Supplement of the Progress of Theoretical Physics, No. 50, 1971 65 Observation Problem of Quantum Mechanics*>

The observation problem of the quantum mechanics had been discussed with great interest, including philosophers, prior to and during World War II. The discussions became stagnant after the War because the physicists were mostly occupied with practical problems, and the people became not very enthusiastic about philosophical discussions in general. But I was informed that there was considerable progress made in this problem at an international conference in 1957. Shoichi Sakata published a paper, titled "On Interpretation of the Quantum Mechanics " (in Japanese) in Kagaku, in 1959,t>**> on his excellent analysis of the problem, together with the introduction of a new movement in foreign countries. Let me quote a few sentences from his paper in order to understand the significance of the Bristol Conference. "There was an international conference on 'observation and interpretion' problems held at Bristol University in 1957. This conference was significant in generating a motivation to focus criticism of the Copenhagen interpretation in the direction of methodological problems for a revolution of physics. ···Criticis