Expanse-Time Theory (XTT): A Unified Framework for Cosmology, Gravity, and Quantum Mechanics, Compendium.

This work presents an observational validation of the Expanse-Time Theory (XTT), a cosmological framework that replaces space-only expansion with a unified expansion of spacetime. By allowing cosmic time itself to expand, XTT eliminates the need for inflation and dark energy, while remaining consistent with general relativity locally. We compare XTT predictions to recent data from JWST/NIRSpec, DESI DR2, Planck 2018, LIGO/Virgo, SDSS DR17, and the Pantheon+ supernovae catalog. All observables — including redshift-time relations, BAO scaling, structure formation timing, and gravitational wave drift — are matched to within sub-percent precision. The theory accurately predicts early massive galaxy formation (e.g., JADES-GS-z10-0 at z = 10.38), phase drift in LIGO waveforms, and redshift drift behavior without invoking ΛCDM-specific parameters. A full table of predictions and residuals is included. This is the first unified cosmological model that is fully consistent with observational data across cosmic epochs — developed without formal training, by a builder independently investigating gravitational time dilation.