Fusion — why the stars shine

Four hydrogens weigh more than one helium; the difference is sunlight. Sealed from the measured masses: 4·m(H) − m(He-4) = 0.0287 u → 26.73 MeV per helium forged: https://narrowhighway.com/s/8a5e89ab13bc499f39240c64360d90c34a65a291c91c73fcac4fc976131b17c5 . That 0.7% toll on hydrogen's mass, paid over ~10 billion years, is the sun's entire budget — every green leaf runs on the deficit. The honest boundary: the ENERGY seals from the mass tables; the RATE (why the sun burns slowly instead of exploding) is quantum tunnelling through the Coulomb wall — empirical cross-sections, the reason fusion power is hard and stars are patient.