> Geometric Algebra is cool. It lets you say things like "the intersection of two spheres that don't touch is a circle with negative radius." You can't even rep

> Geometric Algebra is cool. It lets you say things like "the intersection of two spheres that don't touch is a circle with negative radius." You can't even represent a circle with negative radius in regular geometry. For some notion of "regular geometry". Desargues could produce this result in the early 17th century by lifting the circles into right cones in three dimensions, though he would probably tell you that the circle with negative radius was meaningless.