Photons Have No Mass — So Where Does Their Energy Come From? | PROF LENE HAU

Photons have no mass — yet they power the entire universe. In this video, we break down exactly where a photon's energy comes from, why Einstein's famous equation E=mc² is only half the story, and what three competing interpretations of quantum mechanics actually say about the nature of light. We cover Planck's constant, radiation pressure, electron quantum transitions, wave-particle duality, and the full energy-momentum relation that most textbooks skip entirely. This is the physics your education never finished explaining. 📌 Chapter breakdown below. 🔔 Subscribe — every video in this series builds on the last. 💾 Save this video. Quantum concepts compound. You'll want to rewatch. Playlist: Quantum Mechanics Unfiltered — Full Series #QuantumMechanics #QuantumPhysics #PhysicsExplained 2. ⏱️ TIMESTAMPS (23-Minute Video) 0:00 — The Question Your Teacher Never Asked 0:50 — Why E=mc² Is Only Half the Equation 3:00 — How Photons Are Actually Born (Electron Transitions Explained) 7:00 — Radiation Pressure: The Proof Light Has Momentum 10:30 — Planck's Constant and the Energy-Frequency Link 13:00 — Copenhagen vs. Many-Worlds vs. Hidden Variables 17:00 — What Recent Quantum Research (2025–2026) Actually Says 18:30 — The Next Video Is a Prerequisite — Not Optional 19:00 — Save, Subscribe & What to Watch Next 📂 Full Series Playlist → [Insert Playlist Link] 3. ⚠️ DISCLAIMER This video presents current interpretations of quantum mechanics based on experimental data and peer-reviewed research. Multiple interpretations exist within the physics community — Copenhagen, Many-Worlds, and Hidden Variable theories — and none have been definitively proven over the others. All content is educational and designed to represent the current state of scientific understanding, not settled scientific consensus on interpretive questions. For academic or research purposes, always consult primary peer-reviewed sources and published experimental literature. References to specific studies reflect findings available at the time of production. 4. 🎯 REASON TO WATCH Most physics videos tell you light is a wave-particle and move on. This video goes deeper — into the full Einstein energy-momentum equation, the quantum mechanics of photon creation, and why three completely different pictures of reality all predict the same result. What makes Quantum Mechanics Unfiltered different is that we don't give you a comfortable answer. We give you the real one: the one physicists actually debate. By the end of this video, you won't just understand where a photon's energy comes from — you'll understand why that question exposes the deepest unresolved problem in all of modern physics.