In 1915 it was used independently by Erwin Schrödinger and Marian v. Smoluchowski as the time to first passage of a Brownian motion. In the field of reproduction modeling it is known as the Hadwiger function, after Hugo Hadwiger who described it in 1940.
In 1915, Erwin Schrödinger and Marian v. Smoluchowski used it for Brownian motion's initial passage time. In reproduction modeling, this concept is known as the Hadwiger function, named after Hugo Hadwiger who described it in 1940.