Quantum and Classical Foolishness

[Ken Miller]

In response to:

-> Some assert that "measurements or observations, in the sense
-> required by quantum theory, can only be made by conscious
-> observers".

-> Might the concept of "conscious observer" as used by the
-> qm-theorist have something to do with the conscious observer at the
-> back of cognitive centers?

There is an ancient classical riddle: "When a tree falls in the
forest, and no one is there to hear it, does it make a sound?"  The
idealist philosophers argued that unless some conscious being is
around to register the event, you cannot say it has happened.  The
most solopsistic would say, until *I* register the event, it has not
happened.  This is classical foolishness.  It is logically and
philosophically consistent, but rather useless and pointless.
Ultimately one arrives at the notion that history has not happened
until you choose to read about it in the morning paper.

As Feynmann points out in his lectures in discussing these issues, of
course the falling tree makes a sound.  A sound is a physical event, a
compression wave in the air, and it leaves physical traces --- leaves
that are blown off of a tree, thorns that vibrate and scratch a leaf.
A sound is as physical as the fallen tree itself.  So unless you hold
to the solopsistic notion that the tree does not fall until you wander
by and see it on the ground, then there is no problem about the sound
either.

Quantum mechanics adds many new puzzles to science, but this is not
one of them.  Quantum foolishness is the same solopsistic foolishness
as classical foolishness, there is no new quantum effect here.

Without going into a course on the subject: in quantum mechanics, we
cannot describe a continuous evolution in time in terms of classical
variables.  Rather, there is a quantum state that is a certain kind of
mixture in terms of classical variables, and then at some point there
is a measurement, which just means "something happens", B happens
rather than C, and the quantum state has accordingly "collapsed".

The key point where the foolishness arises is in defining when a
measurement has occurred --- when "something has happened."  The
solopsistic want to say, "well, you really don't know which outcome
happened until a conscious observer sees it, so quantum mechanics
requires consciousness".  And some very good physicists have
unfortunately subscribed to this (but not Feynmann --- see the same
portion of his lectures where he talks about the tree falling) just as
some very good Greek philosophers talked themselves into solopsism.
This statement about quantum mechanics is no different from saying
"you really don't know whether the tree falls until a conscious
observer sees it, so classical mechanics requires consciousness".

The point is, a quantum measurement occurs when some *classical
physical event* has occurred --- some dial on your meter goes up or
down, Schrodinger's cat lives or dies --- and so knowing the outcome
is no different in status from knowing about the sound wave of a
falling tree.  How do you know when this event has occurred?  This is
a classical problem, the same problem the ancient solopsists screwed
around with.  And any sensible physicist would say, it happens when it
happens, because it's a classical physical event that leaves traces
and tracks of its existence whether you look at those traces or not.

The mystery and wierdness of quantum mechanics involves understanding
how classical physical events emerge out of the quantum world, how the
quantum world "collapses" to the classical. But this has nothing to do
with consciousness.  Consciousness only enters in when trying to
figure out when you know that this *classical* physical event has
occurred.  And that's classical foolishness.

So, what does all this have to do with connectionists?  Nothing.  So I
propose we drop the subject of quantum computers until someone has a
specific architecture to propose.

Ken