Einstein thoughts on the quantum

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btw, in reply to your comment in post #1 about Einstein's reluctance to give up realism, there is a famous quote attributed to Einstein from a discussion with Heisenberg, where Heisenberg was making a similar point to you and Einstein replied that the abstraction of spacetime was all nonsense, and not to be taken literally, just a mathematical framework for making predictions of nature.



http://www.aip.org/history/heisenberg/p07c_text.htm
Note realism has particular meaning in physics which means there are properties even between measurement. So Einstein can even believe a world existing with merely spin as the observable can be put under realism so long as it has deteministic values in between measurement. Einstein is so advanced with his spacetime physics but why couldn't he go one step further and believe there was no properties before measurement. Maybe because it can falsify his spacetime idea. So the incompatibility between QM and GR already started in the Bohr Einstein debate in 1927 at the Solvay Congress. But at that time, they never plan to unite QM and GR. Did Einstein plan to do that? I wonder what year was this attempt at unification of QM and GR become a serious endeavors or programme. Anyone?
 
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Note realism has particular meaning in physics which means there are properties even between measurement. So Einstein can even believe a world existing with merely spin as the observable can be put under realism so long as it has deteministic values in between measurement. Einstein is so advanced with his spacetime physics but why couldn't he go one step further and believe there was no properties before measurement. Maybe because it can falsify his spacetime idea. So the incompatibility between QM and GR already started in the Bohr Einstein debate in 1927 at the Solvay Congress. But at that time, they never plan to unite QM and GR. Did Einstein plan to do that? I wonder what year was this attempt at unification of QM and GR become a serious endeavors or programme. Anyone?
Unification of QM and GR isn't a problem of realism, it's a problem of developing a field theory which is renormalizable. If that could be done for quantum gravity (like for QED and QCD) then it wouldn't distinguish between realist and non-realist interpretations of QM (but we have the experiments of Zeilinger and others which deal with that).

Einstein already tried to develop a unified field theory in 1920s after hints from Kaluza that a fifth dimension could unify EM and gravity.

Einstein was a master of statistical physics and classical field theories and he firmly believed that all of reality could be described by physical theories founded on these two pillars. He had been right before when only a minority believed his theories and this must surely have made him ultra stubborn against the "baby-face kids" that created QM (heisenberg, pauli, jordan, dirac were all in their early 20s when QM was established, only Bohr, Born and Schrodinger were from Einstein's generation).

Einstein wasn't naive though, he recognised that Bohm/de Broglie's attempt was too simplistic for instance, but he didn't like the almost mystical way the Copenhagen Interpretation seemed to explain reality. I think today he would be satisfied with decoherence and the post-Bell advances in QM experiments which seem to have shown simple ideas of reality are surely wrong,
 
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Unification of QM and GR isn't a problem of realism, it's a problem of developing a field theory which is renormalizable. If that could be done for quantum gravity (like for QED and QCD) then it wouldn't distinguish between realist and non-realist interpretations of QM (but we have the experiments of Zeilinger and others which deal with that).

Einstein already tried to develop a unified field theory in 1920s after hints from Kaluza that a fifth dimension could unify EM and gravity.

Einstein was a master of statistical physics and classical field theories and he firmly believed that all of reality could be described by physical theories founded on these two pillars. He had been right before when only a minority believed his theories and this must surely have made him ultra stubborn against the "baby-face kids" that created QM (heisenberg, pauli, jordan, dirac were all in their early 20s when QM was established, only Bohr, Born and Schrodinger were from Einstein's generation).

Einstein wasn't naive though, he recognised that Bohm/de Broglie's attempt was too simplistic for instance, but he didn't like the almost mystical way the Copenhagen Interpretation seemed to explain reality. I think today he would be satisfied with decoherence and the post-Bell advances in QM experiments which seem to have shown simple ideas of reality are surely wrong,
Ok. So serious attempt at quantum gravity occurred after t'Hoof discovered that QED was renormalizable, right?
 
Fredrik
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Unification of QM and GR isn't a problem of realism, it's a problem of developing a field theory which is renormalizable.
...or a quantum theory of gravity that isn't a field theory at all.
 
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...or a quantum theory of gravity that isn't a field theory at all.
yes, the field theories may just be effective low energy descriptions of something completely different.
 
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Ok. So serious attempt at quantum gravity occurred after t'Hoof discovered that QED was renormalizable, right?
Well, depends what you mean by serious. We may still be at a stage as hopeless as Einstein's attempts at unification due to ignorance about what actually exists in nature (Einstein didn't know the weak and strong forces existed). But assuming it's no more than standard model (+SUSY maybe) + gravity then potentially workable theories have been developed only in the last few decades. Physicists aren't that bothered about mathematical rigour as long as the theory makes correct physical predictions. Feynman et al got the Nobel for qed long before it was made mathematically rigorous. Feynman himself proposed graviton theories in the 1950/60s which was a "serious" attempt at QG.
 
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In a message to Alxm, Demystifer wrote:

Maybe you misunderstood me. I'm pretty sure that physics can explain the behavior of biological systems, including the behavior that we usually think of as a "conscious" behavior. But that's exactly what the problem is. We can explain the BEHAVIOR in terms of known PHYSICAL mechanisms. But these mechanisms do not involve anything like subjective conscious experiences. Subjective conscious experiences are simply not needed to explain the objective behavior. In fact, the whole scientific method explores the objective, not the subjective. I can measure your voice when you cry, I can measure your EEG waves in the brain when I torture you, but I cannot measure your FEELING of pain. I cannot even conceive how to measure someone's feeling of anything.


It's even more egoistic than you think. It's not about humans, but about myself (or yourself). I feel only my feelings, and nobody else's. If I could experience someone else's feelings, then they would no longer be purely subjective, but objective phenomena researchable by the scientific method. But I can't.
Demystifier. There is a question that bothered me the whole weekend. Do you think this subjective conscious experience or qualia can be modelled by math? Or could they belong to a realm that is outside math altogether. Is this possible? Or are all things in the universe eventually modellable and describable by the language of math. What do you think?
 
Demystifier
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Demystifier. There is a question that bothered me the whole weekend. Do you think this subjective conscious experience or qualia can be modelled by math? Or could they belong to a realm that is outside math altogether. Is this possible? Or are all things in the universe eventually modellable and describable by the language of math. What do you think?
It seems to me that it cannot be modelled by math. Which is exactly why science is silent about it.
 
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It seems to me that it cannot be modelled by math. Which is exactly why science is silent about it.
Do you think there is unification program that is akin to it. I mean. Is there possibility for example that quantum mechanics and general relativity are emergence of a third theory that is no longer describable by math.. meaning we will never have a quantum gravity or quantum spacetime because it would be beyond physics already. Is this possible? Why and why not?
 
Fredrik
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a third theory that is no longer describable by math..
If math can't deal with it, then it's not a theory.

meaning we will never have a quantum gravity or quantum spacetime because it would be beyond physics already. Is this possible? Why and why not?
It's conceivable that "the ultimate reality" can't be described by math, but considering how successful the mathematical approach has been so far, it seems more likely that it can be. However, that only means that there is a final description. However, it's possible (I would say very likely) that we will never find it. Even if we do, it may not be falsifiable. (That's why I said "final description" rather than "final theory"; if it's not falsifiable, it's not a theory).
 

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