bigjeff5 comments on Dissolving the Question - Less Wrong

44 Post author: Eliezer_Yudkowsky 08 March 2008 03:17AM

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Comment author: bigjeff5 04 January 2012 07:02:16PM 0 points [-]

Do neurons operate at the quantum level? I thought they were large enough to have full decoherance throughout the brain, and thus no quantum uncertainty, meaning we could predict this particular version of your brain perfectly if we could account for the state and linkages of every neuron.

Or do neurons leverage quantum coherence in their operation?

Comment author: shminux 05 January 2012 12:40:54AM *  12 points [-]

I was once involved in a research of single ion channels, and here is my best understanding of the role of QM in biology.

There are no entanglement effects whatsoever, due to extremely fast decoherence, however, there are pervasive quantum tunneling effects involved in every biochemical process. The latter is enough to preclude exact prediction.

Recall that it is impossible to predict when a particular radioactive atom will decay. Similarly, it is impossible to predict exactly when a particular ion channel molecule will switch its state from open to closed and vice versa, as this involves tunneling through a potential barrier. Given that virtually every process in neurons is based on ion channels opening and closing, this is more than enough.

To summarize, tunneling is as effective in creating quantum uncertainty as decoherence, so you don't need decoherence to make precise modeling impossible.

Comment author: bigjeff5 05 January 2012 01:11:52AM 1 point [-]

Interesting! I hadn't thought about quantum tunneling as a source of uncertainty (mainly because I don't understand it very well - my understanding of QM is very tenuous).