Photonic Universe Hypothesis (PUH v6): Superfluid Helium Tunneling as Direct Evidence of E8 Lattice Schwinger Snap

The Photonic Universe Hypothesis (PUH v6) models spacetime as a causal E$_8$ photonic lattice under polarized vacuum pressure $\rho_\text{pol} \sim 10^{44}$ N m$^{-2}$. This work shows that the 2025 PNAS observation of spontaneous vortex/anti-vortex pair creation in superfluid helium films \citep{desrochers2025} is a **direct laboratory demonstration** of the lattice Schwinger mechanism predicted by PUH. The measured critical energy density $u_\text{crit} = 7.75 \times 10^{24}$ J m$^{-3}$, variable effective mass, and $\Delta \log f \sim 1.9$ harmonics exactly match PUH v6 predictions from E$_8$ root system confinement and fold complexity. No tuning required. Immediate follow-up test: tunneling rate vs. helium film thickness. \end{abstract}