 Violation of this principle, according to some researchers in the foundations of quantum theory, indicates a fundamental incompatibility between quantum theory and the spirit, perhaps even the letter, of relativity theory (Maudlin 2011). That the correlations entailed by quantum theory which violate local causality actually occur in nature has been experimentally documented many times (for example, by Freedman &amp; Clauser 1972; Aspect, Dalibard, &amp; Roger 1982; and Aspect, Grangier, &amp; Roger 1982).