Speed of light relative to universe expansion?

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SUMMARY

The speed of light, denoted as 'c', is a constant that remains unaffected by the expansion of the universe or the motion of its source. Measurements of light's speed yield consistent results regardless of the observer's velocity, as established by experiments such as the Michelson-Morley experiment and the behavior of pi mesons. While some theories suggest a variable speed of light, these claims lack substantial evidence and are not widely accepted in the cosmology community. Understanding the speed of light requires a solid grasp of Special Relativity (SR) and General Relativity (GR), particularly regarding the curvature of spacetime.

PREREQUISITES
  • Special Relativity (SR) principles
  • General Relativity (GR) concepts
  • Michelson-Morley experiment
  • Sagnac effect in physics
NEXT STEPS
  • Study the implications of the Michelson-Morley experiment on the constancy of light speed
  • Explore the Sagnac effect and its relevance in GPS technology
  • Investigate the relationship between spacetime curvature and light propagation in General Relativity
  • Review current theories on the variable speed of light and their critiques within the scientific community
USEFUL FOR

Students of physics, astrophysicists, and anyone interested in the fundamental principles of light speed and its implications in cosmology.

  • #31
pervect said:
Do you have a reference that calls this the sagnac effect? I have some doubts that the term is being used properly - it seems to me that you are talking about simple doppler shift and calling it the "sagnac effect". AFAIK the sagnac effect only occurs in rotating systems. As I said, if you have a reference for this I'd like to see it.

pervect - I am citing these not for content, but for nomenclature

http://arxiv.org/ftp/physics/papers/0609/0609202.pdf

Http://www.geocities.com/mail0110261847/npa/npa2007y.pdf

I will recheck that last link - may not be correct
 
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  • #32
pervect - The link seems to work - take a look at page 8 for how this guy views the Sagnac phase shift as actually a translational affect.

I don't have a reference for the rectangle with the source/receiver moving with uniform velocity v along one leg - but by analogy with the rotation of the entire frame about some center point of the mirror system, the same phase shift should occur for v = wr and v = dx/dt so long as v is measured relative to the at rest lab frame. If you need more on the one way Sagnac - you might google one way Sagnac effect in GPS
 
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