Hi Iain,
actually ther reason this idea isn't correct is because quantum physics is
non-deterministic. When an electron in a hydrogen atom, for example, decides to
drop down to a lower-energy orbital is completely random with a
characteristic half-life. Nothing in physics determines the actual moment of time when it
must happen. And so it goes with everything else. Everything has
well-defined averages but is nonetheless random at the atomic level. Because there are
so-many atoms, the averages seem deterministic at the macroscopic level. But
microscopically it is random.
This microscopic randomness does make macroscopic differences because of
symmetry breaking and because of chaos. If you could perfectly balance a pencil
on its point, quantum mechanics says that it must fall within 7 seconds. But
which way it falls is totally unpredictable because when it is standing on its
point everything is symmetric. When it finally does choose to fall, it falls
in any one direction of the compass and so then the symmetry has been broken.
The broken symmetry occurs first at the quantum level (where randomness
prevails) and then grows to macroscopic proportions.
Similarly, chaotic systems are ones that, because of their mathematical
structure, are super-sensitive to initial conditions. Thus, when little random
fluctuations happen at the quantum level, these fluctuations grow to macroscopic
sizes.
As a result, quantum mechanics predicts a vast array of possibilities could
happen, but which one actually will occur seems completely random. This is
where the various interpretations of quantum mechanics comes it. CI says only
one of the possibilities occurs, and that human consciousness is somehow
involved in the decision that erases all the possibilities except one. Hidden
variables says that there is something in physics that we don't know about that
makes the decision. MWI says that all possibilities actually occur. MWI isn't
just an ad hoc assertion. We know that in a real sense all the possibilities
have a real existence, because the quantum mechanical wave is mathematically
nothing more than all those possibilities. They constructively and destructively
interfere with each other, like waves do, and thus we see that all the
possibilities really are there. If they weren't there, then there would be no
interference patterns. The big question is: where do they go after the
interference patterns go away? MWI is in a sense the simplest answer, because it posits
nothing additional into the theory. It points out that they don't have to go
anywhere. The reason we don't see them anymore is because the wave gets
decoherent, just at the physics predicts, and so we don't expect to see
interefernce patterns any more. Thus, MWI claims to be the simplest theory. However,
it does raise other thorny problems and it is on the basis of those other
problems that the other interpretations claim to be better. This is where we reach
the end of what i know. :-)
God bless!
Phil
Received on Fri Mar 3 09:34:35 2006
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