Why is it that visible light is shifted to lower frequencies but gamma rays aren’t? Shouldn’t they have become X rays after all that distance?

Stephen Wood
Orlando, Fla.

All wavelengths are redshifted. That means that high-energy gamma rays beyond a detector’s energy range would get shifted into the detectable range by cosmic expansion, while slower-energy gamma rays would get shifted to below the detector’s range .—R. Cowen