I wonder, might the fact that 'observation' has measurable effects, e.g. in the double-slit experiment, be a vector for inquiry into the question of qualia? I don't need to observe the path of a photon in the DSE to know whether someone else has observed it if I can see the presence or absence of an interference pattern. If we get better at formalising what 'observation' means in that context, do you think it could be used to arrive at a measure of subjectivity?
