From David Clark
After reading “A bit in two minds” (5 December 2015, p 28) it occurred to me that Matthew Fisher's estimate of the time the Posner molecule maintains quantum coherence – about a day – might be the very reason that brains would have evolved to use this molecule, since it fits in handily with the day-night cycle.
Speculating further, it seems likely that the daily rough and tumble would cause a build-up of “decoherence”, necessitating a period of coherence-building rest. This is as good an explanation as any of the need for sleep.
A malfunction leading to full or partial “decoherence” might also be responsible for the vegetative state. I look forward to hearing more of this exciting idea as techniques and tests are developed. These thoughts came to me the morning after reading the article, awaking with a fully coherent brain following a good night's sleep!
Sandy Bay, Tasmania, Australia
