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Bell's theorem is a logical argument in support of the completeness of **quantum theory**. The theorem argues against the existence of any hidden or unknown variables that might deterministically explain otherwise seemingly random events predicted by quantum **mechanics**.

Bell's theorem was devised in 1964 by British physicist John Stewart Bell. Sometimes known as Bell's inequalities, in **quantum mechanics** the theorem is an analysis of a paradox first advanced by physicists **Albert Einstein**, Boris Podolsky and Nathan Rosen (EPR) in a 1935 *Physical Review* article titled "Can Quantum Mechanical Description of Physical Reality be Considered Complete?" As a consequence, Bell's theorem is used to argue against any incompleteness or hidden variables in the quantum mechanical description of nature.

Bell's theorem examines the expected results of EPR-type experiments when it is assumed that particle properties such as **momentum** and position have real values prior to measurement. This assumption is made...

This section contains 433 words(approx. 2 pages at 300 words per page) |