In 1935 Einstein et al. [1] challenged the ► orthodox approach to the quantum formalism by asking whether the formalism was complete or not. The specific point that led them to this conclusion was based on a puzzle that arose when two particles were in an entangled state (► entanglement). These states are characterised by the fact that the ► wave function of the individual particles are not well defined, being ambiguous until the state of one of them was measured. The difficulty arose when the two particles were separated by a large distance and were not interacting with each other through any known classical potential. If a measurement was made on one of the particles, the state of the other became *immediately* well defined, even though it was removed far from the apparatus measuring the state of the first particle. How does this come about?

## Keywords

Quantum Theory Entangle State Hide Variable Bell Inequality Quantum Potential## Preview

Unable to display preview. Download preview PDF.

## Primary Literature

- 1.A. Einstein, B. Podolsky, N. Rosen: Can Quantum-Mechanical Description of Physical Reality be Considered Complete. Phys. Rev.
**47**, 777–780 (1935)zbMATHCrossRefADSGoogle Scholar - 2.D. Bohm:
*Quantum Theory*(Prentice-Hall, Englewood Cliffs, NJ 1951, pp. 614–623)Google Scholar - 3.D. Bohm: A Suggested Interpretation of the Quantum Theory in Terms of Hidden Variables, I and II. Phys. Rev.
**85**, 166–179; 180–193 (1952)CrossRefADSMathSciNetGoogle Scholar - 4.D. Bohm, B. J. Hiley: On the Intuitive Understanding of Nonlocality as Implied by Quantum Theory. Found. Phys.
**5**, 93–109 (1975)CrossRefADSGoogle Scholar - 5.D. Bohm, R. Schiller, J. Tiomno: A Causal Interpretation of the Pauli Equation (A). Nuovo Cim.
**1**(supl.), 48–66 (1955)CrossRefMathSciNetGoogle Scholar - 6.C. Dewdney, P. R. Holland, A. Kyprianidis: A Causal Account of Non-local Einstein-Podolsky-Rosen Spin Correlations. J. Phys. A Math. Gen.
**20**, 4717–4732 (1987)CrossRefADSMathSciNetGoogle Scholar - 7.J. S. Bell: On the Problem of Hidden Variables in Quantum Theory. Rev. Mod. Phys.
**38**, 447–452 (1966)zbMATHCrossRefADSGoogle Scholar - 8.J. S. Bell: On the Einstein—Podolsky–Rosen Paradox. Physics
**1**, 195–200 (1964)Google Scholar - 9.A. Aspect, J. Dalibard, G. Roger: Experimental Realization of Einstein—Podolsky—Rosen— Bohm Gedankenexperiment: A New Violation of Bell's Inequalities. Phys. Rev. Lett.
**49**, 91–94 (1982)CrossRefADSMathSciNetGoogle Scholar - 10.P. H. Eberhard: Bell's Theorem and the Different Concepts of Locality. Nuovo Cim.
**B 46**, 392–419 (1978)CrossRefADSMathSciNetGoogle Scholar - 11.A. Shimony: Events and Processes in the Quantum World, in
*Quantum Concepts in Space and Time*, ed. R. Penrose, C. Isham (Clarendon Press, Oxford 1986, pp. 182–203)Google Scholar

## Secondary Literature

- 12.J. F. Clauser, A. Shimony: Bell's Theorem: Experimental Tests and Implications. Rep. Prog. Phys.
**41**, 1881–1927 (1978)CrossRefADSGoogle Scholar