Matter Isoradiality: Experimental and Falsifiable Proof of the Invariant Spherical Hypersurface in the "Time Bubble Universe" (TBU) Theory

Standard cosmology models the universe as an expanding 3D volume. The Time Bubble Universe (TBU) framework refutes this geometry, positing that cosmic matter resides on an expanding 2D spherical hypersurface with an invariant coordinate radius R(t) at any emission time t_em. This paper provides the formal, kinematic, and falsifiable proof of the TBU model. Through a dual analytical framework (retro-propagation to the past t_em and inverse projection to the present t_0), we demonstrate that the apparent radial discrepancy observed across celestial objects reflects the projective effect of the cosmic divergence angle θ. Setting Andromeda (M31, R_0 ≈ 1,044.5 kpc) as baseline, all tested systems strictly lie on the same invariant spherical shell.