mkserkan said:
So are these valid objections for consciousness hypothesis ?
I don't think so. There's a common misconception, in my view, about the difference between "collapse" and "decoherence." The latter is a fairly well understood aspect of quantum mechanics theory, and is also well observed, in experiments like the ones you cited. There's no question that interactions can docohere a projected wave function onto its various eigenstates of that interaction/measurement, regardless of whether or not a consciousness is involved in that measurement. But this only produces a "mixed state" when you project onto the observable subspace-- it still does not produce a definite outcome. Decoherence just doesn't do that. So the question of "collapse" remains unanswered: what chooses the actual outcome that is perceived? Some think there is a dynamical collapse that happens in the measurement that is not described by quantum mechanics (the Copenhagen interpretation says this), some think there is a dynamical collapse in the brain of the perceiver that is not described by quantum mechanics (and the Copenhagen interpretation can easily be modified to say this), while others say the collapse never actually happens at all, it is just an illusion that happens in the mind (the Many-Worlds view holds this). Other interpretations say various other things, and none of these are currently testable. Thus the answer must await a new theory that does not admit to all these various interpretations.
Personally, I suspect that such a new theory will end up siding with the consciousness does cause collapse, along the lines of Wheeler's view, but I don't think it will be a dynamical process-- I think it will change how we view what physics is doing, and old notions of what "dynamics" is will have to change with it. But who cares what I think, the future will tell.
So what happens behind scenes, Wave function collapses (because of obtained information) then re-constructed because information obtained destroyed ??
Delayed choice experiments bring in a new wrinkle-- the insight you get when you correlate observations. Much ballyhoo is made of the fact that if you look at which slit the particle goes through, you get only a pair of single-slit diffraction patterns, rather than one double-slit pattern. But I think delayed choice experiments make it quite clear what is and is not happening there-- the pair of single-slits pattern can be made in one of two ways:
1) incoherently superimposing two double-slit patterns that are shifted relative to each other.
2) incoherently superimposing two single-slit patterns that are shifted relative to each other.
If we track the which-way information, and correlate, we are led to conclude that #2 is what happened, but if we erase the which-way information, and correlate, we are led to conclude that #1 is what happened. However, since #1 and #2 give the same final result, it is just an illusion that either of those ways "really happened"-- reality was ambivalent to the distinction all along. So delayed choice experiments don't expose something reality is doing, they expose something reality doesn't need to do and so is ambivalent about. The only physical effect is that sideways shift that is induced by the apparatus that is able to detect which-way information-- whether or not that information is erased. Thus what you are worried about is something that reality does not adjudicate-- it is a non-issue.
