Me asking questions of a proper PhD in GR physics in another forum.

Me: I have a friend asking a lot of questions based on his uneducated (but nonetheless pretty darn good) understanding of GR. And he's got this notion that in a universe of only photons, it becomes meaningless to talk about inertial reference frames, and since all that's left is photons, the only things left to observe the universe see it with no volume or time.

ProbablyMagnets: I think he's mostly right about a universe of just photons, under some assumptions that theres no unification. It's true at least that to completely describe the hilbert space of that universe you dont need the whole thing, only a single lightcone.but in that context theres no analogy to measurement so you're bound to find some things that dont make sense



IDK exactly what he just said, but I'm pretty sure he said you're onto something, ong.


EDIT: Dafuq happened to the formatting when I copy/pastad?