Photons and probability distribution

[SamBridge]

Theoretically, if I had a photon, it's probability distribution exists pretty much indefinitely through space, so if I shot a beam of light in a vacuum and predicted exactly where it should end up in one second, 180,000 miles away, couldn't I possibly measure the photon being a position somewhat significantly ahead of that mark because the correlation of its probability density to space is not dependent on time or relativity, giving the illusion that it had traveled slightly more than the speed of light?

[elfmotat]

Good question. What we find is that the "propagator" (which gives the probability [amplitude] of a particle to travel from one place to another) is never spread outside of the light-cone. In other words, if a photon is emitted at time t=0 at x=0, there is zero probability that the particle will be found at a location where x>ct.

[SamBridge]

Good question. What we find is that the "propagator" (which gives the probability [amplitude] of a particle to travel from one place to another) is never spread outside of the light-cone. In other words, if a photon is emitted at time t=0 at x=0, there is zero probability that the particle will be found at a location where x>ct.

It makes sense to me at first, but then again time symmetry, I suppose the correlation of the field exists everywhere, but your saying that an oscillation of light doesn't "propagate" to that location? But wait, isn't there a different between "light" and an individual photon? Perhaps an individual photon could, but you would maybe measure a general burst of light as not doing that for some reason. It makes sense in a way, but I could use some more detail on why exactly its impossible, because perhaps this could account for the error at CERN. If propagation has a finite speed like that, it doesn't completely make sense why we don't see matter falling apart as it approaches the speed of light, which I know is incorrect, but bosons "propagate" a c between particles, but somehow always or already existed after propagation in an interaction to sustain an atom, an actual oscillation of a particle can't take time to travel in the same sense can it? That doesn't seem to make sense to me.

Edited February 15, 2013 by SamBridge