Statement
Problem 3.5 of Goto et al.: how does one formulate a theory of measurement (detector operators, POVMs) when interactions are stringy — non-local at the string scale — rather than pointlike? What consequences follow for the “observer as detector” and “observer as operational limitation” viewpoints?
Why It Matters
Peripheral to the group, but it shares a concern with the group’s impossible-measurements question: naive sharp/local measurements are pathological in relativistic and gravitational settings, and both problems ask what a physically admissible measurement is. Stringy non-locality is the far-UV version of that caution.
What We Know
- Unruh–DeWitt detectors model measurement via local field–detector coupling; the group uses these (spin-1 UDW work).
- Sorkin’s impossible measurements show ideal projective measurements can violate causality in QFT.
- A stringy/non-local measurement formalism is not established.
Possible Approaches
- Extend detector models to non-local (smeared over string scale) couplings and test causality.
- Connect to algebraic (POVM-on-a-region) formulations that avoid ideal measurements.