# Of Light and Double-Slit Experiments

**URL:** <https://boards.straightdope.com/t/of-light-and-double-slit-experiments/820856>\
**Category:** Factual Questions\
**Created:** [September 6, 2018, 3:00am UTC](https://boards.straightdope.com/t/of-light-and-double-slit-experiments/820856 "2018-09-06T03:00:12Z")\
**Posts on this page:** 2\
**Page:** 2

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**Author:** ![k9bfriender](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/k9bfriender/32/3283_2.png) [@k9bfriender](https://boards.straightdope.com/u/k9bfriender)\
**Post date:** [September 9, 2018, 5:15pm UTC](https://boards.straightdope.com/t/of-light-and-double-slit-experiments/820856/21 "2018-09-09T17:15:50Z")

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> [@Chronos](#):
>
> Bell took a set of assumptions which each seem reasonable and intuitive, and showed that that set of assumptions leads to conclusions which are at odds with our observations of reality. From this we can conclude that at least one of those assumptions, despite seeming reasonable and intuitive, must actually be wrong. We can’t, however, conclude which one of them is wrong. We can make judgements about which of them seem to be “more intuitive” or “more reasonable” than the others, and say that the least-intuitive or least-reasonable one is the wrong one, but that’s entirely subjective, and if two different physicists (or philosophers) come to different conclusions on that question, we have no way of settling who’s right.

The physics Thunderdome: Two theories enter… and two theories leave, with neither of them being a clear winner.

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**Author:** ![Half\_Man\_Half\_Wit](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/half_man_half_wit/32/21766_2.png) [@Half\_Man\_Half\_Wit](https://boards.straightdope.com/u/Half_Man_Half_Wit)\
**Post date:** [September 9, 2018, 5:39pm UTC](https://boards.straightdope.com/t/of-light-and-double-slit-experiments/820856/22 "2018-09-09T17:39:59Z")

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> [@Chronos](#):
>
> Bell took a set of assumptions which each seem reasonable and intuitive, and showed that that set of assumptions leads to conclusions which are at odds with our observations of reality.

Yes, everybody agrees to that—but the controversy is about what, exactly, those assumptions are, with one camp claiming it’s a combination of ‘locality’ and a further assumption, often phrased as ‘realism’, ‘counterfactual definiteness’, ‘hidden variables’ or the like, while the other maintains that ‘locality’ alone suffices.

The received view is the former—to prove Bell’s theorem, you need both locality and some assumption that boils down to incompatible observables simultaneously having definite, albeit not simultaneously observable, values. Becker’s book, and also George Musser’s recent work _Spooky Action at a Distance_, pretty much take the line that the latter camp is correct, which is at least premature (and by my lights, pretty much dead wrong).

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