A guided journey of small interactive experiments — paper, vectors, light cones, gravity wells — that build intuition for spacetime before you ever see an equation.
Most people meet relativity as equations or analogies that never quite click. Light Matters is the other way in — a sequence of small drawings you can hold in one hand, then tilt, dial, and break open until the geometry tells you what the math meant all along.
Light Matters exists because other people made relativity visible long before this site did — scientists who found the geometry, and communicators who handed it to the rest of us.
And to every teacher, writer, and explainer who ever drew a diagram on a napkin — thank you for making the universe legible.
Spend ninety minutes inside the diagram and the universe stops being a lecture.