from Hacker News

There exists a classical model of the photon after all

by inglesp on 2/23/15, 2:40 PM with 84 comments

• by Strilanc on 2/23/15, 6:10 PM

  Scott Aaronson has commented negatively on a previous paper by the same authors [1]. I don't know if similar issues apply to this one:

  > [...] the paper advances the prediction that quantum computation will never be possible with more than 3 or 4 qubits. [...] I wonder: before uploading their paper, did the authors check whether their prediction was, y’know, already falsified? How do they reconcile their proposal with (for example) the 8-qubit entanglement observed by Haffner et al. with trapped ions [...]

  (Note: that's a critique of the previous paper, not the linked one. Although the linked post mentions quantum computers not working, the linked paper does not touch the subjet.)

  1: http://www.scottaaronson.com/blog/?p=1255

• by btilly on 2/23/15, 6:11 PM

  They claim to have found a classical system that reproduces quantum mechanical effects. But if they manage to extend it to many particles, interacting, they will find that they have just come up with another interpretation of QM which is experimentally indistinguishable from the rest. And it wouldn't even be the first one. (Bohm's hidden variable theory has precedence.)

  Furthermore the "incompressible fluid" they postulate sounds like it enables non-local behavior (which it has to to match current versions of the Bell test) so it is unable to help resolve the issue of reconciling GM with QM.

  So this does rather less than they claim. Assuming that their claimed result is correct.

• by cevn on 2/23/15, 5:26 PM

  "Updating this with modern knowledge of quantised magnetic flux, we show that if you model a flux tube as a phase vortex in an inviscid compressible fluid, then wavepackets sent down this vortex obey Maxwell’s equations to first order; that they can have linear or circular polarisation; and that the correlation measured between the polarisation of two cogenerated wavepackets is exactly the same as is predicted by quantum mechanics and measured in the Bell tests."

  How long would I have to study physics to be able to understand everything in this sentence?

• by yiyus on 2/23/15, 6:08 PM

  "our paper shows that the main empirical argument against classical models of reality is unsound.". That's quite an affirmation!

• by phkahler on 2/23/15, 5:56 PM

  I hope this is as awesome as it sounds. It sums up everything I've been thinking about quantum physics, from "someone should look closer at Couders work" to "spooky action at a distance is BS" to "Quantum computers will never work - see spooky action".

• by nilkn on 2/23/15, 11:06 PM

  When models like this are proposed, a lot of people are interested because of the philosophical implications of a classical theory of quantum phenomena.

  The question I have, though, is this: does this model actually help model phenomena that we can't already model? Quantum gravity is the big spectacular example, but there are many others.

  For instance, the Standard Model is very successful at predicting the anomalous magnetic moment of the electron. But it is not successful at predicting the same quantity for the muon. There are many other issues with the Standard Model that aren't so high-flung as quantum gravity.

  Are classical models like these, if they can be shown to incorporate multiple particles interacting simultaneously, capable of going beyond the Standard Model or merely replicating it?

• by vilhelm_s on 2/23/15, 10:48 PM

  I don't know any physics, but it seems like a bit of a warning sign that these new discoveries in fundamental physics are annouced on... a computer security blog?

• by snarfy on 2/24/15, 5:20 AM

  > Updating this with modern knowledge of quantised magnetic flux

  It sounds like they are using quantum mechanics to explain quantum mechanics.

• by taybin on 2/23/15, 8:21 PM

  "if the fundamental particles are just quasiparticles in a superfluid quantum vacuum"

  well obviously.

• by tjradcliffe on 2/23/15, 10:43 PM

  This paper has a variety of issues, the most glaring of which is that their "explanation" of the experimental violation of Bell's inequalities (specifically the CHSH form that has been realized in many experiments on polarization) is dependent on a static setup of precisely the kind that Aspect's experiments were intended to avoid.

  Aspect's work is one of the most beautiful pieces of careful and precise experimental testing of an idea in the past half-century, and while it has been attacked from many perspectives it is still a very robust argument for the non-locality of reality. One of the important things about it is that the polarization direction was switched in a quasi-random way after the photons had left the source. Variations on this trick have been performed since, and they all agree with the predictions of quantum theory.

  The authors say in this paper "The CHSH assumption is not true in Faraday's model. Instead there is prior communication of orientation along phase vortices such as(4), communication which the CHSH calculation excludes by its explicit assumption."

  In experiments like Aspects, prior communication is ruled out because the experimental setup is varied in one arm of the apparatus outside forward light cone of the other photon. Each photon gets detected before the other one could possibly know (based on signalling at the speed of light) what polarizer orientation it should be lined up with.

  So this is an interesting bit of work that might be useful in creating photonic quasi-particles in magnetic fluids that would allow for study of photon properties that might be difficult to get an experimental handle on otherwise, but the claim that they have a classical model that violates Bell's inequalities in a way that is relevant to the actual experimental work done in this area is considerably overblown.