4 ms·
Also to what extent does “beginning and end” apply to a photon, which exists on a null geodesic? I realize that a photon can have no perspective, so I won’t try
by UpshotKnothole 8y ago
Also to what extent does “beginning and end” apply to a photon, which exists on a null geodesic? I realize that a photon can have no perspective, so I won’t try to talk about what a photon “sees,” and from our perspective a photon is emitted, travels, and is absorbed. Still, if you look at a spacetime diagram emission and absorption exist along the null axis.
Talking about photons hurts my brain. ><
- lisper 8y agoI don't know why you're getting down-voted. It's a perfectly reasonable question. > emission and absorption exist along the null axis Only if the photon travels through free space. If it's reflected or refracted this is no longer true.