I think you missed the point. In that post I equated choice to the collapse of the wave function. Human choices didn't enter into it. And, as I said in a more recent post, I don't believe that there is a significant relationship between the two.
I don't assume that quantum uncertainty is at all relevant to human choices. You seem to be confusing two different things.
- maybe this Prof. Stapp's quote helps here (and many of his other papers are worth reading, too):
quote:By adopting a quantum-theoretical approach we open the way, of course, to a quantum treatment of various chemical processes that are important to the functioning of the brain. But that is NOT the point here. Those atomic processes can surely be treated to sufficient accuracy by a quasi-classical model that merely adjusts atomic-scale properties that have little to do directly with our consciousness. The point of going to the pragmatic/quantum framework is to accommodate the huge macroscopic quantum effects that are directly forced upon us by the Heisenberg uncertainty principle, and that make the reduction of the wave packet of decisive importance in the determination the large-scale behaviour of the body/brain. These reductions of the wave packet are, within the pragmatic/quantum framework, projections of our knowings onto our mathematical representation of physical reality .
It is sufficient to consider a model of the brain that is mainly classical. To a good first approximation the introduction of quantum theory merely involves introducing on top of the normal classical statistical ensemble arising from our incomplete knowledge a further statistical ensembles of classical motions arising from the irreducible quantum uncertainties.
At first sight this just seems to overlay the classical statistical ensemble of brain states by another layer of statistical uncertainty that adds nothing perceptible to the uncertainties already present.
But there is a basic difference. In any single empirical instance only one member of the classical component of the statistical ensemble is actually present, but all of the members of the quantum superposition that are forced to be present by the uncertainty principle are necessarily all present simultaneously, until a reduction occurs. This presence in principle of the various superposed possibilities is the essence of quantum theory: it is entailed by the fact that the different superposed members of the quantum ensemble can interact with each other.
The presence of these superposed possibilities means that in any given empirical instance, no matter which classical element of the ensemble is actually present, the quantum ensemble spreads over all of the various possible attractors. Consequently, this quantum reduction exercises an overriding control over the choice of attractor: this choice could be the same for each of the alternative possible members of the classical ensembles, and hence independent of which of the alternative classical states (generated, for example, by the thermodynamical mixture of possibilities) is present. For the quantum principles are absolutely mute on this sort of unphysical question: What would the choice have been if the occurring situation had been other than what it actually is?
Thus the quantum choice could in principle be independent of which member of the classical statistical ensemble is present. But in that case the quantum choice would wipe out the classical uncertainties introduced by the thermal noise.
This point is raised merely to emphasize that the quantum choice is the decisive control element in cases---such as the human brain---where the irreducible quantum uncertainties are so great that essentially all of the alternative macroscopic possibilities are included within the range spanned by the quantum uncertainties.
I'm not sure I understood the passage quoted by Alex, but reading it left me with a question. Are there any macroscopic processes which quantum mechanics predicts better than relativistic mechanics? I remember that the standard textbook example of a large-scale phenomenon which classical Newtonian mechanics could not explain, but Einstein's theory of relativity could, was the orbit of Mercury. Is there a similar example for quantum mechanics? Something where our experimental setup is not dealing with individual photons or quarks, but where our macroscopic effect is different under quantum and classical interpretations?
Probably this piece of an old discussion with Dr. Stapp is well worth remembering:
quote:Varela: How does your picture account for the many levels of structure in brain processing that lie between the quantum events at the atomic level and consciousness?
Stapp: In the first place the quantum events are not at the atomic level. According to Heisenberg's idea, the quantum events, that is the actual events, occur only when the interaction between the quantum system and the measuring device, "and hence the rest of the world", comes into play. The actual events that I am talking about occur at a MACROSCOPIC level: the whole Geiger counter "fires", or the whole pointer on the measuring device is actualized as swinging to the left, rather than to the right. The quantum events select from among the alternative possible COHESIVE MACROSCOPIC PATTERNS OF ACTIVITY. As for the many levels of processing in the brain, these are considered to be mechanical brain processes: they are consequences of the quantum-mechanical laws of motion, which determine the evolution of the "propensities" for the various alternative possible quantum events. In most other theories of the mind-brain connection there is no basis for a fundamental ontological difference between brain processes that are consciously experienced and those that are not. This is because their basic ontological structure is monistic, rather than dualistic, as it is in quantum theory. Quantum theory thus allows for a FUNDAMENTAL physical difference between brain processes that are experienced and those that are not.
