If you try to create a classical situation that obeys similar mathematics to a quantum situation, you're bound to get "quantum-like behaviour" isn't it? Wouldn't this be some kind of an analog computer for simulating the two-slit experiment in the classical realm? If so, what would this offer to the interpretation of quantum mechanics that cannot be gleaned from the mathematics itself?
Fluid Tests Hint at Concrete Quantum Reality
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Re: Fluid Tests Hint at Concrete Quantum Reality
#92Yes! But the best theory is not Copenhagen or Pilot Wave. Eliezer Yudkowski has a brilliant treatise on the Many Worlds interpretation here: http://lesswrong.com/lw/r5/the_quantum_physics_sequence/ that really should be required reading for anyone that wants to talk intelligently on the subject. Edit: seriously, don't even bother reading the article. It (like most science journalism) is garbage. Take the time to work…
So please explain in a few sentences what is that that Yudkowski writes, did he make any new contribution to the standard model or made something else or do you agree that the standard model is the most researched and most usable model up to now, and he just made a lot of posts where he just writes a lot of text? I see a lot of links in the article you gave, but I don't understand what we're supposed to discover in Y…
Yudkowsky's contribution is pedagogical rather than anything fundamentally new. He explains quite well in short the process of "decoherence" and links it well to the many worlds interpretation. He makes a case for why the "many worlds interpretation" is not really an "interpretation", but is just stating what the mathematics says on its face anyway .. and hence is the one we should adopt. In particular, he does a good job of connecting this to "timeless physics" - i.e. the Weyl equation for the "wavefunction of the universe" which does not have time in it.
Re: Fluid Tests Hint at Concrete Quantum Reality
#93I was under the impression that Bohmian mechanics were known to be equivalent if and only if hidden variables were strictly non-local (in the case of the macrophysical observations, the "universe" can for a reasonable higher-order approximation be the limits of the chamber being observed). IIRC, There is also an interesting 'alternative' relativity which has non-local effects and a universal frame of reference formul…
I was under the impression that Bohmian mechanics were known to be equivalent if and only if hidden variables were strictly non-local
Correct. The same is true of Bell's theorem; it shows that no local hidden variable theory can reproduce the predictions of standard quantum mechanics. It's true that the "local" part often gets left out in pop science treatments of Bell's theorem; but Bell himself was quite clear about it, and about the fact that Bohm's pilot wave theory is nonlocal. The article completely fails to mention this, which IMO is a huge omission.
Re: Fluid Tests Hint at Concrete Quantum Reality
#94Earlier quoted context omitted.
> the interpretations which, consequently, are not scientific theories or even hypotheses, but firmly on the side of philosophy of physics. Thanks, that's exactly what I wanted to know. I'm completely satisfied with the "shut up and calculate" approach. For me, until somebody shows that he/she can calculate (that is, predict) more than what physicists achieve, they are the ones the closest to "the truth" and not the…
Bring it back to the scientific method. The way to differentiate between competing hypotheses is by devising experiments that falsify some of them, and then running the experiments and either falsifying or failing to falsify them. The issue here is subtle, and it's that the most popular interpretation, Copenhagen, isn't a complete theory because it doesn't tell you algorithmically when collapse occurs. For any possib…
spacehome suggested reading Elizer's posts on quantum physics precisely to not bother to deal with outdated statements like "the most popular interpretation, Copenhagen". Afaik, no serious physicist uses this any more, not even to explain quantum theory. To use wavefunction collapse to "explain" QM is like invoking "God" to explain the universe - i.e. it is not much of an explanation, and it raises more questions than it answers.
Text books ought to be rewritten to teach decoherence instead of outdated stuff like wave-particle duality, wavefunction collapse and such. That is the history of the development of QM and not QM as it is known today, in my limited knowledge.
If you get decoherence, much of the "mysteriousness" and "spookiness" that's talked about in such magazines just disappears and you find them all, every one of them, shallow.
Re: Fluid Tests Hint at Concrete Quantum Reality
#95Yes! But the best theory is not Copenhagen or Pilot Wave. Eliezer Yudkowski has a brilliant treatise on the Many Worlds interpretation here: http://lesswrong.com/lw/r5/the_quantum_physics_sequence/ that really should be required reading for anyone that wants to talk intelligently on the subject. Edit: seriously, don't even bother reading the article. It (like most science journalism) is garbage. Take the time to work…
I want to upvote out of agreement, but I really, really hate when people recommend a very long work they expect me to read on faith without a summary of what it offers so I can know Of it's worthwhile.
