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Comment by cevn | Hacker News Reader

"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?

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> 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 introductory QM book that I know of. If you managed to read Electrodynamics, you should by now know enough calculus for this book, too. But you also need to know about complex numbers here.

The "inviscid compressible fluid" is about fluid mechanics. I don't know any splendid textbook on that.

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.

Landau/Lifshitz are freely available on the Internet archive:

https://archive.org/search.php?query=creator%3A%22L.D.+Landa...

Wow, so nice to hear props for Griffiths' textbooks. I think he's by far the best physics textbook author.

I think Griffiths' E&M book is great. It's very enjoyable and makes a fine book to use before going on to Jackson (although more supplements are often needed to make it through that). I like Griffiths' writing and I liked the problems and examples he gives in this book.

However, I never liked Griffiths' QM book. The writing is OK (it's mostly in the same style as the E&M book, but to me it just seems like he tries too hard). Overall I didn't like his selection of which topics went to examples and which went to problems. I think Cohen-Tannoudji, et al., is the way to go for learning some QM. It's a bit more formal than Griffiths, but I think it makes far more sense and it has tons of good examples in the appendices.

But, to each his own.

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.

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.

You should be able to understand everything in that sentence if you have taken a typical undergraduate curriculum in physics including quantum mechanics and electromagnetism. Though it depends on what you mean by "understand". It should be clear what "quantised magnetic flux" is roughly about, but I have no idea what constitutes the "modern knowledge of quantised magnetic flux" in this context.

That doesn't help with the first part, about a phase vortex in compressible inviscous liquids.

It can take a bit of unpacking, but someone with some sort of college level physics and mathematics background can use Wikipedia to get a basic understanding of what they are talking about.

They are basically saying that the quantum mechanical 'strangeness' of light can be explained with classical, deterministic, physics. It is not necessary to have a separation in which quantum mechanics predominates at one level and trumps classical mechanics.

It call all be understood as movement of 'particles' of light (photons) on an underlying wave.

http://en.wikipedia.org/wiki/Magnetic_flux_quantum

http://simple.wikipedia.org/wiki/Magnetic_flux

http://en.wikipedia.org/wiki/Flux_tube

http://en.wikipedia.org/wiki/Quantum_vortex

http://en.wikipedia.org/wiki/Wave_packet

http://en.wikipedia.org/wiki/Maxwell%27s_equations

http://en.wikipedia.org/wiki/Differential_equation

http://en.wikipedia.org/wiki/Polarization_%28waves%29

http://en.wikipedia.org/wiki/Bell_test_experiments

http://en.wikipedia.org/wiki/Fluid_dynamics

http://en.wikipedia.org/wiki/Pilot_wave

http://en.wikipedia.org/wiki/De_Broglie%E2%80%93Bohm_theory

Pilot wave theory has been known for decades. So can someone explain how whatever they're talking about is different/new?

Their central claim is that they found a specific instance of quantum behavior where they can represent the whole model with only classical mechanics rather than falling back on quantum explanations like wavefunction collapse, etc. We think that describing quantum systems requires quantum explanations, so finding a counterexample could be interesting.

So they claim that up until now pilot wave theory hasn't been able to explain entanglement while remaining consistent with Maxwell's equations.

They are not saying they came up with pilot wave theory, only that they've removed a sticking point.

To really, really get it? The standard electromagnetism semester and a QM semester, both "for majors" (not the simplified general version), and something else for the "inviscid compressible fluid" (fluid dynamics, I assume, this might require some stuff that won't come up until semester 2, not sure), and a factor difficult to express in terms of semesters that you are not merely aping the mathematical results you are being taught by rote, but actually understand how to manipulate the math and follow deeply when you see other people do it. (Which I mean quite straight, not sarcastically.)

I'm pretty sure this would all be accessible to an undergrad physics major who passes my math criterion above. It would probably be beyond them to do the work, but they should be able to follow it.

An aerospace major who took a QM elective, or a physics major who took a couple of aerodynamics electives, would probably cover the necessary material by the end of year 2 of an undergraduate program. If you've got a solid, intuitive grasp of calculus and differential equations, you could probably learn enough from lecture notes to understand this in a few weeks. This is the most accessible physics paper that you'll ever see make the news.

Just about every concept (mathematical and physics) in the arXiv paper linked from the article is covered by the end of a typical undergraduate course in electromagnetism and quantum mechanics. The ones that aren't (specifically with respect to certain particulars of fluid dynamics and flux) are easily supplemented with material of the same depth and complexity (i.e. undergraduate level).

It depends on what you mean by "understand everything". That is a very terse, densely packed sentence of jargon intended for practitioners but a physicist who is a skilled communicator could describe the main results to a high school kid. To be able to fully understand the arguments leading to those results... it would take very serious study and decently sophisticated mathematical background before even starting.

A lifetime, or long enough that it would feel like a lifetime. The real question to ask is that how you really want to spend your life? The fact that you're asking makes me think you've already chosen another path.

It does not take a lifetime. It took me about 6 months to cover upper-division electricity and magnetism and quantum mechanics, which is probably all that you would need to get the most basic but complete understanding of this paper.

Climbing to 20,000 ft from the 16,000 ft makes you think that climbing mountains is easier than it's going to be for the person at sea-level that you're advising. If you've been at 16,000 ft for some time even just that acclimatisation is going to make a huge difference.

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