Entanglement is quantum mechanics’ way of integrating parts into a whole. Individual properties of constituents cease to exist for the benefit of a strongly correlated total system. Or, in the words of string theory pioneer Leonard Susskind, “It would not make sense for a mechanic to say, I know everything about your car but unfortunately I can’t tell you anything about any of its parts. But… in quantum mechanics, one can know everything about a system and nothing about its individual parts.”
