTW You would be a good physics teacher.

    Thanks........Don
     
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