Phys Rev Lett. 2026 Jul 17;137(3):031501. doi: 10.1103/q81l-xfkx.
ABSTRACT
We show that the canonical formulation of the semiclassical Einstein equation, where the matter terms in the constraints are replaced by expectation values of the corresponding operators in quantum states, is inconsistent due to the nonclosure of the resulting constraint algebra.
PMID:42537109 | DOI:10.1103/q81l-xfkx
