Seven Questions for Quantum Physicists

[dron]

I am interested in the irrational. I have the usual layman's understanding of the double-slit experiment, which I am told is the cornerstone of quantum irrationality. I have a question to clear up my understanding of this, and a few more questions about irrationality in physics.

You will soon see that I am not a scientist or expert. My grasp of scientific nomenclature is weak at best, and I have quite a naive understanding of modern scientific discoveries. Please, if you reply, can you assume you are talking to a bright GCSE teenager rather than a professor of differential calculus.

1. The double slit experiment works with matter or light, right? What are the "particles" ("quanta"?) that are fired at the slits?

2. The particles "know" when they are being measured, right? They are behaving like waves, going through both slits, and then when they are measured they suddenly only go through on slit, right?

3. What the double-slit experiment must "mean" is that the elementary particles of light / matter are behaving in a way that the brain cannot adequately imagine, in the same kind of way that the brain cannot imagine a line infinitely long, or an object that must be spun 720 degrees to get back to its original point.

4. I seem to remember reading of a particle like this, that has to be spun twice to get back to the start. Is this right?

5. What other unimaginable or irrational things happen in the quantum world? Can someone give me, or point me towards a nice little list of things that happen that don't make sense, or rather that can't make sense because they are paradoxical or somehow infinite?

6. Like I say, I am very interested in the relationship between infinity, paradox and the unimaginable. Anything that anyone has to say that might open up new explorations of these themes would be welcome. I'm not interested in "psuedoscience" or religion (at least abrahamic religion), rather aesthetics and the nature of perception.

7. Finally, on a completely different topic, probably not physics at all, I recently read that "systems theorists have shown that natural systems and organisms have an innate tendency to move towards complexity, creating a structures which are more than the sum of parts. Apparent order and complexity are not created by genetic mutations, but by the innate emergent properties of matter." Is this so? Where can I read more about this?

Thank you for your time.

 

[vanesch]

Given that you are interested in the irrational, the paradox and the unimaginable, what do you hope one can give you as an answer ?

It's because of the spaghetti monster. 42, remember ? Never sneeze. In Tartiflette we trust.

(is that irrational enough ? I'm trying...)

Seriously, science is about trying to get a more or less rational (even if totally strange) picture of nature. Don't confuse bizarre, weird, strange, unintuitive with irrational, paradoxial, unimaginable. The first are contradictions with our "intuition" and our "common sense" - the second are contradictions with intellectual activity. In as much as science can accept, and often leads to, the first kind of sensations, it can only do so because it tries to avoid at all price the second. If you're interested in the second, we can't help. At all.

 

[dron]

Seriously, science is about trying to get a more or less rational (even if totally strange) picture of nature. Don't confuse bizarre, weird, strange, unintuitive with irrational, paradoxial, unimaginable. The first are contradictions with our "intuition" and our "common sense" - the second are contradictions with intellectual activity. In as much as science can accept, and often leads to, the first kind of sensations, it can only do so because it tries to avoid at all price the second. If you're interested in the second, we can't help. At all.

I realize that few scientists would accept that there is much in reality that is irrational, paradoxical, unimaginable, infinite, eternal and so forth; but are you saying then that such things have no place in science? I understand the results of the double-slit experiment to be paradoxical. Perhaps the first experimenters in this field "avoided" the paradoxical "at all price," but they seemed to have found it. Perhaps if scientists didn't avoid such things at all costs they would make more interesting discoveries?

 

[Vanadium 50]

You will soon see that I am not a scientist or expert.

Perhaps if scientists didn't avoid such things at all costs they would make more interesting discoveries?

I see. You aren't a scientist yourself, but scientists are doing it all wrong.

 

[dron]

I see. You aren't a scientist yourself, but scientists are doing it all wrong.

I didn't say "they are doing it all wrong", but even if I was, the fact that I am not a scientist does not necessarily make such a claim less worthwhile, useful, true or interesting.

 

[russ_watters]

...the fact that I am not a scientist does not necessarily make such a claim less worthwhile, useful, true or interesting.

Yes, it does. You have no way of knowing if what you say is true, much less any way to prove it. All you have is a feeling of discomfort about science, combined with a pretty high level of ignorance about it*. And it is self-evident: when you don't understand the rational basis for something, you are likely to find it irrational. The solution would seem obvious: learn about science, and maybe your discomfort with it will go away via understanding. To see that science is rational, you have to learn and understand the rational basis of it.

*And oh, by the way: science has worked better than any other method of attempting to understand how the universe works. Hands down. The period just before science was invented was called "The Dark Ages" for good reason. So it is a little arrogant to believe that out of your ignorance can come a superior method for approaching understanding of the universe.

 

[atyy]

5. What other unimaginable or irrational things happen in the quantum world? Can someone give me, or point me towards a nice little list of things that happen that don't make sense, or rather that can't make sense because they are paradoxical or somehow infinite?

