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There exists a classical model of the photon after all

lightbluetouchpaper.org

61–70 of 86 posts

Re: There exists a classical model of the photon after all

#61

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…

I'm not a physicist, but I've always wondered about Caroline Thompson's work, like:

"Chaotic Ball" model, local realism and the Bell test loopholes

http://arxiv.org/abs/quant-ph/0210150

...any thoughts?

Re: There exists a classical model of the photon after all

#62
post #25
post #21

Earlier quoted context omitted.

I haven't read it, and it may be too advanced for this purpose, but Landau's books are generally held in extremely high regard and volume six of his Course of Theoretical Physics is on fluid mechanics. For what it's worth, volumes two and three cover electrodynamics and quantum mechanics, respectively.

> Landau's books Landau's presentation is extremely condensed. Griffiths is much more friendly towards the reader. I would compare Landau to Knuth's The Art of Computer Programming. Some people do read them, but the rest of us just hold them in extremely high regard :-).

The Landau Lifshitz series is absolutely amazing. It works so well with my brain, entirely concise with just enough textual clarification as needed.

Eg, volume 1 is classical mechanics. By page 3 or so you e already derived the Lagrangian equations of motion.

Re: There exists a classical model of the photon after all

#63
post #13

Earlier quoted context omitted.

Reasoning from intuition has a terrible track record, I'm afraid.

Really? Did Einstein have empirical proof of his ideas?

Why do you think this addresses the claim "Reasoning from intuition has a terrible track record?"

1) Einstein didn't work from intuition, but from a particularly narrow insistence on that the laws of physics be the same for all observers. This informed both SR and GR, and in fact his "intuition", such as it was, led him wildly astray in the run-up to GR. His papers in the 1913-1915 timeframe were all over the map. Furthermore, the final decades of Einstein's life were almost completely sterile in terms of new physics because he let his intuition guide him: he insisted that "god does not play dice" and so on, which turned out to be a hiding to nowhere.

2) Even if Einstein had worked primarily on the basis of intuition (which he didn't) and had been right (which he wasn't when he relied primarily on intuition) it would not in any way absolve us from the duty of taking experimental results far more seriously than theoretical intuitions, because against that one (actually imaginary) triumph of intuition we would have to balance thousands of years of intuitions from very smart people that turned out to be false.

"Things fall toward the center of the Earth and planets move in perfect circles about it" was intuitively obvious to Aristotle. So were a lot of other falsehoods. Galen had a whole raft of intuitions about human physiology that were false. Everyone from Kant to the Positivists believed it was intuitively obvious that detecting a violation of the law of non-contradiction of the kind implied by the experimental violation of Bell's inequalities was impossible. And so on.

So even if we had a single instance of intuition being correct, we would still be crazy to rely on it given its long track record of abject failure. "It just makes sense" are the most dangerous four words you can speak, because they are the terminus of critical thought.

Re: There exists a classical model of the photon after all

#64
post #43
post #17

Earlier quoted context omitted.

I don't know and don't keep track. I lost interest after realizing that it can be made compatible with any possible observation. I'm personally a fan of the Everett interpretation. Also called the many worlds. Which is what you get if you assume that quantum mechanics applies to the observer. Then the act of observation throws the observer into a superposition of possible states where different things were observed.…

There's a problem with with many-worlds that I haven't seen convincingly refuted: when collapsing superposition of two states you might need to (or rather almost always) need the ratio of worlds with outcome A to worlds with outcome B to be irrational. So unless you create a continuum of new worlds each time it won't work.

The wavefunction is a superposition of n independent wavefunctions at different amplitudes, like you can divide a piano's sound into a bunch of pure sine waves. "From the inside" each feels like a self-contained world (in a physically rigorous sense), but the ratio between their amplitudes and phases can be an arbitrary complex number - just as even if you're only playing a C and a G, the ratio of their amplitudes can be anything.

Re: There exists a classical model of the photon after all

#65
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?

Re: There exists a classical model of the photon after all

#66
post #8

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".

It's quite exciting to see these sorts of papers. What fascinates me is that we have achieved so much in the "quantum age" of the past century using the models derived from a quantum mechanical approach to physics. That the bedrock [or lack of one] of that could be removed and provide a better, more consistent, approach seems so counter-intuitive. But then one recalls how long the Newtonian or Aristotelian approaches…

The wheel of science turns, but it doesn't turn backward. Einstein refined Newton, but in no sense represented a return to Aristotle. Perhaps more to the point, the Bell Inequalities are true and have been experimentally verified; reality provably contains either nondeterminism or nonlocality. If you find the model with instantaneous communication along these "flux tubes" easier to work with then by all means work with it, but it's just another interpretation; most of us find the nondeterministic but local model is ultimately easier to reason about.