Here's what I would have added: Yudkowsky explains quantum mechanics in terms of the decoherence interpretation and how it makes logical sense as following from a simple rule that nonetheless contradicted widely held philosophical assumptions that kept its simple truth from being appreciated.
Re: Fluid Tests Hint at Concrete Quantum Reality
#96Earlier quoted context omitted.
My understanding is that the pilot wave theory is a non-local hidden variable theory, which doesn't contradict Bell's theorem at all. Of course, this presents ftl information transfer, presumed to be impossible, which is part of the reason such theories have been unpopular for so long.
Non-locality does not imply the possibility of FTL information transfer - a theory can be non-local but make exploiting the non-locality impossible.
This is a vitally important point. Many people still naively believe entanglement allows communication. Simultaneous randomness doesn't permit a signal.
Re: Fluid Tests Hint at Concrete Quantum Reality
#97Earlier quoted context omitted.
I'm skeptical, if only because this should be a big deal and hasn't gotten much press. > We're able to set the spin (rotational direction) of these particles in a predetermined state, verify this spin and subsequently read out the data. This is terribly unclear. I don't have access to the article - maybe its better explained there? The problem with using quantum entanglement for information transfer is that you can't…
Paper in short: http://download.repubblica.it/pdf/2014/scienze/science-xpres... Paper in full: http://arxiv.org/abs/1404.4369 To the physicists among the us, please share your opinion on the paper with the rest of us. It's not easy to digest the paper. The finding is not only going to change finance, but also the whole data economy will speed up. Now 'Quants' can be located anywhere and everyone has can enjoy same ad…
Luboš Motl reviewed it. http://motls.blogspot.com/2014/05/constructor-theory-deutsch...
He didn't like it, as if there were any doubt.
Re: Fluid Tests Hint at Concrete Quantum Reality
#98Yes! But the best theory is not Copenhagen or Pilot Wave. Eliezer Yudkowski has a brilliant treatise on the Many Worlds interpretation here: http://lesswrong.com/lw/r5/the_quantum_physics_sequence/ that really should be required reading for anyone that wants to talk intelligently on the subject. Edit: seriously, don't even bother reading the article. It (like most science journalism) is garbage. Take the time to work…
I'd like to propose a thought experiment that in my opinion speaks for a many world interpretation.
Imagine Schrödingers Cat. Only we have a physicist in the box instead! Also inside the box is a photon emitter programmed to send a photon after 30 seconds. Our dear physicist has been instructed to, if he is still alive after 20 seconds (adjusted to have 50% prob) to move the emitter just a tiny little bit to the left. Now according to the quantum laws, the photon from the original position should create an interference pattern with the photon from the slightly moved position... provided we succeeded in creating a superposition of dead/alive physicist. Of course, every single experiment would just give one detection, so we would have to do it many times, to really verify that it worked.
The experiment could of course be scaled up, so that we instead proved that we had superpositions of planets being blown up or something. At some point, when the system in superposition is large enough - or significant enough -, I don't see how you could refrain from calling that many worlds.
Re: Fluid Tests Hint at Concrete Quantum Reality
#99Earlier quoted context omitted.
And why should we read Yudkowski instead, rather than other physicists on this matter, as far as I know he's not in a position of authority in this area.
I would never say instead of. Read whomever you like; read them all. Though, I would suggest that anyone who still takes Copenhagen seriously really needs to digest that sequence. Eliezer is a smart guy with great insights into how to think about questions. His "position of authority" is that he writes in a way that's clear and conveys meaningful novel insights. If you think that only Ph.D.s have insights worth readi…
>>And why should we read Yudkowski instead
>I would never say instead of.
When you recommend something, you're implicitly advocating that it be read in preference to other works on the matter.
It makes no sense to say "I recommend this, but it's no better than anything else."
Re: Fluid Tests Hint at Concrete Quantum Reality
#100I was under the impression that Bohmian mechanics were known to be equivalent if and only if hidden variables were strictly non-local (in the case of the macrophysical observations, the "universe" can for a reasonable higher-order approximation be the limits of the chamber being observed). IIRC, There is also an interesting 'alternative' relativity which has non-local effects and a universal frame of reference formul…
An interesting response to the fluid experiments discussed in the article:
http://arxiv.org/abs/1405.0466
Comment on Y. Couder and E. Fort: "Single-Particle Diffraction and Interference at a Macroscopic Scale", Phys. Rev. Lett. (2006)