The Speed of Light has Absolutely Nothing to Do With Light

Science educators love to make videos about relativity, but surprisingly few of them seem to understand what this stuff really means. They are very good at explaining “what“ we know, but very few of them ever stop to explain “how“ we know it. In this video, we explore a first-principles derivation of the Lorentz transformation. Without even mentioning the word “light,“ we can mathematically derive a universal speed limit from the basic properties of time, space, and motion. The speed of light therefore has nothing whatsoever to do with light. It’s a statement about the very geometry of space and time. Read the script here: See also: Pelissetto, A., and Testa, M., “Getting the Lorentz transformations without requiring an invariant speed,“ American Journal of Physics, 83, 338 (2015) 338-340 link: