Martin Karplus, a Novel Prize-winning theoretical chemist who used computers to model how complex systems change during chemical reactions, a process that has led to advances in the understanding of biological processes, died on Dec. 28 at his home in Cambridge, MA. He was 94.

Scientists can control the chemicals in a reaction, and they can measure and evaluate the results, but what happens inbetween is a mystery. As explained by Sven Lidin, chairman of the Nobel selection committee when announcing the 2013 winners in chemistry, “It’s like seeing all the actors before “Hamlet” and all the dead bodies after, and then you wonder what happened in the middle. This is what theoretical chemistry provides us with — the whole drama.”

Dr. Karplus earned a distinguished academic reputation at the nation’s top universities, and had crossed paths with some of the most important scientists of the 20th century, including Linus Pauling and J. Robert Oppenheimer. He supervised close to 250 graduate and doctoral students, most of whom have gone on to successful academic careers. They are collectively known as Karplusians.