[bmcooley]

I have a limited understanding, but I think this is just further reproduction of the same science. I believe there's some controversy over non-locality in that entanglement and spooky action at a distance is still a result of hidden local variables. By increasing the distance between the sources of the photons, you would give more evidence to nonlocality. Please correct me if this is offbase.

[abdullahkhalids]

"Good" [1] Bell experiments have already been performed by several groups, giving us high confidence that any local hidden variables theory is incorrect. So, there is very little controversy over the matter. Moreover, the Bell test here is not a "good" Bell test, since the results were post-selected i.e. only some experimental data points were selectively used.

The important part of the paper is the first result about two-photon interference. It shows that two photons from Sun and Earth can be made indistinguishable from each other and hence show maximum interference. This is evidence for the postulate of quantum theory that all photons (or other fundamental particles) can be made identical to each other.

[1] that take care of all prerequisite conditions of Bell's theorem. Also called loop-hole free Bell experiments. See https://en.wikipedia.org/wiki/Bell_test_experiments#Hensen_e...

[longtom]

Non-locality means that the way the probability of presence (wave function) of a photon is determined is by trying out all possible paths through the entire universe at once rather than only in regions nearby the photons?

[Misdicorl]

The path integral formulation is the most prevalent and successful version of quantum physics (this is what you describe in the second half). Non locality is different; it supposes that there are hidden mechanisms we have not uncovered (and may but be able to uncover) instead which describes our world. It must be non local to get the observed experimental results. Non local means data about the universe is teleporting faster than (conventional) causality allows i.e. the speed of light

[longtom]

Either case seems to require faster-than-light or instant communication between alternative paths that are being tried out, so the distinction is whether the combination of different paths is mediated by another faster-than-light (non-local) particle or whether the combination is axiomatic to the laws of the universe without a particle mediating it?

[Misdicorl]

No, the path integral formulation does not require faster than light communication. Time is an explicit parameter