Bell's Theorem

CORE DEFINITION

In theoretical physics, Bell's theorem shows that. Bell's theorem is a no-go theorem, also known as Bell's inequality. This theorem is exceptionally important in physics and the philosophy of science because it implies that quantum physics must violate either the principle of locality or counterfactual definiteness. Published in 1964, Bell's theorem is named after the Northern Irish physicist John Bell. The experimental verification of Bell's theorem has yielded results consistent with the predictions of quantum mechanics and shows that certain quantum effects appear to travel faster than light. Due to this verification, all viable quantum theories classified as hidden variable theories are restricted to non-local types. In 2015, Ronald Hanson et al. at Delft University of Technology published a cover article in Nature claiming to have closed all loopholes, showing that quantum theory describes quantum entanglement more accurately than local hidden variable theories.