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Everything in the universe is deterministic

  1. Nov 11, 2004 #1
    I used to believe that everything in the universe is deterministic because it obeys physical laws. So we could theoretically predict events. But does the quantum theory undermine this idea? To which extent does uncertainty with the behaviour of the tiniest particles affect bigger events?
  2. jcsd
  3. Nov 11, 2004 #2
    Physical laws are essentially not deterministic.

    Quantum mechanics is not and is the most fundamental theory.

    Statistical mechanics is deterministic only on the averages but it deals essentially with the effects of large numbers of particles that cannot be studied or observed in a deterministic way (practically impossible on a detailled level).

    Determinism even in classical theory is limited by experimental precision. In many circonstances experimental precision is limited by the system being studied. This applies to statistical mechanics. This applies also to the well known three-body system for which long-term unpredictability is the rule. Chaotic systems and turbulence are other examples.

    Determinism is the exception apparently. It is limited to classical and simple systems well prepared and defined (there are always limits on preparation). Even then, it applies usually only on "short" periods of time. (when the experiment is switched who can predict what follows? what the scientists will do for example)
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