  We present a logical proof that computing machines, and by extension physical
systems, can never be certain if they possess conscious awareness. This implies
that human consciousness is associated with a violation of energy conservation.
We examine the significance that a particular interpretation of quantum
mechanics, known as single mind Q (Barrett 1999), might have for the detection
of such a violation. Finally we apply single mind Q to the problem of free will
as it arises in some celebrated experiments by the neurophysiologist Benjamin
Libet.
