Einstein’s criticism of the Copenhagen interpretation, detailed in a 1935 paper he co-authored with Podolsky and Rosen and commonly referred to as the EPR paper included a thought experiment which involved the position and momentum of two particles and how these quantities could be determined. His thought experiment morphed into one involving 'spin' and a theory of entangled particles that could communicate faster than the speed of light, and this along with experiments conducted with photons and orientation, were used to support the idea of 'spooky action at a distance' which Einstein repudiated and which can be shown to be unfounded.
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