Hi all, Let's say you are at rest with respect to the galaxy, and you have low energy photons all around you. Now, if I crank my energies up relatvisitcally, the frequency and thus E = hf of those photons will increase. Red Light becomes Blue Light, Blue Light becomes UV, UV to X-ray, and finally X-ray to Gamma Ray. But the limit of not finding photons of higher energy than Gamma is pair production. Could I ever move with high enough energy through the universe that all photons will look like pair-produced particles, first electrons and anti-electrons, then maybe something heavier like protons and anti-protons? That is to say, if I moved with high enough energy, would I not actually see anymore light, but particles where light used to be? I know that you need a recoil atom for pair-production, but let's say these are mostly available. As a side-note: If there are not recoil atoms for pair production, what kind of photon would I have at such extreme, relatvistic energies?