I know this must be nuts, could someone ELI20?
The light comes from bottom left, then gets into Beam Splitter (BS) and splits in two. The top-left detector has a pre-selected filter and a measurement device after a delay line. As far as I understand, this device gives binary output: either light received or not. The top-right detector captures whole image of the light ray, but does so only if the left detector has seen light.
The result is that the image from the top-right detector is highly correlated with the pre-selected filter of the top-left detector, even though they're placed in different arms of Beam Splitter! https://advances.sciencemag.org/content/advances/5/7/eaaw256...
This paper is showing a way to produce a visual image of a bell inequality and explores ways that these inequalities can be used for other visual techniques.
Every time I read about the struggle between realism and locality, it makes me feel unhappy because I have a choice between assuming it's me that's really dumb or everyone else. I can't understand why it should be a real problem.
Classical Gravitation defines a force field that is nonlocal, as it propagates instantaneously. Move a mass from point a to point b, and the entire universe immediately updates the force they experience.
Classical Electromagnetism defines a field that only propagates changes at a finite speed. If you move a charged mass from point a to point b, the change in the electric and magnetic fields radiate outward at the speed of light. One way to think about this is to observe that time update equations for E+M only rely on values infinitesimally near a point. If you need to compute the next time step on a grid, you only need to look at the neighbors of a point to figure out how to update a given point.
Just saying "this field has a value elsewhere" means you are talking about something that is not near your given point. And having different values at different points is what I thought a field was.
https://physics.aps.org/articles/v8/123
The first link gets bonus points for the 40-year-old advertisements included in the scan.