The 'Decoherence' Approach to the Measurement Problem in Quantum Mechanics

Decoherence results from the dissipative interaction between a quantum system and its environment. As the system and environment become entangled, the reduced density operator describing the system "decoheres" into a mixture (with the interference terms damped out). This formal result prompts some to exclaim that the measurement problem is solved. I will scrutinize this claim by examining how modal and relative-state interpretations can use decoherence. Although decoherence cannot rescue these interpretations from general metaphysical difficulties, decoherence may help these interpretations to pick out a preferred basis. I will explore whether decoherence solves nagging technical problems associated with selecting a preferred basis.