Wave superposition nothing more than abstraction?

In summary, the conversation discusses the double slit experiment and the concept of superposition in quantum mechanics. The main point of contention is whether or not the mathematical abstractions used in the theory should be taken literally as a description of reality. Some argue that physics should focus on understanding the rules of the universe through mathematics, while others believe that the physical interpretations of these equations should not be ignored. Ultimately, there is no clear answer and it is a philosophical debate.
  • #1
CyberShot
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I was recently watching a video about the double slit experiment that said if we fire electrons one by one, the QM superposition principle says that the single electron goes through both holes, goes through one, vice versa, and none all at the same time. i.e a Superposition of states.

However, it really, really bothers me how much this seems to not be a true depiction of reality, but instead nothing more than a mathematical abstraction.

Think of when we calculate population averages, and we come up with decimal values. Obviously, we can't have fractional humans (we could, but it's not truly allowed) so the answer isn't physical. It's only a mathematical way to visualize the solution. Much like the superposition principle, it doesn't occur in reality but only serves to help physicists wrap their head around the intangible.

Thus, I get the feeling that physics is all about "making the equations conform to observation", kind of like filling in a puzzle piece as one sees fit. That's a very distasteful, boring way to go about science, in my opinion.

..or Maybe quantum mechanics is not supposed to be an entirely physical theory, at least not yet?
 
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  • #2
I see you are entering the field of metaphysics, touching such subjects as 'what is physical', 'what is real', etc.
I fully agree that wavefunctions are just mathematical tools to predict observable results. I am afraid, you want to think about electrons as about something real, physically passing one slit or another like football ball is passing the goal. Such view is hard to maintain, but some people like it. The most appealing interpretation of QM in terms or 'real' particles is Bohmian interpretation, you may start from Wiki and follow references http://en.wikipedia.org/wiki/Bohm_interpretation
Personally, I don't like this interpretation - I definitely prefer non-realistic model, in which it makes sense to speak about 'particles' only at the very moment of their detection/emission/interaction.
 
  • #3
The timeline of your argument is wrong, the mathematical framework of quantum mechanics was developed before many of the predictions it made were actually observed (eg. quantum entanglement I believe was predicted 80 years before we ever saw it in a lab). It's a model, it agrees extremely well with physical observation, why throw it out on the basis that it "bothers" you? That would be a far bigger crime.
 
  • #4
CyberShot said:
it really, really bothers me how much this seems to not be a true depiction of reality, but instead nothing more than a mathematical abstraction.

What's the difference? Consider this: it would be possible to take just the mathematical equations of QM, plug them into a computer, and simulate a mini-universe whose physics is identical to our own in all respects. Given that the math is all you need to describe reality, why do you think there is anything to understand besides mathematics?
 
  • #5
xts said:
I see you are entering the field of metaphysics, touching such subjects as 'what is physical', 'what is real', etc.

Don't you think this should be the goal of physics, and not just meta-physics/philosophy? Physics should be about deducing the rulebook of the Universe. Why should we leave out thoughts about "what's physical and what's real?" How else are we supposed to "figure out the mind of God?" if we leave physical interpretations out? After all, the Universe is a REAL thing, at least I hope.
The_Duck said:
What's the difference? Consider this: it would be possible to take just the mathematical equations of QM, plug them into a computer, and simulate a mini-universe whose physics is identical to our own in all respects. Given that the math is all you need to describe reality, why do you think there is anything to understand besides mathematics?
I didn't mean for abstractions to be the same thing as equations. I'm fine with that. In fact, I believe I'm one of the few that agrees that the Universe is nothing more than a complex computing machine.

What I have a problem with is physicists taking mathematical superposition to be literal and saying "it's both in this state and that state at the same time." No, it's really not, that's just a mathematical abstraction so that when we square quantities and do other things with them , those abstractions cancel out and disappear to produce a physical model that fits with observation. I think people are reading into abstraction to much. Abstraction is just abstraction, don't take it literally. Instead we get in this whole mess of violating causality just because people take things literally.
 
