Figure 2: https://advances.sciencemag.org/content/advances/5/7/eaaw256...
Figure 3: https://advances.sciencemag.org/content/advances/5/7/eaaw256...
Figure 4: https://advances.sciencemag.org/content/advances/5/7/eaaw256...
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.
The first link gets bonus points for the 40-year-old advertisements included in the scan.
BBC article is https://www.bbc.com/news/uk-scotland-glasgow-west-48971538, discussed at https://news.ycombinator.com/item?id=20423884.
Relatively recent experiment using photons from stars in the Milky Way "Cosmic Bell Test: Measurement Settings from Milky Way Stars" http://web.mit.edu/asf/www/Papers/Handsteiner_Friedman+2017.... The experiment excludes local-realist models with local hidden variable younger than 600 light years. Similar test with cosmic microwave background could push the limit to the early universe.
If a solution did exist, it would probably be because of some convenient symmetry or law w.r.t. how the Bell violations played out. But you can use the behavior of arbitrary computer programs to trigger Bell tests, and computer programs are not a well behaved sort of thing. So that makes it seem unlikely for a set of O(S*T) Bell violations out in the world to follow a well behaved pattern that could be compressed into O(S) bits. Like, suppose I decide to dovetail through all computer programs, running a Bell test every time one of the programs halts. This would appear to force the initial state to encode information about solutions to the Halting problem, without the benefit of encoding it into a process that executes over time. But the Halting sequence is algorithmically random; incompressible...
“Yet more foreign to the usual way of reasoning in physics is the “free-will loophole.” This is based on the idea that the choices of orientations we consider independent (because of relativistic causality) could in fact be correlated by an event in their common past. Since all events have a common past if we go back far enough in time—possibly to the big bang—any observed correlation could be justified by invoking such an explanation. Taken to its logical extreme, however, this argument implies that humans do not have free will, since two experimentalists, even separated by a great distance, could not be said to have independently chosen the settings of their measuring apparatuses. Upon being accused of metaphysics for his fundamental assumption that experimentalists have the liberty to freely choose their polarizer settings, Bell replied: “Disgrace indeed, to be caught in a metaphysical position! But it seems to me that in this matter I am just pursuing my profession of theoretical physics.” I would like to humbly join Bell and claim that, in rejecting such an ad hoc explanation that might be invoked for any observed correlation, “I am just pursuing my profession of experimental physics.”
Free will seems to be the most difficult philosophical question. Accepting SD invalidates the scientific method's approach to learning about the world.
You may be interested in other non-local hidden variable theories as a way to sidestep Bell's Theorem & the Copenhagen interpretation.
Please elaborate. It seems like it’s not even possible to phrase a question about free will that makes sense.
What would it mean for an entity to have free will, such that you could ask a question about whether or not we had it?
If you could ask a meaningful question, it doesn’t seem as difficult as explaining why anything does or does not exist, or qualia.
1. the part of cellular automata describing a thinking entity can be separated from the rest of the world: that is changing states of cells anywhere outside of it doesn't change the state of the entity itself.
2. it is not possible to replace the computation describing this entity with anything simpler.
2 means that any method of predicting what this thinking entity choses is completely equivalent to that entity living and making the choice it wants by itself. And 1 means that the part of network is indeed a separate entity.
With superdeterminism 1 can not be true, and a spin change of a single particle far away triggers very complex change in behavior of all thinking entities that were close to that particle in the past.