From More or Less: This is an episode from another show presented by Tim Harford. How a forgotten French mathematician scooped economists by half a century. Louis Bachelier anticipated both Einstein's theories and the application of maths to the stock market. Born in the 1870s, his work was unusual at the time. With the help of Alison Etheridge, Professor of Mathematics at the University of Oxford, we explain how his ideas were rediscovered decades after his death. (Photo: Pocket watch. Credit: Kanyapak Lim/Shutterstock)