Then a longer version of that sentence appears: "This hydrodynamic system has since been shown to exhibit several features previously thought to be peculiar to the microscopic, quantum realm: single-particle diffraction, tunneling, wave-like statistics in confined geometries, quantized orbits, spin states, orbital-level splitting, and more."
@Semiclassical Ah, well, it's along the line of what I expected. It's not that hard to cook up systems that can exhibit all those ''quantum'' effects because they're not quantum. This is not new, but I guess it's cool since it's tied to an experimental setup. The really hard part is to reproduce contextuality, as through Bell's experiment. This the actual "new" part of QM from CM...
@Semiclassical But yeah, I think the abstract is a bit on the over-sold side of things as the claim that these features were ''thought to be peculiar to QM'' is just false if you asked the relevant people...
@Semiclassical But it IS peculiar, just not like that.
@Semiclassical I just happen to have attend a great many conferences on foundational QM/ quantum information and the state of the art is often WAY beyond what is discussed at that level.
I mean, I don't think PWT is actively harmful/misleading in terms of predictions. But it doesn't give you new predictions so much as a different picture for those predictions.
@Semiclassical Like I told you before, it was meant originally by Bohm to demonstrate that Bell's theorem does not imply what people think it does and for that, it serves its purpose.
@Semiclassical But the field of foundational QM HAS had many advances, it's just that people do not discuss them so much as it become quite abstract. People are constantly twisting and poking at QM in a very intense manner in order to restrict what QM is actually about.
In that line of thought anything about wave-particle duality, interferences and the likes has been kinda thrown out the window.
@G.Bergeron oh, sure. That's what I'm getting at, really: That the progress made has been in directions for which I think PWT is not really going to tell you anything you don't already know
I actually find the modern discussions/results on this topic actually quite stimulating and interesting and possibly useful in leading the way forward with QG.
I feel like the situation is one of: If you give me a sufficiently complicated QM experiment, then there is an internally consistent dBB account of that experiment.
But the thing is---what have you actually gained by doing that?
I don't think it actively harms things, but it seems more like a curiousity.
But it pisses me off BIG TIME to see papers like the following being published in Nature Comm.: nature.com/articles/ncomms6814
''Such wave–particle duality relations (WPDRs) are often thought to be conceptually inequivalent to Heisenberg’s uncertainty principle, although this has been debated.''
Like, who thinks that beyond the 20th century?
If I was the reviewer, I would have asked to nick the entire introduction!
And it does not tell you much, I mean the ''wavefunction'' is just the components of a state in the position basis, not even a state per se, but rather an overlap.
This way you get out of the abstract, algebraic formalism of QM into differential operators because these abstract operators gets realized by those differential operators.
Then you get people trying to interpret deeply what is essentially a coefficient in a change of basis, come on!
According to Huygens Principle, secondary Wavelets are generated from every point of the primary Wavelets. Is the Amplitude of these secondary Wavelets same as that of Primary Wavelets?
if anything, I'm saying why the dBB account is both internally consistent and also a dead end
or that if feels like that to me
Can you attribute trajectories to a quantum system in a consistent (if seemingly unintuitive) way? Yes. Does that make building a QC any easier? Probably not.
@G.Bergeron well, the pilot wave story has to be consistent with the probability stuff as well. the point is that, whatever 'conceptual clarity/satisfaction' it may bring you, it doesn't give you anything empirically that QM didn't already contain.
(there are variants on dBB that would, but I don't really buy them)
@G.Bergeron feel thats clearcut case of "moving the goalposts". it is hard to cook up the systems because it took over 1century to discover them. btw, they were discovered by undergraduates working with Couder... o_O this also relates highly to the "(in)commutability of a classical vs QM system" question...
@G.Bergeron huh?!? ofc bohm took his own theory quite seriously.
@G.Bergeron sounds preposterous to me. have never heard such a claim. nothing in his writing supports it. agreed many other physicists dont take it seriously.
@G.Bergeron not sure what you mean. wave-particle duality is really just another aspect of "complementarity" emphasized/ advocated etc by bohr. the "establishment" originator/ leader, so to speak.
@Semiclassical it is widely thought to be a dead end but not enough serious analysis has gone into it yet if you ask me. ie variant of self-fulfilling prophecy aka confirmation bias. "absence of evidence is not (nec) evidence of absence..."
