Quantum Mechanics and Consciousness

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mentari (September 07, 2009, 00:29:11 AM):
Terms such as “feeling”, “intention”, “knowing” and “choice” are thus not viewed as primary causal factors of consciousness, but a byproduct of these blind interactions.
Since this sentence was generated by your consciousness is the sentence itself thus a product of blind interactions? And if so why should we then believe the sentence.
Peter Grant (September 07, 2009, 14:31:12 PM):
Why are we proposing Quantum computing when the ordinary kind does the trick?
Mefiante (September 07, 2009, 15:46:49 PM):
Why are we proposing Quantum computing when the ordinary kind does the trick?
Because certain instances of a special class of computational problems called “BQP” lend themselves to what is in effect massively parallel, non-deterministic processing. Put simply, that’s like letting billions of blindingly fast networked computers loose at the same time on a particular problem — except that there’s a price to pay for the number and speed of those computers: each of them only produces a correct result with a certain probability (hence “non-deterministic”), sometimes spitting out garbage. By comparing the results of all of these individual “dodgy” computers, the correct answer can be found very quickly and with a high degree of certainty.

(More here.)

'Luthon64
Peter Grant (September 08, 2009, 12:38:02 PM):
Why are we proposing Quantum computing when the ordinary kind does the trick?
Because certain instances of a special class of computational problems called “BQP” lend themselves to what is in effect massively parallel, non-deterministic processing. Put simply, that’s like letting billions of blindingly fast networked computers loose at the same time on a particular problem — except that there’s a price to pay for the number and speed of those computers: each of them only produces a correct result with a certain probability (hence “non-deterministic”), sometimes spitting out garbage. By comparing the results of all of these individual “dodgy” computers, the correct answer can be found very quickly and with a high degree of certainty.

(More here.)

'Luthon64


I wouldn't argue that human brains don't have a tendency to sometimes spit out garbage, but how quickly and accurately do we actually solve these BQP problems? Wouldn't ordinary deterministic computing provide sufficient explanation for our somewhat limited abilities? Does proposing a quantum brain offer any explanatory value?
Mefiante (September 08, 2009, 18:31:44 PM):
I wouldn't argue that human brains don't have a tendency to sometimes spit out garbage…
True enough, but quantum computing is more akin to individual neurons occasionally firing haphazardly, rather than the whole brain going off the rails. As long as some majority (above a certain threshold) of the neurons fire in concert, the brain will produce a definite answer (or so neuroscientists are currently inclined to believe). The correctness of the answer will depend on several other factors which can be loosely grouped under the heading “inputs.”

… but how quickly and accurately do we actually solve these BQP problems?
Theoretically, a quantum computer would solve certain general instances (NB! not all of them) of BQP (and P) problems very, very fast – much faster than even the most powerful modern supercomputers and superclusters that presently are capable of speeds in the order of ten teraflops. However, there are some tricky technical problems to overcome first before quantum computing becomes a reality. Execution time on a quantum computer will grow sub-linearly with desired accuracy.

Wouldn't ordinary deterministic computing provide sufficient explanation for our somewhat limited abilities?
It seems unlikely. If it was so, we would probably be able to simulate a human brain fairly decently, which is something we still cannot do. Moreover, the brain can exhibit problem solving behaviour that is outside the P complexity class. For example, often when you solve a crossword and are looking for the answer to a particularly vexing clue, you don’t systematically run through all the possibilities, although naturally you’ll try a few. The answer, when it comes, suddenly pops clearly into your head and is almost instantly recognised.

Does proposing a quantum brain offer any explanatory value?
Not at present but it may do one day, although it does seem rather unlikely. Consciousness is an essential dimension of a functioning human brain but nobody knows what consciousness is. The squabble in this thread is over just this crucial issue: the complete QM-consciousness model is still a wild guess because it is missing several key ingredients. It is scientific only insofar that some aspects of it can be tested, at least theoretically, but the essential difficulty of how QM effects produce brain activity (and/or consciousness) remains entirely obscure and a matter of considerable speculation. Also, a large part of the problem is that “quantum” has in many quarters (especially in New Age ones) become the next Supremely Transcendent Universal Principle of Ignorant Deduction (STUPID), much like god/gods was/were in the past: “I don’t quite know how this works, so it must be quantum. Hallelujah!”

'Luthon64

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