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23522Re: Determinism

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  • Nik Weaver <nweaver@math.wustl.edu>
    Mar 1, 2003
      Steven D'Aprano wrote:

      > Quantum phenomena are said to be random, but there is no
      > justification for assuming that they are non-determinant.
      > Tossing a coin is random, but deterministic, and we have no
      > way of telling whether quantum randomness is like coin-tossing.
      > For instance, the randomness of radioactive decay is almost
      > certainly due to the perfectly deterministic behaviour of the
      > nucleus, and even the decay of isolated baryons like the neutron
      > is probably determined by its quarks. On the other hand, the
      > decay of an excited atom into a lower energy state appears to be
      > non-deterministic, but that shouldn't be considered proven by any
      > means.

      "almost certainly": you are wrong. The randomness of radioactive
      decay is exactly the same as the randomness of atomic decay. Both
      are instances of a transition from a higher energy state into a
      lower energy state, mediated by thermal interaction with an external
      field.

      If you'd like to see the math, I found a nice description on
      the web at
      www.physics.ucla.edu/class/02S/ 115C_Abers/notes/TDPT01.pdf
      www.physics.ucla.edu/class/02S/ 115C_Abers/notes/TDPT02.pdf
      --- if this doesn't suit you, just do a web search for "Fermi's
      golden rule".

      I can't wait to hear your explanation of why you felt comfortable
      labelling as "almost certain" something which anyone who knows the
      subject would reject as trivially false.

      "shouldn't be considered proven": and what would constitute a
      proof?

      I can't see how, in principle, one could ever conclusively "prove"
      that some phenomenon was truly random. What one can do is show
      that if quantum mechanics is valid then any deterministic
      substructure must have undesirable features such as non-locality.
      (This is what Bell's theorem shows.) One can also give physicists
      a century to try to find a plausible underlying deterministic
      mechanism and see if anyone comes up with one --- that experiment
      has also failed.

      I sympathize with your desire to preserve determinacy, but barring
      a massive change in our understanding of modern physics, this is
      just wishful thinking.

      Nik Weaver
      Math Dept.
      Washington University
      St. Louis, MO 63130 USA
      nweaver@...
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