I would like to know what theories there are (and the specifics of
them) about the effects an observer (person watching/monitoring)
quantum physics (sub-atomic) experiments has on the outcome, and
conclusions about how or why the act of observation has an impact on
sub-atomic experiments (i.e. light as a particle or a wave, Schrodinger's cat, etc)

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Clarification of Question by matt74-ga on 28 Aug 2004 13:47 PDT

Just to be clear - I am looking for as much of a useful summary as
possible - with links to additional resources.

To observe a sub-atomic particle you must "look at it" on some way:
with light, X-rays, *something*. At those super-small sizes, the
energy of the medium you use to do the "looking" -- that is, the
energy of the light, X-rays, "something" -- is sufficiently high in
proportion to that which is being looked at that it causes a change in
some aspect of that which is being looked at (observed), typically
either the direction or the velocity. Thus the very act of observation
changes one or more fundamental aspects of the obseved. This is, of
course, a simplification of Heisenberg's Uncertainty Principle.
   The "Schrodinger's Cat" thought experiment is related buut
addresses a different issue, the "probability" of a given occurrence. 
To keep it simple, theoretically the cat is both "alive" amd "dead"
until an observer opens the box and confirms for herself it's state,
this collapsing the probability wave in which it is mathematically
defensible to say that the cat has components of life and death.
   Check out http://www.amazon.com/exec/obidos/tg/detail/-/0704530716/qid=1093729383/sr=1-5/ref=sr_1_5/002-0401797-9277655?v=glance&s=books

excellent comment, anonoboy.

This concept is fascinating to me.  The act of "looking at it" is
essentially bouncing some kind of particles off of "it."  I think of
it as throwing a handful of ball bearings at an inflated beach ball. 
You can see where the bearings bounce back from, but by then the force
of the collision has moved the beach ball, rendering the observation
imprecise.

http://www.aip.org/history/heisenberg/p08.htm
http://dmoz.org/Science/Physics/Quantum_Mechanics/
http://directory.google.com/Top/Science/Physics/Quantum_Mechanics/

Thanks for the comment Anonoboy.  I think this has clarified for me
some of the questions.  Very precise analysis.

Thanks again.