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Von Neumann's Argument for the Projection Postulate

Published online by Cambridge University Press:  14 March 2022

Joseph D. Sneed*
Affiliation:
University of Michigan

Abstract

Much of the recent discussion of problematic aspects of quantum-mechanical measurement centers around that feature of quantum theory which is called “the projection postulate.” This is roughly the claim that a change of a certain sort occurs in the state of a physical system when a measurement is made on the system. In this paper an argument for the projection postulate due to von Neumann is considered. Attention is focused on trying to provide an understanding of the notion of “the state of a physical system” which is compatible with the argument von Neumann offers. An attempt is made to formulate the argument in terms of an objectivistic interpretation of probability concepts. It is seen that such an interpretation does not provide a suitable way of understanding the argument. An attempt is made to illustrate the source of this failure in terms of a non-quantum-mechanical example.

Type
Research Article
Copyright
Copyright © 1966 by The Philosophy of Science Association

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References

[1] Bothe, W. and Kirchner, F., Handbuch der Physick. 2. Auflage, Bd. XXIII, Tl. 2, Springer Verlag (1933).Google Scholar
[2] Braithwaite, R. B., Scientific Explanation. Harper and Brothers (1960).Google Scholar
[3] Compton, A. H. and Allison, S. K., X-Rays in Theory and Experiment. von Nostrand (1935).Google Scholar
[4] Compton, A. H. and Simon, A. W., Physical Review. V. 25, pp. 289 (1925).CrossRefGoogle Scholar
[5] Dicke, R. and Wittke, J., Introduction to Quantum Mechanics. Ch. 7, Addison-Wesley (1960).Google Scholar
[6] Durand, L., Philosophy of Science. 27, p. 115 (1960).CrossRefGoogle Scholar
[7] Feyerabend, P. K., Colston Papers, IX, (1957).Google Scholar
[8] Green, H. S., Il Nuovo Cimento. V. 9, p. 880 (1958).10.1007/BF02903128CrossRefGoogle Scholar
[9] Margenau, H., Philosophy of Science, V. 25, No. 1 (1958).10.1086/287574CrossRefGoogle Scholar
[10] Margenau, H., Philosophy of Science, V. 30, No. 1 (1963).Google Scholar
[11] Margenau, H., Philosophy of Science, V. 30, No. 2 (1963).Google Scholar
[12] Merzbacher, E., Quantum Mechanics, pp. 275280, Wiley (1961).Google Scholar
[13] Messiah, A., Quantum Mechanics, V. 1 North-Holland (1961).Google Scholar
[14] Nagel, E., International Encyclopedia of Unified Science. V. 1, No. 6, University of Chicago Press (1939).Google Scholar
[15] von Neumann, J., Mathematical Foundations of Quantum Mechanics. Princeton University Press (1955).Google Scholar
[16] Popper, K. R., Colston Papers, IX, (1957).Google Scholar
[17] Reichenbach, H., Philosophic Foundations of Quantum Mechanics. University of California Press (1948).Google Scholar
[18] Schrodinger, E., Die Naturwissenschaften. V. 23 (1935).Google Scholar