Nonlocality Definition and 51 Threads

I have heard a phrase, that the general theory of relativity supports nonlocality. This phrase is strange for me, because I always thought, that Einstein was an opponent of the quantum mechanics because of its nonlocality ("spooky action at distance"). Can you help me understand this phrase?

Suppose a system which looks at votation of each citizen, answers being yes/no coded as 1,-1. Since a lot of people vote it gives an average value that is encoded as an angle ##\theta##, the score 50/50 corresponding then to ##\pi/2## since the average with 1,-1 were 0...

Half a year ago a group of authors published a paper in Nature Physics https://www.nature.com/articles/s41567-020-0990-x which seems to be a proof of nonlocality even stronger than Bell nonlocality. More precisely, according to a popular exposition by one of the authors...

Usually spacetime curvature is localized/proximal to what is "causing" it, right? I'm wondering whether there is a term for the situation seen with gravitational waves where there is some relatively flat space between observable gravitational effects and the mass(es) that "caused" them? I'm...

A 2015 paper in Nature Communications by M.Fuwa et al arxiv [1412.7790] Experimental Proof of Nonlocal Wavefunction Collapse for a Single Particle Using Homodyne Measurement Authors:Maria Fuwa, Shuntaro Takeda, Marcin Zwierz, Howard M. Wiseman, Akira...

Do nonlocality theorems imply that the local inertial frame principle of general relativity is wrong (since it is local) ?

The main message of this post is that quantum theory is local, that "``spooky action at a distance'' was just shicky Einstein's slogan from a letter to Born in 1947. Einstein directed it against the individual interpretation of a quantum state. This interpretation is often referred as the...

Suppose we produce a polarisation-entangled photon pair ##A_1## and ##A_2##. Then we entangle another pair ##B_1## and ##B_2##. Now suppose that these photons will not interact with anything, sending ##A_1## and ##B_1## to Alice and ##A_2## and ##B_2## to Bob. Alice measures the polarisations...

Hello everyone! Recently I saw this paper: https://arxiv.org/pdf/1304.4801.pdf ("Any nonlocal model assuming “local parts” conflicts with relativity " by Antoine Suarez). He mentions standard experimental configuration with beam-splitters and detectors. Then he distinguishes possible models...

Thought this was an interesting paper that people might not know of: https://arxiv.org/abs/1205.3118 It constructs a state ##\rho## whose correlations have a local hidden variable model, but those of ##\rho \otimes \rho## do not.

Becker et al. 2019, Asymmetry and non-dispersivity in the Aharonov-Bohm effect The paper is open access and published in Nature Communications.

In https://arxiv.org/ftp/arxiv/papers/1409/1409.5158.pdf, the author (Donald A. Graft) concludes that Bell tests cannot refute local realism, because they employ a wrong analysis. He says: "The quantum joint prediction cannot be recovered in an experiment with separated (marginal) measurements...

From what I understand, the most reasonable explanation of the violation of the Bell inequalities is that nature is non local. If we accept this, is there a reasonable argument that nature is not deterministic? I.e. could it be that the probabilistic predictions from QM are just averaging --...

The Nature (Sept 4, 2009), (Science News, Oct. 24, 2009) article on the violation of Bell’s Inequality in Josephson phase quibits exquisitely demonstrated by Dr. John Martinis with his Martinis Group at UC Santa Barbara and Dr. Chris Monroe’s “Schrödinger’s Cat” demonstration with a Be+ ion...

[Moderator's note: spun off from another thread.] And yet modern physicists accept non-locality which is far worse :) Do you know where Newton expressed his misgivings? It would be interesting to know exactly what he thought.

Wikipedia says https://en.m.wikipedia.org/wiki/Quantum_nonlocality#Differences_between_nonlocality_and_entanglement But isn't wave function collapse nonlocal without any quantum entanglement?

http://motls.blogspot.com/2014/05/measure-for-measure-debaters-love-to.html?m=1 According to lubos, bohmian mechanics is certainly wrong because "its basic classical object – the guiding wave – is in principle unobservable because a change of it should in principle impact things at a distance...

Do interpretations of QM that are non local (Bohmian, collapse, transactional) violate relativity since they allow for faster than light travel?

http://advances.sciencemag.org/content/2/8/e1600162.full They claimed to have shown that non local causaulity models of QM do not work. But does that include the Transactional interpretation, which is non local and retrocausal?

With a modest understanding of 'spooky action at a distance', I've been informed that using entangled particles as a form of quantum bit system would not work for vast distances. It wouldn't be a viable option to communicate instantly with points like our moon, satellites orbiting Jupiter, or...

jfizzix submitted a new PF Insights post Steering: How the EPR-Paradox Fits Between Entanglement and Nonlocality Continue reading the Original PF Insights Post.

To explain the correlation in a Bell experiments three solution are considered : 1) faster than light communication 2) preexisting values are revealed at each measurement points 3) nonlocality applies 1) is ruled out by relativity 2) is ruled out by Bell's theoremRemains nonlocality. But what...

For some time now I’ve been intrigued by the famous argument between Bohr and Einstein, and which was apparently settled when Bell’s inequality was tested in various experiments carried out by Alain Aspect. After going around and around the whole issue for a while, I don’t think I’m convinced...

If correct, Uzan refutes Popescu and Rohrlich. To me this seems like a big deal. Super-Quantum, Non-Signaling Correlations Cannot Exist Pierre Uzan http://arxiv.org/abs/1602.01135 Comments?

