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B How does one dimensional light warp multiple dimensions?

  1. Aug 10, 2017 #1
    If light is one dimensional, yet has gravity, and gravity is the warpage of spacetime, and spacetime has four dimensions, then how does a one dimensional wave/particle warp multiple dimensions?
     
  2. jcsd
  3. Aug 10, 2017 #2

    BvU

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    Hello Mazelkas, :welcome:

    Being philosophical eh ? Interesting questions. Any references where you got this ?

    It does not.
    It is not. The presence of mass warps spacetime. Light just follows the shortest path.
     
  4. Aug 10, 2017 #3

    Drakkith

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    Light is not one dimensional. Electromagnetic waves, in both the quantum and classical theories, are three-dimensional disturbances in the EM field.

    My understanding was that light does indeed alter spacetime because of its energy, and thus does "have gravity".

    What do you mean, BvU? Isn't gravity exactly what Mazeikas said it was? The warpage of spacetime?
     
  5. Aug 10, 2017 #4
    Thank you for the welcome. Are you certain light does not exert its own gravity? I am not saying you are incorrect, I just do not know. I thought I read that electromagnetic waves gave off gravity. Also, perhaps I am misunderstanding gravity. Is it not the warpage of spacetime?
     
  6. Aug 10, 2017 #5
    Hello Drakkith! It is interesting we have received different perspectives regarding this, I thought a photon was one dimensional, I am not certain I am correct, but I think a lot of people believe this.
     
  7. Aug 10, 2017 #6

    BvU

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    At what stage are you in your curriculum ? I'm worried you are even further out on a limb than I was with my experimentalist's reply. (To me, your wording suggested that).
     
  8. Aug 10, 2017 #7
    BvU, I am actually just self taught right now, as far anything I may have correct, I am not sure. I am just full of curiosity and thought I would ask! :)
     
  9. Aug 10, 2017 #8

    Drakkith

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    All fundamental particles are regarded as being "point-like", which naively is taken to mean that they are zero-dimensional. But a closer look into quantum mechanics muddies up the issue greatly. The particles are point-like in the sense that if you measure the location of a particle, it will always appear in one spot, no matter how small you constrain your area you're measuring. You will never measure half the particle in one spot and half in another, as you might do when you measure the location of a basketball. We can definitely say that a basketball is 3-dimensional because different parts of it are found in different locations in space. The same cannot be said of a fundamental particle.

    However, we would then need to get into the issue of what the wavefunction is, what it means in regards to the dimensionality of a particle. There is no widely accepted answer to these questions as far as I know.
     
  10. Aug 10, 2017 #9
    Drakkith, great thoughtful response, I appreciate that. You are informing me, and I think you raise a valid point. Could light exist in more than one dimension as a wave and in one dimension as a particle? With the direction of movement being one dimension, and the oscillation of the wave as another, is it reasonable to hypothesize that a wave exists in at least two dimensions? Just my two cents. :)
     
  11. Aug 10, 2017 #10

    Drakkith

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    An EM wave moves outwards from the source and is already moving in a 3D motion (meaning its motion can be described using the standard 3D Cartesian coordinate system). The oscillation of the wave is not a physical oscillation. Nothing is moving. Instead, the electric and magnetic field vectors (the things that describe the direction of the force applied to a particle by the wave) oscillate in direction and magnitude.

    A photon is basically the quantized interaction of the EM wave with matter. Photons are not like little bullets streaming out from a source, nor are they individual oscillating objects. They are discrete transfers of energy and momentum from the wave to matter.

    I'd elaborate a bit more, but it's nearly 4 AM here and I've been up for about 20 hours and am about to go to bed.
     
  12. Aug 10, 2017 #11
    Well perhaps you should get some sleep. :) Thank you for your input, you have given me something to think about. Take care!
     
  13. Aug 10, 2017 #12

    Dale

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    This discussion is a little bit difficult because it mixes photons from QED and GR, which is known to be problematic. I cannot answer that question, but I can talk about classical waves of light and GR.

    The source of gravity in GR is the stress energy tensor, and since light has energy and momentum and so forth it has a valid non-zero stress energy tensor. Meaning that EM fields do curve spacetime.

    There are a set of solutions in GR called the pp-wave spacetimes which represent the curvature due to EM radiation.
     
  14. Aug 10, 2017 #13
    Dale, thank you for your insight. :) Once again, I am learning more, and I am grateful for that. I have more to look into.
     
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