Physics and particularly quantum physics are often invoked in discussions of consciousness. But what can physics actually tell us? I will first discuss what physics does not tell us: physics does not provide any criteria with which to distinguish conscious systems from non-conscious systems. As far as physics is concerned, consciousness is like free will – it characterizes either nothing or everything. Since we are conscious, it is reasonable to regard everything else as conscious, too. If we make this assumption, the question of interest becomes: what systems are conscious of what? Physics is fundamentally a theory of interaction, so it can tell us a lot about this. The first thing it tells us is that being conscious of something requires expending energy. How much energy a system can expend determines how much it can be conscious of. This energy requirement has surprising consequences, some of which I will describe.
This talk was recorded at SAND