Phenomenological spacetime engineering and observations

Determine whether future observations will provide sufficient guidance to identify or falsify phenomenological spacetime constructions (e.g., singularity-excision spacetimes) that model quantum gravity effects at macroscopic scales.

Background

Engineered spacetimes (e.g., regular black holes, throat geometries) provide testbeds for potential macroscopic quantum gravity manifestations. Their observational viability depends on whether data can meaningfully distinguish such constructs.

This open question asks if such modelling can be steered by forthcoming measurements.

References

Open questions: Will observations provide sufficient hints regarding the nature of the underlying theory?

— Black Holes Inside and Out 2024: visions for the future of black hole physics  (2410.14414 - Afshordi et al., 2024) in Enrico Barausse, Section "Phenomenological modelling"

Despite the progress, there are many open issues one should think about. For instance, the macroquantumness, namely the expected large scale effects that a spacetime condensate should exhibit.

— Condensates: A Bridge to Quantum Gravity  (2609.28789 - Nicolini, 23 Sep 2026) in Section 5, “Conclusions”