Inspired by stevendaryl's description of an EPR-like setting that doesn't refer to a particle concept, I want to discuss in this thread a generalized form of his setting that features a class of long-distance correlation experiments but abstracts from all distracting elements of reality and from...

Hi there. I have been studying on Bell Inequalities and hidden variables problem for quite some time now however my general knowledge on the problem of superluminal communication is superficial at best. I know that non of the standing interpretations (Everett, Copenhagen, Bohmian, QBist etc.)...

Hi, In all the discussions about EPR, Bell's inequality and interpretations of QM locality seems to be a property that nobody likes to drop light-heartedly. This is somehow understandable since SR is an extremely successful theory. But SR only says that we cannot transmit information faster...

http://arxiv.org/pdf/1308.5290v2.pdf I'll just highlight some stuff " "We submit: Doesn’t quantum theory itself, which is a local theory, account for its own predictions? As the authors of this quote know very well, experi- mental data contradict Bell’s theorem [22,23], which im- plies that —...

A GEDANKEN EXPERIMENT REGARDING BELL'S THEOREM AND NONLOCALITYLet’s say I have four boxes with three compartments in each one, and each compartment contains either a white sock or a black sock. This is analogous to photons having spin components either clockwise or counterclockwise (black or...

Just posted to the archives is a great new paper from a top experimental team. These are some of the same individuals that performed the now standard citation regarding a Bell test under strict locality conditions. They have now extended their concept to GHZ states, and also close the...

Hello All, Here is the paper I'd like to ge opinions of. As for interpretations of QM I am open-minded agnostic.But: what about F.Tipler's article "Nonlocality as evidence of myltiverse cosmology", where he uses nonlocality and argue for MWI? Here: http://arxiv.org/pdf/1008.2764.pdf What...

What, if anything, do the nonlocal correlations in the results of EPR experiments indicate with regards to causation? (That is, with regards to whether or not/how causation is [is not] operative in giving the resulting correlated measurements?)

Is anyone familiar with Suarez's papers in this area? I've posted his most recent and pertinent papers on the topic below and even though I read them all, I'm still having trouble understanding his arguments: Single-photon space-like antibunching http://lanl.arxiv.org/pdf/1204.1712.pdf The...

from my thinking nonlocality and entanglement are never a problem because in a totally determinstic universe, the information about what is going to be instantaneously tranferred from a to b is already known to the universe. we may not be in block time but the universe acts as if it were. this...

Supposed reality was described by String Theory and there were 6 compactified dimensions. Could it describe quantum non-locality or does it still take light speed to travel in the compactified dimension? For example. You live in New York, I live in California. If we can send signal in one of the...

It is often said that QM is not truly nonlocal, because the "only" thing which is nonlocal are the correlations; there is no true nonlocal causation involved. At the same time, the Bohmian interpretation is accused for being "too" nonlocal, by involving a true nonlocal causation. But what...

I'm not a physics student, just a layperson, and I'm wondering if anyone can briefly explain to me the concept of nonlocality in the context of quantum mechanics. My understanding is that basically it means that an electron at one physical location (or just theoretical?) can instantaneously...

Phys. Scr. 82 065002, 2010. Is quantum mechanics nonlocal? A factual inconsistency of the nonlocality theory is demonstrated via a careful analysis of the conceptual and formal contents of Bell's theorem and the inequalities associated with it. The conceptual inconsistency of the theory...

I am trying to understand the meaning of nonlocality and its implications in physics. My concept of locality is not very precise but when I try to read papers myself, I come across terms like "nonlocality", "not-too-local operator", "ultralocal operator" etc. Can anybody help me understand these...

I just wonder to the doubters after so many experiments proving nonlocality, what type of "Proof" would be "proof" enough for the people out there who still think a local interpretation could ever describe reality?

I've been studying EPR and such for about a month and I have a question which may be interesting or may be basic-- I can't tell. Imagine we have two correlated particles in a spin singlet state. We know that if we measure the spin of one in any particular direction, the spin of the other...

http://www.physorg.com/news113824784.html

Is quantum mechanics (QM) local or nonlocal? Different formulations/interpretations (FI) of QM, with or without hidden variables, suggest different answers. Different FI's can be viewed as different algorithms, which leads me to propose an algorithmic definition of locality according to which a...

I hear a lot about nonlocality and it's relationship to quantum mechanics and relativity. But I don't know anything about it. Please give me a basic description.

Is there an obvious reason why the compactified dimensions of string theory are never invoked as a “medium” for quantum theory’s nonlocal communication? Lightspeed restrictions apply in the extended spatial dimensions but it would seem that all parts of the universe would be in touch almost...

Can someone explain the mathamatics behind locality and nonlocality?

I originally posted this under philosophy and someone suggested I go here though it may be a little speculative for some but here goes. I don't know how widely accepted in the physics community nonlocality is. From the double-slit experiment and Aspect's results it seems that nonlocality...

I don't know how widely accepted in the physics community nonlocality is. From the double-slit experiment and Aspect's results it seems that nonlocality seems to be a true attribute of the world around us. This being the case, if subatomic particles are "nonlocal" then so is my brain and...

I was reading about Bohms interpretation of QM and the Hamilton-Jacobi equation with the quantum potential: Q = \frac{- \hbar^2}{2 m} \frac{\nabla^2 R}{R} and \Psi = R e^{i S / \hbar} with R and S real valued functions. It is claimed that Q is the source of non-locality in...

I've got a few questions here, is the non-local "communication" between 2 entangled particles instantaneous, or is it just simply faster than the speed of light? Is this communication simply part of their common wavefunction or is it somehow a physical signal which somehow travels faster than...