The counterintuitive prognostications of quantum mechanics about vigorously correlated systems were first discussed by Albert Einstein in 1935, in a joint paper with Boris Podolsky and Nathan Rosen. In this study, the three formulated the Einstein–Podolsky–Rosen paradox (EPR paradox), a cerebration experiment that endeavored to show that "the quantum-mechanical description of physical authenticity given by wave functions is not consummate." However, the three scientists did not coin the word entanglement, nor did they generalize the special properties of the state they considered. Following the EPR paper, Erwin Schrödinger inscribed a letter to Einstein in German in which he utilized the word Verschränkung (translated by himself as entanglement) "to describe the correlations between two particles that interact and then disunite, as in the EPR experiment."
Schrödinger shortly thereafter published a seminal paper defining and discussing the notion of "entanglement." In the paper, he apperceived the paramountcy of the concept, and verbalized: "I would not call [entanglement] one but rather the characteristic trait of quantum mechanics, the one that enforces its entire departure from classical lines of mentally conceived." Like Einstein, Schrödinger was dissatisfied with the concept of entanglement, because it seemed to breach the haste limit on the transmission of information implicit in the theory of relativity Einstein later famously derided entanglement as "spukhafte Fernwirkung"or "spooky action at a distance."
The EPR paper engendered consequential interest among physicists, which inspired much discussion about the substructures of quantum mechanics (perhaps most famously Bohm's interpretation of quantum mechanics), but engendered relatively little other published work. Despite the interest, the impotent point in EPR's argument was not discovered until 1964, when John Stewart Bell proved that one of their key posits, the principle of locality, as applied to the kind of obnubilated variables interpretation hoped for by EPR, was mathematically inconsistently erratic with the presages of quantum theory.
Categorically, Bell demonstrated an upper limit, optically discerned in Bell's inequality, regarding the vigor of correlations that can be engendered in any theory complying with local realism, and showed that quantum theory presages infringements of this inhibition for certain entangled systems. His inequality is experimentally
Caption this Meme
