Each concept here is mapped to its prerequisites — the ideas you'd need first to understand it — all the way down to four foundations: Space, Time, Energy, Pattern. Click any prerequisite to drill down, or scroll for the chain graph.
Length emerges as a quantifiable property of space that enables the comparison of distances between points, allowing us to describe the extent of spatial separation in a measurable and standardized way.
External reference — all senses of the word “long” on Wiktionary. This atlas concept maps to only the slice of meaning relevant to the prerequisite graph.