Bill

Another way to look at this issue is to consider a computer random number generator. Most good ones have a "random seed" that is computed in some physical way so as to cause the sequence of randomly-generated numbers to vary from one series of calls to the next.

However, by preserving the "random seed" number, it is possible to obtain the exact same results from the "random number generator" program. Thus, a computer does not generate truly random (unpredictable) numbers, but only pseudo-random numbers (numbers that have the proper random distribution over the allowed set of results if you run the algorithm for a sufficiently long period of time).

Given the way the brain works (by integrating results over space and time), it is virtually impossible for any typical quantum fluctuation to have any measurable effect on the desired output. The basic neural mechanisms are designed to cope with and eliminate all random factors. Thus, as near as I can see, our brain functions as a fully-causal (and "deterministic") computing engine; or at least as much of one as a Pentium 4 computer chip is.....

== Bill

Bill

The randomness that is predicted to occur due to quantum mechanical effects occurs on an extremely small scale. The chances of any particular electron being affected by some sort of "quantum weirdness" (vanishing and then reappearing a short time later) are almost vanishingly small. For all practical purposes, no more than a single electron in any given chemical stew can be presumed to be experiencing "quantum weirdness" (and all this is true only if quantum mechanics is not eventually forced to yield to causality, which remains a viable option).

The time scale that quantum effects operate on is also vanishingly small. Presuming that the electron disappears and reappears due to "quantum weirdness," you would never actually notice it with any instrumentation currently useable on a human brain. In quantum mechanical terms, a nanosecond might well be equivalent to a billion years in our terms.

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All chemical processes are chaotic in detail. You never know exactly where the electrons are which bind the atoms together to form a molecule. And yet, we are certain that these chemical bonds are reliable enough so that we don't expect any substantial quantity of any given chemical to "change its character" in any measurable way during the lifetime of the chemical product.

Yes, its possible that all of the atoms in the air in the room you occupy as you read this might all choose to run to the wall furthest away from you right now, but you need not worry about whether or not you will continue to breathe, because the effects will be for a vanishingly-small amount of time before the random effects of such a gathering will cause the air to once again surround your body. If it happened, it would happen so fast that you would never even notice that you were in a vacuum for a while.

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We tend to learn scientific thories in a way that almost anthropomorphizes physical processes so that they beome understandable to us. We picture electrons as little ping-pong balls, and yet that isn't what an electron is in any real sense (an electron is an effect in space/time, but hardly a physical ball in any real sense). Our tendency to picture things in our minds (or even with hand-drawn images) leads us to forget the relative scales of physical effects.

Quantum Mechanics deals with matters in the realm of ten to the minus a whole heck of a lot. Quantum Mechanics is no good at all in predicting anything we can actually see or experience (duration). Physicists can design experiments that will amplify and measure the output from billions-upon-billions of quantum effects so as to obtain a measurable result. But that doesn't change the fact that "quantum weirdness" cannot (even by quantum theory) affect more than a miniscule percentage of any given collection of atomic particles (particularly electrons, since electrons are the smallest "regular particle", consisting of a single quark; protons and nutrons each consist of three quarks; everything else in particle physics is smaller and weirder, but generally doesn't affect chemical reactions).

I wish I had the time to hunt down the relative scales of quantum effects (even presuming that quantum effects are acausal in the first place; I consider that to be a very open question). But I don't, so I will need to leave the finding of the actual numbers as an exercise for the student. Sorry!

== Bill

jj

Whoa, there. Chemical binding is EXACTLY Quantum Mechanics, Bill. They are all the same thing. QM, the location of an electron, putting a C and an O2 together into CO2, are all QM. Physical chemestry these days can even relate simpler reactions directly back to the Schroedinger Wave Equation.

The timescale is that of the occurance (not the overall rate, which is also thermodynamically limited) of reactions when the actual molecules are near each other.

"Quantum Wierdness" is not a technical term I'm aware of, and is simply not germane here.

Grab any phi-chem book, read it. You'll find that QM starts as soon as mechanisms are involved, and proceeds to the bitter end. Orbitals, binding angles, etc, are all derived nowadays from the QM solutions to the Schroedinger Wave Equation, at least for simpler substrates, etc.

It's insoluable in the general case, yes, but that does not mean that QM is not involved, only that the solutions are mindnumbingly complicated.

Ergo: Your objections are both inaccurate and not well taken. Sorry, but that's all there really is to it.