What Is the Temperature of Light?

Anhe thought that maybe this cosmic micra way back on radiation, if you could spot it, would be evidence for this. And what made them think that radio would be a better way to see it than other wave lengths? So they did this calculation. They thought, how hot was it back then? And it was about three thousand degrees kelvin. And if that light was still around, what would be its wave length now? As the universe expands, member space stretches. That light gets to longer and longer frequencies. It doesn't get slowed down. Light tet like zigs and zags really quickly.