There is also the theory that the universe has stopped expanding. The redshift we observe is equal for galaxies that are the same distance away from us.
I understand that Hubble, De Broglie, and Enrico Fermi, passed away without believing in the expansion of the universe because this does imply earth would be at the center of the universe.
There are experimental measurements of light losing energy to the medium through which it propagates.
R. M. Santilli, "Experimental Verifications of IsoRedShift with Possible Absence of Universe Expansion, Big Bang, Dark Matter, and Dark Energy," The Open Astronomy Journal, 124 (2010), http://www.santilli-foundation.org/d...soredshift.pdf