Here is an interesting idea I've come across, to explain redshift;

http://fqxi.org/data/forum-attachments/2008CChristov_WaveMotion_45_154_EvolutionWavePackets.pdf

Basically that while single spectrum light will only redshift due to recession, multi-spectrum "packets" will redshift over distance, as the higher frequencies dissipate faster.

The deeper implication of this is the quantization of light is then a consequence of its absorption and measurement, not fundamental to the light itself.

Here is another paper, making that very point.

It's the pdf link attached to this contest entry;

https://fqxi.org/community/forum/topic/1344

Here is an interview with Carver Mead, arguing for waves being fundamental and particles as artifacts;

http://worrydream.com/refs/Mead%20-%20American%20Spectator%20Interview.html

All interesting reads.

My suspicion is that cosmic background radiation is the light of ever further sources, shifted off the visible spectrum. Basically the solution to Olber's paradox.