Those plasma temperatures are extremely hard to achieve on earth.
We only need to show that compton-scattering is active on atoms and electrons that have much energy. I thought of a particle accelerator that shoots protons or helium-ions. And one that shoots electrons. They could be combined both, but at some point a laser light pointed at the beams should give a change in wavelength when it crosses the particle beam(s). This may depend on the combination of the wavelength of the light and the speed of the particles. Initially it might be easier to have a full spectrum light, to see the effects on the different wavelength-bands first.
In essence, absolutely nothing happens to light as it travels. However the mass of particles is gradually increasing with time. This means that later on all light emissions are moved towards the more energetic or blue end of the spectrum as they directly depend on mass of nuclear particles. So when we see distant galaxies, we see light that was made long ago when all matter was less massive and light frequencies were redder.
I arrived at this same idea and then found I was not the first. My reason for this was that harmonics theory ( http:ray.tomes.biz/maths.html ) predicts that energy gradually moves to smaller scales throughout the universe. Incidentally this also explains the exact6 relationships between LNH (Large Numbers Hypothesis) and the strength of gravity fits perfectly with Hubble relationship of red shift.
