Bohr-Einstein debate: why did Bohr not simply say

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In summary, Bohr countered Einstein's arguments by relying on classical conservation laws, but Einstein still thought that using classical concepts such as momentum was a serious threat to physics.
  • #36
mr. vodka said:
Hello,

We've all heard of the Bohr-Einstein debates to some degree (the essence of them being: Einstein tried to convince Bohr that the uncertainty principle is not true by claiming to have found concrete thought experiments that seemed to violate it). Bohr countered Einstein's arguments.

But what I don't understand is why Bohr not simply said "but you're using classical reasoning", since Einstein heavily depended on classical conservation laws, for example that of momentum. Okay conservation of momentum is still true for statistical averages in the QM formalism, but Einstein really used them classicaly: imagining one particle bouncing off a wall imparting momentum to the wall in such a way as to keep the total momentum fixed.

For example, if Bohr hadn't given the conclusive counter-arguments which he did (incidentally also using classical conservation laws), would others have accepted Einstein's reasoning? Or would they simply have countered with "yes but you're using a classical reasoning"? I think the latter. Hence I'm confused why Bohr didn't immediately answer with it.

NOTE: please don't reply with "the UP is merely a statistical statement that can be derived from the formalism and which talks about the standard deviations of the position and momentum distribution": I know this, but this is not in the least what the above question is about.

EDIT: some people apparently, for some reason, interpreted my OP as inviting general comments about Einstein's realistic view, which is not what this thread is about, every sentence I wrote down was supposed to be specific to the two thought-experiments Einstein brought forth in the Bohr-Einstein debates and are not with a greater generality than that. My question is simply why Bohr thought Einstein's reasoning using classical concepts such as conservation of momentum (not averaged) was a serious threat, saying things like "it would be the end of physics if Einstein were right" etc, although these concepts are not really part of quantum mechanics and so can hardly be used to derive a contradiction.



Well this is what Bohr thought: "Albert asked about a photon and a screen and a double slit screen, so my answer must contain a photon, a screen and a double slit screen. Now I just have to think what really happens to the photon, the screen and the double slit screen"
 
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  • #37
Hello, I'm just replying to ask whether you've found out the answer for your question. I think even if Bohr had said "but you're using classical reasoning", it would not help his side of the argument very much. I'm not sure if you'll get this analogy but saying "but you're using classical reasoning" is like a laywer saying "but you're a thief" to a thief in a court. The lawyer and the thief both know that the thief if a thief but how will that help the lawyer prove that the lawyer is correct to the jury. In a similar sense, Bohr and Einstein both knew Einstein was using classical reasoning but how will that help Bohr prove that he is correct. I hope you get where I'm coming from but I'm not even in a University yet so I've probably said something wrong. If you have found a more reliable answer to your question as I am genuinely interested in finding out the answer.
 
  • #38
MusaKusa said:
Hello, I'm just replying to ask whether you've found out the answer for your question. I think even if Bohr had said "but you're using classical reasoning", it would not help his side of the argument very much. I'm not sure if you'll get this analogy but saying "but you're using classical reasoning" is like a laywer saying "but you're a thief" to a thief in a court. The lawyer and the thief both know that the thief if a thief but how will that help the lawyer prove that the lawyer is correct to the jury. In a similar sense, Bohr and Einstein both knew Einstein was using classical reasoning but how will that help Bohr prove that he is correct. I hope you get where I'm coming from but I'm not even in a University yet so I've probably said something wrong. If you have found a more reliable answer to your question as I am genuinely interested in finding out the answer.

If I argue that A implies B. And you are arguing Not B then you need to point out that Not A is possible (since A implies B = B or Not A.)

"You're thinking classically" is saying that one is using implicit assumptions (A's) which should not be accepted a priori when "thinking quantum mechanically". Classical thinking is very difficult to unlearn as it is what we use in everyday experience (to good effect). It is analgous to the problem of thinking in terms of absolute time vs thinking (special) relativistically. It is counterintuitive until you systematically retrain your intuition. We have the advantage of being able to review Bohr's and Einstein's written thoughts while they had to struggle to understand a new paradigm.

[Edit, an additional comment.]
In your lawyer analogue, it is more like the prosecutor saying "your a convicted thief so your testimony is questionable" while the defense is pointing to evidence that the witness was in fact wrongly convicted and thus not a thief and so we should listen to what he has to say.
 

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