Total newbie here but just pondering things. (and sorry if already debated to no end)

Its my understanding the most of the expansion theories are based upon the concept of an expanding universe per the witnessed redshift effect.

From what i understand we know now the impact of photons passing through molecular hydrogen have the displayed the same redshift as photons portraying a Doppler effect - couldn't the redshift more so quantify the mass of molecular hydrogen vs sustain the expansion theory? (or a little bit of both?)

Could it simply be that redshift quantifies the abundance of life giving molecular hydrogen and prove that you're seeing the photons as they were emitted 14 billion years ago from very hydrogen rich galaxies in a very young universe?

Just thinking out loud i guess. Occums Razor seems to come to mind when it try and fathom dark energy/dark matter/WIMPs and other theoretical energies when there could be something as simple as hydrogens abundance to explain it.

again, i'm a total computer nerd.. i only know astronomy from what i read and obviously there is bad astronomy out there so you can't beleive everything you read