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Currently Playing: How Did One Equation Predict Antimatter (…and Spin)?

Get 86% off Private Internet Access and 4 extra months free: http://piavpn.com/physicsexplained You can help support this channel via the Physics Explained Patreon account: https://www.patreon.com/physicsexplained What happens when you actually solve the Dirac Equation? In this second part of the series, we walk step-by-step through the structure of Dirac spinors, uncovering why the equation predicts four distinct solutions — two for particles, two for antiparticles — and how this leads to some of the most remarkable discoveries in modern physics. We begin by solving the Dirac equation for a particle at rest, revealing the emergence of negative-energy solutions and the mathematical necessity of antiparticles. We then extend the analysis to particles in motion and show how the energy–momentum relation naturally arises. Finally, we explore the deep connection between spin and symmetry, and demonstrate how the equation predicts intrinsic angular momentum — spin-½ — as a built-in feature of relativistic quantum theory. This is Part Two of a two-part series. If you missed Part One, which explores what motivated Dirac to write down his equation in the first place, you can watch it here: https://www.youtube.com/watch?v=upX1MmQwGBU You can follow me on instagram: https://www.instagram.com/physics_explained_ig You can follow me on X: https://twitter.com/PhysicsExplain1 References: Inward Bound - Abraham Pais Modern Particle Physics - Mark Thomson Gauge Theories in Particle Physics - Aitchison and Hey Introduction to Elementary Particles - David Griffiths Quantum Field Theory for the Gifted Amateur - Tom Lancaster and Stephen Blundellhttps://warwick.ac.uk/fac/sci/physics/staff/academic/boyd/stuff/neutrinolectures/dirac.pdf https://www2.ph.ed.ac.uk/~playfer/spinors.pdf https://quantummechanics.ucsd.edu/ph130a/130_notes/node490.html