Quantum mind/Temp
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=Quantum mind/Temp= Almost the only point of agreement on consciousness is that it is a property not detected in the universe outside of he brain. The so called 'hard problem' is to explain how the matter of the brain could generate a property not detected elsewhere in the universe. Many people find the mainstream neuroscience or IT driven theories of consciousness lacking in explanatory power, because they do not show how aspects of the brain such as fluctuations in electrical potential or amino acids could give rise to a previously undetected physical property.
One reason for resorting to the quantum level is that it is only at this level that we find given properties of the universe such as mass, charge and spin that cannot be subject to further reduction and explanation. It is at least in principle possible to insert consciousness as a given property, not capable of further reduction, at this level.
==Penrose/Hameroff Model== Several models of quantum consciousness have been developed in recent years. The Penrose/Hameroff model is arguably the most developed of these, since it provides both an argument for why consciousness could only spring from the quantum level, and a model for how it could be physically generated in the brain.
Penrose builds his theory from a mathematical angle, which can be initially off putting to the non-mathematical. The core of this part of the argument is Godel's Theorem. In 1931 the mathematician and logician, Kurt Godel demonstrated that with any set of axioms it would be possible to produce a statement that was obviously true, at least to mathematicians, but could not be proved by means of the axioms. This much is uncontroversial in modern thinking.
What is, however, highly contentious is the use that Penrose made of Godel's Theorem. He claimed that the ability of the human mind to go beyond what could be demonstrated by mathematical axioms showed that there was something in the functioning of the brain that was not based on algorithms. Therefore the brain would always be able to do things that computers could not, because they were entirely based on algorithms.
Penrose went on to look for what it was in the brain that was not based on algorithms. The only aspect of the physical world that fitted this description was the collapse of the quantum wave function. When the individual quanta goes from wave to particle, the position chosen for the particle is random.
However, Penrose could see that a random collapse was not a promising basis for the apparently purposeful functioning of consciousness in the brain. He, therefore, went beyond existing physics by suggesting an alternative version of the collapse of the wave function.The modern view of wave function collapse is that it occurs when quanta interact with the rest of their environment. Penrose proposes that there is an additional version of collapse that occurs without interaction with the environment. He suggests that superpositions of quanta represent blisters or separations into separate space time geometries. Once the separation becomes greater than the Planck length the wave fnction collapses. Penrose suggests that this, as opposed to the conventional collapse, is an access to the fundamental space time geometry of the universe and the only feasible place for consciousness, by dint of the unsuitability of the other possible places.
==Hameroff== At the time that Penrose first proposed this theory, he faced a considerable explanatory gap as to how such a wave function collapse could occur in the brain, and in particular how it could collapse so as to effect a macroscopic structure such as the brain.
Hammeroff had approached consciousness from the direction of anaethesia. He thought that structures within the neurons known as microtubules might be involved in consciousness. In the Penrose/Hameroff joint theory it is suggested that they could support Bose-Einstein condensates. These are macroscopic quantum objects in which billions of quanta are locked in phase. They are suggested to exist in neurons linked by gap junctions as opposed to normal synapses. The condensates could extend between these gap junction neurons as a result of quantum tunnelling and thus extend over large areas of the brain. Gap junctions are common in areas associated with consciousness. When the separation between the superpositions involved exceeded the Planck length, the wave function would collapse generating consciousness. The whole condendate would decohere and collapse together.
==Objections to Penrose/Hameroff== The most cogent objection to Penrose/Hameroff is that the condensates would not survive conditions in the brain for a useful length of time, quickly interacting with and decohering in the complex brain environment. Hameroff's main counter argument is that the interior of the microtubules could be screened by water and actin in an ordered state next to the surface of the microtubules.
There is some limited experimental support for the theory. MRI brain scanning has artificially induced quantum coherence. This persisted for around 25 milliseconds in the frontal, parietal and occipital lobes. This ties in with the observed 40Hz oscillation between the thalamus and the cortex, which more mainstream researches such as Crick and Koch identified as a correlatate of consciousness. Persephone19 20:45, 29 October 2006 (UTC)
==References== Hameroff, Stuart: Ultimate Computing: Elsevier Science Publishing (1987) ISBN 0 444 70283 0 www.quantumconsciousness.org Penrose, Roger: The Emperor's New Mind: Oxford University Press: (1989) ISBN 0-19-2861198-0 Penrose, Roger: Shadow's of the Mind: Oxford University Press (1994) ISBN 0-19-853978-9 Richter, Lee, Warren (1993) Richter, Lee, Warren, He Q Science 262: 2005-2009 Richter, Lee, Warren (1995) He Q Science 267: 654-657 Vathyam, Lee, Warren (1996) Science 272: 92-96 Warren et al, (1998) Science 281: 247-251 Rizi et al, (2000) Magnetic Resonance in Medicine 43: 627-632