Re: There exists a classical model of the photon after all

#67
post #54

Earlier quoted context omitted.

>good reason to believe that quantum mechanics does not describe humans One simple idea is that the more energy and matter you shove into the wave function, the easier it is to collapse, so that at the macro level quantum effects are rendered impossible.

The problem is that there is absolutely no experimental or theoretical reason to believe that quantum states ever collapse. And there is an explanation for why we would perceive collapse even if there is none. If you take those ideas seriously, you're forced into the Everett interpretation.

But the "explanation" assumes what it sets out to prove.

If there is no reason to believe in collapse, there is no reason to believe that we can only be conscious of our state of entanglement with one component of a wavefunction rather than both.

That is, the Everret interpretation assumes that for some unknown reason we can only be conscious of the classical world, and uses this assumption to "explain" that we are conscious only of the classical world.

Consider a polarizing beam splitter with detectors in either arm. We are only ever conscious of a photon being detected in one arm or the other. But why not both, since the matter of our brain is necessarily entangled with both components of the photon wavefunction?

All Many Worlds does is push the central mystery around, from "Why do photons prepared in the same initial state collapse into different final states?" to "Why aren't we conscious of being entangled with both photon polarization states rather than just one?" It won't do to simply say, "Well, consciousness doesn't work that way." We know it doesn't. The question is, given the otherwise completely continuous physics describing the world, why is the physics of the brain such that it can't generate consciousness of that world?

Decoherence and similar approaches have the same problem, because they assume that for some reason the brain is unable to detect the quantum world without the aid of such classical phenomena as interference patterns in photon detection, but there is simply no warrant for that assumption.

If you restrict your description of the universe to non-collapsing QM you would never guess at the existence of the classical world. Ergo, a brain fully-described by non-collapsing QM is a quantum brain, and there is no particular reason why it shouldn't be in all states at once. That is it not in all states at once is manifestly true, but the question is "Why not?" It won't do to simply assume it, as all these alternative interpretations of QM do.

Getting the brain to be aware of only a single classical world is exactly the same problem as getting a wavefunction to collapse. It has just moved the problem around, not solved it.

Re: There exists a classical model of the photon after all

#68
post #18
post #2

"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 qua…

> How long would I have to study physics to be able to understand everything in this sentence? Just start reading David J. Griffiths: Introduction to Electrodynamics . A very well written textbook. The problem might be, if you don't know vector calculus, you might not be able to read this book, so you need to learn some vector calculus, too. Then start reading Introduction to Quantum Mechanics by Griffiths, too. Best…

For superfluid mechanics (which they seem to be using as a foundation) Donnelly's "Quantized Vortices in Helium II"'s introduction is a pretty good start. The field is quite hermetic, though.

Re: There exists a classical model of the photon after all

#69
post #18
post #2

"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 qua…

> How long would I have to study physics to be able to understand everything in this sentence? Just start reading David J. Griffiths: Introduction to Electrodynamics . A very well written textbook. The problem might be, if you don't know vector calculus, you might not be able to read this book, so you need to learn some vector calculus, too. Then start reading Introduction to Quantum Mechanics by Griffiths, too. Best…

I disagree with the suggestion of Griffith's QM. Somehow, Griffiths made an excellent EM book, but terrible QM. I find Shankar's Principles of Quantum Mechanics to be much more comprehensive and easy to follow.

Re: There exists a classical model of the photon after all

#70

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…

I'm not a physicist, but I've always wondered about Caroline Thompson's work, like: "Chaotic Ball" model, local realism and the Bell test loopholes http://arxiv.org/abs/quant-ph/0210150 ...any thoughts?

The scrutiny that Bell test experiments get from loophole people is always much appreciated, but the problem with Aspect's results in particular is that lovely parenthetical remark that appears in several of his figures, to the tune of "The dotted line is not a fit to the data, but the quantum mechanical prediction for this result."

While it is easy to imagine selective-detection effects that mess up the results enough to invalidate the test at the level of the inequality, it is very, very difficult to maintain all the physics required for precise, detailed agreement between theory and experiment of the kind that Aspect and others have shown. Here is an example of a "local realistic model" that reproduces the quantum mechanical results for in-time coincidences, but completely messes up any number of auxiliary measurements: http://www.tjradcliffe.com/?p=590

So while I'd love to see a modern version of Aspect's work using state-of-the-art entangled photon sources and the like, the likely reason it hasn't been done is that the odds of it revealing anything new and different are trivially small (but not zero, of course!)

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