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

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Discussion Overview

The discussion centers on whether space can be considered a "medium" for light, akin to air or water. Participants explore this concept through arguments related to the nature of light as a wave and the implications of redshift in light from distant galaxies.

Discussion Character

  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant argues that space qualifies as a medium because light is a wave that generally requires a medium for propagation, and the theory of redshift suggests that light waves are stretched as they travel through expanding space.
  • Another participant counters that the arguments presented do not provide predictive value and that labeling space as a medium does not lead to new predictions about light propagation.
  • A later reply indicates that the reasoning proposed by the first participant could have predictive value, but it is contingent upon accepting the premise that space is a medium.
  • Another participant asserts that the discussion of personal theories or original research is not appropriate for the forum, emphasizing that mainstream science does not classify space as a medium.

Areas of Agreement / Disagreement

Participants express disagreement regarding whether space can be classified as a medium. There is no consensus, as some participants support the idea while others reject it based on the lack of predictive capability.

Contextual Notes

The discussion highlights the challenge of defining "medium" in the context of space and light, as well as the implications of personal theories versus established scientific consensus.

GrantSB
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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?
 
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GrantSB said:
Does this imply that space qualifies as a medium?

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.
 
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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.
 
GrantSB said:
I do have a line of reasoning that would have predictive value

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.
 

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