Experimental Pre-Registration: Gravitational Anomaly in BSCCO-2223 at the Superconducting Phase Transition

A formal experimental pre-registration establishing a permanent public timestamp that the theoretical prediction stated below was made before any experimental data was collected. Entropic Field Theory (EFT) predicts a non-monotonic gravitational anomaly in a BCS-type superconductor cooling through its critical temperature. The effective gravitational coupling G_eff(T)/G = √(Var_normal(Tc) / Var_BCS(T)) follows a non-monotonic curve with a parameter-free sign change at 0.88 Tc. For a 110g BSCCO-2223 sample at 77K, the predicted apparent weight anomaly is +10.8g (≈10%). The prediction carries zero free parameters. The dip-then-rise signature with sign change at exactly 0.88 Tc is the decisive observable. Effect is absent in the normal state (T > Tc) and in non-superconducting controls. Sample: Bismuth strontium calcium copper oxide Bi-2223, bulk disc 80mm diameter, >85% relative density, >90% phase purity, measured at 77K (liquid nitrogen). Two units for independent replication. EFT standalone publication: DOI 10.5281/zenodo.18963986 Companion paper EQ(vT): DOI 10.5281/zenodo.18917317 Full experimental methodology will be disclosed upon publication of results.