  • #6
CyberShot said:
What I have a problem with is physicists taking mathematical superposition to be literal and saying "it's both in this state and that state at the same time." No, it's really not, that's just a mathematical abstraction so that when we square quantities and do other things with them , those abstractions cancel out and disappear to produce a physical model that fits with observation. I think people are reading into abstraction to much. Abstraction is just abstraction, don't take it literally. Instead we get in this whole mess of violating causality just because people take things literally.

Physical theory is a useful description of reality. (In fact, read my tag line.) I do not know of many scientists who confuse the description with the thing being described. So when someone says it is in both states simultaneously, they mean it is "as if".

There are many interpretations and hypotheses regarding significance of the mathematical nature of physical laws such as Relativity and Quantum Theory. As has been pointed out, this is really a philosophical point. No one really has a deeper answer. By the way, your viewpoint ("no it's really not...") has even less basis than many others - since there is no actual evidence to support it.
 
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  • #7
DrChinese said:
Physical theory is a useful description of reality. (In fact, read my tag line.) I do not know of many scientists who confuse the description with the thing being described. So when someone says it is in both states simultaneously, they mean it is "as if".

There are many interpretations and hypotheses regarding significance of the mathematical nature of physical laws such as Relativity and Quantum Theory. As has been pointed out, this is really a philosophical point. No one really has a deeper answer. By the way, your viewpoint ("no it's really not...") has even less basis than many others - since there is no actual evidence to support it.

I know there's not much evidential basis for my argument. However, I did recently stumble upon an article in which Penrose seems to argue the same point.---

http://discovermagazine.com/2009/sep/06-discover-interview-roger-penrose-says-physics-is-wrong-string-theory-quantum-mechanics/article_view?b_start:int=1"In quantum mechanics an object can exist in many states at once, which sounds crazy. The quantum description of the world seems completely contrary to the world as we experience it.

It doesn’t make any sense, and there is a simple reason. You see, the mathematics of quantum mechanics has two parts to it. One is the evolution of a quantum system, which is described extremely precisely and accurately by the Schrödinger equation. That equation tells you this: If you know what the state of the system is now, you can calculate what it will be doing 10 minutes from now. However, there is the second part of quantum mechanics—the thing that happens when you want to make a measurement. Instead of getting a single answer, you use the equation to work out the probabilities of certain outcomes. The results don’t say, “This is what the world is doing.” Instead, they just describe the probability of its doing anyone thing. The equation should describe the world in a completely deterministic way, but it doesn’t.Erwin Schrödinger, who created that equation, was considered a genius. Surely he appreciated that conflict.Schrödinger was as aware of this as anybody. He talks about his hypothetical cat and says, more or less, “Okay, if you believe what my equation says, you must believe that this cat is dead and alive at the same time.” He says, “That’s obviously nonsense, because it’s not like that. Therefore, my equation can’t be right for a cat. So there must be some other factor involved.”

When you accept the weirdness of quantum mechanics, you have to give up the idea of space-time as we know it from Einstein. You come up with something that just isn’t right.So Schrödinger himself never believed that the cat analogy reflected the nature of reality?Oh yes, I think he was pointing this out. I mean, look at three of the biggest figures in quantum mechanics, Schrödinger, Einstein, and Paul Dirac. They were all quantum skeptics in a sense. Dirac is the one whom people find most surprising, because he set up the whole foundation, the general framework of quantum mechanics. People think of him as this hard-liner, but he was very cautious in what he said. When he was asked, “What’s the answer to the measurement problem?” his response was, “Quantum mechanics is a provisional theory. Why should I look for an answer in quantum mechanics?” He didn’t believe that it was true. But he didn’t say this out loud much.
 
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  • #8
CyberShot said:
"...Dirac is the one whom people find most surprising, because he set up the whole foundation, the general framework of quantum mechanics. People think of him as this hard-liner, but he was very cautious in what he said. When he was asked, “What’s the answer to the measurement problem?” his response was, “Quantum mechanics is a provisional theory. Why should I look for an answer in quantum mechanics?” He didn’t believe that it was true..."

