My issue with it having already occurred (i.e. there's a distinction between a information arrival event and a past event the information is about) is that in the mirror case I know in advance, with 100% mathematical certainty, that I'll be getting a photon back - eventually if I repeat...
But until I observe it emitting a photon, has it actually done so?
By correlation, say if I observe a supernova 450000 ly away. In my timeframe, did it occur 450000 years ago, or does it occur when I observe it?
I'm at a bit stumped with respect to simple thought experiment.
Imagine I fire a photon at a mirror and observe the photon returned. First, I send off a photon. It traverses space to the mirror. It bumps into an electron in the mirror, gets absorbed, the electron has no stable orbit for the...