Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Oil droplets guided by pilot waves do not give rise to double-slit interference

quantamagazine.org

Post reply on HN
Print view View original

101–110 of 130 posts

Re: Oil droplets guided by pilot waves do not give rise to double-slit interference

#101

Post by acjohnson55 »

branksy wrote: post #85

> Unsustained by the particle or droplet, the wavefront disperses long before reaching its slit, and there’s no interference pattern. The Danish researchers verified these arguments with computer simulations. Wait, what? From what I've always understood, the math behind de Broglie-Bohm interpretation results in the same exact results as the Copenhagen interpretation. It shouldn't be possible for any "computer simulat…

If you read all the way to the end, de Broglie-Bohm is discussed. I think the point is that the simpler, original pilot wave theory, which was never fully nailed down, is disproven.

Re: Oil droplets guided by pilot waves do not give rise to double-slit interference

#102

Post by acjohnson55 »

naasking wrote: post #73
twtw wrote: post #58

Bohm's pilot wave theory is interesting to me not because it is so intuitive or tasteful or something, but because it works without sacrificing realism, and thus demonstrates that the Cophenhagen interpretation (neither local nor real) claims strictly more about the nature of the universe than is required by the evidence we have. Nonlocality is established by experiment, non-realism is not. In my experience, this ten…

> I personally favor epistemological interpretations, in which the wave function models our knowledge These have been largely ruled out via no-go theorems [1]. [1] https://en.wikipedia.org/wiki/PBR_theorem

Could you explain this further? The Wikipedia article doesn't go into much depth, especially w.r.t. de Broglie-Bohm interpretation.

Re: Oil droplets guided by pilot waves do not give rise to double-slit interference

#103

Post by Strilanc »

naasking wrote: post #77
lmm wrote: post #65

Earlier quoted context omitted.

The whole value of pilot wave theory was that it was an interpretation of QM in terms of things that behaved like ordinary macroscopic particles and waves. Given that ordinary particles and waves don't actually behave like that, there's absolutely no reason to prefer pilot wave theory over simpler, more direct interpretations of QM.

I think your whole characterization of pilot theory's value and its relation to other interpretations is incorrect. Firstly, it's primary value is that it's an ontological interpretation, meaning it preserves realism where most other interpretations sacrifice realism. The motion of its beables has nothing to do with this. Secondly, pilot wave theory still requires the fewest number of assumptions, roughly on par with…

> pilot wave theory still requires the fewest number of assumptions, roughly on par with Many-Worlds, which means it's axiomatically simpler than other interpretations

Isn't the most common complaint about pilot-wave that the wave corresponds to normal QM and the pilot is a superfluous detail? I would not pick minimalism as one of its strengths.

Re: Oil droplets guided by pilot waves do not give rise to double-slit interference

#104

Post by platz »

acjohnson55 wrote: post #101
branksy wrote: post #85

> Unsustained by the particle or droplet, the wavefront disperses long before reaching its slit, and there’s no interference pattern. The Danish researchers verified these arguments with computer simulations. Wait, what? From what I've always understood, the math behind de Broglie-Bohm interpretation results in the same exact results as the Copenhagen interpretation. It shouldn't be possible for any "computer simulat…

If you read all the way to the end, de Broglie-Bohm is discussed. I think the point is that the simpler, original pilot wave theory, which was never fully nailed down, is disproven.

correct, and the Broglie-Bohm uses an abstract amplitude wave just like copenhagen - the only difference is in copenhagen the result auto-magically appears, in-toto, when it is "measured" (¿), and in Broglie-Bohm the particle really exists the whole time and travels the whole path mapped out by what the abstract amplitude wave specified.

Re: Oil droplets guided by pilot waves do not give rise to double-slit interference

#105

Post by rusk »

dotancohen wrote: post #69
rusk wrote: post #39

Earlier quoted context omitted.