The problem with most of your "irrational" things is that they're nowadays considered old hat. I still consider the "infinitesimal" of Newton and Leibniz worse than anything in quantum mechanics (the mathematicians have thrown it away, but I think most physicists still use it).

What are the most far-out things that are still considered "respectable science"?

http://www.quiprocone.org/Protected/DD_lectures.htm (This one is probably not weird enough for you)
http://www.qubit.org/people/david/Articles/Frontiers.html
http://arxiv.org/abs/astro-ph/0204479

 

[dron]

Yes, it does. You have no way of knowing if what you say is true, much less any way to prove it. All you have is a feeling of discomfort about science, combined with a pretty high level of ignorance about it*. And it is self-evident: when you don't understand the rational basis for something, you are likely to find it irrational. The solution would seem obvious: learn about science, and maybe your discomfort with it will go away via understanding. To see that science is rational, you have to learn and understand the rational basis of it.

I'm not quite sure what I have said that warrants such a hostile tone. Please note that I am not saying much here; and so its truth or falsehood is moot. I am asking questions. If you have answers, please give them to me, if my questions are foolish, please point out why.

I did say "the fact that I am not a scientist does not necessarily make such a claim less worthwhile, useful, true or interesting." Which I hold to. There is nothing to say that a non-scientist cannot point out a scientist's error. This is not what I am doing here though.

You are right that I have "a high level of ignorance" about science. There is a lot of science out there though, isn't there? I've read a few "popular science" books, but that's not saying much.

I'm not uncomfortable about science though. Honest.

Perhaps there is a semantic problem here. When I say "irrational" I mean that what the double-slit experiment seems to mean cannot be thought about or imagined; in the same way as infinity cannot be thought about or imagined. A symbol can represent infinity or paradox, and we can think about that, but actual infinity cannot be experienced by finite machinery. That's what I mean when I say infinity and paradox and what the double-slit experiment means are irrational. Perhaps I should use a different word though.

(I do believe that infinity and paradox can be experienced, by the way, just not with the mind; with something more intelligent)

*And oh, by the way: science has worked better than any other method of attempting to understand how the universe works. Hands down. The period just before science was invented was called "The Dark Ages" for good reason. So it is a little arrogant to believe that out of your ignorance can come a superior method for approaching understanding of the universe.

You seem to be reading quite a lot into my few words.

Anyrate, the dark ages have this name, as far as I know, because we know very little about what happened during them, not because they were a time of darkness. They almost certainly were a time of darkness, but then the so-called "enlightenment" was hardly a time of peace, cooperation and tolerance. Also the thirteenth century saw some of the greatest architecture Europe has seen and the appearance of transcendent personal romantic love as something to value and strive towards.

As far as I know the greatest period of human history that we have any (albeit indirect) record of was between six and twelve thousand years ago; very little warfare, non-hierarchical societies, not much disease. This period definitely preceded science I'd say. Also there have been more than a couple "primitive" tribes, completely ignorant of science, who have displayed far great social intelligence, cooperation and creativity than our "scientific" (if that's what it is) world has yet come up with.

 

[dron]

atyy - thanks for the links, very interesting; but I'm not so much in the market for weird theories as weird discoveries and observations (like this double-slit business). I'd really like to know about particles that seem to telepathically understand each other and that simultaneously appear and disappear and all that stuff.

 

[Dale]

2. The particles "know" when they are being measured, right? They are behaving like waves, going through both slits, and then when they are measured they suddenly only go through on slit, right?

Don't anthropomorphize. When you measure which slit they go through you change the experimental set up so it shouldn't be terribly surprising that you change the experimental result. It doesn't imply any sentience to particles.

3. What the double-slit experiment must "mean" is that the elementary particles of light / matter are behaving in a way that the brain cannot adequately imagine, in the same kind of way that the brain cannot imagine a line infinitely long, or an object that must be spun 720 degrees to get back to its original point.

It might mean that it behaves in a way that you cannot adequately imagine today. But since it can be adequately described by math and since math is a construct of the human imagination that is only a question of time and your desire to really learn.

5. What other unimaginable or irrational things happen in the quantum world? Can someone give me, or point me towards a nice little list of things that happen that don't make sense, or rather that can't make sense because they are paradoxical or somehow infinite?

Since you are talking about a list of things that don't make sense to you or that you cannot imagine then you are the only one who can generate such a list. QM has a solid mathematical framework, so although it may be strange to you it is perfectly logical.

 

[dron]

Don't anthropomorphize. When you measure which slit they go through you change the experimental set up so it shouldn't be terribly surprising that you change the experimental result. It doesn't imply any sentience to particles.

Here I am not anthropomorphising. This is why I put "know" between speech marks.

I didn't know the experimental set-up was so radically changed. Are you saying that the bizarre results of the double-slit experiment are just down to this?

It might mean that it behaves in a way that you cannot adequately imagine today. But since it can be adequately described by math and since math is a construct of the human imagination that is only a question of time and your desire to really learn.

