**Ask a monkey a physics question thread**

[OngBonga]

Watching that again reminds me of another problem... if all energy is radiation, then does that not imply that quantum information is lost? How can you go back in time to calculate the events of the universe if... there is no time?

[MadMojoMonkey]

Watching that again reminds me of another problem... if all energy is radiation, then does that not imply that quantum information is lost? How can you go back in time to calculate the events of the universe if... there is no time?

All that matters is that the path of the photons could be time reversed, such that they would be traveling in the opposite directions, and that doesn't change the laws of physics or what you would observe in the universe, which is still true.

There wont be anything non-photon to observe this universe, but that doesn't mean there's no spacetime, I think. I didn't follow your argument that without matter, there's no space. I don't see that at all. Without matter, there's only flat spacetime, sure, but to say that spacetime cannot exist unless there's mass to curve it doesn't sound right to me.

Quantum information is like, the energy of the photon, the fact that it's a boson, not a fermion, it's a spin 1 object that propagates in c in all inertial reference frames. All that information is there, and there's no problem with quantum information loss in the production of photons in the first place, so the continued existence of produced photons is indeed the conservation of that information.


EDIT: I think the mere fact that photons are in the universe implies inertial reference frames through which they travel. It's not only mass that curves spacetime, because of the mass-energy equivalence, the photons will still curve spacetime as they propagate. Maybe.

IDK. It just doesn't seem right at all to assume that just 'cause no matter = no space and/or no time.