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lightnix said:
On the other hand, the "Copenhagen Interpretation" of quantum theory says that light is neither wave nor particle, but exists in an in between state, known as a wavicle (or wave function) until it is observed, at which point it "collapses" into "being" one or the other, according to how it is observed /ubbthreads/images/graemlins/thinking.gif
Scarily enough, the same seems to be true of matter. For example: electrons, which are generally accepted as being tiny particles, can easily be made to exhibit wave phenomena in the laboratory /ubbthreads/images/graemlins/naughty.gif
Sleep well /ubbthreads/images/graemlins/wink.gif
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As a trained physicist, and as one who is in daily contact with world class particle physicists, I can tell you that the Copenhagen interpretation is NOT universally accepted by scientists. Especially is this the case when it comes to physicists who have studied quantum measurement theory, and solid state physics.
Without dredging up a rather unexciting argument/conversation, let's just say that there are plenty of us physicists who do NOT agree with the whole simple minded "observation" collapsed wave-function. For starters, what constitutes an "observation"? Some people I've talked with actually seem to have this idea that we can "look" and see this stuff and that the human consciousness is what constitutes the observation. Hogwash.
Consider the famous Shrodinger's Cat paradox. In a box is a cat, a radioactive isotope, a detector, and a mechanical device which dispenses poison gas when the detector gets a radiation count. The idea is that the radioactive atom(s) has an amplitude to decay, thus causing a gamma ray to strike the detector, but this may or may not happen, and in fact, until an "observation" takes place BOTH things (decay/ non-decay) happen and exist in an "in-between" state, or in parallel universes, if you really want to screw things up. And because of this, the cat, whose life is directly tied to the decay probability, is also both alive and dead. The problem with this muddle headed paradox, is that THE RADIATION DETECTOR IS THE OBSERVATION! As soon as the detector gets a count, the wave function is collapsed, and thus the cat is either dead or not. Except in very, very special situations, no macroscopic object can be in a superposition of states or eigen values. The interaction of the gamma ray and the gieger counter constitutes an irreversible interaction, a change in the universe, that in no way can be completely undone. This is why it is an observation, and it has nothing to do with the consciousness of either a human or a cat. Too much mysticism has crept into QM, in exactly the wrong way.