Statement
Problem 3.2 of Goto et al.: is an observer an additional structure required for consistency of quantum gravity, an emergent notion appearing only semiclassically (geometry, horizons, causal patches, detectors), or merely an artifact of a particular description? The paper stresses these possibilities are not mutually exclusive.
Why It Matters
Conceptual/foundational; peripheral to the group’s calculational programs but the interpretive backdrop to the observer’s-algebra work (reference-structures-for-observables-in-qg, dynamical-observer-backreaction-and-algebra) that the group does touch via the crossed product.
What We Know
- In CLPW-type constructions the observer is an added ingredient that makes entropy finite — suggesting at least a “required structure” role in the semiclassical algebra.
- Whether that structure is fundamental or emergent in full QG is open.
Possible Approaches
- Compare the algebra types obtained with vs. without an explicit observer.
- Track whether observer-dependence survives beyond the semiclassical limit.