ijuin wrote:This is important because it is the mis-interpretation of this that results in the whole "conscious observer" issue. An "observation" does not require an actual mind to perceive it. Rather, a particle/wave is "observed" as having certain characteristics whenever it interacts with any other particle/wave in a way that would require it to have those characteristics. As in Eogan's example. if a particle/wave is involved in a collision, then its wavefunction must "collapse" into a subset that is compatible with it having been at that particular time and place and having the particular energy and vector required for the collision. In short, particles observe each other wherever and whenever they interact. It is actually quite difficult to get any large number of particles to interact without collapsing.
This is a nice statement of what's wrong with all quantum interpretations, including Many Worlds and decoherence approaches: they assume what they should be explaining, which is why the unitary classical world is what we are conscious of, when their theories contain nothing like it.
What is this "collision" thing? If we just focus on Schrondinger's equation you'll see no such thing is represented anywhere. All wavefunctions evolve smoothly. Where does the classical world come from? Everrett never explains why we aren't aware of other worlds--he just takes for granted that we aren't. But why aren't we? Components of our initial wavefunction are entangled with different components of the scattering particle's wavefunction, but how come we're only aware of ONE such set of components? Decoherence approaches say we are only aware of quantum effects via what amounts to interference phenomena, and so when they go away we are no longer aware of them, but again, how come?
No quantum interpretation does anything but obfuscate and dance around the fundamental question, which is why we are only aware of the classical world, and why there is an entire phenomenological substrate--the world described by classical physics--that obeys rules (causality, locality) that are not part of the quantum corpus. This is the central mystery, and contra Penrose et al it is clear that consciousness is a purely classical phenomenon: if it wasn't we'd be aware of the quantum world, whereas manifestly we are not.
The question is not "why is the quantum world so weird?" but "why is there a classical world at all?"