How do we Observe Relational Observables?

Abstract

In theories with a diffeomorphism symmetry, such as general relativity and canonical quantum gravity, it is often proposed that the empirical content is encoded in relational observables. But how do relational observables actually make contact with experience? I argue that this question can only be answered by providing a schematization of the observer which is appropriate for the context of a diffeomorphism-invariant theory. I suggest that this may require us to move away from a `passive awareness' conception of consciousness towards a more agential conception, because there is a clear sense in which an embodied agent must experience herself as localised at a time. Finally, I consider what this means for the prospects of using quantum reference frames to address the problem of time, arguing that the way in which quantum reference frames are standardly described does not give us adequate resources to model agency, so some other kind of internal reference frame may be required to fully explain how we observe relational observables in the quantum context.