I thought some scientists hadn't really closed the book on bell's inequality, and though most agree with it there were some gotchas that leave room for doubt as to correctness
Do physicists really believe in true randomness?
11–20 of 58 posts
Re: Do physicists really believe in true randomness?
#12Perhaps someone else more knowledgeable can chime in -
Isn't true randomness unverifiable? In other words, it seems (to me) that there is no body of evidence that would verify that a particular event was "caused" by (i.e. was the result of) true randomness (as opposed to the result of hidden events/variables)
Re: Do physicists really believe in true randomness?
#13Can someone explain this a bit better? As far as I can tell, the argument is basically "these particle effects should be predictable. I can't predict them, therefore they're impossible to predict". That sounds like nonsense to me... And I don't understand the cos equation. The argument seems to assume that the experiment is perfectly controlled, and given that we're still figuring out quantum effects, this seems to b…
I really don't think you read the entire article, but: "As another aside, Bell’s Inequality only proves that the reality assumption and locality (nothing can travel faster then light) can’t both be true. However, locality (and relativity) work perfectly, and there are almost no physicists who are willing to give it up. Except for Bohm, who’s an ass."
Re: Do physicists really believe in true randomness?
#14Bohmian Mechanics is an interpretation of Quantum mechanics which does not have any "true" randomness.
It is effectively a hidden variable theory consistent with quantum mechanics.
So at least some physicists do not believe in true randomness.
Re: Do physicists really believe in true randomness?
#15Earlier quoted context omitted.
There are deterministic interpretations of quantum mechanics, under which the usual randomness in quantum mechanics is not truly random.
But Bell's inequality says that these hidden variable theories are incompatible with the results of experiments. Real experiments. Like these: http://en.wikipedia.org/wiki/Bell_test_experiments It may be the case that there really is a hidden variable, but it would need to communicate it's value nonlocally, which I'd argue is stranger than the universe just being somewhat random.
Bell's theorem is based on the assumption of free will, see eg http://en.wikipedia.org/wiki/Superdeterminism
Re: Do physicists really believe in true randomness?
#16> If, on the other hand, you try to predict something like the moment that a radioactive atom will radioact, then you’ll find yourself at the corner of Shit Creek and No
I love it!
Re: Do physicists really believe in true randomness?
#17Bohmian Mechanics is an interpretation of Quantum mechanics which does not have any "true" randomness. It is effectively a hidden variable theory consistent with quantum mechanics. So at least some physicists do not believe in true randomness.
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Re: Do physicists really believe in true randomness?
#18Perhaps someone else more knowledgeable can chime in - Isn't true randomness unverifiable? In other words, it seems (to me) that there is no body of evidence that would verify that a particular event was "caused" by (i.e. was the result of) true randomness (as opposed to the result of hidden events/variables)
In the particular context of this post, it isn't. The local hidden variable theory is conclusively wrong. Not sure if there are recent results about nonlocal hidden variables, but last time I checked we couldn't say anything about that.
There's a great (and pedagogical enough) discussion of this at the back of Griffith's Introduction to Quantum Mechanics
Re: Do physicists really believe in true randomness?
#19I love the idea of true randomness because it seems, to my uninformed mind, to allow us the possibility of free will. Without true randomness, while we may enjoy the illusion of free will, our decisions are ultimately left to deterministic hidden variables. That makes me sad. But given true randomness, we may in fact have some mechanism whereby we are truly autonomous. How that might work is way beyond me and probably leads very quickly to pseudoscience and quackery, but it's certainly fun to think about.
Re: Do physicists really believe in true randomness?
#20This article completely misses the point. You can never disprove hidden variable theories in a stochastic system, because hidden variable theories make the exact same predictions as 'true random' theories - the difference is only philosophical. What you can disprove are local hidden variable theories, which were somewhat popular (and favored by Einstein, for example) prior to Bell's thought experiment being empirically supported. See what Einstein wanted was for all of quantum mechanic's weird results to be explainable by local interactions that took place when two particles interact - so that when they become entangled and subsequently drift apart, you don't have to have any "spooky action at a distance" to explain the results of experiments you do on them separately. However, what Bell's experiment shows is that the dice don't get rolled until one of the particles is measured - and that the way in which a measurement is performed on one particle affects its correlation with the other. So in fact you do need instantaneous nonlocal interaction to explain the real world. The result, unfortunately, has nothing to do with 'hidden variables' vs. 'true randomness'. What it does say though, is that you can't just explain away the weirdness of quantum mechanics as the result of some yet-to-be-found local hidden variables.