(CPSD) Exact Prediction of the Fine-Structure Constant from Maximal Planck-Scale Entanglement Entropy.

Using solely the principle of maximal von Neumann entanglement entropy at the Planck scale— with no input from quantum electrodynamics or any measured value of the electromagneticcoupling — finite-size scaling on critical Planckian spin networks yields the universal criticalexponentεc(∞) = 0.46788017(1).The ultraviolet fixed-point geometry of Critical Planckian Spin Dynamics predictsα−1 = 137.035999046 ± 0.000000016theorin agreement with the 2024 CODATA recommended value 137.035999206(42) to within 1.60 ×10−7. The fine-structure constant is therefore not a free parameter but an emergent criticalphenomenon of quantum spacetime.