Quantum mechanics is very mysterious. Consciousness is often brought into play to explain quantum phenomena. Is this only a matter of convenience, or is consciousness inherent to interpreting quantum mechanics? What is the role of the mind in affecting the wave function? What counts as a conscious being? Is the wave function all in our minds, and can we change it just with our thoughts?
closed as off topic by David Z♦ May 19 '11 at 17:17
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Dear Cupcake, the only special role of a conscious being - and indeed, it's an important one - is that it can verify the validity of the laws of physics.
When this object or subject ;-) wants to predict the future, it will use quantum mechanics or some simplified approximation of it and get the predictions. If it uses the right theory, it will find out that the theory works. Of course, to do such a thing, it inevitably has to have a sufficient number of interacting building blocks so that the approximate classical framework to think about the events is as legitimate as it is for humans.
Otherwise, your sharp separation of objects to conscious and unconscious isn't used by any law of physics. You may imagine that any property of a physical system that may imprint itself into the environment - so that it has decohered - is being "realized" by the corresponding physical system.
Yes, we can change the wave function in our thoughts. That's what people are doing when they imagine that the wave function has collapsed, for example. Other people may continue to evolve the wave function without any collapse - so that each person will use a different wave function - and they will only make the collapse once they are aware of a measured property. It's important to realize that when the wave function collapses in someone's mind, it's just his simplification of a calculation; it doesn't affect any actual observations that will be done or their calculations as long as the calculations are done properly.
In particular, it's not true that one may single out a subclass of "conscious beings" who know some special password and who have some special supervisor rights to the quantum Universe so that they may interfere with the predictions of quantum mechanics or modify the future facts in any physical way. Every object, including people, obeys the laws of physics without any modification. The conscious people are just those who can realize that.
Sorry that the answer is vague and has no formulae to make the points quantitative but it is because the question is vague and unquantitative. Physics is simply not about consciousness. The aspects of consciousness that are available to the scientific method are studied by neurobiology and similar disciplines.
Physics is a systematic method to reconcile, explain, and predict perceptions from the physicist's observations of all other objects in the world and all such objects have to be treated as if they were dead and dull conglomerates of particles and fields.
Of course, the observer himself who is using physics may think that he is something more, and he arguably is. But that doesn't affect anything about physics predictions whatsoever. In particular, other physicists may consider the first physicist to be a dull bound state of particles, too. They will get the right probabilistic predictions for any question they may ask.
So it's legitimate to employ any idea about who has consciousness or who doesn't. For example, it's totally OK to use solipsism - a paradigm according to which I am the only conscious being. Despite the apparent subjective character of this prescription, it leads to no contradiction. For example, using equations of quantum mechanics, it's possible to show that if another person (treated as a dull bound state of particles) clearly sees something in the skies, I will see it, too.
the introduction of Consciousness into the interpretation of quantum theory is more because of desire for the world to be a particular way than of convenience. It perhaps particularly wants human agency to be unfettered, or at least to be less fettered by hard rules. Consciousness is certainly not inherent to the interpretation of quantum theory, except insofar as someone does have to decide to do an experiment or to try to construct a new theory and to publish the results in a journal, but this decision process falls outside Physics qua Physics.
Quantum mechanics is a theory in Physics that deals with statistics. No-one has found that the statistics of results change in a statistically significant way when someone wills for the result of an experiment to come out one way or another. It can be said that very few Physicists look for such effects, so of course they haven't been found, but AFAIK what searches there have been have not shown significant results.
Physicists have been able to find extensive systematic order in the statistics of our records of experimental results, but any event that happens only once is largely outside the scope of Science because of the almost absolute requirement that experiments must be reproducible for them to be considered to be Science, essentially as a matter of definition. The idea of reproducibility has come to be one of statistical reproducibility, which gives up all unique events to non-Science. Of course every apple is unique, but we can still talk about a dozen apples that are the same enough that they are at the same time unique and not unique, so stand back while we try Science.
As for what counts as a conscious being, I'd say that's outside Physics qua Physics. Philosophy Stack Exchange is almost there!
Insofar as the wave function is a concept in our heads, we can have as many of them as we want and we can change them as we like, but constructing or finding a piece of the world for whatever wave function we think of may not be easy to do. The Map is not the Territory, however good the map is, and drawing a map is no guarantee that there is a country that has that shape. Unless we're living in the Matrix, in which case the territory is a map. Not Physics, probably.