> I can't seriously imagine Newton saying .. But he did. He called it Gravity. He didn't let figuring out "how gravity works" hold him back. He just figured out the equations that predict its effects based on observation. The unknowns happened to conveniently coalesce around a single constant G, but that doesn't make them "known". [IANAP - do we have any convincing popularly accessible models for how gravity works ev…

Actually, both you and GP got it wrong. There is no need to speculate what Newton was thinking, it was all recorded. Newton was looking for methods to manipulate (push, pull) objects at a distance without touching them. He had strong ideas about the occult and what we today call black magic, in addition to being an alchemist. He devised that the Earth was manipulating the untouched Moon (capitalized, proper noun) and…

LOL is that for real! Please please can you give me a couple of good citations for that?

Re: Oil droplets guided by pilot waves do not give rise to double-slit interference

#106

Post by matthewwiese »

mileszim wrote: post #76
whatshisface wrote: post #59

Earlier quoted context omitted.

One excercise that is fun to do: reduce the Schrodinger equation by splitting the real and complex parts, the figure out how to build a damped spring system that can support the wave. My interpretation of quantum mechanics is that everything is springs and dashpots in the end.

This is great, I think I'm going to explain it using your method from now on. Edit: I love that there's a segment of people in the QM community approaching these "very serious" thought experiments like Schrodinger's Cat (as the classic example), instead using absurdism to produce equivalent but blatantly ridiculous results. Like the Surrealist reactionary art movement but with the often insane results QM produces. So…

My favorite of these types of bizarro QM communities is that of the "holographic fractal" universe. Nassim Haramein[1] being one of the popular figures of this movement. If you're willing to sift through the mysticism, the r/holofractal subreddit has some interesting ideas to chew on during an otherwise dull lunch break.[2]

[1] https://resonance.is/about-haramein/

[2] https://old.reddit.com/r/holofractal/

Re: Oil droplets guided by pilot waves do not give rise to double-slit interference

#107

Post by Strilanc »

pg_bot wrote: post #9

I was thinking about the double-slit problem the other day, and was trying to make connections to any other phenomenon that exists in the natural world and I think I came up with one. In conditional probability theory, there exists something called the boy or girl paradox. The paradox shows that the likelihood of an event can be drastically affected by how you know even seemingly innocuous information. I think that o…

If it were just a probability paradox, Bell's theorem wouldn't be a thing. You can win certain coordination games more often using quantum correlations than is possible with classical correlations.

That being said, I have complained about specific papers and articles making this exact mistake. For example, explanations of delayed choice eraser experiments are almost always confusing correlation or post-selection for causation ( http://algassert.com/post/1720 ). But Bell tests are not of that form, which is why the first thing you should ask of any proposed interpretation is "How do you deal with Bell tests?".

Re: Oil droplets guided by pilot waves do not give rise to double-slit interference

#108

Post by naasking »

acjohnson55 wrote: post #102
naasking wrote: post #73

Earlier quoted context omitted.

> I personally favor epistemological interpretations, in which the wave function models our knowledge These have been largely ruled out via no-go theorems [1]. [1] https://en.wikipedia.org/wiki/PBR_theorem

Could you explain this further? The Wikipedia article doesn't go into much depth, especially w.r.t. de Broglie-Bohm interpretation.

It has no effect on Bohmian mechanics because it posits a real wave function. PBR rules out most "psi-epistemic" models where the wave function represents only our ignorance of the system, and not some fundamental, real property of the system.

Re: Oil droplets guided by pilot waves do not give rise to double-slit interference

#110

Post by naasking »

Strilanc wrote: post #103
naasking wrote: post #77

Earlier quoted context omitted.

I think your whole characterization of pilot theory's value and its relation to other interpretations is incorrect. Firstly, it's primary value is that it's an ontological interpretation, meaning it preserves realism where most other interpretations sacrifice realism. The motion of its beables has nothing to do with this. Secondly, pilot wave theory still requires the fewest number of assumptions, roughly on par with…

> pilot wave theory still requires the fewest number of assumptions, roughly on par with Many-Worlds, which means it's axiomatically simpler than other interpretations Isn't the most common complaint about pilot-wave that the wave corresponds to normal QM and the pilot is a superfluous detail? I would not pick minimalism as one of its strengths.

> I would not pick minimalism as one of its strengths.

Minimalism is one of its strengths. The type of objection you raise is a fundamental misunderstanding of both pilot wave theories, and what "minimalism" actually means when it comes to selecting among competing theories.

Post reply on HN