Is the Moon There When Nobody Looks? Reality and the Quantum Theory

APR 01, 1985

Einstein maintained that quantum metaphysics entails spooky actions at a distance; experiments have now shown that what bothered Einstein is not a debatable point but the observed behavior of the real world.

DOI: 10.1063/1.880968

N. David Mermin

In May 1935, Albert Einstein, Boris Podolsky and Nathan Rosen published an argument that quantum mechanics fails to provide a complete description of physical reality. Today, 50 years later, the EPR paper and the theoretical and experimental work it inspired remain remarkable for the vivid illustration they provide of one of the most bizarre aspects of the world revealed to us by the quantum theory.

References

1. Daniel Greenberger, discussion remarks at the Symposium on Fundamental Questions in Quantum Mechanics, SUNY, Albany, April 1984.
2. A. Einstein, B. Podolsky, N. Rosen, Phys. Rev. 47, 777 (1935).https://doi.org/PHRVAO
3. Quoted by M. Jammer, The Philosophy of Quantum Mechanics, Wiley, New York (1974) p. 151.
4. A. Pais, Rev. Mod. Phys. 51, 863 (1979).https://doi.org/RMPHAT
5. The Born‐Einstein Letters, with comments by M. Born, Walker, New York (1971).
6. J. S. Bell, Physics 1, 195 (1964).
7. D. Bohm, Quantum Theory, Prentice‐Hall, Englewood Cliffs, N.J. (1951) pp. 614–619.
8. A. Aspect, P. Grangier, G. Roger, Phys. Rev. Lett. 47, 460 (1981). https://doi.org/PRLTAO
A. Aspect, P. Grangier, G. Roger, Phys. Rev. Lett. 49, 91 (1982). https://doi.org/PRLTAO
A. Aspect, J. Dalibard, G. Roger, Phys. Rev. Lett. 49, 1804 (1982).https://doi.org/PRLTAO
9. For a discussion of the views of today’s physicists toward the meaning of the quantum theory, see the interesting and provocative essay “Cognitive Repression in Contemporary Physics” by E. F. Keller, Am. J. Phys. 47, 718 (1977).https://doi.org/AJPIAS
10. L. Rosenfeld in Niels Bohr, His Life and Work as Seen by His Friends and Colleagues, S. Rozental, ed., North Holland, Amsterdam (1967) pp. 114–36.
11. G. Zukav, The Dancing Wu‐Li Masters—An Overview of the New Physics, Morrow, New York (1979) p. 282. On the same page it is also said that “Bell’s theorem is a mathematical construct which as such is indecipherable to the non‐mathematician,” a view that I hope the rest of this article will dispel.
12. H. Stapp, Nuovo Cimento 40B, 191 (1977).
13. A. Pais, “Subtle is the Lord…” The Science and the Life of Albert Einstein, Oxford U.P., New York (1982) p. 456.
14. N. Bohr, Phys. Rev. 48, 696 (1935).https://doi.org/PHRVAO
15. What follows is a somewhat refined version of an argument I published a few years ago in Am. J. Phys. 49, 940 (1981), incorporating some improvements suggested by Richard Friedberg. https://doi.org/AJPIAS
For other elementary treatments see J. S. Bell’s, beautiful essay, “Bertlemann’s Socks and the Nature of Reality,” J. Phys. (Paris) 42, C2‐41 (1981), https://doi.org/JOPQAG
B. d’Espagnat’s article in the November 1979 Scientific American, or d’Espagnat’s recent book, In Search of Reality, Springer‐Verlag, New York (1983).
16. For a survey of other attempts to realize the EPR experiment, and the variants of Bell’s original argument used to interpret experimental tests, see J. F. Clauser, A. Shimony, Repts. Prog. Phys. 41, 1881 (1978).https://doi.org/RPPHAG
17. R. P. Feynman, Int. J. Theor. Phys. 21, 471 (1982).https://doi.org/IJTPBM

More about the Authors

N. David Mermin. Cornell University.