THE ALGEBRA OF SHADOWS

Why did a librarian in ancient Alexandria only need a stick and its shadow to calculate the size of the entire Earth? Why did a seventeenth century Danish astronomer discover the speed of light not by watching a beam of light, but by timing the exact moment a moon vanished into another planet's shadow? And why, in 2019, did the most anticipated astronomical photograph in a generation show scientists something they could never actually see?

In this gripping, rigorously researched work of popular science, physicist Dr. Pavla Winterfield-Olu reveals that shadow is not an absence of information but a precise, rule governed phenomenon, one that has repeatedly handed scientists knowledge no direct measurement of light could provide. From Eratosthenes and the speed of light to solar eclipses, the sundial's hidden mathematics, the birth of photography, Caravaggio's dramatic darkness, Plato's cave, the biology of how living things read the dark, engineered materials blacker than anything in nature, and the first ever photograph of a black hole's shadow, this book traces a single, continuous thread of discovery spanning two thousand years.

Blending real science, real history, and vivid, page turning storytelling, The Algebra of Shadows will change the way you see the darkness falling across your own floor, forever.