We give the Greeks all the credit for geometry, but Babylonian engineers were actually using it to fix their math problems 4,000 years ago.
April 10, 2026
Original Paper
An Old Babylonian coefficient, its origin and impact on our understanding of measures on circles, including the radian measure
arXiv · 2604.08098
The Takeaway
We usually think of the radian as a high-level theoretical discovery in trigonometry. This paper shows it is actually a direct descendant of a practical scaling factor used by ancient builders to bridge the gap between straight measurements and circular curves.
From the abstract
This study reconstructs the origin of a constant, here called $\Xi$ (Xi), as a primary scaling factor in Old Babylonian mathematics and astronomy. $\Xi$ arises from the practical necessity of precise measurements on the sky or a circle, through the harmonization of length-measure systems. The analysis of the Nippur measure (with its famous cubit) and the Gudea measure shows that $\Xi = 375/360$ represents the ratio of these established Old Babylonian measure systems. As a precision factor for ci