@Semiclassical they have already gone beyond QM because they were unthinkable by the founders and decades/ generations of physicists, and they are classical. etc.
@Semiclassical it could be regarded somewhat as a "thought experiment" but he worked on it for decades, hardly something one would say he didnt take seriously. he built an entire philosophy/ metaphysics around it far beyond anything bohr did wrt QM. (who had similar tendencies on smaller scale.)
@Semiclassical admittedly there is ("currently") no widespread concession of any failure similar to the "blackbody catastrophe" that ushered in/ even precipitated the 20th century/ QM revolution.
there are some complexities as to how Bohm felt about his 'theory', I think
but that's not really surprising, given that what he presented was entirely in the realm of non-relativistic QM
I don't think he'd have insisted that the equations he wrote down in that paper were the end of the story, though I think he would have insisted that captured something essential
think the elephant in the room should be spelled out: the diverse hydrodynamic experiments replicating key QM properties/ phenomena should be seen as strong circumstantial evidence in favor of Bohmian mechanics & even to a degree vindicating! ofc almost nobody credible/ established is claiming that, maybe partly out of timidity and/ or fear...
ehh. the thing which @G.Bergeron said which I basically agree with is that, when it comes to applications like quantum information, I don't see hydrodynamics as being terribly helpful.
plus I'm not sure whether the experiments in that vein have been successful in replicating the features of Bell's inequality.
@Semiclassical believe they are getting close, and yeah, in theory that should be the nail in the coffin so to speak... think La Cour/ Ott have already demonstrated it (or something very similar) and (almost) nobody is paying attn o_O ... actually do have in mind my own tabletop experiment, may get to it at some pt...
anyway there are textbooks right now that say double slit experiment is impossible to replicate in classical physics and is unique to QM and theyre now proven flat out wrong at this point. they literally need to be rewritten! note that double slit experiment was also heralded by feynman as a key nonclassical experiment epitomizing QM mystery. he was wrong too o_O
@vzn No, they were confused. Not exactly the same thing.
@vzn Nobody ever got close to it, ever. I know you wish for that to be true, but it ain't. People wouldn't ignore this. All my quantum information friends would be raving about this!
@vzn Nope, an interpretation cannot be vindicated by an experiment by definition.
@vzn You know, Bohr stuff is kinda old...
@vzn This point is a non-argument, you could justify anything with that.
Q)What will be the potential difference and charge on the 8uF capacitor?
Ans)214uC ; 27V
Could you please turn this to a simpler circuit? Which of the capacitors are in series and which in parallel connections? Are there any that are short-circuited?
I tried multiple times but i just dont seem t...
@G.Bergeron one can be confused and wrong at the same time.
@G.Bergeron what might be called "the social element of knowledge". memes... speaking of "justifying anything" reminds me of argumentum ad ignorantiam + bandwagon fallacythebestschools.org/magazine/15-logical-fallacies-know
@vzn Ok, so ''absence of evidence is not evidence of absence'', so there might be a galaxy of those flying teapots behind jupiter, or you know, pick any silly hypothesis. The thing is that, either we are arguing about interpretations in which case Occam's razor should be kept in mind or else we are talking about this being beyond QM, in which case there ARE strong evidences against what you claim.
@vzn Also, there are no bandwagons here... In science if there are NO evidences after repeated and sustained attempts, yes, we take it as evidence of absence!!! Otherwise we do nothing. This is not a debate, this is science.
@vzn Now that you mention it, how you sometime argue makes more sense: you seem to approach this as in a debate. Appealing to the authority of fore-fathers, trying to dismiss my arguments as sophisms...
