Cosmology Views

Red Shift Photons

the comment to the post Evidence in Cosmology:

 are you pointing out that the various photons we're receiving in our detectors might have come from within a galaxy/quasar, etc, but that the objects within those that spawned the photons aren't necessarily moving with the (relative) motion of the galaxy? Or am I reading this wrong?

my reply:

I can try again.

Galaxies and quasars radiate light in all directions.
Their light must pass through the inter-galactic medium, where hydrogen atoms result in a cumulative red shift. This was known in the 1920's.

This red shift has nothing to do with anything's velocity.

Quasars are quasi-stellar objects because they are dimmed by surrounding clouds which become ionized from the quasar's intense radiation extending to X-rays.

Quasars have a spectrum of many emission lines from these ions, and even from high velocity protons capturing an electron to become a hydrogen atom. None of these emission lines have anything to do with a quasar's velocity.

Only an atom or star exhibits the Doppler effect because each is a single mass in motion. The Doppler effect involves a transfer of energy. It can occur only with a single mass in motion. Our Sun wobbles and we can look for exoplanets using the wobble method aka, the radial velocity method.
By the way, I never use the word photon. Light exhibits wave behaviors and has a measured frequency or wavelength. Our communication devices target frequency bands. They do not generate quasi-particles. A spectrum analysis involves measured wave lengths, not a wave function. There is no particle behavior here.