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Some heretical thoughts. How do we measure distance to galaxies? By measuring redshift of the light from those galaxies and making an assumption that the only c
by akomtu 4y ago
Some heretical thoughts. How do we measure distance to galaxies? By measuring redshift of the light from those galaxies and making an assumption that the only cause of redshift is spacetime expansion? What if photons slowly lose energy, and those very far galaxies are in fact much closer?
- ncmncm 4y agoThat is the "tired light" hypothesis. It is not favored lately because if it were the principal cause of redshift, certain observed details would differ. I don't think it is entirely ruled out, but two causes of redshift are considered less likely than one.
- cygx 4y agoErrors in Tired Light Cosmology: https://www.astro.ucla.edu/~wright/tiredlit.htm https://www.astro.ucla.edu/~wright/tiredlit.htm