Adequately described is not the same as experiencing. As far as I know the thinking rational 'scientific' brain can experience dichotomy, discrete information and so forth, but can no more experience non-discrete continuous qualitative information than my nipples can fire laser beams.

I'm pretty confident that the part of the brain that does maths will never be able to experience infinity and paradox.

Since you are talking about a list of things that don't make sense to you or that you cannot imagine then you are the only one who can generate such a list.

Were it so! Alas I do not have access to electron microscopes, large hadron colliders, oscillating hyper-static ion-chambers, and the like. Nor do I have the kind of knowledge and aptitude for understanding the reports of those that do. I was hoping to get a few crumbs from the table here.

 

[atyy]

atyy - thanks for the links, very interesting; but I'm not so much in the market for weird theories as weird discoveries and observations (like this double-slit business). I'd really like to know about particles that seem to telepathically understand each other and that simultaneously appear and disappear and all that stuff.

The key words to search for are probably: EPR Paradox, Bell's theorem, Aspect Experiment. You can also search for quantum teleportation, but it's not as weird as it sounds.

Bell's Theorem
http://www.upscale.utoronto.ca/PVB/Harrison/BellsTheorem/BellsTheorem.html

An experimental test of non-local realism
Simon Groeblacher, Tomasz Paterek, Rainer Kaltenbaek, Caslav Brukner, Marek Zukowski, Markus Aspelmeyer, Anton Zeilinger
http://arxiv.org/abs/0704.2529

Experimental test of nonlocal realistic theories without the rotational symmetry assumption
Tomasz Paterek, Alessandro Fedrizzi, Simon Groeblacher, Thomas Jennewein, Marek Zukowski, Markus Aspelmeyer, Anton Zeilinger
http://arxiv.org/abs/0708.0813

The Free Will Theorem
John Conway, Simon Kochen
http://arxiv.org/abs/quant-ph/0604079

The Strong Free Will Theorem
Authors: John Conway, Simon Kochen
http://arxiv.org/abs/0807.3286

 

[dron]

Thank you! Just the ticket.

 

[Dale]

Here I am not anthropomorphising. This is why I put "know" between speech marks.

I didn't know the experimental set-up was so radically changed. Are you saying that the bizarre results of the double-slit experiment are just down to this?

Yes.

Adequately described is not the same as experiencing. As far as I know the thinking rational 'scientific' brain can experience dichotomy, discrete information and so forth, but can no more experience non-discrete continuous qualitative information than my nipples can fire laser beams.

I'm pretty confident that the part of the brain that does maths will never be able to experience infinity and paradox.

You originally said "imagine", not "experience". If you can describe it you can imagine it (even when you don't want to, e.g. the imagination that your "nipples can fire laser beams" description evoked). What would be the point of imagination if it were limited to experience?

That said, yes, we are too big to experience the quantum world, but we can imagine it in great detail.

Were it so! Alas I do not have access to electron microscopes, large hadron colliders, oscillating hyper-static ion-chambers, and the like. Nor do I have the kind of knowledge and aptitude for understanding the reports of those that do. I was hoping to get a few crumbs from the table here.

Simply ask about specific things that interest you without throwing around anti-scientific words like "irrational"; you will get more than crumbs.

 

[dron]

You originally said "imagine", not "experience". If you can describe it you can imagine it (even when you don't want to, e.g. the imagination that your "nipples can fire laser beams" description evoked). What would be the point of imagination if it were limited to experience?

In this case I'd say imagine and experience are the same (as imagination for the mind is experience). I cannot experience a paradox in my mind and I cannot imagine it either - in the same way I can imagine, say, two pineapples. In the case of both the pineapples and the paradox I am investigating or using a sign or symbol in my head, but in the case of the paradox there seems to be an inherent uncertainty in the relationship between the sign and what it represents.

That might be bo@!$cks though.

Somehow I feel my idea of laser-firing nipples and pineapples is of a different order of idea to "infinity" or "paradox". This is what I am investigating. I beg your indulgence - or your silence.

Simply ask about specific things that interest you without throwing around anti-scientific words like "irrational"; you will get more than crumbs.

As far as I know I have asked about specific things that interest me. Atyy gave me some good answers too. I've never considered the word "irrational" to be "anti-scientific" just lying significantly (although not totally) beyond the cast of its net; like love, for example, or creativity.

But as I say, its a question of semantics. For me, for example, there is a difference between illogical, irrational, insane and wrong. I should have made my terms clearer.

 

[Dale]

In this case I'd say imagine and experience are the same

OK, then we can describe/imagine/experience QM. I think that is stretching credulity on the use of the word "experience", but I won't argue the point.

I've never considered the word "irrational" to be "anti-scientific" just lying significantly (although not totally) beyond the cast of its net; like love, for example, or creativity.

Science is a method for applying empirical observation and reason towards gaining knowledge. To describe one of the greatest accomplishments of science as "irrational" (without reason) is therefore very antagonistic, which is why I said anti-scientific instead of just unscientific.

