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[Ether_Snake]

“New opinions are always suspected, and usually opposed, without any other reason but because they are not already common.” ~ John Locke

Of the many counterintuitive features of quantum mechanics, perhaps the most challenging to our notions of common sense is that particles do not have locations until they are observed. This is exactly what the standard view of quantum mechanics, often called the Copenhagen interpretation, asks us to believe. Instead of the clear-cut positions and movements of Newtonian physics, we have a cloud of probabilities described by a mathematical structure known as a wave function. The wave function, meanwhile, evolves over time, its evolution governed by precise rules codified in something called the Schrödinger equation. The mathematics are clear enough; the actual whereabouts of particles, less so. Until a particle is observed, an act that causes the wave function to “collapse,” we can say nothing about its location. Albert Einstein, among others, objected to this idea. As his biographer Abraham Pais wrote: “We often discussed his notions on objective reality. I recall that during one walk Einstein suddenly stopped, turned to me and asked whether I really believed that the moon exists only when I look at it.”

But there’s another view — one that’s been around for almost a century — in which particles really do have precise positions at all times. This alternative view, known as pilot-wave theory or Bohmian mechanics

A very simple but clear explanation of what is actually happening:
https://www.youtube.com/watch?v=rbRVnC92sMs

A short clip showing a bit of the recent experiments on this: https://www.youtube.com/watch?v=fnUBaBdl0Aw Narrated by Morgan Freeman

They have basically recreate (or revealed) the behavior of quantum mechanics, at macro scale, a few years ago.

They have even reproduced the double slit experiment using the silicon droplets, and it shows that particles don't go through "both slits at once" or anything like that; particles are piloted by their own waves and the waves of previous particles. Sometimes that will draw them into one slit, sometimes the other. There is no need for multiverse, or "collapsing the probability function when observed". The particles are not in multiple places at once. Basically, it's all deterministic, and this experiment illustrates how "quantum mechanics" are deterministic.

The differences between Bohm and Copenhagen become clear when we look at the classic “double slit” experiment, in which particles (let’s say electrons) pass through a pair of narrow slits, eventually reaching a screen where each particle can be recorded. When the experiment is carried out, the electrons behave like waves, creating on the screen a particular pattern called an “interference pattern.” Remarkably, this pattern gradually emerges even if the electrons are sent one at a time, suggesting that each electron passes through both slits simultaneously.

Those who embrace the Copenhagen view have come to live with this state of affairs — after all, it’s meaningless to speak of a particle’s position until we measure it. Some physicists are drawn instead to the Many Worlds interpretation of quantum mechanics, in which observers in some universes see the electron go through the left slit, while those in other universes see it go through the right slit — which is fine, if you’re comfortable with an infinite array of unseen universes.

By comparison, the Bohmian view sounds rather tame: The electrons act like actual particles, their velocities at any moment fully determined by the pilot wave, which in turn depends on the wave function. In this view, each electron is like a surfer: It occupies a particular place at every specific moment in time, yet its motion is dictated by the motion of a spread-out wave. Although each electron takes a fully determined path through just one slit, the pilot wave passes through both slits. The end result exactly matches the pattern one sees in standard quantum mechanics.

There are many videos on youtube covering this.
Here is a video of the original experiment, showing the movement of the particles
https://www.youtube.com/watch?v=nmC0ygr08tE

The wikipedia article https://en.wikipedia.org/wiki/Pilot_wave

In theoretical physics, the pilot wave theory was the first known example of a hidden variable theory, presented by Louis de Broglie in 1927. Its more modern version, the de Broglie–Bohm theory, remains a non-mainstream attempt to interpret quantum mechanics as a deterministic theory, avoiding troublesome notions such as wave–particle duality, instantaneous wave function collapse and the paradox of Schrödinger's cat.

The de Broglie–Bohm pilot wave theory is one of several interpretations of quantum mechanics. It uses the same mathematics as other interpretations of quantum mechanics; consequently, it is also supported by the current experimental evidence to the same extent as the other interpretations.

In the 2000s, Couder and colleagues performed experiments[1][2] on hydrodynamic analogs of single-particle quantum systems.[3]

[]

Yves Couder and co-workers in 2010 discovered a macroscopic pilot wave system in the form of walking droplets. This system exhibits behaviour of a pilot wave, heretofore considered to be reserved to microscopic phenomena.

Lucien Hardy[14] and John Stewart Bell[12] have emphasized that in the de Broglie–Bohm picture of quantum mechanics there can exist empty waves, represented by wave functions propagating in space and time but not carrying energy or momentum,[15] and not associated with a particle. The same concept was called ghost waves (or "Gespensterfelder", ghost fields) by Albert Einstein.[15]

A particle can produce a wave that will move forward, but then the particle can be drawn in another direction by another wave, as seen in the double slit experiment with the droplets; the wave will continue through one slit, as the particle goes along with another wave into the other slit. Hence waves can go on without the particle, and subsequently affect other matter.

edit: A great clear explanatory video, which even explains how we are getting the results we get from the double slit experiment deterministically Bohmian Mechanics- An Alternative to Quantum


Edit:


Worth a read: Why don't more physicists subscribe to pilot wave theory?

