Mathematics
Non-Euclidean Geometries and Curved Space
Quick fact
The geometry of the universe itself might be curved, and its overall shape—whether flat, spherical, or saddle-like—determines the ultimate fate of cosmic expansion.
Why this is interesting
You've always been taught that the angles of a triangle add up to 180 degrees. But what if that's not always true? On Earth's surface, a triangle drawn from the equator to the North Pole has angles that sum to more than 270 degrees!