Recent paper by S. Machida and T. Namiki proposed a very interesting idea of the generalization of quantum mechanics to macroscopic systems. Using this formalism, they have shown that the so-called “reduction of wave packet” in measuring process is explained without having the observer outside the measuring apparatus in the theory itself.
H. Araki proposed a framework of general theory of physics, which is in accord with the idea of Machida and Namiki. Following these ideas, together with the experimental evidence of Bell's inequalities, we have now a strong feeling that the nature has in principle a structure which allows us to formulate the physical theory which is general enough to include hitherto existing theories both in microscopic and macroscopic scales. Some fundamental problems on these ideas are discussed.