 

[icelevistus]

I agree that the use of "irrational" is having a destructive effect on what you're trying to say. "Irrational" implies that there is not rigorous reasoning behind something, which there is for all accepted physics. Perhaps the word you are looking for is "counter-intuitive"?

Unfortunately, most all physics developed in the past hundred or so years is counter-intuitive. Part of the reason for this is that physics has been exploring regimes that are outside of the world we can normally observe, where intuition really has no place.

The fact that time is relative is often met with rotten vegetables when presented to high school physics students. (How can time progress slower in a fast-moving spacecraft relative to the earth?). BUT, if you accept the fact that light travels at the same speed in all reference frames (which is incontrovertibly true), then a little math proves this time dilation.

The fact that no one travels fast enough to FEEL the effects of time dilation means your intuition is useless.

Quantum physics falls into the same category. We like to imagine that we can measure something without affecting it, but that's because we're big dumb animals. You can't measure a length without, for example, observing a constant bombardment of photons reflecting off the object and ruler into our eye. These photons have a small effect on large systems (ones that can be seen with the naked eye...even a speck of dust), but when you're looking at an atom or something of that size, hitting it with a photon is like throwing a wrench into the gears of a machine.

The grand paradox of quantum physics is that things do not have a definite state until the act of measurement forces it into one. For example, an electron could be spinning one direction or the other, but we don't know (actually, it is spinning in both directions) until measuring it. This is counter-intuitive until you see the rigorous math going into it, the predictions it has made, and that spectacular experiment showing that the act of repeatedly measuring a system will (probabilistically) forbid it from changing states.

To answer your first question, the particles are usually photons (or electrons).

 

[vanesch]

I agree that the use of "irrational" is having a destructive effect on what you're trying to say. "Irrational" implies that there is not rigorous reasoning behind something, which there is for all accepted physics. Perhaps the word you are looking for is "counter-intuitive"?

Unfortunately, most all physics developed in the past hundred or so years is counter-intuitive. Part of the reason for this is that physics has been exploring regimes that are outside of the world we can normally observe, where intuition really has no place.
.

That's exactly the point I wanted to make in my first post in this thread. There is a mountain of difference (in fact, almost a pure opposition) between "counter-intuitive and weird" on one hand, and "paradoxical and irrational" on the other.

As you say, most modern physics is counter-intuitive and weird at first (until you get used to it, and then you start getting some "intuition" for it). There are really bizarre things out there. But, and that's important, most of these things have adequate, logical theoretical descriptions - even though they go against about all we think we can feel about nature. It shouldn't surprise us: "intuition" and "familiarity" comes about because of accumulated experience. If you enter in a domain where you don't have any experience, your accumulated experience is not bound to give valid hints. That's what happens.

However, when one talks about "irrational and paradoxical", then that means: "truth" and "falsehood" have no longer any meaning. Statements are both truth and false. Logical deduction fails (if A is true, and if B is true, then A and B can nevertheless be false). Thinking fails. You saw the red light flash, I saw the green light flash, and when we compare our observations, we agree that there was no light flashing, or something of the kind. If this were somehow common in "science", then it couldn't be counter-intuitive at all, simply because it would not be possible to explore anything beyond the intuitively and commonly "known": no logical deduction, no mathematical calculation would be trustable, given that logic, and hence mathematics, is bound to fail (that's what it means: irrational and paradoxical). We couldn't deduce anything. So we couldn't deduce anything "counter-intuitive". It would be all "gut feeling and amazement".

 

[dron]

A paradox is irrational.

This is a paradox: A and B cannot both be true at the same time. A is true. B is true.

This is (an example of) quantum physics: A photon cannot be both a wave and particle at the same time. A photon is a wave. A photon is a particle.

Therefore the results of quantum physics are irrational? Please point out the fallacy here. I have am happy to be shown wrong.

I'm not saying the reasoning (theories, technique, etc) of QP is irrational, but the results (the observations, etc) are. This to me makes sense, as life itself is fundamentally irrational. Not completely irrational; it is partly rational, and that for that part we have science. (scientists err, in my opinion, by using rationality to understand the un-understandable - but I digress).

Would anyone like to take a stab at answering my questions? I'm quite satisfied with atyy's links, but anything else on this tack would be valued. Thanks for the info about photons icelevistus - are photons and electrons found in light and matter, or is one found in one and another in another, or what?

 

[vanesch]

A paradox is irrational.

This is a paradox: A and B cannot both be true at the same time. A is true. B is true.

This is (an example of) quantum physics: A photon cannot be both a wave and particle at the same time. A photon is a wave. A photon is a particle.

Well, a photon is neither a (classical) particle, neither a (classical) wave, but its behavior is sometimes similar to that of a (classical) particle, and sometimes similar to that of a (classical) wave, and most of the time, it's different from both. A photon is an excitation of a quantum field.
It is true that the Copenhagen picture of quantum theory is somewhat paradoxial and irrational, but you're not obliged to adhere to it. There are much cleaner pictures of quantum theory.

