 And, again, note that this does not mean that only branches in one physically preferred basis are real. Rather, it means that every branch in every decomposition of a composite system is real in Everett’s operational sense of ‘real’ since any such state might in principle entail observational consequences. That Everett considered alternative branches of the universal wave function to be in principle empirically detectable and hence operationally real represents a significant difference between his position and most subsequent many-worlds interpretations, where alternative worlds are typically assumed to be undetectable.