Added: Standford Encyclopedia of philosophy's article on Bohmian mechanics

 

[The Hermit]

I don't get it

But man, when I die I want a eulogy narrated by Morgan Freeman

 

[DopeyFish]

But this doesn't help me understand why the wave disappears when the particles are observed in double slit

Quantum mechanics shreds my brain.

 

[Ether_Snake]

But this doesn't help me understand why the wave disappears when the particles are observed in double slit

Quantum mechanics shreds my brain.

I guess I should explain things more in the OP.

Did you watch the video? What they show is that we can see how particles behave at a macro scale, as they would at a quantum scale, and the macro results match what we would expect from quantum scale.

So we can see what happens in the double slit experiment by simply filming the silicon droplets as they make their way, and what we see is that there is nothing surprising about how they behave: the particle can be seen moving toward one slit, and sometimes being dragged to the next one by the waves from previous particles or its own. Since we can get the same diffraction pattern while being able to observe the silicon droplets, we can conclude that there is no need to believe that the particles are in multiple places at once until "observed", since the droplets are obviously not.

What it shows instead is that particles are moved by the waves; their own, and the ones resulting from other particles.

Watch this video which explains it very clearly https://www.youtube.com/watch?v=rbRVnC92sMs

The interference pattern occurs simply because the environment allows it

 

[Ether_Snake]

A more recent article on the subject:

New Support for Alternative Quantum View

An experiment claims to have invalidated a decades-old criticism against pilot-wave theory, an alternative formulation of quantum mechanics that avoids the most baffling features of the subatomic universe.

Decided to update the OP completely to be clearer.

And having done a quick search on Google, I'm glad to see I'm not the only one who thinks particle-wave theory could explain why the Em Drive works.

 

[Crayon]

But this doesn't help me understand why the wave disappears when the particles are observed in double slit

Quantum mechanics shreds my brain.

Yeah I'm not getting that part. That's the weird part.

Explanation of the classic conundrum for those who aren't familiar:

https://youtu.be/A9tKncAdlHQ?t=8m13s

 

[LookAtMeGo]

So its a particle and a wave? A wavicle? What aboot when they observe it after the slit and it still acts like a particle?

Im at work, I cant watch the video righ na.

 

[Ether_Snake]

Yeah I'm not getting that part. That's the weird part.

Explanation of the classic conundrum for those who aren't familiar:

https://youtu.be/A9tKncAdlHQ?t=8m13s

So its a particle and a wave? A wavicle? What aboot when they observe it after the slit and it still acts like a particle?

Im at work, I cant watch the video righ na.

The particle is always a particle, but is moved by a wave. So the particle goes through ONE slit, but the wave goes through both. Imagine you pushed a balloon on the water surface; it would go through one or the other slit, but the wave would go through both. In this theory, the wave drives the particle, hence pilot-wave, as shown in the experimental silicon droplet experiment. Since the wave (or wave function) determines where the particle will go, it is in no way surprising that it would behave like a wave even if it's a particle. So that explains the double slit experiment; the particle is always moving in a deterministic fashion, before and after going through the slit. The only reason we get a wave pattern is because, well, a wave is driving the particles! So of course you get a wave pattern after firing a bunch of particles, but no individual particle ever moves in any non-deterministic manner, it's never in two places.

Now you can even imagine many implications that result from this, such as the waves of one particle affecting other particles. This is shown in the experiment when both droplets circle one another. Presumably, a wave can therefore affect another particle even if the particle that was driven by that wave isn't anywhere close, just like the wakes of a boat. This I think will be shown to be occurring with the Em Drive, or in future experiments.

 

[Wolfe]

So basically it's presenting an explanation for the interference pattern itself due to pilot waves? If so seems like an understandable explanation.

I thought this was going to explain the observed/unobserved difference in the slit experiment at first.

Edit: Unless I'm missing something and am mistaken, in which case educate away.

 

[Ether_Snake]

So basically it's presenting an explanation for the interference pattern itself due to pilot waves? If so seems like an understandable explanation.

I thought this was going to explain the observed/unobserved difference in the slit experiment at first.

Edit: Unless I'm missing something and am mistaken, in which case educate away.

There is no observed/unobserved difference, it's outright wrong, the experiment as it is explained is false.

How do we make the observation? We put the detectors in front of the slits, and can see that the particle goes through either slit, right? Well of course, it always did go through only one slit, whether we looked or not.

The interference pattern is the sum of all the previously fired particles hitting a wall, which indicates that the particles must have followed a wave-like path, NOT that they are themselves waves for some time.

Hence, the pilot-wave; the wave drives the particle forward, and the particle follows it along, through a slit, and eventually hits the wall. This happens for each particle fired. But the result on the board will be an interference pattern because what led the particles to the board was the waves. So it is not surprising to have the interference pattern, it is exactly what you would expect to get from waves driving particles forward successively.

Putting a detector ahead of the slits does nothing more than show us where the particle is at that time, and people have been mistakenly saying "oh, so when we look it's not a wave anymore". It never was, they just never looked for the wave itself, they just looked at the result when many particles had hit the wall and concluded that since the result is a wave, the particles must have been waves at some point. They never were, they were particles moved along by waves. There is no difference whether we observe it or not, and hence no "particles are everywhere at once until measured" nonsense, no multiverse, etc. It's just good old deterministic physics.