I'm not saying the reasoning (theories, technique, etc) of QP is irrational, but the results (the observations, etc) are. This to me makes sense, as life itself is fundamentally irrational. Not completely irrational; it is partly rational, and that for that part we have science. (scientists err, in my opinion, by using rationality to understand the un-understandable - but I digress).

That's what some people claim(ed). It doesn't have to be looked up that way. The "paradoxes" only come about because we want to force upon modern physics certain properties/views which are not compatible with it. If you let these a priori notions go, then the paradoxes go away too.

 

[Dale]

A paradox is irrational.

This is a paradox: A and B cannot both be true at the same time. A is true. B is true.

This is (an example of) quantum physics: A photon cannot be both a wave and particle at the same time. A photon is a wave. A photon is a particle.

Therefore the results of quantum physics are irrational? Please point out the fallacy here. I have am happy to be shown wrong.

The part highlighted in red is the fallacy. In QM all particles (photons, electrons, baseballs) have wavefunctions, so all particles have behavior that is classically associated with waves, e.g. diffraction. The reverse is also true, in QM all waves have quanta, so all waves have properties that are classically associated with particles, e.g. momenutm. In QM there is no demarcation between "particles" and "waves"; those classical terms are two sides of the same QM coin.

 

[Vanadium 50]

But as I say, its a question of semantics. For me, for example, there is a difference between illogical, irrational, insane and wrong. I should have made my terms clearer.

Fair enough. Do you think QM is irrational? Or do you think it's illogical? Insane? Wrong? Which one?

I would maintain that one person's discomfort with a theory - particularly someone who hasn't studied it in depth doesn't make it illogical, irrational, insane or wrong.

 

[atyy]

This is (an example of) quantum physics: A photon cannot be both a wave and particle at the same time. A photon is a wave. A photon is a particle.

Yes, I always felt somewhat cheated about an electron being called a "particle". It's a technical definition, somewhat divorced from everyday language, like the definition of "work" in Newtonian physics. In experiments at places like CERN, it is a "particle" with no definite position, but with definite momentum. I felt much better about such usage after reading:

“Energy and momentum are important concepts because of two facts: first they are, in the context of quantum mechanics, enough to describe completely the state of a single free particle (disregarding internal properties such as spin and charge), and second, they are conserved. ... Normally we specify the state of a particle by its position and its momentum at a given time ... It is easy to “explain” something that everybody can actually see in the macroscopic world that we live in, but particles do not necessarily behave in that fashion. We must treasure those properties that are the same at the quantum level as well as macroscopically. The laws of conservation of energy and momentum belong to those properties. So this is our way of treating the difficulties of quantum mechanics: talk about things you know and understand, and just do not discuss whatever you cannot know. If you cannot know where the particle is located let us not talk about it.” (Veltman, Facts and Mysteries in Particle Physics, World Scientific, 2003, Chapter 4, Energy, Momentum and Mass-Shell)

 

[atyy]

A paradox is irrational.

I'm not saying the reasoning (theories, technique, etc) of QP is irrational

Well, one has to be careful about everyday words like "irrational" which have slightly different meanings in everyday speech depending on context. But have you heard of Goedel's incompleteness theorem?

One could imagine that there is such a thing as a completely "rational" logical system, in which there are no paradoxes, and every meaningful statement is either true or false. (The truth or falsity of meaningless statements are not even interesting, like in English: meow is greener than my cat). In such a system, every meaningful statement would be either true or false. What Goedel showed is that if we devise a logical system powerful enough to describe arithmetic, then we can formulate statements that are meaningful within that system, but are neither true nor false.

In this framework, a paradox is not a meaningful statement that is both true and false. Rather, it is a meaningful statement that is neither true nor false - so we can decide, for example, that it is false (or true, but not both). Goedel showed that if we enlarge our logical system with the additional axiom that this particular statement is false, then we automatically generate another meaningful statement that is neither true nor false.

This is all in the context of logic, which is full of interesting things I know little about. For example, Count Iblis recently made a very interesting comment about a different piece of logic (not the Goedel incompleteness theorem) called the axiom of choice:
https://www.physicsforums.com/showthread.php?t=254602&highlight=axiom

 

[vanesch]

What Goedel showed is that if we devise a logical system powerful enough to describe arithmetic, then we can formulate statements that are meaningful within that system, but are neither true nor false.

If I may nitpick: Goedel shows that there are meaningful statements *of which the truth or falsehood cannot be demonstrated through logical proof* within the axiomatic system.

There's a difference, especially when the axiomatic system is a model for another system (like nature). It means that we don't have the logical means, within the axiomatic system, to *prove* the truth or falsehood of said statement. However, the statement as such can have a truth or falsehood statement "in the modeled system".

This is not "illogical" or "paradoxical". It is just a limit to the formal technique of proof from axioms.

