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I'm just an amateur physicist... but since you're a pro, I'm sure you don't really mean it when you say Einstein 'used a theory he didn't believe was correct (q

by Luc 16y ago

I'm just an amateur physicist... but since you're a pro, I'm sure you don't really mean it when you say Einstein 'used a theory he didn't believe was correct (quantum mechanics) to derive conclusions he didn't believe were true'. I mean, that could be misunderstood quite easily as the pop-physics version of history, in which the aging old Einstein just can't hack it, staying stuck in the old ways of thinking. In reality, of course, Einstein was one of the world's top experts in QM, made some large contributions to it, and understood and agreed with the formalism like everybody else - since the experimental verifications were clearly impressive. His opposition was mainly to Bohr's positivism, and to the completeness of QM, but he didn't oppose it's consistency or correctness. At least after about 1930 or so.

bugsy 16y ago
I took his comment to mean that Einstein didn't initially believe in it and it was an intellectual exercise at the time, not that he didn't believe in it after evidence was built up. Kind of the flip side of the Michelson-Morley experiment where they set out to measure the properties of the ether and then tried to find what had gone wrong with their experimental method in that they couldn't detect the ether at all. Belief in the ether was wrong, yet they experimented on it anyway. Likewise, if a religious person decides to do experiments to find evidence the earth is not very old, and his experiment is done properly and fully documented, the experimental results he gets, whatever they are, can still be useful and valid. Maybe the results prove the earth is very old. Maybe they show that different methods of dating the same material give different results and that leads to a breakthrough in more accurate dating.
yummyfajitas 16y ago
I mean, that could be misunderstood quite easily as the pop-physics version of history, in which the aging old Einstein just can't hack it, staying stuck in the old ways of thinking. This is totally the opposite of what I meant to convey. Einstein/Podolsky/Rosen were doing great work. They helped us understand an important implication of quantum mechanics - that if our configuration-space based theories are correct, we must have some non-local hidden variables. They proposed an experiment to validate this, and for philosophical reasons they believed the experiment would invalidate QM. Their guess was wrong, but so what? My point is not that Einstein couldn't hack it - it's the exact opposite. My point is that EPR was a fantastic result, discovered by a group who believed the underlying theory was wrong and their predictions would not come true. Their beliefs were wrong, but their science was sound.
- Luc 16y ago
  Okay, cool! Though (and again I'm sorry for continuing to blab about this, but I don't often get the opportunity) I think it's actually a bit more tricky. When it was published, EPR showed that action by contact (the separation principle) and the _completeness_ of QM can't both be valid. At least, this was Einstein's intention with EPR - in letters to Schrodinger he expresses his chagrin with the way Podolsky, who wrote the paper, buried Einstein's main point in technicalities. Now, when you say he derived conclusions he didn't believe were true, that's kind of wrong, since all he derived was a dilemma (completeness or separation, not both (but possibly neither)). He took this to show that if we maintain the separation principle, then QM needs to be viewed as a statistical account of objects with properties it can't describe (but he never took that to mean hidden variable theories like Bohm's were the answer). So, my point is, he believed in the correctness of QM (just not in the completeness). He believed in QM being true - just not that is was the whole truth. He believed in the correctness of the EPR derivation and in the correctness of the dilemma at the end. When you say he used a theory he didn't believe was correct, I think that's wrong - he just didn't believe it was the finished article. And when you say he derived conclusions he didn't believe were true, I think that's wrong too, since he derived a dilemma that he very much believed in. In the end he chose the wrong side, but that's not relevant here. You say Einstein believed this was a reductio ad absurdum - but that's flat out wrong I think. EPR relates to the completeness of the formalism (if the separation principle is taken to be true), not the correctness.
  - yummyfajitas 16y ago
    When it was published, EPR showed that action by contact (the separation principle) and the _completeness_ of QM can't both be valid. Yes, that's the scientific conclusion. Actually, the history is a bit more muddled - EPR alone doesn't show this, strictly speaking. The EPR paper (1935) concludes with a statement that the authors believe a local and complete theory of QM is possible. We were not 100% certain it was impossible until the discovery of Bell's Inequality (1964, 9 years after Einstein's death). Einstein actually spent a lot of time searching for such a theory. In addition to the scientific conclusions in the EPR paper, EPR also expressed some non-scientific beliefs. They believed that reality would eventually prove itself to be local and therefore that QM would be shown to be incomplete. From the original paper: We are thus forced to conclude that the quantum mechanical description of physical reality given by wavefunctions is not complete [...] No reasonable definition of reality could be expected to permit this. http://prola.aps.org/pdf/PR/v47/i10/p777_1 http://prola.aps.org/pdf/PR/v47/i10/p777_1