Now the wave itself, THAT is the interesting part that needs to be looked into, and what the implications are once we factor it into the equation.

 

[archangelmorph]

How does Pilot-Wave theory explain quantum entanglement though?

More specifically where two particles are very very far apart (e.g. other sides of the universe) and yet behave in a highly correlated fashion?

 

[Izayoi]

Bookmarked. Particle physics have always been really interesting, to me. I'd love to learn more about the subject.

 

[Crayon]

Putting a detector ahead of the slits does nothing more than show us where the particle is at that time, and people have been mistakenly saying "oh, so when we look it's not a wave anymore".[/QUOTE]


Putting the detector and observing the result has the curious side effect as well as reporting the slit the particle passes thru. It changes the interference pattern to the two-band pattern.

Like this:

Right? Or...?

 

[G.ZZZ]

The de Broglie-Bohm interpretation has two big issues:

- occam's razor, as it imply the existence of an almost infinite number of variables for each particle which seems wasteful and
- violate the speed limit as all said variables can travel instantly whenever the wave collapse.

No one take it seriously in consideration for good reason, and the thing has been around for almost one hundred years. It seems just obstination from people that can't accept the probabilistic aspect of reality.

 

[Crayon]

It seems just obstination from people that can't accept the probabilistic aspect of reality.

I was getting that vibe myself. From the language being used.

 

[Ether_Snake]

How does Pilot-Wave theory explain quantum entanglement though?

More specifically where two particles are very very far apart (e.g. other sides of the universe) and yet behave in a highly correlated fashion?

I don't have an answer, but I don't see how it would explain it any worst than the Copenhagen-view of QM. Pilot-wave theory gives us the same results as QM does, except it doesn't need far-fetched explanations.

Here a wiki link that sheds some light on what the answer might be: https://en.wikipedia.org/wiki/De_Br...aradox.2C_Bell.27s_theorem.2C_and_nonlocality

Alain Aspect performed a series of Bell test experiments that test Bell's inequality using an EPR-type setup. Aspect's results show experimentally that Bell's inequality is in fact violated—meaning that the relevant quantum mechanical predictions are correct. In these Bell test experiments, entangled pairs of particles are created; the particles are separated, traveling to remote measuring apparatus. The orientation of the measuring apparatus can be changed while the particles are in flight, demonstrating the apparent nonlocality of the effect.

The de Broglie–Bohm theory makes the same (empirically correct) predictions for the Bell test experiments as ordinary quantum mechanics. It is able to do this because it is manifestly nonlocal. It is often criticized or rejected based on this; Bell's attitude was: "It is a merit of the de Broglie–Bohm version to bring this [nonlocality] out so explicitly that it cannot be ignored."[50]

The de Broglie–Bohm theory describes the physics in the Bell test experiments as follows: to understand the evolution of the particles, we need to set up a wave equation for both particles; the orientation of the apparatus affects the wavefunction. The particles in the experiment follow the guidance of the wavefunction. It is the wavefunction that carries the faster-than-light effect of changing the orientation of the apparatus. An analysis of exactly what kind of nonlocality is present and how it is compatible with relativity can be found in Maudlin.[51] Note that in Bell's work, and in more detail in Maudlin's work, it is shown that the nonlocality does not allow for signaling at speeds faster than light.

 

[Amir0x]

The de Broglie-Bohm interpretation has two big issues:

- occam's razor, as it imply the existence of an almost infinite number of variables for each particle which seems wasteful and
- violate the speed limit as all said variables can travel instantly whenever the wave collapse.

No one take it seriously in consideration for good reason, and the thing has been around for almost one hundred years. It seems just obstination from people that can't accept the probabilistic aspect of reality.

Seriously. There's a reason the pilot-wave interpretation is considered fringe bullshit science at this point. Virtually no prominent scientists hold to it anymore due to the preponderance of evidence.

And evidence, such as it is, isn't going to go away because the implications make us uncomfortable. The Universe is what it is.

 

[Ether_Snake]

Putting the detector and observing the result has the curious side effect as well as reporting the slit the particle passes thru. It changes the interference pattern to the two-band pattern.

Like this:

Right? Or...?

No, the experiment works like this:

Well, we can do one more experiment: this time, we shoot electrons one-at-a-time at this wall, but at each slit, we shine a bit of light, and detect which slit the electron goes through. As each electron is fired, one (but never both) of the detectors goes off, telling you which slit the electron went through. But — and here’s the crazy part — the pattern on the screen now shows no interference, and instead we just get two separate peaks corresponding to the two “classical”, particle-like paths the electrons could have taken.

The "detector" is affecting the wave-function. Same reason you won't get an interference pattern if you close one of the two slits, which is also explained in the video I posted: the path is not a straight line just because you shut one of the two slits, it's just significantly altered to the point where it narrows the wave to the point where you won't get an interference pattern.

Seriously. There's a reason the pilot-wave interpretation is considered fringe bullshit science at this point. Virtually no prominent scientists hold to it anymore due to the preponderance of evidence.

And evidence, such as it is, isn't going to go away because the implications make us uncomfortable. The Universe is what it is.

First of all, you are basically saying that many prominent physicists currently investigating the theory are crackpots. If it was some cookoo stuff, the wiki article would say so it, it doesn't. https://en.wikipedia.org/wiki/Pilot_wave

The pilot wave theory shows that it is possible to have a realistic and deterministic hidden variable theory, which reproduces the experimental results of ordinary quantum mechanics.

