Relativity 103b: Galilean Relativity - Spacetime Separation (Interval) Vector and Invariance

From a channel Lumen includes in full: eigenchris posts long, derivation-first lecture series on tensor calculus, general relativity, spinors and related maths, one of the most thorough free self-study routes into these topics.

A 15-minute video from eigenchris's catalogue; the title names its topic.

Video by eigenchris, played through YouTube's embedded player.