by Luc 16y ago

bugsy 16y ago

I took his comment to mean that Einstein didn't initially believe in it and it was an intellectual exercise at the time, not that he didn't believe in it after evidence was built up. Kind of the flip side of the Michelson-Morley experiment where they set out to measure the properties of the ether and then tried to find what had gone wrong with their experimental method in that they couldn't detect the ether at all. Belief in the ether was wrong, yet they experimented on it anyway. Likewise, if a religious person decides to do experiments to find evidence the earth is not very old, and his experiment is done properly and fully documented, the experimental results he gets, whatever they are, can still be useful and valid. Maybe the results prove the earth is very old. Maybe they show that different methods of dating the same material give different results and that leads to a breakthrough in more accurate dating.

yummyfajitas 16y ago

I mean, that could be misunderstood quite easily as the pop-physics version of history, in which the aging old Einstein just can't hack it, staying stuck in the old ways of thinking. This is totally the opposite of what I meant to convey. Einstein/Podolsky/Rosen were doing great work. They helped us understand an important implication of quantum mechanics - that if our configuration-space based theories are correct, we must have some non-local hidden variables. They proposed an experiment to validate this, and for philosophical reasons they believed the experiment would invalidate QM. Their guess was wrong, but so what? My point is not that Einstein couldn't hack it - it's the exact opposite. My point is that EPR was a fantastic result, discovered by a group who believed the underlying theory was wrong and their predictions would not come true. Their beliefs were wrong, but their science was sound.

Luc 16y ago
Okay, cool! Though (and again I'm sorry for continuing to blab about this, but I don't often get the opportunity) I think it's actually a bit more tricky. When it was published, EPR showed that action by contact (the separation principle) and the _completeness_ of QM can't both be valid. At least, this was Einstein's intention with EPR - in letters to Schrodinger he expresses his chagrin with the way Podolsky, who wrote the paper, buried Einstein's main point in technicalities. Now, when you say he derived conclusions he didn't believe were true, that's kind of wrong, since all he derived was a dilemma (completeness or separation, not both (but possibly neither)). He took this to show that if we maintain the separation principle, then QM needs to be viewed as a statistical account of objects with properties it can't describe (but he never took that to mean hidden variable theories like Bohm's were the answer). So, my point is, he believed in the correctness of QM (just not in the completeness). He believed in QM being true - just not that is was the whole truth. He believed in the correctness of the EPR derivation and in the correctness of the dilemma at the end. When you say he used a theory he didn't believe was correct, I think that's wrong - he just didn't believe it was the finished article. And when you say he derived conclusions he didn't believe were true, I think that's wrong too, since he derived a dilemma that he very much believed in. In the end he chose the wrong side, but that's not relevant here. You say Einstein believed this was a reductio ad absurdum - but that's flat out wrong I think. EPR relates to the completeness of the formalism (if the separation principle is taken to be true), not the correctness.
- yummyfajitas 16y ago
  When it was published, EPR showed that action by contact (the separation principle) and the _completeness_ of QM can't both be valid. Yes, that's the scientific conclusion. Actually, the history is a bit more muddled - EPR alone doesn't show this, strictly speaking. The EPR paper (1935) concludes with a statement that the authors believe a local and complete theory of QM is possible. We were not 100% certain it was impossible until the discovery of Bell's Inequality (1964, 9 years after Einstein's death). Einstein actually spent a lot of time searching for such a theory. In addition to the scientific conclusions in the EPR paper, EPR also expressed some non-scientific beliefs. They believed that reality would eventually prove itself to be local and therefore that QM would be shown to be incomplete. From the original paper: We are thus forced to conclude that the quantum mechanical description of physical reality given by wavefunctions is not complete [...] No reasonable definition of reality could be expected to permit this. http://prola.aps.org/pdf/PR/v47/i10/p777_1 http://prola.aps.org/pdf/PR/v47/i10/p777_1