Girl sneezing
Mark Nicas has given some of his best years to spittle. He builds models – the mathematical kind – of how someone else’s slobber ends up on you. The size of the particles, whether they come out in a dry cough or a wet sneeze, their evaporation rate, air speed – these are all complications, reasons why people like Nicas can spend careers piling up academic papers, all the while building up a healthy respect for pathogens.