Hi all, What is the highest frequency photon ever seen, whether in nature or the lab? This is based on an earlier post of mine, but I think has merit as its own post. Since E=hf, there is no maximum freq or energy of a photon, it seems, on a max freq of a photon. It seems that such high powered gamma rays could be generated near the supermassive black hole our hole galaxy orbits. What is the highest freq photon that can be generated at the center of our galaxy? But, since the center of our galaxy is 30,000 light years away, we wouldn't see such gamma rays because the probability of them hitting an atom in interstellar space is too high, and such gamma rays would pair produce. Is this reasoning correct? Given the probability of hitting an interstellar atom (or a chain of them), what is the highest energy photon we could reasonably expect to detect on Earth?