Is the speed of light constant with time?

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SUMMARY

The discussion centers on the constancy of the speed of light in relation to the expansion of the universe, as explained by Professor Brian Cox in BBC's "Wonders of the Universe." It is established that while space is expanding at a rate of 74 km per second per megaparsec, the speed of light remains constant despite the observed redshift. The argument emphasizes that the frequency of light decreases to balance the increase in wavelength due to this expansion. Furthermore, the term "stretching of space" is critiqued as a misleading analogy, with a recommendation to explore "metric expansion" for a more accurate understanding.

PREREQUISITES
  • Understanding of the Big Bang theory
  • Familiarity with redshift and wavelength concepts
  • Knowledge of gravitational waves
  • Basic grasp of metric expansion in cosmology
NEXT STEPS
  • Research "metric expansion of space" for a deeper understanding of cosmic expansion
  • Study the implications of redshift on light frequency and wavelength
  • Explore the properties and significance of gravitational waves
  • Investigate the theories surrounding the constancy of the speed of light
USEFUL FOR

Astrophysicists, cosmologists, science educators, and anyone interested in the fundamental principles of light and the universe's expansion.

vijayst
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In, BBC - Wonders of Universe, Professor Brian Cox explains that universe is stretching and the space that we live in is stretched from the early universe.

If space is stretched as a result of Big Bang, and space is stretched at the speed of 74 km per second / megaparsec. is the speed of light through vacuum constant with respect to time?

[Please close this thread. Due to observed red shift or increase in wavelength, speed of light should be constant, as frequency decreases to counter the increase in space. Even if speed of light is not constant in time, c is the speed of "gravitational waves"]
 
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Space does NOT "stretch". That is an analogy used in pop-science TV shows and has nothing to do with reality. Google "metric expansion" and/or see the link in my signature.
 

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