Challenging local realism with human choices

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Challenging local realism with human choices

Quote:A Bell test, which challenges the philosophical worldview of local realism against experimental observations, is a randomized trial requiring spatially-distributed entanglement, fast and high-efficiency detection, and unpredictable measurement settings. While technology can perfect the first two of these, and while technological randomness sources enable device-independent protocols based on Bell inequality violation, challenging local realism using physical randomizers inevitably makes assumptions about the same physics one aims to test. Bell himself noted this weakness of physical setting choices and argued that human free will could rigorously be used to assure unpredictability in Bell tests. Here we report a suite of local realism tests using human choices, avoiding assumptions about predictability in physics. We recruited ~100,000 human participants to play an online video game that incentivizes fast, sustained input of unpredictable bits while also illustrating Bell test methodology. The participants generated 97,347,490 binary choices, which were directed via a scalable web platform to twelve laboratories on five continents, in which 13 experiments tested local realism using photons, single atoms, atomic ensembles, and superconducting devices. Over a 12-hour period on the 30 Nov. 2016, participants worldwide provided a sustained flow of over 1000 bits/s to the experiments, which used different human-generated bits to choose each measurement setting. The observed correlations strongly contradict local realism and other realist positions in bi-partite and tri-partite scenarios. Project outcomes include closing of the freedom-of-choice loophole, gamification of statistical and quantum non-locality concepts, new methods for quantum-secured communications, a very large dataset of human-generated randomness, and networking techniques for global participation in experimental science.

I skimmed through this - it has some interesting points though I feel it's always a bit difficult to know if the experimental results truly are in alignment with authorial conclusions.

That said, the words "challenging local realism" sounds immaterialist to me. Wink
'Historically, we may regard materialism as a system of dogma set up to combat orthodox dogma...Accordingly we find that, as ancient orthodoxies disintegrate, materialism more and more gives way to scepticism.'

- Bertrand Russell

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Here's a summary from Nature

Crowdsourced quantum reality-check gets crowdsourced peer review

Quote:So here’s the conundrum: does quantum mechanics really violate local realism, or could it be the case that some unknown factors would complete the theory and explain these apparent violations? In the 1960s, the physicist John Bell offered a way to tackle the problem in the laboratory, by studying quantum correlations in the form of entanglement. In these experiments, sequences of spatially separated measurements on entangled particles lead to computing a quantity that can have values not possible in the context of local and realistic theories. Bell tests have confirmed the validity of quantum theory many times, but they include assumptions that leave wiggle room for non-quantum explanations as to why local realism is violated, and so physicists have been looking for ways to close these loopholes ever since.

In 2015, physicists showed that successful Bell tests could not be due to speed-of-light communication between the particles, or to inefficient detection processes during the measurements. But another, more subtle, loophole was still open. Bell tests also assume that experimenters have free choice over which measurements they make on each particle. And yet, hidden parameters could be influencing these choices to produce correlations that give the illusion of entanglement.

The BIG Bell Test closes this freedom-of-choice loophole. The various experimental groups had no say in which measurement settings to use. Instead, they performed their measurements according to the unpredictable streams of bits received from the 100,000 gamers.

The results show the presence of correlations strong enough to contradict local realism. Maybe that’s how 30 November 2016 might be remembered: the day the people of the world came together to test quantum theory.
'Historically, we may regard materialism as a system of dogma set up to combat orthodox dogma...Accordingly we find that, as ancient orthodoxies disintegrate, materialism more and more gives way to scepticism.'

- Bertrand Russell

(This post was last modified: 2018-05-25, 04:55 PM by Sciborg_S_Patel.)
This sounds like the kind of experiment that was proposed by Lucien Hardy last year, and discussed a bit on Skeptiko then:

Based on my attempt to get my head around it previously ( ) it seems to be telling us there's no escape from "spooky action at a distance" - unless all the physical processes that appear to be random are really only pseudo-random, and unless that also includes the human mind.
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(2018-05-26, 09:32 AM)Max_B Wrote: It’s just what QM already knew about realism, and that there is no spooky action at a distance. Things are correlated because of their past interactions. Nothing goes faster than light.

I suppose it depends what you mean by "spooky action at a distance". Obviously it refers to the correlations between distant entangled particles, which Einstein didn't like because they looked like faster-than-light communication (even though they are just correlations rather than communications). If I understand correctly, this experiment is ruling out a rather arcane possibility that might dispel the spookiness, just as Einstein's proposals to dispel it were ruled out previously.

It's interesting because - again if I understand correctly - the arcane loophole would have involved apparently random physical processes not being truly random, and the experiment uses random numbers generated by the human mind to get around this possibility.
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(2018-05-26, 12:18 PM)Max_B Wrote: There is no spookiness to dispel. Things are correlated because of their past interactions.

Evidently that’s true. But it doesn’t mean the effect isn’t spooky. I’m with Einstein there. Wink  

But it’s too hot to argue about semantics.
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(2018-05-26, 02:45 PM)Max_B Wrote: Well, Einstein's arguments turned out to be wrong, there was no conflict between the principles of QM and Relativity, there was no 'spooky action at a distance'.

As I said, it depends what you mean by “action at a distance”. Entanglement doesn’t allow one observer to send a faster-than-light signal to another, so no conflict with special relativity. But if an observation affects an entangled particle, there is also an effect on the other particle it’s entangled with, and that does happen faster than speed-of-light communication. That’s where the “spookiness” lies. Einstein may have been wrong in thinking there was a way of modifying quantum mechanics to eliminate the spookinesss, but I don’t think he was wrong to find it spooky.
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I feel like "spooky" is the word in contention.

Max - am I understanding that for you "spooky action at a distance" is a reference to hidden variables a la superdeterminism,?

Chris - am I understanding that for you the phrase means causation in the Present that is different from how we usually think of cause-effect relationships?

I know Braude has mentioned causation over temporal gaps isn't necessarily illogical, though I've not found a place where he elaborates on this...
'Historically, we may regard materialism as a system of dogma set up to combat orthodox dogma...Accordingly we find that, as ancient orthodoxies disintegrate, materialism more and more gives way to scepticism.'

- Bertrand Russell

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