Mathematics
The Hyperbolic Plane: Models of Non-Euclidean Geometry
Quick fact
In hyperbolic geometry, the sum of the angles of any triangle is always less than 180 degrees, and the deficit is directly proportional to the triangle's area—the larger the triangle, the smaller the angle sum.
Why this is interesting
Imagine you could draw an infinite number of parallel lines through a single point—not just one. In a space that curves like a saddle, that's actually possible.