Any quotes from verified physicists about superposition?

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<Moderator's note: Approved. The original thread has been this. The relocation in QM is better suited in case the thread turns into a direction where physical questions are the subject rather than quotations.>

I have heard many astounding things about QM. For example, that particles have no location until measured. However, I would like an actual quote from a validated physicist that before the wave collapses a particle has no specific location and can be anywhere.
 
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I agree with Carl Sagan that extraordinary claims require extraordinary evidence. The claims of QM are extremely extraordinary. I will never understand the math and I know that one should be skeptical of authority but a quote from a big time physicist that confirms that QM violates common sense intuitions such as that an object must have a location will make me realize that Niels Bohr was right when he said, " If quantum mechanics hasn't profoundly shocked you , you haven't understood it yet."
 
  • #3
Nugatory
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If you're not going to look at the math you're never going to see what QM actually says, or even enough to judge for yourself whether the century of experimental evidence that we've built up is sufficient to justify the counterintuitive claims of the theory.

However, you could give Giancarlo Ghirardi's "Sneaking a look at God's cards" a try. It's written by a real physicist and has the supporting quotes that you're looking for.
 
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So QM is not unusual? That , for example, Bohr's quote has to be seen in context and QM is not really that shocking?
 
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I am beginning to believe that all this QM is different is just way overblown and there is nothing unusual about it. There isn't even one quote that specifically says how QM violates our common sense notions?
 
  • #6
DrChinese
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The claims of QM are extremely extraordinary....For example, that particles have no location until measured. However, I would like an actual quote from a validated physicist that before the wave collapses a particle has no specific location and can be anywhere.
A specific quoted claim to discuss would make this easier. The actual "claims" of QM are not as extraordinary today simply because they are subject to experimental verification. Consequently, this discussion is really more about enlightening you to the extremely large body of specific tests of QM which have confirmed it within statistical limits.

Particles may have very specific positions at any time. There is nothing that requires anything otherwise. On the other hand, a quantum particle cannot have both a very specific location AND simultaneously a very specific momentum. That's a very simplistic statement of the Heisenberg Uncertainty Principle (HUP). Essentially, knowledge of one precludes knowledge of the other.

The HUP can be demonstrated experimentally in many ways, so there is no stretch required on this. Take a particle with a very specific location. Then measure its momentum. Whoops, now it is lost (!) - i.e. not in its expected location. I'm not sure I would use the phrase "it could be anywhere" to describe its location, but there is definitely no way to predict where it will be found with accuracy exceeding the statistical limits of the HUP.
 
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You wrote, "On the other hand, a quantum particle cannot have both a very specific location AND simultaneously a very specific momentum. " I agree. But that is extraordinary. It is not saying that it is our inability to know both, its that the particle does not have both.
 
  • #8
DrChinese
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...QM is not really that shocking?
"Shocking" is in the eye of the beholder. Bohr's comments were 80+ years ago. I don't think folks around here "hype" QM too much, it is what it is. For most people, the initial introduction into QM is in fact some degree of "shocking" or "mystifying". But once one gains more knowledge, it becomes familiar and therefore less "shocking".
 
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Do you agree that QM violates our common sense notions, such as something cannot be A and not A? Particle and wave.
 
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It is A ( a particle ) and not A ( a wave)
 
  • #11
DrChinese
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You wrote, "On the other hand, a quantum particle cannot have both a very specific location AND simultaneously a very specific momentum. " I agree. But that is extraordinary. It is not saying that it is our inability to know both, its that the particle does not have both.
As far as experiments go, that would be the logical conclusion: "the particle does not have both."

However, there are interpretations of QM that allow both to exist, but they say that the HUP represents a lack of knowledge. So that is considered a viable alternative. The down side of that interpretation - Bohmian Mechanics - is that it requires non-locality (instant interaction of widely separated systems). That may bother you even more. :smile:
 
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I apologize for my ignorance but my understanding is that until measured it is both a particle and a wave.
 
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Neither is also weird! If it is not a particle or a wave , what is it?
 
  • #14
DrChinese
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Do you agree that QM violates our common sense notions, such as something cannot be A and not A? Particle and wave.
I don't agree with that statement about "A and ~A", no. A quantum system is definitely not one or the other, it simply sometimes behaves as if it is one or the other at times. It can be any mixture of particle and wave at other times as well. It can be 90% particle and 10% wave, to make a simplification.
 
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It is A ( a particle ) and not A ( a wave
Wave-particle duality is an outdated concept. You can use 'search' button and look up for discussions about it. It's been discussed quite a few times.
 
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Pardon the poor metaphor, so its like a lake with little rubber ducks on it?
 
  • #17
DrChinese
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I apologize for my ignorance but my understanding is that until measured it is both a particle and a wave.
That is a simplistic way of expressing it. The HUP states it mathematically... and precisely.
 
  • #18
DrChinese
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Pardon the poor metaphor, so its like a lake with little rubber ducks on it?
I don't get the analogy. Trying to use metaphors is almost certainly going to keep you in the dark. Go back to Nugatory's wise comment about the math.

Please note that there is no requirement that the mathematical description of the quantum world be reducible to a simple and accurate analogy. The simpler it is, the less accurate it will be.
 
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So we have no idea of what is going on? Sure I can talk about the square root of negative one and actually calculate with it. Do I understand what it is? Of course not! Imaginary numbers are useful but we have no idea how such a paradoxical thing can be.
You wrote, "The actual "claims" of QM are not as extraordinary today simply because they are subject to experimental verification." I have no doubt that QM has been experimentally verified. Similarly, I would still be astonished if it was proven that square circles exist on the subatomic level. Actually my sense of wonder would be increased rather then diminished.
 
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Imaginary numbers are useful but we have no idea how such a paradoxical thing can be.
There is nothing paradoxical about imaginary and complex numbers in general...
 
  • #21
DrChinese
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So we have no idea of what is going on?
Again, that is not accurate from a scientist's perspective because the mathematical description *is* there.

When you ask "what is happening beyond where we can see" you are basically answering your own question...
 
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The square root of negative 1 is incomprehensible because it is paradoxical. If the square root of -1 is negative, a negative times a negative is positive. If it is positive , a positive times a positive is a positive. How can we comprehend a number that is not positive, negative or zero?
 
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Sure I can postulate square circles and might even be able to develop a whole geometry based on the idea that square circles exist. . But do I really know what a square circle is?
 
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Suppose QM was based on square circles ( I know it isn't ) and a whole math was designed around the idea that square circles exist. Suppose I totally understand all that square circle math. Would I understand QM? My contention is , "no".
 
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Hi wittgenstein,
Neither is also weird! If it is not a particle or a wave , what is it?
It's both, it's neither. It's complicated. :smile:
(and so then it may follow you may consider QM to be weird, which is an opinion. :smile:)

Well, it's complicated only if we insist things must be either particles or waves.
Personally I view them* as quantum objects that behave according to the laws of quantum mechanics.

* The things we in physics often just call particles, e.g. electrons, protons, neutrons etc.
 

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