Quantum-Gravity-Inspired Effects in Neutron Stars: A Critical Map from Microscopic Assumptions to Observables

Abstract: Claims that neutron stars constrain quantum gravity often compare models whose new physics enters at different stages of the stellar calculation. This article provides a critical map of three representative routes: generalized-uncertainty-principle deformations of microscopic thermodynamics, noncommutative-inspired modifications of the effective matter source, and higher-curvature or scale-dependent modifications of gravitational dynamics. For each route we identify the quantity that is changed, the dimensionless parameter controlling the correction, and the consistency conditions required before masses, radii, or tidal deformabilities can be compared with observations. A deformed phase-space measure must be implemented in a thermodynamically consistent interacting equation of state; a smeared density must be completed by a conserved stress-energy tensor, generally with anisotropic pressure; and a gravitational effective field theory must remain within its derivative expansion and be applied consistently to both the equilibrium background and tidal perturbations. Simple scale estimates show that coefficients of natural size suppressed by the Planck scale are negligible in neutron stars. Observable effects consequently constrain model-dependent effective scales or enhanced couplings, not microscopic quantum gravity directly. The resulting framework is intended to separate robust phenomenological bounds from effects produced by inconsistent implementations or by degeneracies with the high-density equation of state.