A paradox is something else: a paradox is a meaningful statement for which BOTH a proof exists which shows it to be true, and a proof exists which shows it to be false. An axiomatic system that contains paradoxes is essentially useless, because one can show that such an axiomatic system can make ANY meaningful statement into a paradox if it contains just a few elementary rules of inference.

Something which is "illogical" means: it is not open to any form of axiomatisation and logic inference. There's no way to organize truth and falsehood values according to any logical organization. "God's decisions" would be illogical for instance.

 

[dron]

It is true that the Copenhagen picture of quantum theory is somewhat paradoxial and irrational, but you're not obliged to adhere to it. There are much cleaner pictures of quantum theory.

I may not be obliged to adhere to it, but given the choice (which I seem to have) I will. I much prefer the somewhat paradoxical and irrational over the somewhat not.

I didn't know the experimental set-up was so radically changed. Are you saying that the bizarre results of the double-slit experiment are just down to this? - Yes.

So you're saying it is possible to set up the experiment so that the results come out un-paradoxically?

In QM all particles (photons, electrons, baseballs) have wavefunctions, so all particles have behavior that is classically associated with waves, e.g. diffraction. The reverse is also true, in QM all waves have quanta, so all waves have properties that are classically associated with particles, e.g. momenutm. In QM there is no demarcation between "particles" and "waves"; those classical terms are two sides of the same QM coin.

Hmm. I believe Mr Feynman said that anyone who claims to understand the double slit experiment is lying. I'm not saying you are claiming to understand it, or that you are lying, but, forgive me; I can't help feeling that this kind of explanation rather finesses what I understand to be the outstanding weirdness of the quantum world.

Fair enough. Do you think QM is irrational? Or do you think it's illogical? Insane? Wrong? Which one?

I would maintain that one person's discomfort with a theory - particularly someone who hasn't studied it in depth doesn't make it illogical, irrational, insane or wrong.

I think QM is irrational and illogical. It is irrational in the way I have explained - paradoxical. In this way love and great art are irrational, so no problem there. I think it is illogical in the same way I think science is usually illogical; it puts second thing first. Insane is a more complex concept, which I won't go into here, but let's say I don't think QM is insane. And I don't think it's wrong either, although, not knowing much about it, I'm not qualified to say.

Above all I am not uncomfortable with it. Far from; the results and implications of the double-slit experiment strike me as wonderful. They start to take away the power of the scientific priesthood; a significant step towards beauty and awe; which, at the moment, are generally considered (by mediocre scientists) to be "unscientific".

(Thank you for your interesting contributions atyy.)

 

[atyy]

There's a difference, especially when the axiomatic system is a model for another system (like nature). It means that we don't have the logical means, within the axiomatic system, to *prove* the truth or falsehood of said statement. However, the statement as such can have a truth or falsehood statement "in the modeled system".

A paradox is something else: a paradox is a meaningful statement for which BOTH a proof exists which shows it to be true, and a proof exists which shows it to be false. An axiomatic system that contains paradoxes is essentially useless, because one can show that such an axiomatic system can make ANY meaningful statement into a paradox if it contains just a few elementary rules of inference.

In this framework, a paradox is not a meaningful statement that is both true and false. Rather, it is a meaningful statement that is neither true nor false - so we can decide, for example, that it is false (or true, but not both). Goedel showed that if we enlarge our logical system with the additional axiom that this particular statement is false, then we automatically generate another meaningful statement that is neither true nor false.

Yes, what you wrote about being able to add to the axioms is in agreement with what I wrote about being able to enlarge the logical system.

Goedel's theorem is usually related to the Liar's paradox, so I don't think I'm using unusual terminology. A paradox could be thought of as a direct contradiction, as you said, or within the framework of Goedel's theorem, a statement that is neither true nor false. Though now reading this, I may not have been quite correct about how to go about adding to the axioms:
http://www.ltn.lv/~podnieks/gt5.html

 

[Dale]

So you're saying it is possible to set up the experiment so that the results come out un-paradoxically?

No, I am saying that it was never paradoxical in the first place.

I think QM is irrational and illogical. It is irrational in the way I have explained - paradoxical.

Can you rigorously demonstrate any paradox? Don't use these terms until you can back them up.

Rather than actually learn anything in order to make informed conclusions you come from an admitted place of complete ignorance and begin using emotionally-charged and anti-scientific words like "irrational" and "illogical" to describe QM. What I don't understand is your goal. It obviously is not to learn about QM: people who want to learn don't deliberately go out of their way to antagonize people from whom they want information. It is also obviously not to teach since you carefully proclaim your ignorance. So what do you want out of this discussion?

 

[vanesch]

What I don't understand is your goal. It obviously is not to learn: people who want to learn don't deliberately go out of their way to antagonize people from whom they want information. It is also obviously not to teach since you carefully proclaim your ignorance. So what do you want out of this discussion?

I think it is confirmation of mysticism.

 

[dron]

Can you rigorously demonstrate any paradox?

