Quantum Superposition & Philosophy


by Elvin12
Tags: philosophy, quantum states
wuliheron
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Dec11-10, 03:08 PM
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Quote Quote by ferenan View Post
I quite understand. But it is hopeless for us all to take this attitude too seriously. We need those who strive to forward our understand in science as it will lead to breakthroughs in understanding and at the very least lead to new technologies which we all enjoy. Their entire premise may be wrong that the universe and for that matter fundamental reality can be so easily pigeon holed into understandable logic concepts. I certainly feel a huge resistance from scientists to accept the possibility that realism is not as fundamental as we think. The whole searching for smaller and smaller building blocks of matter seems flawed given their ethereal nature. How does string theory really gel with non locality? We just cannot seem to give up the concept that matter is a physical thing with a definitive place and structure. Still I for one would be devastated if people stopped trying!

The idea that we can only be motivated by preconceptions and expectations is also flawed. Feynman and many of the more famous physicists who made great advances managed to retain that childlike wonder and curiosity about anything that everything.

In fact, Einstein once complained that he should of have deduced the HUP himself from his photoelectric effect some twenty years earlier. Perhaps if he had been less metaphysically oriented he would have.
ferenan
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Dec11-10, 03:57 PM
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Quote Quote by wuliheron View Post
The idea that we can only be motivated by preconceptions and expectations is also flawed. Feynman and many of the more famous physicists who made great advances managed to retain that childlike wonder and curiosity about anything that everything.

In fact, Einstein once complained that he should of have deduced the HUP himself from his photoelectric effect some twenty years earlier. Perhaps if he had been less metaphysically oriented he would have.
I am not sure if you are agreeing with me or not.

Still I do agree with you. Did you mean if Einstein was "more" metaphysically inclined? But anyway it takes great minds to make these advancements. The rest of us have to try even if many of us cannot overcome our preconceptions. The fact is most do take what they learnt as gospel and will fight change. This can still advance some knowledge even if it does not lead to the biggest breakthroughs.
wuliheron
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Dec11-10, 05:00 PM
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Quote Quote by ferenan View Post
I am not sure if you are agreeing with me or not.

Still I do agree with you. Did you mean if Einstein was "more" metaphysically inclined? But anyway it takes great minds to make these advancements. The rest of us have to try even if many of us cannot overcome our preconceptions. The fact is most do take what they learnt as gospel and will fight change. This can still advance some knowledge even if it does not lead to the biggest breakthroughs.

I suppose I am agreeing and disagreeing (I'm not really sure!)

There will always be those like Einstein who insist an answer must exist for metaphysical reasons and no doubt such an approach worked extremely well for him. However, making metaphysical assumptions is not an objective approach and history has also demonstrated many cases where it was counterproductive. Therefore as useful as it can be to make metaphysical assumptions it must never be forgotten that objectivity is paramount.
GodPlaysDice
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Dec11-10, 05:33 PM
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Quote Quote by ferenan View Post
Further more, even if we know we are observing something not in a superposition, to an outside observer separate from us ,they can consider us as being in a superposition of states. So us being conscious alone is not enough to definitively collapse a wave function as we can be considered to be in a superposition with our environment by someone else who has yet to observe us. So a wave function collapse is not either a true or false thing. It is MUCH more subtle than that, and it is this point that causes the most confusion as we like to make things fit our everyday understanding. Just as a object can be in superposition of two or more states at once, the superposition can be both existing and non existing! Agghh, my heard is starting to spin. .
That is a good point you made, (about an observer being in a superposition themselves). How would you describe the interaction between two observers observing each other?!...Or perhaps even multiple observers observing each other? If they were to not interact with any other observer, their situation would only be real to them, since to other observers, who have not yet made the observation, they (the original two observers) would be in a superposition, even though they are not in a superposition, according to them only. My head is spinning too. In that case, we would just live in our own reality until someone else's collided or acknowledged ours, thus validating ours in the first place. Now my head is really spinning.
SprocketPower
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Dec11-10, 08:30 PM
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Maui,

Dismissing everything that doesn't fit our world view is not rational and reasonable especially if that world view is wrong.
baywax
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Dec11-10, 09:11 PM
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Quote Quote by Elvin12 View Post
According to Quantum Physics (or at least my understanding of it), when a particle is not observed it doesn't exist in the way one imagines is to be. Instead, it is a wave function with infinite possibilities (sum-over histories by Feynman), and only when observed it takes on a definite state. This what I got from books that I've read, but its still quite hard to understand as how a particle interferes with itself while traveling through a double-slit and why exactly is it the observer that chooses the fate of Scholidinger's cat in the box?
One other thing I'm wondering has more to do with philosophy but can be tied in here also. Geroge Berkeley said that if no one looks at a tree, it doesn't exist, in other words "esse est percipi" or "to be is to be perceived". Scientists have found that even particles large enough to be observed by microscopes (bucky-balls) also interfere. So I'm wondering whether George Berkley is right, and a tree doesn't exist if not perceived, but rather a wave function with infinite different possibilities?
If what I said makes no sense, I apologize, but please correct me so I have a better understanding.
We have to consider the fact that a tree really is there when we don't observe it... this is proven by the fact that it produces oxygen during the day and this is a direct result of the tree's existence that we are breathing whether we observe the tree or not.

