The Dynamical Reduction Program: An Example of a Quantum Theory without Observers

  • GianCarlo Ghirardi
Part of the Vienna Circle Institute Yearbook [1999] book series (VCIY, volume 7)


After more than 70 years of debate about the difficulties that one encounters in working out a coherent view of physical processes based on the standard formulation of quantum mechanics, there is now a widespread belief that such difficulties do not arise from philosophical prejudices (as has been repeatedly asserted by many of the supporters of textbook quantum mechanics) but represent precise mathematical and physical challenges which call for a physical solution. As J.S. Bell appropriately stated1 “the way ahead is unromantic in that it requires mathematical work by theoretical physicists, rather than interpretations by philosophers”. It is also encouraging, for those who share this position, to see that now there are explicit proposals indicating possible ways out in which the process of measurement (and more generally all those measurement-like processes2 “we are obliged to admit ... are going on more or less all the time, more or less everywhere”) is analysed not in terms of vague assertions or resorting to ill-defined and/or contradictory dualistic evolution processes (the linear and deterministic evolution for microsystems and the nonlinear and stochastic wave packet reduction for the macroscopic ones) but in terms of more fundamental physical concepts. In particular, approaches of this kind, which S. Goldstein3 has appropriately denoted as “observer-free formulations of quantum mechanics”, can be grouped in three categories: the pilot-wave theories: the decoherent histories and the spontaneous localization models.


Bohmian Mechanic Standard Quantum Mechanic Dynamical Reduction Mass Density Distribution Property Attribution 
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Copyright information

© Springer Science+Business Media Dordrecht 1999

Authors and Affiliations

  • GianCarlo Ghirardi
    • 1
  1. 1.Departimento di Fisica TeoricaUniversitá degli Studi di TriesteTriesteItaly

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