@s.patroller Of course, get every undergrad to buy the new revolutionnary n th edition of a book they'll never read beyond undergrad years!
when it comes to how QM is taught, I wouldn't be at all shocked if there's some bad history being peddled
and I'd also say that, when it comes to doing problems the Schrodinger equation etc, I think that pilot wave / hydrodynamics stuff is not bad and may even be clarifying if used judiciously
the real problem is that the Schrodinger equation is not the end-all-be-all of QM
what about intro qm starting with a feynman quote about how he doesn’t understand qm and saying to the lecture room “don’t worry if y’all don’t understand what we do in the course because even feynman didn’t understand it ::laughter::”
awesome now i dont feel bad for not knowing how to use bra kets properly
@Semiclassical The real problem is that he claims that someone reproduce Bell's experiment in a classical system and that nobody cares... All the rest is fine.
when I refer to the schrodinger equation, mind, I don't mean the more general notion of $i\hbar \partial_t \Psi = H\Psi$. but rather the specific case of $H$ being a differential operator
I think my attitude is: If you're in a setting where wave-particle duality is truly a relevant part of the story, then stuff like pilot wave theory may be illuminating. But that's not the full scope of applications of QM, and the amount of time intro courses devote to the stuff like solving the 1D schrodinger equation I think tend to color that
in particular, one shouldn't expect to get a lot of insight about QC from that
(it might come in handy when considering the implementation of a QC. but in terms of software on a QC, I see no role for PWT / hydrodynamics at all)
@Abhinav Now you could calculate mechanically the parameters, or use a witty trick (mostly me not wanting to pull out a calculator) and notice that 18 and 36 are in a ratio of 1:2 so the 18uF cap has half the cap has twice the voltage of the 36uF cap or 2/3 of the total of 40V -> 27V, now as the 8-4-6 caps are in parallel, they have the same voltage accross them, so 27V. Now you easily compute the charge q as 8uF * 27V...
for implementation, I have in mind stuff like: Maybe having visualizations of how a particular element in a QC will make it easier to design them in an optimal way
but 1) that's speculation out the wazoo, and 2) if you're programming a QC, you probably don't care about the hardware so much as what software you can do
@Abhinav If you really want to ''mechanically'' compute the charge, you'd start from the current through series capacitors being equal (it's a Kirchhoff loop) and, for instance, integrate a charging current.
@s.patroller I thought you were talking about the capacitors...
but you absolutely need that if you want to talk about the Stern-Gerlach experiment, and imo that gives much more the flavor of how QM works in applications
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"At some moment, we got to the demand "Lidovky [a dissident's newspaper at that time" have to be liberated. Comrade Morávková said: "Kids, we can't include this sentence. If you liberated Lidovky, you could very well allow Nazi newspapers, too!" – I, somewhat affected by the daily listening to Radio Free Europe, responded: "Dear Miss Morávková, the ideology of your Rudé Právo [communist daily, Red Right or Red Law] is comparable to the fascist ideology!""
Huh. I was thinking along the lines of "there exists a neighborhood $U$ around the point $p$ such that the intersection of $U$ and the curves solely contains $p$"
$0,1,2,3,4,... < \omega$ (Increment = add 1 for 1 times per step)
$\omega, \omega 2, \omega 3, \omega 4, ... < \omega^2$ (Increment = add $\omega$ for 1 times per step)
$\omega^2, \omega^3, \omega^4, \omega^5, ... < \omega^{\omega}$ (Increment = add n for $\omega$ times for step n)
(which you can start to see how suddenly the growth accelerates and why associativity of exponentiation started to break down soon, because for each step, the stuff to be added increments by $\omega$. This is still linear thus associativity is still ok)
$\omega^{\omega},\omega^{\omega^{\omega}}, {}^{4}\omega, ... < \epsilon_0$ (Increment = add n for $\omega^n$ times for step n)
(Now you see even the number of things you need to add to even get to the next step is equal to the value of the next step itself, thus the growth is a lot faster. This change in the number of things to add for each step thus breaks down associativity of exponentiation and tetration)
(If multiplication is not defined, then it is impossible to reach $\omega^{\omega^{\omega}}$ because it cannot be reached from below via addition)
$\epsilon_0,\epsilon_{\epsilon_0},\varphi(2,\varphi(2,\varphi(2,0))), ..., < \zeta_0 = \varphi (3,0)$ (Increment = multiply n for $\epsilon_n$ times for step n)
$\varphi(3,0), \varphi(\varphi(3,0),0), \varphi (\cdot,0) \circ^2 \varphi(3,0), ... < \Gamma_0$ (Increment = hyperoperate n for $\omega$ times for step n)
(Here, the growth itself is actually growing very rapidly despite the number of times of doing it is constant)
