Several recent theories involve a modification of the Schrödinger equation, which dynamically suppresses coherent superpositions of macroscopically different states and so avoids Schrödinger’s cat paradox. It is shown that these theories violate energy conservation and are incompatible with the existence of equilibrium and steady states. The reasons for these troubles are pointed out.

• Received 24 August 1990

DOI:https://doi.org/10.1103/PhysRevA.43.9