Mathematics
Quaternions: A Number System for Three-Dimensional Rotations
Quick fact
Quaternions were invented by William Rowan Hamilton in 1843, who was so excited he carved the fundamental formula into a bridge in Dublin. They are still used today in virtually every 3D graphics engine, including those in VR and robotics.
Why this is interesting
You've probably rotated objects in 3D games or used a phone's orientation sensor, but did you know that the math behind it often relies on a four-dimensional number system discovered in the 19th century? These numbers, called quaternions, are the secret hero of smooth 3D rotations.