Why Does Everything in the Universe Spin?

Everything in the universe spins. Every planet, every star, every galaxy, every electron. Tonight, we follow the origin of that spin from the very largest structures in the observable universe down to the smallest things that physics can describe. We trace the flat protoplanetary disk that built the solar system to the barely perceptible rotation of a molecular cloud amplified by gravitational collapse. We visit Vera Rubin's discovery of flat galaxy rotation curves, and the dark matter whose existence was first revealed by the fact that stars at the outer edges of galaxies were spinning too fast. We explore how neutron stars spinning hundreds of times per second, born in supernova explosions, gave us instruments sensitive enough to detect the gravitational wave background from supermassive black hole pairs merging across the observable universe. We descend into the quantum world and find that quantum spin, though nothing physically rotates, is the same angular momentum conserved by the same law, and that this fact is why matter takes up space, why chemistry exists, and why MRI machines can image the human brain. All of it, from galaxy to electron, is one conservation law: the rotational symmetry of the laws of physics, proved by Emmy Noether in 1918. Sources: Noether, E. (1918). Invariante Variationsprobleme. Nachrichten der Koeniglichen Gesellschaft der Wissenschaften zu Goettingen. Rubin, V.C. & Ford, W.K. (1970). Rotation of the Andromeda Nebula from a Spectroscopic Survey of Emission Regions. Astrophysical Journal, 159, 379. Kerr, R.P. (1963). Gravitational Field of a Spinning Mass as an Example of Algebraically Special Metrics. Physical Review Letters, 11, 237. Dirac, P.A.M. (1928). The Quantum Theory of the Electron. Proceedings of the Royal Society A, 117, 610. Penrose, R. (1969). Gravitational Collapse: The Role of General Relativity. Rivista del Nuovo Cimento, 1, 252. Pauli, W. (1940). The Connection Between Spin and Statistics. Physical Review, 58, 716. NANOGrav Collaboration (2023). The NANOGrav 15 yr Data Set: Evidence for a Gravitational-Wave Background. Astrophysical Journal Letters, 951, L8. Gravity Probe B Team (2011). Gravity Probe B: Final Results of a Space Experiment to Test General Relativity. Physical Review Letters, 106, 221101. EMC Collaboration (1988). A Measurement of the Spin Asymmetry and Determination of the Structure Function g1 in Deep Inelastic Muon-Proton Scattering. Physics Letters B, 206, 364. Fabrycky, D. & Tremaine, S. (2007). Shrinking Binary and Planetary Orbits by Kozai Cycles with Tidal Friction. Astrophysical Journal, 669, 1298. Winn, J.N. et al. (2009). HAT-P-7: A Retrograde or Polar Orbit, and a Third Body. Astrophysical Journal Letters, 703, L99.