Testing the Strong-Field Predictions of the Order Parameter Spacetime Theory with the EHT M87* Black Hole Shadow Observation

We test the strong-gravity predictions of the Order Parameter Spacetime Theory using the Event Horizon Telescope (EHT) 2018 observation of the M87* black hole shadow. The information–Einstein equations of the theory admit an exact solution in a static, spherically symmetric background, predicting a deviation of the black hole shadow radius due to the behavior of the information dissipation tensor near a Type-B traversable singularity. The deviation is controlled by a dimensionless parameter λ. The EHT 2018 observation measured a shadow diameter of 43.3+1.5−3.1 μas for M87*, consistent within errors with both the 2017 first result (42 ± 3 μas) and the general relativistic prediction (~42 μas). By comparing the theoretically predicted shadow radius correction formula with the EHT data, we place a constraint on the information dissipation strength parameter λ. Under the standard parameterization of the Type-B singularity, the shadow correction coefficient is β = 1, leading to λ ≲ 0.07 (68% confidence level). The Order Parameter Spacetime Theory is thus self-consistent with general relativity in the strong-field limit. Together with previous tests of the theory in the cosmological weak-field limit using DESI DR2 BAO and DESI DR1 full-shape data, the theory has now passed independent tests at two opposite physical extremes — the weak field (cosmic expansion and structure growth) and the strong field (black hole horizon) — forming a complete complementary verification system across weak and strong gravity.