July 1849: Fizeau publishes results of speed of light experiment

How fast is the speed of light? ⚡️💡☀️ For many years it wasn’t known. Then in July 1849, French scientist Armand-Hippolyte-Louis Fizeau published a measurement of light's speed on Earth within ~5% of today's numbers. Find out how: https://t.co/YwAubDr4Cq #PhysicsHistory #FBF

— APS Physics (@APSphysics) July 15, 2022