- #1
- 10,761
- 3,616
I was reading an interesting article on the Bohr/Einstein debates. Interestingly it got most things right including the real reason Einstein thought QM incomplete - its not the probabilistic nature - it was that it didn't gel with his intuition on how nature works having features like entanglement - in fact the article goes further and argues his objections were all really about entanglement - but that is not what I want to talk about here.
But it gave in Bohr's own words his idea of complementarity:
'Now, the quantum postulate implies that any observation of atomic phenomena will involve an interaction with the agency of observation not to be neglected. Accordingly, an independent reality in the ordinary physical sense can neither be ascribed to the phenomenon or to the agencies of observation. . . .This situation has far-reaching consequences. On one hand, the definition of the state of a physical system, as ordinarily understood, claims the elimination of all external disturbances. But in that case, according to the quantum postulate, any observation will be impossible, and, above all, the concepts of space and time lose their immediate sense. On the other hand, if in order to make observation possible we permit certain interactions with suitable agencies of measurement, not belonging to the system, an unambiguous definition of the state of the system is naturally no longer possible, and there can be no question of causality in the ordinary sense of the word. The very nature of the quantum theory thus forces us to regard the space-time co-ordination and the claim of causality, the union of which characterizes the classical theories, as complementary but exclusive features of the description, symbolizing the idealization of observation and definition respectively. (Bohr 1928, 54-55)'
Further the author says 'These few words have given rise to much confusion in the secondary literature'. Golly gee - much of it makes no sense to me at all eg 'Accordingly, an independent reality in the ordinary physical sense can neither be ascribed to the phenomenon or to the agencies of observation' Really - I thought that was interpretation dependent. Now I realize this was 1928, Dirac's transformation theory was only published in 1927 and exactly what it means has certainly not been fully worked out yet. But that's my issue - how can even as great a scientist like Bohr know that until it has been studied fully? And without an actual proof, even after years of study, you can't be sure.
I won't be participating much in this tread but I am curios what others think.
Thanks
Bill
But it gave in Bohr's own words his idea of complementarity:
'Now, the quantum postulate implies that any observation of atomic phenomena will involve an interaction with the agency of observation not to be neglected. Accordingly, an independent reality in the ordinary physical sense can neither be ascribed to the phenomenon or to the agencies of observation. . . .This situation has far-reaching consequences. On one hand, the definition of the state of a physical system, as ordinarily understood, claims the elimination of all external disturbances. But in that case, according to the quantum postulate, any observation will be impossible, and, above all, the concepts of space and time lose their immediate sense. On the other hand, if in order to make observation possible we permit certain interactions with suitable agencies of measurement, not belonging to the system, an unambiguous definition of the state of the system is naturally no longer possible, and there can be no question of causality in the ordinary sense of the word. The very nature of the quantum theory thus forces us to regard the space-time co-ordination and the claim of causality, the union of which characterizes the classical theories, as complementary but exclusive features of the description, symbolizing the idealization of observation and definition respectively. (Bohr 1928, 54-55)'
Further the author says 'These few words have given rise to much confusion in the secondary literature'. Golly gee - much of it makes no sense to me at all eg 'Accordingly, an independent reality in the ordinary physical sense can neither be ascribed to the phenomenon or to the agencies of observation' Really - I thought that was interpretation dependent. Now I realize this was 1928, Dirac's transformation theory was only published in 1927 and exactly what it means has certainly not been fully worked out yet. But that's my issue - how can even as great a scientist like Bohr know that until it has been studied fully? And without an actual proof, even after years of study, you can't be sure.
I won't be participating much in this tread but I am curios what others think.
Thanks
Bill