No theory is really "true". Simply that some theories may be more useful some of the time. Ever heard the saying, "it's the exception that proves the rule"? Most theories work except when they don't.

At any rate, one major flaw in your hypothesis is that a double slit setup has slit 1 and slit 2 interfering, even when there is one particle. That shouldn't happen if superpositions are not "real".
 
  • #9
CyberShot, i understand your objections on the *being in 2 places at once* thing. As Dr. Chinese say, in these expressions what is actually meant is *AS IF it were in 2 places at once*. Whats happening in 'real'? We do not know. We don't have a deeper understanding of what a superposition of states really is. The sure thing is that we don't meet these in the classical world, and there are good reasons for this (Check: Decoherence)
I don't know what your views are in general, but if you think that particles are just tiny tiny things, like tiny balls, think again.
I'll just tell you this:
Have you ever seen an electron? Have you ever seen ANY particle? No matter how big it is?
You'll say: *No, i haven't seen an electron because its too small but i see my cellphone, which is a huge system of particles*.
But realize that you actually don't *see* the particles (or your cellphone), you just detect the photons scattered and emmited by them. So what you see... is just something created by photons in your eye! You don't actually observe the *actual* particle, if such thing can be defined!
And here is the thing:
Quantum mechanics can explain everything. You may know that QM describes particles as, spread in space, wavefunctions. We do not know anything more about what particles are, most that we know is their wavefunction. You may be confused with the fact that the classical world has (at first sight) nothing to do with the quantum mechanical world, since particles are wavefunctions in QM and not something that is *here* and you can *touch*! However... QM can (in principle) model every macroscopic object, like your cellphone, and predict exactly what you observe!
For example, you observe that your phone is located in a specific place on your desk. QM predicts that as well even thought it treats the cellphone as a huge wavefunction! Again, the reason is called "Decoherence".

My point is that everything you see around you is as QM predicts using the wavefunctions. So, take it a little more seriously, and stop thinking that QM is wrong because particles are *actually* located somewhere specifically and they are not a wavefunction as QM says. You have never seen a particle, so you're false in saying such things.
 
  • #10
I agree that Quantum Mechanics isn't a very aesthetically pleasing theory, but it is better than classical mechanics.
 
  • #11
Thus, I get the feeling that physics is all about "making the equations conform to observation", kind of like filling in a puzzle piece as one sees fit.

That's generally true from the perspective that we seem to have more mathematical theories than we do observations...so only some, so far, "fit" observations.

When you "solve" a problem in physics, you often have to pick out the correct equation to use...most will not solve your particular, specific, problem. Newtonian mechanics won't work well at speeds close to that of light.

And only some of our mathematical theories fit THIS world. But if there are really an infinite number of universes [parallel worlds] we don't have nearly enough math! And as noted above in previous posts, there are a number of situations where the math was discovered first and made predictions which were, remarkably, later observed.

The bending of light was forecast in GR and observed later by Arthur Eddington as another example where math came before observation...And it turned out, oddly, that the Euler beta function had unusual characteristics related to the strong nuclear force...but more importantly, string theory!. You just never know for sure where that "abstract" math will turn out to be useful in this universe.
 
  • #12
When someone says things like "superposition is an abstraction, why do they ALWAYS ignore evidence from chemistry (bonding/antibonding), and from the Delft/Stony Brook SQUID experiments? Why?

Is it because these people are ignorant of the physics involved in those observations, but yet, they are so ready to draw up a conclusion regarding what they don't know well? I find this practice to be orders of magnitude more dubious than what QM says about superposition.

Zz.
 
  • #13
Well, Albert Einstein and many other phycisist thought the same... the last century.

Nowadays there is strong experimental evidence that support superposition as "physically real"
 
  • #14
..
Dear CyberShot,

seeking to encourage you in your studies, you might like to have a look at:

http://www.nature.com/ncomms/journal/v2/n4/full/ncomms1263.html?