Can you explain what you mean here? I can demonstrate paradoxes which the thinking rational brain cannot adequately understand.

Rather than actually learn anything in order to make informed conclusions you come from an admitted place of complete ignorance and begin using emotionally-charged and anti-scientific words like "irrational" and "illogical" to describe QM. What I don't understand is your goal. It obviously is not to learn about QM: people who want to learn don't deliberately go out of their way to antagonize people from whom they want information. It is also obviously not to teach since you carefully proclaim your ignorance. So what do you want out of this discussion?

I did not admit complete ignorance, nor did I admit ignorance of anything other than quantum mechanics (in this I belong to very large group of people). My use of terms like "irrational" and "illogical" are only emotionally charged if you feel emotional when you read them. My goal is to enjoy myself and learn something interesting. I am not going out of my way to deliberately antagonise you, and find it quite remarkable that you are antagonised - emotionally, I assume. My purpose here is not to teach you anything about Quantum Mechanics, of course, but I can help you deal with these troublesome emotions if you like.

I think it is confirmation of mysticism.

Mysticism is a word that has many meanings. Which one are you using here? Anyrate I'm wouldn't seek to confirm anything important with science, that would be daft.

 

[DrChinese]

Perhaps if scientists didn't avoid such things at all costs they would make more interesting discoveries?

1. If you learn what scientists actually discuss and consider, you will discover that they are not avoiding anything. I can assure you that scientists have first rate minds and are open to the "inconceivable". They do not avoid scary subjects or questions. But there is a process - the Scientific Method - and this serves as the arbiter as new ideas are considered. Two important questions for any theory or hypothesis:

a) Does it fit known facts (prior experiements)?
b) Does it makes useful or testable predictions different than current theory?

If the answers are Yes, then you will likely see it investigated.

2. To address some of your questions: the double slit experiment is not really the "cornerstone" of quantum weirdness (although there are famous quotes to that effect). There are many elements of QM that are could be considered "weird". Quantized electron orbitals are one. Virtual particles are another. I personally consider the Heisenberg Uncertainty Principle to be one of the weirdest, and this is essentially the source of the phenomena of the double slit. But it leads to many other strangle things too, including the EPR Paradox and Bell's Theorem.

 

[linton]

You can't go into an arena and bandy about words that have very specific definitions relative to that arena, and expect a coherent (from your perspective) response.
If someone berates you for the use of those terms, then find out what exactly it is you should be asking, and then be specific about that.
Also, the questions you asked, and your admitted lack of formal or informal education regarding this specific subject makes it pretty hard to give any kind of answer.
for instance, if you don't know what is used in the experiment, or have a decent understanding of it, you can't understand the result to any large degree other than "it's magic" and then you can stumble on terms like wave particle duality. You then apply an understanding that something is magically what it shouldn't be, using a layman’s understanding of the classic definition of particles and waves.

Anyhow, in any technical arena, you need to be aware that there are very specific meanings with reference to specific words, and if you use one out of place, you will not actually be asking what you think you are.
And, relative to this topic, describing quantum mechanics as irrational is ... well
suicidal for your thread.

If you want to see what is unintuitive, just study the subject for yourself. It will require that you equip yourself with the mathematical tools to understand most of the subject matter though.

 

[dron]

Thank you for your courteous answer Dr Chinese. I do enjoy good-natured responses - more than accurate ones, even in a physics forum. This, straight away, singles me out as unlikely to be a scientist.

1. If you learn what scientists actually discuss and consider, you will discover that they are not avoiding anything.

I have to disagree with that one. Science is entirely objective (and I am using objective here in my own way - which I will explain - I do adhere to and 'agree' with the usual subjective-objective split, but for the purposes of discussions like this I find it better to use a much stranger, more fundamental, split - objective being anything that I experience - which can include emotions, guesses, religious ideas, whatever - subjective for me is not personal emotions and unverifiable experience, these are just other kinds of objects (less helpful 'scientifically') - rather the pure silent witnesser - something that scientists - and a good many other people - tend to avoid)

I can assure you that scientists have first rate minds and are open to the "inconceivable".

Depends what you mean by "first rate". If you mean full of knowledge and techniques to use that knowledge, I'd call that second rate. If you mean attentive, perceptive, loving, creative I'd say that very few scientists have such "minds".

They do not avoid scary subjects or questions.

I wonder what their wives would say about that.

But there is a process - the Scientific Method - and this serves as the arbiter as new ideas are considered. Two important questions for any theory or hypothesis:

a) Does it fit known facts (prior experiements)?
b) Does it makes useful or testable predictions different than current theory?

If the answers are Yes, then you will likely see it investigated.

Such things exclude everything most important in life, which is why a very clever machine could do this kind of "science" quite successfully.

I'm not knocking science, or machines. I find science interesting (particularly when what I'd call a "first-rate" mind is involved) and machines useful (with material things). But both are as useless as religion when it comes to anything really important in life (love, suffering, creativity, learning, survival skills...). Of course science does touch upon these matters. Take cooking - the "scientific method" - trial and error, fitting known facts and all that - is a useful tool for improving my recipes and perhaps understanding them. Yes. But what makes me really attentive, really creative, really enjoy and benefit from the results - here science must be silent.