You're saying that Yves Couder (and the MIT more recently) were wasting their time with the silicon droplet experiment and that the conclusions are meaningless.

The Pilot wave theory, also known as the de Broglie-Bohm Wave theory, or the causal interpretation, was one of the many interpretations of quantum mechanics in its early stages of conception and development. It was initially proposed by Louis de Broglie in his 1927 paper "Wave Mechanics and the Atomic Structure of Matter and Radiation", although this had been done only for a single particle. This theory was later developed by David Bohm. The theory suggests that all particles in motion are actually borne on a wave-like motion, similar to how an object moves on a tide. In this theory, it is the evolution of the carrier wave that is given by the Schrödinger equation. It is a deterministic theory and is entirely nonlocal.

It is an example of a hidden variable theory, and all non-relativistic quantum mechanics can be accounted for in this theory. The theory was abandoned by de Broglie in 1932, and it gave way to the Copenhagen interpretation. The Copenhagen interpretation does not use the concept of the carrier wave or that a particle moves in definite paths until measurement is made. The Copenhagen Interpretation has stood the test of time as the widely accepted interpretation of Quantum Theory since then.

However, an experiment conducted by Yves Couder and Emmanuel Fort, physicists at the Université Paris Diderot in 2006, involved millimeter scale fluid droplets. The droplets bounced up and down on a vibrated fluid bath. The experiment has revived the debate on the correct interpretation and formalism of quantum mechanics. Moreover, it is now considered that more experiments similar to Couder's can actually shed some light on the peculiar results of the Quantum theory.

And more recently: Pilot-Wave theory gains experimental support

Nearly a quarter-century later, a group of scientists has carried out an experiment in a Toronto laboratory that aims to test this idea. And if their results, first reported earlier this year, hold up to scrutiny, the Bohmian view of quantum mechanics — less fuzzy but in some ways more strange than the traditional view — may be poised for a comeback.

The paper it refers to in question:

Experimental nonlocal and surreal Bohmian trajectories

Dylan H. Mahler1,2,*, Lee Rozema1,2, Kent Fisher3, Lydia Vermeyden3, Kevin J. Resch3, Howard M. Wiseman4,* and Aephraim Steinberg1,2

Abstract

Weak measurement allows one to empirically determine a set of average trajectories for an ensemble of quantum particles. However, when two particles are entangled, the trajectories of the first particle can depend nonlocally on the position of the second particle. Moreover, the theory describing these trajectories, called Bohmian mechanics, predicts trajectories that were at first deemed “surreal” when the second particle is used to probe the position of the first particle. We entangle two photons and determine a set of Bohmian trajectories for one of them using weak measurements and postselection. We show that the trajectories seem surreal only if one ignores their manifest nonlocality.

The theory is increasingly gaining attention, not from crazy people either.

 

[bobbytkc]

No, the experiment works like this:



The "detector" is affecting the wave-function. Same reason you won't get an interference pattern if you close one of the two slits, which is also explained in the video I posted: the path is not a straight line just because you shut one of the two slits, it's just significantly altered to the point where it narrows the wave to the point where you won't get an interference pattern.



First of all, you are basically saying that many prominent physicists currently investigating the theory are crackpots. If it was some cookoo stuff, the wiki article would say so it, it doesn't. https://en.wikipedia.org/wiki/Pilot_wave



You're saying that Yves Couder (and the MIT more recently) were wasting their time with the silicon droplet experiment and that the conclusions are meaningless.



And more recently: Pilot-Wave theory gains experimental support

Nearly a quarter-century later, a group of scientists has carried out an experiment in a Toronto laboratory that aims to test this idea. And if their results, first reported earlier this year, hold up to scrutiny, the Bohmian view of quantum mechanics — less fuzzy but in some ways more strange than the traditional view — may be poised for a comeback.

The paper it refers to in question:

Experimental nonlocal and surreal Bohmian trajectories

Dylan H. Mahler1,2,*, Lee Rozema1,2, Kent Fisher3, Lydia Vermeyden3, Kevin J. Resch3, Howard M. Wiseman4,* and Aephraim Steinberg1,2



The theory is increasingly gaining attention, not from crazy people either.

The whole exercise is pointless because they didnt make any new predictions. Every single prediction of the pilot wave theory can be made using the Copenhagen interpretation and vice versa.When 2 theories make the same predictions, they are effectively the same theory. Which one you choose is basically not a reflection of reality and more of a personal preference.

 

[DopeyFish]

But didn't one experiment say they left the detectors on the slits but just the act of collecting the data caused the wave to disappear? If they didn't collect the data, the particles started acting like waves again.

That's what messes with my head

 

[DevilDog]

IMO science is what works, not necessairily the truth.

The "detector" is affecting the wave-function.

In what manner? Do they know anything about this Quantum Force yet, or are they still in the process of uncovering it?
Does the equation show what happens if light is involved?

 

[Ether_Snake]

The whole exercise is pointless because they didnt make any new predictions. Every single prediction of the pilot wave theory can be made using the Copenhagen interpretation and vice versa.When 2 theories make the same predictions, they are effectively the same theory. Which one you choose is basically not a reflection of reality and more of a personal preference.

Maybe if we just accepted things as they are without question, but that is changing.

Fluid Tests Hint at Concrete Quantum Reality

Particles at the quantum scale seem to do things that human-scale objects do not do. They can tunnel through barriers, spontaneously arise or annihilate, and occupy discrete energy levels. This new body of research reveals that oil droplets, when guided by pilot waves, also exhibit these quantum-like features.

To some researchers, the experiments suggest that quantum objects are as definite as droplets, and that they too are guided by pilot waves — in this case, fluid-like undulations in space and time. These arguments have injected new life into a deterministic (as opposed to probabilistic) theory of the microscopic world first proposed, and rejected, at the birth of quantum mechanics.

“This is a classical system that exhibits behavior that people previously thought was exclusive to the quantum realm, and we can say why,” said John Bush, a professor of applied mathematics at the Massachusetts Institute of Technology who has led several recent bouncing-droplet experiments. “The more things we understand and can provide a physical rationale for, the more difficult it will be to defend the ‘quantum mechanics is magic’ perspective.”

By taking the possibility that the pilot-wave is real, it is opening the doors to shed more light on what might really be happening at the quantum level, and will open the door to new experiments. This is happening, the research has been picking up pace over the past ten years.

Some physicists now disagree. “Quantum mechanics is very successful; nobody’s claiming that it’s wrong,” said Paul Milewski, a professor of mathematics at the University of Bath in England who has devised computer models of bouncing-droplet dynamics. “What we believe is that there may be, in fact, some more fundamental reason why [quantum mechanics] looks the way it does.”

 

[bobbytkc]

Maybe if we just accepted things as they are without question, but that is changing.

Fluid Tests Hint at Concrete Quantum Reality



By taking the possibility that the pilot-wave is real, it is opening the doors to shed more light on what might really be happening at the quantum level, and will open the door to new experiments. This is happening, the research has been picking up pace over the past ten years.

You keep repeating this experiment, but it makes not a single new prediction. None.

 

[Crayon]

But didn't one experiment say they left the detectors on the slits but just the act of collecting the data caused the wave to disappear? If they didn't collect the data, the particles started acting like waves again.

That's what messes with my head

I've talked to other people that deny that happens at all. It's like he-said she-said. It's a repeatable experiment. I wish I could see someone actually doing it instead of the common illustration.

 

[Ether_Snake]

IMO science is what works, not necessairily the truth.



In what manner? Do they know anything about this Quantum Force yet, or are they still in the process of uncovering it?
Does the equation show what happens if light is involved?

No idea, but like I said all aspects of the double slit experiment were reproduced at macro, observable (and filmed ) scale.

In a groundbreaking experiment, the Paris researchers used the droplet setup to demonstrate single- and double-slit interference. They discovered that when a droplet bounces toward a pair of openings in a damlike barrier, it passes through only one slit or the other, while the pilot wave passes through both. Repeated trials show that the overlapping wavefronts of the pilot wave steer the droplets to certain places and never to locations in between — an apparent replication of the interference pattern in the quantum double-slit experiment that Feynman described as “impossible … to explain in any classical way.” And just as measuring the trajectories of particles seems to “collapse” their simultaneous realities, disturbing the pilot wave in the bouncing-droplet experiment destroys the interference pattern.

Droplets can also seem to “tunnel” through barriers, orbit each other in stable “bound states,” and exhibit properties analogous to quantum spin and electromagnetic attraction. When confined to circular areas called corrals, they form concentric rings analogous to the standing waves generated by electrons in quantum corrals. They even annihilate with subsurface bubbles, an effect reminiscent of the mutual destruction of matter and antimatter particles.

So you get the same result, without any magic, purely in a typical deterministic way.

You keep repeating this experiment, but it makes not a single new prediction. None.

What the experiment shows is that there is no need for any of the usual explanations to explain the outcome of the double slit experiment and instead the same old laws that determine how a tennis ball would move could explain it all.

 

[Amir0x]

N

First of all, you are basically saying that many prominent physicists currently investigating the theory are crackpots. If it was some cookoo stuff, the wiki article would say so it, it doesn't. https://en.wikipedia.org/wiki/Pilot_wave

You're saying that Yves Couder (and the MIT more recently) were wasting their time with the silicon droplet experiment and that the conclusions are meaningless.

Did you seriously just argue "wikipedia proves it's not cookoo"? I mean, Christ, it may well not be cookoo, but wikipedia ain't gonna be the thing that demonstrates this "fact." Come on.

And you can't prove things are "crackpot" (and btw, I'll drop the loaded terms if it makes this easier: science wouldn't exist without the whole process which includes testing competing theories to find which reflects nature, and so it is a necessary component to the Scientific process. Therefore we don't even need to use anything but "incorrect") without having experimental evidence to kill such theories. Plenty of experiments disprove the pilot-wave theory. And if no credible scientists attempted to test those theories, then we really would just be absent truth. Just because credible physicists are testing things in a widely discredited theory, does not mean they actually believe the theory they are testing is credible itself. They can just as easily be performing the experiment while believing that it will kill yet another argument for said theory.

So no, I'm not saying it's a waste of time to test predictions in the pilot-wave theory or whatever theory someone has that may not be widely accepted. Because provided these predictions and theories are testable, it can be yet another door we close so we have a clearer picture of what reality really is. There's always value in that.

It doesn't change that the vast, vast majority of the scientific community has widely discredited the pilot-wave theory due to endless experimental data killing components of its theory. Because credible scientists have tested it. If they didn't, then this would be more of a question.

 

[Ether_Snake]

Did you seriously just argue "wikipedia proves it's not cookoo"? I mean, Christ, it may well not be cookoo, but wikipedia ain't gonna be the thing that demonstrates this "fact." Come on.

And you can't prove things are "crackpot" (and btw, I'll drop the loaded terms if it makes this easier: science wouldn't exist without the whole process which includes testing competing theories to find which reflects nature, and so it is a necessary component to the Scientific process. Therefore we don't even need to use anything but "incorrect") without having experimental evidence to kill such theories. Plenty of experiments disprove the pilot-wave theory. And if no credible scientists attempted to test those theories, then we really would just be absent truth. Just because credible physicists are testing things in a widely discredited theory, does not mean they actually believe the theory they are testing is credible itself. They can just as easily be performing the experiment while believing that it will kill yet another argument for said theory.

So no, I'm not saying it's a waste of time to test predictions in the pilot-wave theory or whatever theory someone has that may not be widely accepted. Because provided these predictions and theories are testable, it can be yet another door we close so we have a clearer picture of what reality really is. There's always value in that.

It doesn't change that the vast, vast majority of the scientific community has widely discredited the pilot-wave theory due to endless experimental data killing components of its theory. Because credible scientists have tested it. If they didn't, then this would be more of a question.

Not at all, it was disregarded early on based on points which were later found to be incorrect, and by then the copenhagen view had been widely accepted. I'll post some quotes tomorrow that say as much, from physicist /MIT folks.

It has certainly not been proven wrong at all, it in facts gives us the same expected results that you would expect from QM.

 

[Oblivion]

Wait, Newtonian physics don't jibe when objects are under high speed? I thought Newtonian physics work in every instance with the exception of quantum mechanics? At least, that's what one of my old physics professors in college claimed.

 

[Chichikov]

Wait, Newtonian physics don't jibe when objects are under high speed? I thought Newtonian physics work in every instance with the exception of quantum mechanics? At least, that's what one of my old physics professors in college claimed.

Newtonian physics is an approximation of special relativity.
A very good one at speeds that are significantly lower than the speed of light, but an approximation nonetheless.

Consider momentum, in Einstein's theory it's
p=mv/sqrt(1-v^2/c^2)

in "normal" speeds v^2/c^2≈0 and therefore p≈mv (which is the newtonian physics definition)

Not at all, it was disregarded early on based on points which were later found to be incorrect, and by then the copenhagen view had been widely accepted. I'll post some quotes tomorrow that say as much, from physicist /MIT folks.

It has certainly not been proven wrong at all, it in facts gives us the same expected results that you would expect from QM.

That's at best part of it.
One of the main criticisms of the De Broglie–Bohm theory is that it seem driven by a desire to reach a specific conclusion - in this case a deterministic universe, rather than a neutral attempt to explain our observed world.
It doesn't mean that it's wrong mind you, and as I'm sure you know, we still haven't been really able to form an experiment that would prove or falsify those interpretations. It should also be noted that as far as making verifiable predictions based on QM, the interpretations don't matter that much (or at all).

With all of that being said, the De Broglie–Bohm interpretation is still considered a rather fringe theory and I don't see that experiment change that in any real way.

 

[KDR_11k]

The Morgan Freeman video certainly makes it sound crackpot ("renegade scientists"?).

I'm not certain how the pilot wave collapse works at a distance, could you make a measurement so that only one slit's pilot wave collapses and the other's remains intact to create a weird interference pattern?

 

[infinitys_7th]

I see a thinly veiled implication behind this pilot-wave theory that determinism is better than probabilistic collapse.

Why is that preferable/more elegant exactly?

 

[ibyea]

It's still too early to root for pilot wave theory (or heck, any interpretation). Not only can one not tell the difference between pilot wave and other interpretations, pilot wave also has its own "magical" aspect to it, which is its complete non locality. Basically, it's a pick your poison situation, determinism or locality, not both. Furthermore why complicate the math when it gives no further benefit since it gives the same result anyways without being reconcilable with relativity? In fact, how would you make a wave guide version of quantum field theory? Honestly until there is a way to tell the difference, I wouldn't worry about it. The silicon drop experiment is pretty cool though.

 

[Nabbis]

I see a thinly veiled implication behind this pilot-wave theory that determinism is better than probabilistic collapse.

Why is that preferable/more elegant exactly?

People who deal with logical constructs their whole life don't like spooky things.

 

[cooltrainer]

That silicon drop experiment is pretty cool, I wonder if you could do something similar at home? It's a pretty neat visual model for how electrons behave even if a lot of things are probably different. They seemed like they paired up nicely and I always had a hard time understanding why electron pairs were more stable.

 

[Koren]

the particle can be seen moving toward one slit, and sometimes being dragged to the next one by the waves from previous particles or its own.

I think there's an interesting point here... The difference between "previous particles" and "its own" is... HUGE.

If it is influenced by previous particles, the rate of the particle emission should have an impact on the result, and if you're doing the double-slit experiment in both directions at the same time, and/or possibly with different angles, you could get different results.

That's a pretty "easy" experiment to do, no?


If its its own, that's more interesting, I'd say. But it may be totally impossible to see a difference between this and quantum mechanics, except maybe in specific decoherence problems.

I'd say both theories could be true, because if they predict the exact same things, there's not really one that is more "right". I'm not convinced there's a theorical "right" for nature laws, anyway. But I suppose that they should predict slightly different things, and that's were the really interesting things are.


Also, the same, important, question remain: at what speed this wave travel? How is it linked to relativity?

 

[Mr.Ock]

I'm just an amateur, but can this theory explain the Casimir effect, for example?

 

[cyberheater]

Yeah. So when you close the other slit the particles that got through the first slit goes though a different path because the magical pilot wave is somehow different.

Yeah. That sounds a lot better then what we had before.

 

[Gallbaro]

Yeah. So when you close the other slit the particles that got through the first slit goes though a different path because the magical pilot wave is somehow different.

Yeah. That sounds a lot better then what we had before.

As someone who works in RF, the effects of different propagation paths is something I see daily.

 

[Ether_Snake]

I think there's an interesting point here... The difference between "previous particles" and "its own" is... HUGE.

If it is influenced by previous particles, the rate of the particle emission should have an impact on the result, and if you're doing the double-slit experiment in both directions at the same time, and/or possibly with different angles, you could get different results.

That's a pretty "easy" experiment to do, no?

Others could explain it much better than me. The wave drives the particle, and all waves are "past waves" (be it from itself, or other particles, there is no such thing as a wave that forms before the droplet bounce, at least in these experiments) and they affect the particle's future movement. Again, you can easily see this at a macro scale, so it's not very difficult to understand.

Here a quote on this subject, but the actual research papers are more in depth regarding this:

In these droplet tests, the droplet follows a chaotic path that reveals the statistical distribution in the macroscopic fluid system is the same as expected of particles at the quantum scale. But rather than resulting from spooky or mysterious uncertainty these quantum-like effects are driven by “path memory.” Every bounce of the droplet leaves ripples, and these ripples deterministically influence the droplet’s future bounces and lead to quantum-like statistical outcomes.

The more path memory develops the more precise and quantum-like the statistics become. “Memory generates chaos, which we need to get the right probabilities,” Couder explained. “We see path memory clearly in our system. It doesn’t necessarily mean it exists in quantum objects, it just suggests it would be possible.”

And I found a video that illustrates this differently than the vid posted in the OP. That's not what the subject of the video is, but I think it offers a nice visual representation of how past waves influence the future path of the particle.

Yeah. So when you close the other slit the particles that got through the first slit goes though a different path because the magical pilot wave is somehow different.

Yeah. That sounds a lot better then what we had before.

Maybe if you word it in a way that makes it sound dumb, but physics explain it pretty well, and you can reproduce this in a bath tub with a floating duckie.

You have two openings, and waves emitted from a source; if you close one of the two openings, the wave that goes through the open slit is DEFINITLY still affected by the wave that doesn't go through that slit. That's something you can easily observe at a macro scale. So closing one slit, or changing its scale, or anything you do really, affects the wave function and hence affects where the particles that are fire through the opened slit will go, and that is perfectly normal and expected. I don't know why you would object to that when QM doesn't.

 

[twobear]

The de Broglie-Bohm interpretation has two big issues:

- occam's razor, as it imply the existence of an almost infinite number of variables for each particle which seems wasteful and
- violate the speed limit as all said variables can travel instantly whenever the wave collapse.

No one take it seriously in consideration for good reason, and the thing has been around for almost one hundred years. It seems just obstination from people that can't accept the probabilistic aspect of reality.

the second one (non-locality) is already part of quantum mechanics (highlighted by e.g. bell's theorem); de-broglie bohm just makes it more 'obvious' that quantum mechanics is non-local.

the bigger problem as i understand it is extending the theory to relativistic settings and building a quantum field theory out if it.

Newtonian physics is an approximation of special relativity.
A very good one at speeds that are significantly lower than the speed of light, but an approximation nonetheless.

Consider momentum, in Einstein's theory it's
p=mv/sqrt(1-v^2/c^2)

in "normal" speeds v^2/c^2≈0 and therefore p≈mv (which is the newtonian physics definition)

to add to this, Newton's mechanics also fail to accurately describe the very massive (give or take the mass of the sun), where the General theory of relativity is needed to accurately describe gravitational phenomena.

 

[Just_myles]

If that is the case, doesn't this in a sense debunk quantum computing? Anyone know this scienceGAF?

 

[Ether_Snake]

If that is the case, doesn't this in a sense debunk quantum computing? Anyone know this scienceGAF?

I'm not sure, I wondered the same, but I assume not since no article about pilot-wave that I read said so, and you'd think they would. Instead, what you expect from QM is still present if you consider PW true, so I don't think it would invalidate it. But I don't really know how a quantum computer works, so I have no idea.

edit: Googling shows some results relating to this. http://arxiv.org/abs/1012.4843

Formulations of quantum computing have traditionally been made in orthodox (Copenhagen) and sometimes many-worlds quantum mechanics. We will aim to understand quantum computing in terms of de Broglie-Bohm Pilot-Wave Theory by considering different simple systems that may function as a basic quantum computer. We will provide a careful discussion of Pilot-Wave Theory and evaluate criticisms of the theory. We will assess claims regarding what causes the exponential speed-up in the light of our analysis and the fact that Pilot-Wave Theory is perfectly able to account for the phenomena involved in quantum computing.