Varda: What empirical evidence is there that quantum theory is important in brain processes that are directly connected to consciousness?
Stapp: Chemical processes are essential to brain operation, and hence, a quanturn description is mandated. In fact, quantum mechanics is essential to any understanding of the properties of materials, be they inorganic, organic, or biological. Classical ideas do not suffice to explain properties of materials, and properties of various materials play an essential role in the functioning of the brain.
Varela: The microscopic atomic properties lead to macroscopic properties, such as electric pulses along neurons, that can be described classically. What empirical evidence is there that a classical description is inadequate for describing those brain processes that are directly connected to conscious process?
Stapp: The processes that can be described classically can also be described quantum mechanically, and the latter description is FUNDAMENTALLY better because it fits onto the lower-level chemical processes in a rationally coherent way. Thus one CAN use a quantum description, and at least in principle, SHOULD use a quantum description, because it is universal, or at least CAN be universal: classical physics is known to be inadequate in some respects: it is known to be nonuniversal. The quantmn description is not only required to explain the underlying atomic and chemical processes, it is fundamentally richer also in the treatment of macroscopic properties, as the theory of consciousness described here shows. As Quine has emphasized, theories are underdetermined by data. In order to have any hope of achieving a reasonably unique understanding of nature we must insist upon the unity of science, and strive for a coherent understanding that covers the entire range of scientific knowledge. It is only if science can give us a UNIFIED comprehension of nature that we can turn to it with any confidence for an understanding of our place in nature.
where our experimental setup is not dealing with individual photons or quarks, but where our macroscopic effect is different under quantum and classical interpretations?
- it's a computer for example! There are very macroscopic silicon crystals in every computer; and it's absolutely impossible to understand the macroscopic electric behavior of silicon without quantum theory — because there is the gap of forbidden electron energies in a semiconductor and that gap comes straight from the fact that in a single atom there are gaps between permitted energies.
I explicitly identified the "choice" as the collapse of the quantum wave function
— then the wavefunction of the whole universe must be considered, because the brain is entangled with the entire universe. All the universal wavefunction collapses because of every local experienced event.
That is irrelevant to your misunderstanding - and I will point out that we can certainly deal with individual cases of collapsing wave functions without considering the entire universe. The brain is not so special that we can consider it entangled with "the entire universe" in any sense that does not apply to other systems.
Even if you are correct that would only mean that isolated atoms and particles in experiments are special in NOT being connected to everything else - and then only for a time. And I don't think that you are correct.
quote: The probability function does - unlike the common procedure in Newtonian mechanics - not describe a certain event but, at least during the process of observation, a whole ensemble of possible events.
The observation itself changes the probability function discontinuously; it selects of all possible events the actual one that has taken place. Since through the observation our knowledge of the system has changed discontinuously, its mathematical representation also has undergone the discontinuous change and we speak of a 'quantum jump'. When the old adage 'Natura non facit saltus' is used as a basis for criticism of quantum theory, we can reply that certainly our knowledge can change suddenly and that this fact justifies the use of the term 'quantum jump'.
Therefore, the transition from the 'possible' to the 'actual' takes place during the act of observation. If we want to describe what happens in an atomic event, we have to realize that the word 'happens' can apply only to the observation, not to the state of affairs between two observations. It applies to the physical, not the psychical act of observation, and we may say that the transition from the 'possible' to the 'actual' takes place as soon as the interaction of the object with the measuring device, and thereby with the rest of the world, has come into play; it is not connected with the act of registration of the result by the mind of the observer. The discontinuous change in the probability function, however, takes place with the act of registration, because it is the discontinuous change of our knowledge in the instant of registration that has its image in the discontinuous change of the probability function.
In fact I do agree with it. Note that it states that the only significance to human observation is the change in the observer's knowledge. The shift from an ensemble of possible states to one actual state occurs in the interaction with the measuring device.
Quantum mechanics dictates the probability distribution, having effects at the macroscopic level apparently causes the shift. The nature of the shift is unknown (which is where we find the interpretations of QM)