2. To address some of your questions: the double slit experiment is not really the "cornerstone" of quantum weirdness (although there are famous quotes to that effect). There are many elements of QM that are could be considered "weird". Quantized electron orbitals are one. Virtual particles are another. I personally consider the Heisenberg Uncertainty Principle to be one of the weirdest, and this is essentially the source of the phenomena of the double slit. But it leads to many other strangle things too, including the EPR Paradox and Bell's Theorem.

Thank you.

 

[dron]

You can't go into an arena and bandy about words that have very specific definitions relative to that arena, and expect a coherent (from your perspective) response.
If someone berates you for the use of those terms, then find out what exactly it is you should be asking, and then be specific about that.

I don't understand this. Perhaps you could clear up which words I am "bandying" about, and give me the very specific definitions of them? I've already said that this could be a semantic issue, and I'm quite willing to see that I am using words in a way that scientists do not. Why don't we try to understand each other? Give me your definitions, I'll give you mine, and we'll see if we can meet in the middle, eh?

Also, what should I be asking? All I wanted was some information I could understand about what is weird / irrational / paradoxical / etc (to be cleared up later) in QP.

Also, the questions you asked, and your admitted lack of formal or informal education regarding this specific subject makes it pretty hard to give any kind of answer.

The many "popular science" books out there would suggest that, at least, some people think it is possible to give layman some kind of answer. I know, from those fields that I am more knowledgeable (psychology, literature, anthropology, comparative religions, linguistics, etc) about that I can explain them satisfactorily to a seven year old.

for instance, if you don't know what is used in the experiment, or have a decent understanding of it, you can't understand the result to any large degree other than "it's magic" and then you can stumble on terms like wave particle duality. You then apply an understanding that something is magically what it shouldn't be, using a layman’s understanding of the classic definition of particles and waves.

I beg to differ. I think I am capable of understanding a little more than "it's magic". Of course (assuming for a moment there's just you and me talking) I will never be able to understand if you think I'm not capable!

Anyhow, in any technical arena, you need to be aware that there are very specific meanings with reference to specific words, and if you use one out of place, you will not actually be asking what you think you are.

Yes, I see that. Please help me clear up my confusion here.

And, relative to this topic, describing quantum mechanics as irrational is ... well
suicidal for your thread.

Perhaps. It seems to be going pretty strong so far; and at the very least is of interest to me.

If you want to see what is unintuitive, just study the subject for yourself. It will require that you equip yourself with the mathematical tools to understand most of the subject matter though.

Bugger that!

 

[yaychemistry]

Hello dron,

If I could, I would like to know what your motives are in discovering these "irrational" pieces of Quantum Mechanics are. It seems to me you are not just trying to satisfy an idle curiosity, but are looking for ammunition to take us scientists down a peg, e.g.

the results and implications of the double-slit experiment strike me as wonderful. They start to take away the power of the scientific priesthood; a significant step towards beauty and awe; which, at the moment, are generally considered (by mediocre scientists) to be "unscientific".

This might be why there are several people apparently upset with you, and in response: First of all, the double-split experiment is probably one of the first experiments explained in a college quantum mechanics courses, or even freshman physics. It is well understood in the scientific community, and, in fact, demonstrates the success of science in our ability to understand it. Stating that the double-slit experiment takes anything away from "science" would be similar to the claim that the Michaelangelo's work on the ceiling of the Sistine Chapel deals a fatal blow to "painting" because I, as a non-artist, would never have imagined painting something like that on a ceiling. Both statements are absurd.


In addition, you speak as if you know something about scientists. In response to DrChinese's statement that science is full if first rate minds you stated:

Depends what you mean by "first rate". If you mean full of knowledge and techniques to use that knowledge, I'd call that second rate. If you mean attentive, perceptive, loving, creative I'd say that very few scientists have such "minds".

Besides the fact you are being insulting, your statement bothers me very much. You are broadly characterizing people, who work as scientists, based on what? Do you know what it is like working in a research lab? Do you know all the hopes and dreams of those scientists?
On what authority can you claim that scientists cannot be attentive, perceptive, loving, or creative just because they are scientists?
Would I have the right to characterize machinists or factory workers as dull, repetitive people because they work in factories? Can I claim that patent clerks are unimaginative and not creative because their job is boring?

Be careful not to let -your perception- of science color your perception of scientists. We work with the scientific method in the way that DrChinese outlined. There is a reason that we do. It is the best way to generate an understanding of the physical world. While you appear to interpret the double slit experiment, or perhaps other counter-intuitive or "paradoxical" (quotes indicate that the paradox lies only in an incomplete understanding) experimental results as a blow to the scientific method, but in fact these experiments, and all experiments of quantum theory, show exactly the triumph of science.