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History question on aether

  1. Mar 28, 2007 #1
    I'm working problems on vibrations in crystal lattice for solid state, and a thought occurred to me. Early 20th century and late 19th century scientists supposed an aether for light to pass through. It seemed reasonable at the time - waves travel in a media.

    However, EM waves are transverse. How did they (or did they?) account for the fact that there were no longitudinal light waves?

    Another take on the question is this: what material allows transverse but not longitudinal waves? Am I missing something simple?
     
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  3. Mar 28, 2007 #2

    ZapperZ

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    Hum... I'm not sure why they would need to account for light being only a transverse wave. After all, back then, sound waves was only longitudinal. So if something can be only longitudinal, why can't light be only transverse?

    I can't come up with something off the top of my head. Maybe someone else has an obvious example.

    Zz.
     
  4. Mar 28, 2007 #3
    Waves on the surface of a liquid, perhaps? But that's not exactly "in a media" the way the OP wants.
     
  5. Mar 28, 2007 #4

    ZapperZ

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    I guess if you consider different types of waves propagating in (or using) the same medium, that would certain qualify. I don't know of any in which the same type of waves in the same medium have both transverse and longitudinal.

    This is not a medium, but phonons have both "optical" and "acoustic" modes/branches.

    Zz.
     
  6. Mar 28, 2007 #5

    Mentz114

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    There is no known material that can support transverse displacement oscillations. But a lattice that has an O(3) member at each node can support tranverse 'spin' waves.
     
  7. Mar 28, 2007 #6

    jtbell

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    Can't sound waves in a solid medium be either transverse or longitudinal? Seismic waves, which are sort of like sound, can be either transverse or longitudinal (S and P waves). I don't know when that was discovered, though.
     
  8. Mar 28, 2007 #7

    Mentz114

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    Yes, I could be wrong.


    I'm not sure if the 'transverse' above just refers to the sample orientation. GHz sound ?

    [Edit-------------------------------------------------------------------]
    From here

    http://www.seismo.unr.edu/ftp/pub/louie/class/100/seismic-waves.html

    I learn that P-waves are compression waves like sound, but S-waves are shear waves, like a carpet being shaken. So not sound.

    Modern aether theorists admit that it has to be unphysical to carry the two transverse components, and also have non-local causality.
     
    Last edited: Mar 28, 2007
  9. Mar 28, 2007 #8
    If the ether (space) is in tension, it can support transverse waves - just as does a stretched string. Robertson and others have explained cosmological red shift as a stretching of space ..There was an interesting theory by MacCullagh (1839) that treated particles as dislocations (voids in the continuum) which gave a decent account of light propagation
     
  10. Mar 30, 2007 #9
    Thanks for your replies! They've given me a direction for more research in the topic.
     
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