Similarly, the unobserved moon continues to effect the tides and is therefore, the moon at work.
ferenan
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Dec12-10, 06:21 AM
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Quote Quote by baywax View Post
We have to consider the fact that a tree really is there when we don't observe it... this is proven by the fact that it produces oxygen during the day and this is a direct result of the tree's existence that we are breathing whether we observe the tree or not.

Similarly, the unobserved moon continues to effect the tides and is therefore, the moon at work.
Irrelevant.

The collapse of a wave function doesn't just form the reality of the object at that moment. It is not that before that time there was only a wave function of probability and no tree. There is a temporal nature to it all as well. Remember Wheelers delayed choice double slit experiments.

SO. suppose the tree is unobserved by yourself. It can be very well argued that from your point of view it is in a superpostion if states, and always has been if you have never been there before or had any interaction with it or its environment (how far to take this is hard to say but it is probably very hard to isolate you from it as you are bound to have breathed in he odd O2 molecule that it broke down). Anyway the point is from your point of view it has existed in a superpostion of states from seed to fully grown tree. The moment you interact with it you see a fully grown tree and not some weird seed/tree wave form. The collapse of the wave function solidifies the past as much as the present. SO of course it was producing oxygen the whole time.


Wheelers delayed choice experiment has been theorised to be done at the cosmological level. An experiment can be devised where a measurement we make now could effect the path taken by a photon billions of years ago. This is actually no more impressive than experiments done. Experiments do show decisions we make with this set up effect the past , just by a few nanoseconds though so billions of years seems better. But really it is no different. You cannot think of time as linear when talking about wave functions. Therefore notions of what is existing at any one point in time are also redundant. That photon whose path we can effect long in the past. Does it have an existence before we take the measurement? YES/NO/MAYBE
Maui
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Dec12-10, 09:16 AM
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Quote Quote by baywax View Post
We have to consider the fact that a tree really is there when we don't observe it... this is proven by the fact that it produces oxygen during the day and this is a direct result of the tree's existence that we are breathing whether we observe the tree or not.

Similarly, the unobserved moon continues to effect the tides and is therefore, the moon at work.

My main gripe with this argument is again the classical concepts that fail in closer examination.

If we stick to classical concepts and knowledge only, we would be pressured to question the existence of matter itself, whether we talk about trees, moons, cats, etc.
baywax
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Dec12-10, 02:16 PM
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Quote Quote by Maui View Post
My main gripe with this argument is again the classical concepts that fail in closer examination.

If we stick to classical concepts and knowledge only, we would be pressured to question the existence of matter itself, whether we talk about trees, moons, cats, etc.
The argument does smack of solipsism and the illusionist's theory. Besides, there's no way to prove if matter or the moon exist without observing them, so, there is no way to compare their states of "collapse" or lack thereof. Ultimately there will always be a measurement made and an observation required.
baywax
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Dec12-10, 08:37 PM
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Quote Quote by ferenan View Post
Irrelevant.

The collapse of a wave function doesn't just form the reality of the object at that moment. It is not that before that time there was only a wave function of probability and no tree. There is a temporal nature to it all as well. Remember Wheelers delayed choice double slit experiments.

Does it have an existence before we take the measurement? YES/NO/MAYBE
Not irrelevant. The emergent properties of an emergent phenomenon are a result of its emergence. One cannot escape the effects of these properties even if the phenomenon is not observed. Thus, one has to say, yes, the phenomenon exists regardless of whether I observe it or not.
Maui
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Dec13-10, 03:09 AM
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Quote Quote by baywax View Post
The argument does smack of solipsism and the illusionist's theory.

No, you misunderstand. I said we might be tempted to question if anything exists at all, IF we sticked too tightly to the classical concepts. But we don't(those engaged in fundamenal physics at least).