QUOTE: "One can find various definitions in the literature for what a true Schrödinger cat [27] should be and a number of intriguing experiments have reported the generation of photonic [28] or atomic cat-states [29, 30]. In as far as the term designates the quantum superposition of two macroscopically distinct states of a highly complex object, the molecules in our new experimental series are among the fattest Schrödinger cats realized to date. Schrödinger reasoned whether it is possible to bring a cat into a superposition state of being 'dead' and 'alive'. In our experiment, the superposition consists of having all 430 atoms simultaneously 'in the left arm' and 'in the right arm' of our interferometer, that is, two possibilities that are macroscopically distinct. The path separation is about two orders of magnitude larger than the size of the molecules."
 
  • #15
As a neutral comment: I find it interesting to note that the "pro-QM side" (truly just by lack of a better term) seems to be (unknowingly?) split up into the "as if"-camp and the "really"-camp
 
  • #16
ZapperZ and Gordon Watson,

The OP does not deny the superposition principle. His worries are about the interpretation of it. The experimental data have little to do with interpretational issue of QM.
 
  • #17
JK423 said:
ZapperZ and Gordon Watson,

The OP does not deny the superposition principle. His worries are about the interpretation of it. The experimental data have little to do with interpretational issue of QM.

..
I was responding to the OP's – "Much like the superposition principle, it doesn't occur in reality but only serves to help physicists wrap their head around the intangible" – via reference to some recent interesting and seemingly relevant experimental data.

That is: I was offering the OP additional "food-for-thought" -- that was readily accessible -- adding to the examples offered by ZapperZ.

For now, I'll happily leave it to Zapper (and others) to expand on the subject.
 
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  • #18
JK423 said:
ZapperZ and Gordon Watson,

The OP does not deny the superposition principle. His worries are about the interpretation of it. The experimental data have little to do with interpretational issue of QM.

But in some sense, it does!

The SQUID experiments[1,2] were a clear attempt to check if the supercurrent were flowing in both directions simultaneously based on the formalism. This is no different than saying that a particle is in both locations at the same time. A formal description of it can be found in Leggett's paper[3].

But what is rather puzzling here is that, if you look at the OP's philosophy, then one could argue that ALL of physics is an "abstraction"! So why pick on QM, or superposition for that matter? After all, what are Maxwell equations, for example?

The problem I always have in discussion such as this is that it isn't based on physics, but rather based on a matter of TASTES. It comes down to "Oh, I find it difficult to accept that something can be in two places at once, so it must not be real". Nowhere in there is physics. As I've often said, we might as well argue for favorite colors.

Zz.

[1] C.H. van der Wal et al., Science v.290, p.773 (2000).
[2] J.R. Friedman et al., Nature v.406, p.43 (2000).
[3] A.J. Leggett "Testing the limits of quantum mechanics: motivation, state of play, prospects", J. Phys. Condens. Matt., v.14, p.415 (2002).
 
  • #19
Dear ZapperZ, and other Mentors:
Half of threads like this are moved to lounge->general->philosophy, half stays in Physics threads, no one posts such problems in 'philosophy' branch, all posters decide that such issues are more related to Physics than to General-Philosophy.
Wouldn't it to be wise to make a subforum: Physics -> Philosophy of Physics (QM interpretations, nature of physical reality, etc.) ?
 
  • #20
The ones that stay in physics tend to have more physics content. The ones that don't tend to have less physics content.

It all depends on the intent of the topic, and how the participants respond to it. If a lot of physics is used, then the thread stays here. If there's a lot of handwaving, metaphysical stuff, it goes to you-know-where.

There is no need to create another forum. The Philosophy forum isn't a hot-bed of posts and new topics.

Zz.
 
  • #21
You told me what is a policy to judge if move the thread or not to a basket pretty far away.

You haven't answered my main question: why not to make a Physics->Philosophy of Physics subforum.
If you want more justification why I propose it: there are much more similarities between threads kept in Physics branch (like this) and some moved there, then between discussions like this one and other posts in QM branch, like those asking for explanations of Heisenberg formalism.
 
  • #22
xts said:
You told me what is a policy to judge if move the thread or not to a basket pretty far away.

You haven't answered my main question: why not to make a Physics->Philosophy of Physics subforum.
If you want more justification why I propose it: there are much more similarities between threads kept in Physics branch (like this) and some moved there, then between discussions like this one and other posts in QM branch, like those asking for explanations of Heisenberg formalism.

And I already answered you. In fact, if you look in the Feedback forum, I can cut-and-paste answers to this frequent question when someone suggests such-and-such a forum. We simply cannot create a forum just because someone thinks its a good idea. If we do, we'd have a listing of hundreds of forums! This would be absurd!

There has to be a need AND a high frequency of posting on that topic.

This is the wrong forum to discuss this. If you think this explanation isn't satisfactory to you, please either post in the Feedback forum, or browse the existing responses that we already gave members who proposed forums for their own pet subject areas.

Zz.
 
  • #23
CyberShot said:
I was recently watching a video about the double slit experiment that said if we fire electrons one by one, the QM superposition principle says that the single electron goes through both holes, goes through one, vice versa, and none all at the same time. i.e a Superposition of states.
The superposition principle says that if u and v are states, and a,b are complex numbers, then au+bv is a state too. This is just a sloppy way of expressing one feature of the mathematics that defines the purely mathematical part of the theory. (I consider a specification of how to use the mathematics to make predictions about results of experiments to be a part of the theory. That specification would be the part that's not "purely mathematical").

CyberShot said:
However, it really, really bothers me how much this seems to not be a true depiction of reality, but instead nothing more than a mathematical abstraction.
I would say that QM appears to be a way to calculate probabilities of possibilities, rather than a "description of what actually happens". If this is what bothers you, you're not alone. But if it's really the use of abstract mathematics that bothers you, then you just need to get over it. :smile:

CyberShot said:
Much like the superposition principle, it doesn't occur in reality but only serves to help physicists wrap their head around the intangible.
Doesn't occur in reality? I don't think a state vector should be thought of as telling us "what the particle really is doing", but when you say it like this, it sounds like you think it would be possible to get rid of the superpositions without getting rid of the entire theory. That's certainly not the case. If you're thinking that the superposition u+v really means "either u or v, each with probability 1/2" then you're wrong. The statement in quotes has a different mathematical representation, and it leads to different predictions about results of some of the experiments that can be performed on the system.

CyberShot said:
Thus, I get the feeling that physics is all about "making the equations conform to observation", kind of like filling in a puzzle piece as one sees fit. That's a very distasteful, boring way to go about science, in my opinion.
The part of this that stands out is "as one sees fit". Do you really think that the "pieces" don't need to fit together?

CyberShot said:
..or Maybe quantum mechanics is not supposed to be an entirely physical theory, at least not yet?
QM is supposed to be a set of statements that associate probabilities with verifiable statements of the form "if I use measuring device A on the object S, the result will be in the set E". That makes it a "theory of physics" according to my definitions. I don't think there's a meaningful way to define the term "physical" so that some good theories (in the sense that their predictions are accurate) are physical while others aren't. Do you have a definition in mind?

ZapperZ said:
If a lot of physics is used, then the thread stays here. If there's a lot of handwaving, metaphysical stuff, it goes to you-know-where.

There is no need to create another forum. The Philosophy forum isn't a hot-bed of posts and new topics.
It seems to be a place were you (the mentors) move threads that aren't considered good enough for the nice forums, so maybe it should be called "The dump" instead. :-p
 
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  • #24
ZapperZ said:
But in some sense, it does!

The SQUID experiments[1,2] were a clear attempt to check if the supercurrent were flowing in both directions simultaneously based on the formalism. This is no different than saying that a particle is in both locations at the same time. A formal description of it can be found in Leggett's paper[3].

I disagree. What they observed (i assume) is a probability distribution that matched that of a superposition of states of the current, one state that represents the current flowing in one direction and the other state represents the current flowing in the other direction.
You cannot say that *the supercurrent were flowing in both directions simultaneously* because you don't actually observe the current in both places. So phrases like <<the supercurrent were flowing in both directions simultaneously>> is actually an interpretation of the formalism.
 
  • #25
JK423 said:
I disagree. What they observed (i assume) is a probability distribution that matched that of a superposition of states of the current, one state that represents the current flowing in one direction and the other state represents the current flowing in the other direction.
You cannot say that *the supercurrent were flowing in both directions simultaneously* because you don't actually observe the current in both places. So phrases like <<the supercurrent were flowing in both directions simultaneously>> is actually an interpretation of the formalism.
I'm with you on this. What these experiments show is that there are situations where the predictions derived from a superposition u+v are very accurate, while the predictions derived from "either u or v" are completely wrong. Statements like "the current is flowing in both directions" or "the particle goes through both slits" are asserting things that can't be verified.
 
  • #26
JK423 said:
I disagree. What they observed (i assume) is a probability distribution that matched that of a superposition of states of the current, one state that represents the current flowing in one direction and the other state represents the current flowing in the other direction.
You cannot say that *the supercurrent were flowing in both directions simultaneously* because you don't actually observe the current in both places. So phrases like <<the supercurrent were flowing in both directions simultaneously>> is actually an interpretation of the formalism.

Fredrik said:
I'm with you on this. What these experiments show is that there are situations where the predictions derived from a superposition u+v are very accurate, while the predictions derived from "either u or v" are completely wrong. Statements like "the current is flowing in both directions" or "the particle goes through both slits" are asserting things that can't be verified.

Then you will have a rather fun time trying to explain the whole set of tests of "realism" that has been conducted via the violation of Leggett's inequality. And I'm guessing that I don't have to explain to this crowd what is meant by "realism" in this context.

J. Romero et al., N. Jour. Phys. v.12, p.123007 (2010).
S. Gröblacher et al., Nature v.446, p.871 (2007).
Cyril Branciard et al. Phys. Rev. Lett. 99, 210407 (2007).

Zz.
 
  • #27
What happens if the wall with the slit is in a quantum superposition of being there and not there (ex. wall = a magnetic field in quantum superposition) ? How do we represent it in quantum formalism, as a tensor product of operators ?
 
  • #28
Helletron said:
What happens if the wall with the slit is in a quantum superposition of being there and not there (ex. wall = a magnetic field in quantum superposition) ? How do we represent it in quantum formalism, as a tensor product of operators ?
As a tensor product of state vectors. [itex]|\text{particle}\rangle\otimes|\text{wall}\rangle[/itex].
ZapperZ said:
Then you will have a rather fun time trying to explain the whole set of tests of "realism" that has been conducted via the violation of Leggett's inequality. And I'm guessing that I don't have to explain to this crowd what is meant by "realism" in this context.

J. Romero et al., N. Jour. Phys. v.12, p.123007 (2010).
S. Gröblacher et al., Nature v.446, p.871 (2007).
Cyril Branciard et al. Phys. Rev. Lett. 99, 210407 (2007).
I don't have an easy way to access journal articles, but you seem to be saying that the use of phrases like "the current is going in both directions" is justified by experimental violations of an inequality that holds for some class of "realistic" theories. If that's what you're saying, then my answer is that I don't doubt that such experiments have ruled out the possibility that a member of that class of theories can predict the results of experiments as well as QM*. But this doesn't justify the use of language that suggests that each component of the superposition is "actually happening".

To justify the use of phrases like "the particle is both here and there", it's not enough to disprove "the particle is either here or there". We also have to prove that QM is something more than just a very good assignment of probabilities to possible results of experiments. We would have to find a reason to say that QM also "describes what actually happens". (I can't even think of anything that I would consider a good reason to say that).

Of course, you could argue that since people who oppose such language can't even tell you exactly what they think a phrase like "the particle is both here and there" should mean, you can just define that phrase to mean "the particle is in a pure state of the form a|here>+b|there>". Is that what you did, or did you have something else in mind when you suggested that "the current is going both ways" is a good way to state what's going on?

*) This isn't something I have a reason to "explain". It only makes sense to request that from a person who has suggested that QM isn't a good theory.
 
  • #29
CyberShot said:
[..] What I have a problem with is physicists taking mathematical superposition to be literal and saying "it's both in this state and that state at the same time." No, it's really not, that's just a mathematical abstraction so that when we square quantities and do other things with them , those abstractions cancel out and disappear to produce a physical model that fits with observation. I think people are reading into abstraction to much. Abstraction is just abstraction, don't take it literally. Instead we get in this whole mess of violating causality just because people take things literally.

It's indeed a fallacy to think that a what really happens must be exactly what we think that the equations tell us. As you also gave an example of mathematical abstraction with averages, here's another one of mine: the mathematics of averaging involves adding two initial measures of quantities and then cutting the sum in two - but this is rarely what nature actually does with those quantities. :biggrin:

However, it's one thing to say that we shouldn't take abstractions too literal; it's another to come up with a model that fits with such abstractions and with our concepts of the world.Harald
 
  • #30
Fredrik said:
I'm with you on this. What these experiments show is that there are situations where the predictions derived from a superposition u+v are very accurate, while the predictions derived from "either u or v" are completely wrong. Statements like "the current is flowing in both directions" or "the particle goes through both slits" are asserting things that can't be verified.



How is a conspiracy theory(currents conspire to act as if they went in both directions simultaneously, but they probably didn't) better than to suppose that common, inductive reasoning is right in this case?
 
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  • #31
ZapperZ said:
Then you will have a rather fun time trying to explain the whole set of tests of "realism" that has been conducted via the violation of Leggett's inequality. And I'm guessing that I don't have to explain to this crowd what is meant by "realism" in this context.

J. Romero et al., N. Jour. Phys. v.12, p.123007 (2010).
S. Gröblacher et al., Nature v.446, p.871 (2007).
Cyril Branciard et al. Phys. Rev. Lett. 99, 210407 (2007).

Zz.

Second reference can also be found here:
http://arxiv.org/abs/0704.2529

Last reference can also be found here:
http://arxiv.org/abs/0708.0584
 
  • #32
Maui said:
How is a conspiracy theory(currents conspire to act as if they went in both directions simultaneously, but they probably didn't) better than to suppose that common, inductive reasoning is right in this case?
The reason I don't like phrases like "the current went both ways" is that they suggest that QM should be interpreted as a "description of what actually happens". The phrase "the current went this way or that way" has the same problem. If we define those phrases in the only way that makes sense scientifically, the second one has the additional problem that it's just plain wrong (in this type of experiments).
 
  • #33
Fredrik said:
The reason I don't like phrases like "the current went both ways" is that they suggest that QM should be interpreted as a "description of what actually happens". The phrase "the current went this way or that way" has the same problem. If we define those phrases in the only way that makes sense scientifically, the second one has the additional problem that it's just plain wrong (in this type of experiments).



Well, not liking what quantum mechanical expiments strongly suggest about what happens, certainly doesn't invalidate the straightfoward(imo) conclusions that flow from it. One could easily claim that classical mechanics is also not a true description of experiments at the macro scale.

Edit: I now remember reading a post of yours where you said something to the effect that all our models are likely wrong. That sheds some light on why you seem to react the way you do to the interpretational side of quantum experiments.
 
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  • #34
Maui said:
Well, not liking what quantum mechanical expiments strongly suggest about what happens, certainly doesn't invalidate the straightfoward(imo) conclusions that flow from it. One could easily claim that classical mechanics is also not a true description of experiments at the macro scale.

The difference is that we can see classical mechanics, so I don't think extra care in quantum mechanics is superfluous. In the respect of new discovery, it is often helpful to assume as little as possible.
 
  • #35
mr. vodka said:
The difference is that we can see classical mechanics, so I don't think extra care in quantum mechanics is superfluous. In the respect of new discovery, it is often helpful to assume as little as possible.


Matter looks solid under the classical mechanics treatment of human vision(as you say, you can see it - don't see how that's relevant, but whatever), but classical mechanics was never good enough. This argument has clearly evolved to an argument about personal tastes.
 

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