QUANTUM METAPHYSICS - E-thesis

This does not, however, mean that quantum mechanics maintains complete indeterminism. The
laws of quantum mechanics suffice for determining the probabilities of finding the system in a
given state at a future time. We know something about the future but in many respects we do not
know it exactly. 561 The probability of each possible event can be calculated on a theoretical
basis. The observables of quantum theory are statistically predictable, but, except in pure cases,
quantum mechanics is not able to predict with certainty what values a given variable will assume
upon measurement - for example which transition will happen in an atom or which nucleons in a
specific radioactive sample will decay in the next 60 seconds. If the subject of research is a large
number of systems with the same initial conditions, the distribution of their possible final states
is predictable. Quantum mechanics can be taken as a statistical theory 562 which, when stripped
down to its very basics, deals with either one measurement of an infinite number of particles or
an infinite number of measurements of a single particle.
561 March 1951, 9-11.
562 Quantum mechanics is different from classical statistical mechanics as the latter is a deterministic theory.
Statistical mechanics includes the assumptions of classical particle mechanics but its state-describtion is defined in
terms of statistical state variables. In quantum mechanics, the ”positions” and ”momenta” are not the self-same traits
of particles which in classical mechanics are subject to precise numerical determination. The Psi-function of
quantum mechanics employs a definition of state quite unlike that employed in classical mechanics. Quantum theory
is ”indeterministic” in the important sense that its state-description is associated with a statistical interpretation and
that its predictions are based on statistical assumptions. Nagel 1961, 290-291, 305-308.
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