Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

I Is the fabric of space a "medium" for light?

  1. Jan 6, 2017 #1
    For this question, I don't want to explore what "space" is (quantum chaos or otherwise), or whether it has mass, etc. Instead, I just want to explore if it qualifies as a medium, like air or water.

    I have a line of reasoning I want to explore, but as it is based on "space" being considered a medium, I want to explore this hypothesis first.

    It would seem to me that is a medium. A couple of possible arguments in favor might be:
    - Light is a wave, and generally waves need to propagate in something
    - The current theory of red shift posits that light from distant galaxies increases in wavelength as it passes through the space between us. As the fabric of space expands, it stretches out the light waves passing through it.

    Does this imply that space qualifies as a medium?
  2. jcsd
  3. Jan 6, 2017 #2


    Staff: Mentor

    No, because neither of your arguments have any predictive value. That is, saying that "space is a medium" based on your two arguments does not allow us to predict anything that we couldn't already predict; it's just you wanting to put an arbitrarly label on something.

    By contrast, when we say air is a "medium", we are referring to specific properties of air, such as the way the sound speed in air depends on temperature, pressure, and density, that have predictive value: they affect the way things propagate in the medium.
  4. Jan 6, 2017 #3
    As I mentioned in my post, I do have a line of reasoning that would have predictive value, but as it is predicated on the proposition that space is a medium like air, I thought I would try to address this first.
  5. Jan 6, 2017 #4


    Staff: Mentor

    This would be either a personal theory or original research, and PF is not the place to discuss that. PF is for discussing already established mainstream science. The mainstream science is that space is not a "medium", for the reason I gave in my previous post.

    Thread closed.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook