Quantum Physics: I need some sanity here x_x

[Tez]

Sorry, was in Iran the last couple of weeks, and had a complete laptop crash while there. Spent the last couple of days I've been back recovering. Before I did lose the laptop I found JREF wasnt blocked from there which was good (in fact no western news source semed to be either).

Here's just some quick questions that only need one-word answers. Please don't spend time typing up much more than that. This kind of discussion can time-consuming and we won't change each other's viewpoints, I am sure of that, as we didn't the times before.

So, doesn't the collapse approach add nonsensical negative probabilities to the theory?

No. This tells me you dont know the math at all behind what youre saying. Which makes answering anything else you say probably pointless. Care to back up your claim with an equation?

Now that'd be some good, necessary mathematics right there if it does. It certainly adds the paradoxes of faster-than-light and backwards-in-time effects to violate special relativity and apparent causality.

Where the hell are you getting this nonsense? One of the most amazing things of non-relativistic QM is that it doesn't violate these things despite its nonlocality. Understanding why is presumably a deep insight we've failed to achieve. Care to explicitly back up your claim with an equation?

I have no clue what you were trying to get at with the next bit of your examples/questions. If you can phrase a clearer question I will try and answer.

I have to assume these quantum computer scientists are aware that what you throw away with a collapse approach can come back to haunt what is kept if something is small enough and isolated enough? The collapsed state would then fail to be "the correct state" if the mathematics don't describe all that can cause later effects. Von Neumann wasn't waving his hands around with that one.

Unbelievable. I'm through arguing with you until you demonstrate you actually understand some of the math behind QM. Everything in the above paragraph is based on a complete misconception of how collapse works in quantum mechanics.

Yeah, and Bohr never understood EPR either, Einstein forgot general relativity in an argument against QM, Feynman misunderstood the fundamentals of calculus, and so on. Who knows, maybe even von Neumann did hand-waving consciousness arguments?

For the record, in case anyone is actually interested, I think it is clear Bohr misunderstood Einstein's steering arguments (which pre and post dated EPR), but did understand the EPR paper. His response to EPR does not work with the other arguments, as many, many people have pointed out. Somehow there is this mythology built around EPR that Bohr answered everything Einstein came up with. But with a lot of these discussions, such as the photon in a box thing was written many years later by Bohr, and do not concord with Einsteins correspondence of the time.

e.g For the photon in a box, at that time (similar time to EPR paper) in letters to people what he was saying was "look, after the photon has gone I can choose either to weigh the box, and therefore determine the color of the photon (which is by now far away) or I can measure its time of exit (which determines its spatial location - so for instance when it would hit a remote mirror). That seemed like a paradox to Einstein, for whom the color of a photon and its temporal location should both have been physically real, and therefore how could his observations on the box suddenly seemed to affect the physical properties of the remote photon. (Note this has nothing to do with challenging the uncertainty principle, nor did he "forget" general relativity, which is not actually needed anyway because gravitational time dilation is derivable without full GR from Newtonian potential considerations).

Its a beautiful "paradox" from which anyone can learn a lot about quantum mechanics.

Read some of Don Howard's (historian/philosopher at Pittsburg) papers for several nice pedagogical discussion of such things.

Regarding people borrowing my idea: Its certainly true someone could. In fact I've discussed it with several well known people, and made some notes which have been emailed around, which is some protection I guess (though also more of a risk - I certainly lost one semi-important idea this way). At the moment I see it as simply a mathematical curiosity I'll eventually flesh out (when I find an unwary student!) into something maybe even useful.

 

[wipeout]

I knew your response would be aggressive and dismissive.

After all, you were dismissive of Murray Gell-Mann, a Nobel laureate, for his lack of understanding of EPR, the famous spin version of which was thought up by his close friend and discussion partner of that time, David Bohm.

You, of course, know better than him about that so you would, of course, obviously dismiss me too on similar issues.

I didn't understand what Gell-Mann meant either at first. But I didn't dismiss it. I studied it.

And now I understand.

He sure could do a much better job of explaining it, I'd agree, if that was raised.

But yes, I can find the equations, draw diagrams to explain the experimental set-up, point to the books, and so forth.

I was actually surprised you even asked, I had genuinely assumed you would recognise many of the points, perhaps all. The aim of my post was for you to agree on the flaws, not to point them out.

But since you don't recognise what I refer to, I'd rather have you not know.

Dismiss me. You know you are right to. Oh wait, you already did. Good.

 

[wipeout]

[Edit: double post]

 

[Dancing David]

Here's just some quick questions that only need one-word answers. Please don't spend time typing up much more than that. This kind of discussion can time-consuming and we won't change each other's viewpoints, I am sure of that, as we didn't the times before.

So, doesn't the collapse approach add nonsensical negative probabilities to the theory? Now that'd be some good, necessary mathematics right there if it does. It certainly adds the paradoxes of faster-than-light and backwards-in-time effects to violate special relativity and apparent causality.

The equations remain wave forms before and after the collapse, the 'collapse' is a semantic issue not a reality issue. Particles are waves and remain waves even after the intersectional 'collapse'.

The violations I am not so sure of, the faster than light issue is usually a product of HIP, at least in recent experiments. The apparent causality I couldn't answer.

Ok, here's any isolated system or even the universe. Can the collapse approach predict anything using collapse by an observation without getting into the paradox of outside observation of something you can't be outside of?

'Collapse' is the intersection of wave sets. the collapse is an artifact of semantics. At large scales the quantum effect is not a problem, HIP applies at very small scales. The waveforms of large objects are very predictable?

But that's easy for the collapse approach. So let's go the other way. You start with a collapsed state of any system, maybe even the universe.

the waves do not suddenly become particles, they remain waves throughout, they can be constrained somewhat but they don't 'collapse'. they intersect as a data point fuzzed up by HIP.

Can the collapse approach now retrodict anything that happened before the collapse? Anything in the prior history of system or even the universe? Or is it entirely unable to "uncollapse" and say anything about the past without adding human knowledge of that past external to the theory?

I am not sure that systems the size you are discussing are governed by QM weirdness. I don't believe that waveforms carry out a propagation that would have meaning without knowing the intersectional points and parameters.

I have to assume these quantum computer scientists are aware that what you throw away with a collapse approach can come back to haunt what is kept if something is small enough and isolated enough? The collapsed state would then fail to be "the correct state" if the mathematics don't describe all that can cause later effects. Von Neumann wasn't waving his hands around with that one.



Yeah, and Bohr never understood EPR either, Einstein forgot general relativity in an argument against QM, Feynman misunderstood the fundamentals of calculus, and so on. Who knows, maybe even von Neumann did hand-waving consciousness arguments? Of course, someone pointing that out would be well aware that even the most brilliant can screw up.

I was pointing out that 3point14's understanding was more than fine.

I hope you make progress with your ideas, by the way. I am a little surprised you would risk anyone "borrowing" any idea by talking of it in a forum.

 

[wipeout]

The equations remain wave forms before and after the collapse, the 'collapse' is a semantic issue not a reality issue. Particles are waves and remain waves even after the intersectional 'collapse'.

The violations I am not so sure of, the faster than light issue is usually a product of HIP, at least in recent experiments. The apparent causality I couldn't answer.

People, quite naturally, try apply classical thinking to the EPR result at some point up to and including detection and this application leads then to the seeming appearance of nonlocal effects, negative probabilities or both combined. Talk turns to these faster-than-light effects, the future deciding the past and so on. Others may differ, but I don't think this is a good thing if we can avoid thinking along those lines.

'Collapse' is the intersection of wave sets. the collapse is an artifact of semantics. At large scales the quantum effect is not a problem, HIP applies at very small scales. The waveforms of large objects are very predictable?

I am sure you see like many that needing an observer performing measurements outside the system being studied is never more clearly shown to be inadequate as an interpretation of quantum mechanics than when that system being studied is the universe itself, particularly since the problem that observation was added to solve then spreads to the observer and so remains unsolved.

the waves do not suddenly become particles, they remain waves throughout, they can be constrained somewhat but they don't 'collapse'. they intersect as a data point fuzzed up by HIP.

Talking of the past with a collapse approach that throws away unrealised alternatives will be somewhat harder than another interpretation in which they are always present but hidden.

I am not sure that systems the size you are discussing are governed by QM weirdness. I don't believe that waveforms carry out a propagation that would have meaning without knowing the intersectional points and parameters.

Systems on the borderline of the weirdness.

 

[Almo]

Which Dr Quantum animation did you watch? I think the one about the double slit experiment is actually very good. When I first saw it, it made me wonder why there aren't any explanations as good as that one in documentaries made by actual physicists.



The only thing I don't like about this presentation is that they don't mention that an "observation" is actually an interaction between the physical system (the electron) and the measuring device. Just like any other interaction process, it disturbs both of the interacting systems, so it's a little bit misleading to use expressions like "simply by observing".

I consider this Dr. Quantum video to be evil, because by glossing over the "simply by observing" point, the floodgates are open to all sorts of idiocy. Lots of the What the Bleep business is based on misinterpreting this.

It REALLY needs to make the point about observation being an interaction. Without this, Quantum really does seem like magic.

 

[Dancing David]

People, quite naturally, try apply classical thinking to the EPR result at some point up to and including detection and this application leads then to the seeming appearance of nonlocal effects, negative probabilities or both combined. Talk turns to these faster-than-light effects, the future deciding the past and so on. Others may differ, but I don't think this is a good thing if we can avoid thinking along those lines.



I am sure you see like many that needing an observer performing measurements outside the system being studied is never more clearly shown to be inadequate as an interpretation of quantum mechanics than when that system being studied is the universe itself, particularly since the problem that observation was added to solve then spreads to the observer and so remains unsolved.

Huh, there is no observer in quantum wierdness there is an interaction like the double slit or there is a photon bouncing off a particle. The quantum things are interactions. Observers are large objects that are not subject to the wierd interactions, except at the microcosmic scale.

The universe is a large system as well, quantum wierdness is constrained when applied to larger objects. Or it averages out, like in the Feynman diagrams.

Talking of the past with a collapse approach that throws away unrealised alternatives will be somewhat harder than another interpretation in which they are always present but hidden.

I think one can confuse an interpretation like the Copenhagen with reality. One could also confuse the many worlds interpretation with reality.

Systems on the borderline of the weirdness.

I am not sure where you are headed here.

 

[Soapy Sam]

I kind of like Everett , wheeler and Graham's multiverse model. No collapsing anything, just infinite possibilities. It may be wrong, but at least it's understandable.
(Or less incomprehensible than the alternatives. )

I do wonder though- If EWG are right, must there also be an infinity of universes in which they are wrong and the Copenhagen Interpretation is right?

And if so, which are we in?

 

[tracer]

Shameless plug of the SkepticWiki's page on quantum physics:

http://skepticwiki.org/index.php/Quantum_Mechanics

 

[wipeout]

I kind of like Everett , wheeler and Graham's multiverse model. No collapsing anything, just infinite possibilities. It may be wrong, but at least it's understandable.
(Or less incomprehensible than the alternatives. )

You can also take the view that these "many worlds" are correct theoretical possibilities but only one actually becomes real for an unknown reason not yet in the theory. This is perhaps a form of "many worlds" a lot of people would be quite happy with.

 

[Soapy Sam]

Yes- It's certainly cheaper than the other. But maybe both are real, eh?

At the end of the causal chain, there has to be some level where things just happen.
I tend to suspect that if the quantum level is that level, then each quantum event occurs in every way it possibly can , as in Feynman's "Sum over paths" view, rather than for any specific single reason and by any specific single mechanism. The electron arrives at the detector and the click happens. At that point we are in one of two universes which existed in potentia only, until now. But now we are in the only one that actually exists. The other is now a past potential universe- a hypothetical construct.
My gut response to the Copenhagen Interpretation has always balked at the need for an observer. That just seems profoundly silly.

Still, that's me arguing from personal incredulity- and we all know what that's worth.

 

[schlitt]

Need some advice here if possible

Came across a book yesterday "The quantum enigma" decided to buy it as a starting point for learning about QM.
I think this may have been a mistake... as only a few pages in they are already discussing their bias towards QM's meaning being something extraordinary to do with human conciousness.
At this stage i know NOTHING about QM, but the validity of the book already seems dubious to me.

Does anyone have experience with this book? Is it worth reading, or is it a load of what the bleep do we know type rubbish?

 

[phaed]

The thing about QM is that it is rife with "crazy" (ie, non-intuitive) claims. The difference between QM and woo-woo is that QM is backed up by data.

 

[ben m]

Need some advice here if possible

Came across a book yesterday "The quantum enigma" decided to buy it as a starting point for learning about QM.
I think this may have been a mistake... as only a few pages in they are already discussing their bias towards QM's meaning being something extraordinary to do with human conciousness.
At this stage i know NOTHING about QM, but the validity of the book already seems dubious to me.

Does anyone have experience with this book? Is it worth reading, or is it a load of what the bleep do we know type rubbish?

This book has been quite well reviewed, as far as I can tell. Quantum physics *does* require us to think critically about consciousness. Every account of quantum mechanics must describe some things happening when a phenomenon is "observed", which in some sense means that you have to build a quantum picture of the observer. This is obvious in the Schrodinger's Cat example---certainly you should be able to ask "Doesn't the cat count as an observer?" and the answer depends on your ability to describe the whole cat (including its brain) as a quantum wavefunction. From what I can tell from reviews, "The Quantum Enigma" discusses this side of quantum mechanics, which is quite serious stuff, and carefully dismisses the woo.

 

[Ziggurat]

Quantum physics *does* require us to think critically about consciousness. Every account of quantum mechanics must describe some things happening when a phenomenon is "observed", which in some sense means that you have to build a quantum picture of the observer.

This need have nothing to do with conciousness. The measurement problem in quantum mechanics always and only happens when a system we can model with quantum mechanics interacts with a system which we cannot model with quantum mechanics (because it's too complex and/or we cannot know its initial state). The result of this looks like probabilistic collapse of the wave function, but that may be just an artifact of not being able to track the dynamics anymore. One explanation for what happens is to privilege conciousness on the part of the observer, and say that conciousness is responsible for the collapse, but there's no actual need to do so, and in my opinion no good reason to either. That doesn't mean that this book may not be serious (I don't know the book), but it does mean take anything it says with a grain of salt.

 

[schlitt]

This need have nothing to do with conciousness. The measurement problem in quantum mechanics always and only happens when a system we can model with quantum mechanics interacts with a system which we cannot model with quantum mechanics (because it's too complex and/or we cannot know its initial state). The result of this looks like probabilistic collapse of the wave function, but that may be just an artifact of not being able to track the dynamics anymore. One explanation for what happens is to privilege conciousness on the part of the observer, and say that conciousness is responsible for the collapse, but there's no actual need to do so, and in my opinion no good reason to either. That doesn't mean that this book may not be serious (I don't know the book), but it does mean take anything it says with a grain of salt.

I think i understand what you are saying.
From what VERY little i know of the subject, it seems to me the phenomena is more a problem with measurement, than relating to a concious observer.
If it truly is conciousness, the obvious questions to ask would be does it need be be observed visually, or would just being aware the expirment is happening be enough to collapse the wave function?
It would defineatly not make sense if it is the former, because then it would be linked purely to sight.
But then if the latter is true, you could never conduct a real experiment.
If the conclusion is that a concious observer is what is making this happen, then it begs the question, does this observer have to be human? if the answer is yes, then the rammifiactions are obvious, and you can see where the woo springs from.
Again, it seems as though this phenomena is purely a problem or result of the measurement technique.

I am completely ignorant of this at the moment, so if i am completely off the mark, please dont mock me

 

[RecoveringYuppy]

One explanation for what happens is to privilege conciousness on the part of the observer, and say that conciousness is responsible for the collapse, but there's no actual need to do so, and in my opinion no good reason to either.

And this question of consciousness being responsible didn't start with quantum mechanics. It's at least as old as the tree falling in the forest.

 

[Dancing David]

Need some advice here if possible

Came across a book yesterday "The quantum enigma" decided to buy it as a starting point for learning about QM.
I think this may have been a mistake... as only a few pages in they are already discussing their bias towards QM's meaning being something extraordinary to do with human conciousness.
At this stage i know NOTHING about QM, but the validity of the book already seems dubious to me.

Does anyone have experience with this book? Is it worth reading, or is it a load of what the bleep do we know type rubbish?

Sure sounds whacky, I would recomend some general book about the history of particle physics, that is usually a great introduction to all the weird stuff of QM.

 

[Dancing David]

This book has been quite well reviewed, as far as I can tell. Quantum physics *does* require us to think critically about consciousness. Every account of quantum mechanics must describe some things happening when a phenomenon is "observed",

But is electron interaction with itself (as a sum over histories) in the double slit experiment really observation in that sense, it bouncing a photon off a particle (as in Heisenberg Indetermanancy) really observation?

which in some sense means that you have to build a quantum picture of the observer.

Quantum effects are essential to chemical ineractions, however in macroscopic object the effects become statistical and the wierdeness falls off the screen.

This is obvious in the Schrodinger's Cat example

Not really the cat does not exist in a state of superposition accoding to the Copehagen interpretation. the cats is either alive or dead. the state of the cat is determined by the emission of radiation from a single atom of a radioactive substance. Scroedinger made the error of comparing a macrocosmic object to an interpretation of QM.

---certainly you should be able to ask "Doesn't the cat count as an observer?" and the answer depends on your ability to describe the whole cat (including its brain) as a quantum wavefunction.

Again with macrocosmic objects the effect of QM become statistical to an amazing degree, otherwise we would fall through our chairs and the like.

From what I can tell from reviews, "The Quantum Enigma" discusses this side of quantum mechanics, which is quite serious stuff, and carefully dismisses the woo.

But the quatum weirdness does not exist at macro scales so how does it apply? Granted a partcular cehmical interaction is govered by QM, but that does not mean that water will sudenly act in a weird way.

 

[Dancing David]

I think i understand what you are saying.
From what VERY little i know of the subject, it seems to me the phenomena is more a problem with measurement, than relating to a concious observer.
If it truly is conciousness, the obvious questions to ask would be does it need be be observed visually, or would just being aware the expirment is happening be enough to collapse the wave function?
It would defineatly not make sense if it is the former, because then it would be linked purely to sight.
But then if the latter is true, you could never conduct a real experiment.
If the conclusion is that a concious observer is what is making this happen, then it begs the question, does this observer have to be human? if the answer is yes, then the rammifiactions are obvious, and you can see where the woo springs from.
Again, it seems as though this phenomena is purely a problem or result of the measurement technique.

I am completely ignorant of this at the moment, so if i am completely off the mark, please dont mock me

That is amazingly accurate from my layman's POV. If a photon interacts with another very small partcile then the wave nature of a partcles kind of fuzzes up things for the interaction. So one can know the time of an event but not the location of the event with precision governed by the Heisenberg Indeterminancy Principle and versa visa. It is the place where our classical conception of how large objects behave runs into the reality of how very small things behave. The wave/partcile duality is a human concept for sure, the actual objects will interact as they interact and don't have to meet our expectations. This really bothered Bohr even as he and a bunch of other people struggled to make sense of QM.