 

[Joyful]

So you're saying I have no free will

 

[iamblades]

the second one (non-locality) is already part of quantum mechanics (highlighted by e.g. bell's theorem); de-broglie bohm just makes it more 'obvious' that quantum mechanics is non-local.

the bigger problem as i understand it is extending the theory to relativistic settings and building a quantum field theory out if it.


to add to this, Newton's mechanics also fail to accurately describe the very massive (give or take the mass of the sun), where the General theory of relativity is needed to accurately describe gravitational phenomena.

There are local and non-local interpretations, there are deterministic and non-deterministic, real and unreal(WRT wave function), hidden variables or not, because no matter what something has to go to make something as strange as quantum mechanics fit in with our classical intuitions.

As long as the math(which is way over my head ) works out in the end, all of the interpretation stuff is just fun to think about.


For me the many worlds interpretation makes the most sense, which is both deterministic and local, doesn't have hidden variables or a causal observer role.

But until we further develop these interpretations into actual testable theories(or develop the technology to test them in some cases)...

 

[KDR_11k]

If that is the case, doesn't this in a sense debunk quantum computing? Anyone know this scienceGAF?

Quantum Computers exist, any theory has to be compatible with them or fails immediately.

Though I do wonder: What does this mean for quantum randomness? If the wave collapse doesn't randomly place the particle but just reveals the position it held all along is it still just as random?

OTOH I guess the pilot wave model makes exactly the same predictions as the Copenhagen model in every single situation, that's why we cannot tell which is correct?

 

[Ether_Snake]

OTOH I guess the pilot wave model makes exactly the same predictions as the Copenhagen model in every single situation, that's why we cannot tell which is correct?

For now that's that. Reading on quantum computers, found a good answer here:

Some people feel more comfortable using a different language for the same phenomenon, and that's perfectly valid. In case of programming languages I prefer Python for most of my work, even though I also "talk" C, C++, VBA, VHDL and Verilog (and can pick up the basics of pretty much any other language that I have to adopt for whatever reason). All of these languages are essentially describing the same computational domain. For the context of quantum computing the basic representations of QM (including all of its interpretations) are all low level assembly languages. To the best of my knowledge there is, so far, little progress in defining a formalism that allows non-experts to do quantum computations. That, however, is one of the major theoretical hurdles for quantum computing: how do we let ordinary programmers write software for these systems? After all, programmers of classical computers are not required to be computer architects and to write their own compilers either. If they had to, classical computing would still be in the stone ages of the 1950s.

So there could be an advantage to use the PWT in quantum computing, as in, to make it easier to program for.

For your other questions, found some paper on the subject Origin of quantum randomness in the pilot wave quantum mechanics

And a great reply here to Why don't more physicists subscribe to pilot wave theory?. Added to the OP.

 

[LoveCake]

The easiest guide I have found on this is Dr Quantum - Double Slit Experiment for something more in-depth The Quantum Experiment that Broke Reality | Space Time | PBS Digital Studios

It is the part about observing the particle that changes the path that always gets me.

 

[twobear]

There are local and non-local interpretations, there are deterministic and non-deterministic, real and unreal(WRT wave function), hidden variables or not, because no matter what something has to go to make something as strange as quantum mechanics fit in with our classical intuitions.

As long as the math(which is way over my head ) works out in the end, all of the interpretation stuff is just fun to think about.


For me the many worlds interpretation makes the most sense, which is both deterministic and local, doesn't have hidden variables or a causal observer role.

But until we further develop these interpretations into actual testable theories(or develop the technology to test them in some cases)

yeah, sorry, i should have said, copenhagen ('standard') quantum mechanics is already nonlocal.

 

[Khaz]

I don't know if this hypothesis is correct or not, but I always thought using randomness in physics was a cheap cop-out. Like even though you can't predict when a single particle will decay, they do and in a statistically very predictable way. It just means that there is an underlying mechanism we don't know about.

[edit] apparently, maths says a number cannot be proven to be random. It means that a suite has to be considered random until proven otherwise, null-hypothesis etc. it doesn't say that randomness cannot exist, just that we can push forward eliminating randomness up to... infinity I guess?

______


In order to understand folk quantum theory (the one that use pretty pictures and none of that scary maths), I had painted in my mind the idea that a particle behaved a bit like a ghost, as dense as it is compressed: when left alone it floats in an ethereal manner, with a low density and a large volume that allows it to pass through both slits and the disturbance induced in doing so would make waves in the cloud and make it interacts with itself; when observed/poked it contracts to a single dense point in space that can bounce around. Probably not the greatest explanation, but it seemed coherent enough.

 

[Stinkles]

Worth a read: Why don't more physicists subscribe to pilot wave theory?

Was really interesting, but Occam's razor tells me my lack of full comprehension and the near-absolute rejection of the pilot wave theory, mean there's probably a lot more to it than just "Oh Heisenberg and those jerks were first, otherwise Pilot Wave would be the primary theory..."