As i replied to ZapperZ, you can't re-build a coherent model of the universe from just classical concepts. The moment you attempt to do so, you may fall prey to solipsism.
For the overall consistency of the universe and everything in it, i am willing to believe that it exists apart from my perception, but at the same time,imo, there is an obvious need to re-examine not our basic assumptions about the world, but our classical concepts(as i said earlier, we may need a theory of how brains work).



Besides, there's no way to prove if matter or the moon exist without observing them, so, there is no way to compare their states of "collapse" or lack thereof. Ultimately there will always be a measurement made and an observation required.
This is beside the point i was trying to make. Instead of Instrumentalism, Voodoo or Solipsism(none of these are actually scientific in the true sense of the word) i suggest we interpret the universe by giving more flexibility to our classical thinking.
ZapperZ
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Dec13-10, 05:19 AM
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Quote Quote by Maui View Post
No, you misunderstand. I said we might be tempted to question if anything exists at all, IF we sticked too tightly to the classical concepts. But we don't(those engaged in fundamenal physics at least).

As i replied to ZapperZ, you can't re-build a coherent model of the universe from just classical concepts. The moment you attempt to do so, you may fall prey to solipsism.
For the overall consistency of the universe and everything in it, i am willing to believe that it exists apart from my perception, but at the same time,imo, there is an obvious need to re-examine not our basic assumptions about the world, but our classical concepts(as i said earlier, we may need a theory of how brains work).
This is a little bit of a fallacy, don't you think? ALL of the concepts that we know of are actually classical concepts. This includes the concept of position, momentum, energy, etc. These ARE classical ideas and these are the only quantities that we can extract out of a phenomenon. Furthermore, these things are then verified empirically via measurements that are inherently classical!

You cited string or quantum gravity, etc. All of those are based on classical ideas. Quantum mechanics really is the rule on how these classical idea will give its result when applied to a world in which these idea may not be totally kosher. But we can't get away from that, and there is no way to get away from that at the moment. I asked for you to show an working alternative, and you don't have one, mainly because there's none! So essentially, your argument is based on (surprise!) a matter of TASTES!

BTW, coming back to the original topic (I'm strange, I know!), how many people who've been involved in this discussion actually understand what is meant by a "quantum superposition"?

Zz.
Maui
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Dec13-10, 01:23 PM
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Quote Quote by ZapperZ View Post
This is a little bit of a fallacy, don't you think? ALL of the concepts that we know of are actually classical concepts. This includes the concept of position, momentum, energy, etc. These ARE classical ideas and these are the only quantities that we can extract out of a phenomenon.


Yes, that's how we approximate our models to reality but our classical models are inherently flawed because they are based on those classical concepts. That's NOT how the universe is, is it?


Furthermore, these things are then verified empirically via measurements that are inherently classical!

The results of those measurements can not always be framed in clasical concepts, can they?

Exactly how accurate is the so-called classical-like model of 'wave-particle duality'? Can we understand matter at the tiniest scales in classical concepts? Can you?



You cited string or quantum gravity, etc. All of those are based on classical ideas. Quantum mechanics really is the rule on how these classical idea will give its result when applied to a world in which these idea may not be totally kosher. But we can't get away from that, and there is no way to get away from that at the moment. I asked for you to show an working alternative, and you don't have one, mainly because there's none! So essentially, your argument is based on (surprise!) a matter of TASTES!

If there's none, then we lapse into the 3 remaining alternatives:

1. Instrumentalism
2. Different grades of voodoo that preserve some form of classicality
3. Solipsism

But my choice is definitely not based on a matter of tastes, If something exists in a causal relationship with other entities, there's got to be a coherent description of it. My point is that we would likely have to accomodate a 'relaxed' version of the usual classical notions - exist--not exist; real--not-real; there--not-there, etc. instead of the above 3 choices.


BTW, coming back to the original topic (I'm strange, I know!), how many people who've been involved in this discussion actually understand what is meant by a "quantum superposition"?

Zz.

Superposition is another concept that resists a classical explanation. AFAIK, it's still considered by most only a microscopic phenomenon, but it should in principle be possible to put a larger macroscopic body - bacteria, cell, etc. I need to find the magazine that featured a macroscopic experiement that was done years ago, that demonstrated further the inadequacy of the classical concepts.
ZapperZ
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Dec13-10, 01:32 PM
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Quote Quote by Maui View Post
Yes, that's how we approximate our models to reality but our classical models are inherently flawed because they are based on those classical concepts. That's NOT how the universe is, is it?
How do you know it is not how the universe is?

The results of those measurements can not always be framed in clasical concepts, can they?
Why not? What are your examples to support your view?

Exactly how accurate is the so-called classical-like model of 'wave-particle duality'? Can we understand matter at the tiniest scales in classical concepts? Can you?
What does classical model has anything to do with classical concepts of position, etc.? Classical models can be faulty AND has been shown to be limited in applicability. That isn't the issue.

If there's none, then we lapse into the 3 remaining alternatives:

1. Instrumentalism
2. Different grades of voodoo that preserve some form of classicality
3. Solipsism
If there's any, you haven't shown it.

Superposition is another concept that resists a classical explanation. AFAIK, it's still considered by most only a microscopic phenomenon, but it should in principle be possible to put a larger macroscopic body - bacteria, cell, etc. I need to find the magazine that featured a macroscopic experiement that was done years ago, that demonstrated further the inadequacy of the classical concepts.
This isn't a definition nor an indication that you've understood what "quantum superposition" is, which is the topic of this thread. In other words, you've not answered my question on what is meant by quantum superposition. I know very well all the physical experiment that has demonstrated quantum superposition, even up to "macroscopic" scale, considering that I've mentioned the Delft/Stony Brook SQUID experiments a gazillion times in the physics forums (just do a search if you don't believe me).

Quantum superposition, while it is a quantum concept, still make use of classical parameters of position, momentum, energy, spin, etc... and the experimental measurements are all classical, i.e. they measured these quantities.

Again, talk is cheap, really. I haven't seen a single example where a classical concept isn't invoked, even in the quantum picture. And please, tell me what "quantum superposition" is!

Zz.
Maui
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Dec13-10, 01:48 PM
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Quote Quote by ZapperZ View Post
Why not? What are your examples to support your view?

Okay, i am going to say it - from what you say it follows that you don't understand what matter is. You say we have to stick to our classical concepts, because we don't have a choice. But NOT all of the properties matter fit the classical picture.
Instrumentalism is not viable for philosophy, so we need to move on to the other alternatives.

If there's any, you haven't shown it.

This doesn't mean the approach is wrong. I already stated that i consider the internal workings of the brain an essential part of how the classical notions emerge. Until we have a theory of brains what i propose will lie in obscurity(this holds for the rest of the interpretations as well, imo).



This isn't a definition nor an indication that you've understood what "quantum superposition" is, which is the topic of this thread. In other words, you've not answered my question on what is meant by quantum superposition. I know very well all the physical experiment that has demonstrated quantum superposition, even up to "macroscopic" scale, considering that I've mentioned the Delft/Stony Brook SQUID experiments a gazillion times in the physics forums (just do a search if you don't believe me).

Quantum superposition, while it is a quantum concept, still make use of classical parameters of position, momentum, energy, spin, etc... and the experimental measurements are all classical, i.e. they measured these quantities.

Again, talk is cheap, really. I haven't seen a single example where a classical concept isn't invoked, even in the quantum picture. And please, tell me what "quantum superposition" is!

Zz.


A superposition of states is the simultaneous existence of all possible states of a system at the same time. Including classically impossible states, like left-and-right, up-and-down, dead-and-alive-cat, etc. etc.


Explain to me in classical terms the existence of a virus that's put in superposition of states. I'd prefer a picture/image of it(imagine that we could take a measurement without destroying the superposition).



What does classical model has anything to do with classical concepts of position, etc.? Classical models can be faulty AND has been shown to be limited in applicability. That isn't the issue.

This is the issue. The inadequacy of the classical models. I have no other point to make in this thread, except the limited applicability of the classical concepts for a coherent worldview.
baywax
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Dec13-10, 02:43 PM
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Maui, perhaps your magazine has succumbed to the confines of probability theory and is

P(AnotB) + P(AandB) + P(BnotA) + P(notAnotB) = 1 (magazine)

We may be missing a point here:

no observation means there is no observer. There's no way to prove anything else concerning the lack of observation.
apeiron
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Dec13-10, 03:03 PM
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Quote Quote by Maui View Post
Yes, that's how we approximate our models to reality but our classical models are inherently flawed because they are based on those classical concepts. That's NOT how the universe is, is it?
What do you understand by "classical" (so we can get a clearer idea of what would be non-classical)? And what even does "concept" mean here?

A metaphysical concept (such as position or entropy) is a quality (a qualitative description) that justifies a crisp quantitative measurement in its name. In philosophy, such concepts are formed dichotomously - if A, then not-A. So position is defined by its complementary quality of momentum. Position is what doesn't change, and momentum is all the kinds of possible change. With a well-defined pair of terms like this, you can then make quantitative measurements. You have a spectrum of states that lie now between the absolute limits of complete stasis and complete flux.

So whether classical or non-classical, we would expect the same metaphysical game. We would need to anchor the discussion in terms of complementary pairs of qualities, that then would allow the clear quantification of observables.

