Why does this matter? Does anybody seriously question whether the basic math can work? So somebody found a nice parallel between pilot wave theory and another physical phenomenon, but then the parallel wasn't as strong as thought. This experiment is the equivalent of arguing that light isn't a particle because your tennis ball doesn't bounce off the wall the way you thought it would.<p>When I saw the droplet experiments, I thought "that's cool, but it doesn't prove anything about pilot wave theory because the arguments are over much deeper things than what this is demonstrating". Debunking it is just as meaningless. The people who actually know about this stuff are arguing over determinism and non-locality and what not. I thought oil droplets are just a nice way to introduce people to the concept.<p>Disclaimer: I don't really know anything about any of this
> <i>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.</i><p>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 simulation" to disprove it, by definition.<p>This article feels 1) pointless and 2) like it has an agenda. Oil droplets are a macro-scale approximation of something on the particle level where we already know the math works. This doesn't disprove anything, any more than doing experiments with rubber sheets and basketballs lets you disprove the general theory of relativity.<p>> <i>crushing a century-old dream that there exists a single, concrete reality.</i><p>This is just sensationalist, cheap journalism. I expected far better from Quanta Magazine, and I'm disappointed in them. I've enjoyed many of their articles in the past, but I'm not sure I can trust them editorially any more if they print something so obviously incorrect as this article.
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 tends to be underappreciated (or I'm misunderstanding - please teach me if so).<p>I personally favor epistemological interpretations, in which the wave function models our knowledge, and the universe operates via an as-yet-unknown dynamics. Wave function collapse on measurement isn't weird anymore if the wave function represents your knowledge of the system. Thinking about it this way makes "shut up and calculate" work nicely in my head.
There is recent research on photons (rather than bouncing oil droplets) that backs up the Bohmian interpretation. "Experimental nonlocal and surreal Bohmian trajectories" <a href="http://advances.sciencemag.org/content/2/2/e1501466" rel="nofollow">http://advances.sciencemag.org/content/2/2/e1501466</a><p>I am not sure if the different QM interpretations are only a matter of taste in terms of all predictions. These surreal trajectories are seen as nonsense under the Copenhagen interpretation.
I don't think this is all that surprising to anyone. The "pilot waves" in the oil bath aren't superluminal, so of course they don't correspond with perfectly QM pilot waves, ie. they will only correspond in scenarios where the non-locality doesn't matter.<p>Edit: the article actually agrees with this, so it's hyperbolic all the way through except this critical passage:<p>> In a quantum reality driven by local interactions between a particle and a pilot wave, you lose the necessary symmetry to produce double-slit interference and other nonlocal quantum phenomena. An ethereal, nonlocal wave function is needed that can travel unimpeded on both sides of any wall.
So, am I right in thinking that we have.<p><pre><code> 1. Theory X hypothesizes Q
2. Phenomenon Y models theory X
3. Phenomenon Y does not demonstrate Q
</code></pre>
Surely there would be an insurmountable burden of proof on 2. Similarity does not mean identical. For any Y claiming to be the same as X, why can't it be rebutted with a "No it isn't" Proving that they are the same would be a different thing altogether but if as the article suggests X is not fully defined, it strikes me as impossible to prove. It just ends up in the not-falsifiable bin.
I'm a bit sad that they couldn't reproduce the double slit interference pattern. I'm still holding out hope that we'll eventually develop a model of reality where the apparent indeterminism of quantum mechanics can be explained by currently unobservable interactions in higher dimensional space (such as the space described here: <a href="https://www.quantamagazine.org/physicists-discover-geometry-underlying-particle-physics-20130917/" rel="nofollow">https://www.quantamagazine.org/physicists-discover-geometry-...</a> )
For some background on pilot waves: <a href="https://en.wikipedia.org/wiki/De_Broglie%E2%80%93Bohm_theory" rel="nofollow">https://en.wikipedia.org/wiki/De_Broglie%E2%80%93Bohm_theory</a>.<p>Also from the same source, a couple years back: <a href="https://www.quantamagazine.org/pilot-wave-theory-gains-experimental-support-20160516/" rel="nofollow">https://www.quantamagazine.org/pilot-wave-theory-gains-exper...</a>
Does anyone have a link to a video of the oil drop tunneling experiment?<p><a href="https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.102.240401" rel="nofollow">https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.10...</a><p>(like <a href="https://www.youtube.com/watch?v=nmC0ygr08tE" rel="nofollow">https://www.youtube.com/watch?v=nmC0ygr08tE</a>)
So, pilot wave theory remains a strong intuitive model, by confirming an inability to perfectly predict the future state of a system of quantum events.
I don't understand why non-locality is a problem. Fields are non-local. If particles are point-like, fields are volume-like and permeate all of space. Problems like spooky action at a distance aren't really problems if there is no distance from the field's point of view.
Has anyone done the double slit experiment with the long wall before the slits? I'm not entirely convinced it still works unless it has been demonstrated.
All the paradoxes disappear if we use Quantum Field Theory instead of Quantum Mechanics. I would really like someone with deep knowledge on Quantum Theory to explain if something is wrong with a theory that otherwise makes a lot of sense to me. A good read on the topic is the paper "There are no particles, there are only fields" — <a href="https://arxiv.org/pdf/1204.4616.pdf" rel="nofollow">https://arxiv.org/pdf/1204.4616.pdf</a>
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.<p>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 <i>how you know</i> even seemingly innocuous information. I think that observation of the atoms passing through the slit is affecting the search space for the other atoms in such a way that we currently do not understand. This observation while seemingly innocuous has a drastic affect on the distribution which would explain why we see such confounding results. It follows the same logic as this other naturally occurring phenomenon so I think its an avenue at least worth exploring.<p>An example of the paradox would be if I told you that my neighbor has 2 children and at least one of them is a boy. If I asked you what the probability that their other child is a girl, normally the result would be 2 / 3, but if I know one child is a boy because I spot him in front of a tree then the odds his other child is a girl drops to 1 / 2.<p>[0]: <a href="https://en.wikipedia.org/wiki/Boy_or_Girl_paradox" rel="nofollow">https://en.wikipedia.org/wiki/Boy_or_Girl_paradox</a>