Experimental evidence on cosmological redshift

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Discussion Overview

The discussion revolves around the causes of cosmological redshift, particularly whether it is due to the expansion of space influenced by dark energy or other mechanisms such as energy loss of photons over long distances. Participants explore various arguments and evidence related to these explanations, including the implications of the Tolman Surface Brightness Test.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants argue that the redshift is a result of the expansion of space due to dark energy, which stretches the wavelength of light as it travels between galaxies.
  • Others propose the 'tired light' hypothesis, suggesting that photons lose energy over distance, leading to redshift, and reference the Tolman Surface Brightness Test to challenge this view.
  • One participant clarifies that the expansion of space does not necessarily require dark energy, as the universe could expand under matter domination, with dark energy affecting the rate of expansion.
  • Another participant emphasizes that the distinction between cosmological redshift and Doppler shift is not clear-cut, suggesting they may be different interpretations of the same phenomenon.
  • Some participants express uncertainty about the implications of non-accelerating expansion and its effects on light wavelength, questioning whether redshift is solely due to the stretching of space or also involves Doppler effects from moving objects.

Areas of Agreement / Disagreement

The discussion contains multiple competing views regarding the causes of redshift, with no consensus reached on whether it is primarily due to the expansion of space or other mechanisms such as energy loss of photons. Participants correct and challenge each other's claims without arriving at a definitive conclusion.

Contextual Notes

Participants note that the understanding of redshift may depend on the definitions used and the assumptions made about the nature of space and expansion. The discussion highlights the complexity of interpreting redshift in cosmological contexts.

  • #31
JimJCW said:
The following articles
Are not valid references.
 
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  • #32
JimJCW said:
Big Bang is the prevailing model of the universe. What you are saying is believed by most people. However, the idea that the observable universe expanded from a tiny point of Planck length (1.6×10-35 m) to the present radius of 4.4×1026 m (46.5 Gly) is so overwhelming that some people may have traces of uncertainties back in their minds.
A lot of scientific discoveries are overwhelming. That a single fertilised egg can develop into a fully grown human being. The evolution of life including intelligent, conscious humans.

That the solar system evolved from a cloud of dust. Even that there are trillions of galaxies each with hundreds of billions of stars.

It's not a good argument against a theory simply to say that the theory is mind boggling.
 
Last edited:
  • #33
JimJCW said:
Big Bang is the prevailing model of the universe. What you are saying is believed by most people. However, the idea that the observable universe expanded from a tiny point of Planck length (1.6×10-35 m) to the present radius of 4.4×1026 m (46.5 Gly) is so overwhelming that some people may have traces of uncertainties back in their minds.

The following articles related to expansion of space [have been deleted by the moderators since they are not valid references.]

Please see Wendy Freedman’s 2021 paper, Measurements of the Hubble Constant: Tensions in Perspective, in The Astrophysical Journal.
 
  • #34
Why are you arguing with yourself?
 
  • #35
Vanadium 50 said:
Why are you arguing with yourself?

If I seem to be not committed, it’s because I wish to find the truth.
 

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