Now the essense of classicality is surprisingly complex. But it involves a variety of reductions (a causal reduction being the claim that while complementaries may always be necessary, reality can in fact be reduced to one end of the spectrum as a fundamental truth).

So classicality assumes at least all of the following - locality, atomism, determinism, monism, mechanicalism.

And we can see that QM challenges all of these ontic categories.

And we can see that the "other" is already present in the metaphysics of classicality. To have locality as a crisply meaningful concept (something we can actually measure or quantify), we had to have the idea of its "other" - non-locality or globality. We just do not have a well-developed physics which uses globality as a quality, a causal extreme, to which our measurements of the world can be anchored.

It is the same story for the other ontic categories. We have a clear idea of how to measure atomism, but not holism; monism, but not some kind of dualism or dyadicy (or indeed triadicy); mechanicalism, but not some kind of organicism.

Determinism seems a little different as we do have a well-developed way of measuring randomness (whoops, recent discussions here reveal that the basis of this system is not widely understood).

Anyway, QM is indeed a metaphysical challenge to classicality. But the good news is that classicality is itself so sharply defined as a collection of ontic concepts that the "other" is already clearly in sight if you care to look.

We are not waiting for a philosophical revolution. Just for scientists to step back from what they think they know and appreciate the wider view. When people stop worrying about the weirdness of non-locality and start talking about the effects of globality, then the penny will have dropped.
ZapperZ
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Dec13-10, 04:09 PM
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Quote Quote by Maui View Post
Okay, i am going to say it - from what you say it follows that you don't understand what matter is. You say we have to stick to our classical concepts, because we don't have a choice. But NOT all of the properties matter fit the classical picture.
Instrumentalism is not viable for philosophy, so we need to move on to the other alternatives.
You are confusing classical concepts with classical physics. Classical concepts are parameters such as position, momentum, spin, etc. Look in the Schrodinger equation. NO matter how much you think it is a quantum description, it STILL uses classical concepts! Position and momentum and energy, etc. are all the OBSERVABLES of the system!

I'm an experimentalist. I have to be aware of what I'm measuring. I don't just TALK about it on some public forum.

This doesn't mean the approach is wrong. I already stated that i consider the internal workings of the brain an essential part of how the classical notions emerge. Until we have a theory of brains what i propose will lie in obscurity(this holds for the rest of the interpretations as well, imo).
It does mean that you're making things up without any ample justification for its validity other than simply a matter of tastes. I frankly don't have time to debate on someone's favorite color.

A superposition of states is the simultaneous existence of all possible states of a system at the same time. Including classically impossible states, like left-and-right, up-and-down, dead-and-alive-cat, etc. etc.

Explain to me in classical terms the existence of a virus that's put in superposition of states. I'd prefer a picture/image of it(imagine that we could take a measurement without destroying the superposition).
These two paragraphs clearly show that you don't have a firm understanding of quantum superposition.

1. A superposition of states (or what you call "simultaneous existence of all possible states") isn't anything interesting at all. We have classical superposition all the time in wave mechanics. Yet, no one makes any philosophical discussion ad nauseum on that topic on here. So what's so different with quantum superposition?

2. The difference comes in in what has been called as the First Quantization, i.e. the commutation relation of 2 observables or operators, i.e. [A,B]. When one makes a measurement, the naive view of this process is that the wavefunction is an eigenfunction of the operator, such as A, such that a particular value (eigenvalue) will be the outcome. However, this is NOT the full story! If B commutes with A, then if the wavefunction is non-degenerate, then one would have determined the value of B as well with a measurement of A. But what if B does not commute with A? Then the superposition for observable B REMAINS, i.e. the measurement of A does NOT destroy the superposition represented by observable B.

3. What this means is that the question on whether an object "exists" or not as representing "quantum superposition" is a fallacy! "Exist" isn't an observable. A measurement of position is. One doesn't determine the existence of the ENTIRE object. One determines INDIVIDUAL properties, such as position, momentum, energy, spin, charge, etc... etc., where EACH ONE Of these properties are represented by a particular observable operators (Hermitian operators). Thus, the question of the "existence" of a virus in a superposition of states" is meaningless. One can measure, say, the energy eigenvalue, position eigenvalue, etc. (assuming that the wavefunction are eigenfuctions of these observables, i.e. the matrix is purely diagonal), but to ask if such a thing "exist" in a superposition is a bastardization of quantum mechanics.

This is the issue. The inadequacy of the classical models. I have no other point to make in this thread, except the limited applicability of the classical concepts for a coherent worldview.
I don't think you have the ability to make that judgment.

Zz.


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