In a regular icosahedron (purple), six main interior diagonals (red lines) make equal angles with each other. Credit: Zilin Jiang In a regular icosahedron (purple), six main interior diagonals (red ...

Equiangular lines are an elemental part of geometry. Mathematicians have discovered a tighter limit on the number of such lines that exist in every dimension. Imagine a set of many lines as in a dream ...