1. Einstein, Podolsky and Rosen’s argument of incompleteness of quantum mechanics

3. Einstein, Podolsky and Rosen: Quantum mechanics is not complete According to EPR, any satisfactory physical theory must be: (1) Correct. (2) “Complete”.

4. “If, without in any way disturbing a system, we can predict with certainty (i.e., with probability equal to unity) the value of a physical quantity, then there exists an element of physical reality corresponding to this physical quantity.” EPR’s “elements of reality”

5. The EPR-Bohm experiment

6. EPR’s argument X 2 and Y 2 are both “elements of reality”. In QM, X 2 and Y 2 are incompatible observables (the knowledge of one precludes the knowledge of the other).  QM is incomplete (according to EPR).