Mitchell J. Feigenbaum, a pioneer in the field of mathematical physics known as chaos, died on June 30 in Manhattan. He was 74.

The cause was a heart attack, his stepson Sasha Dobrovolsky said.

Dr. Feigenbaum’s intense, eclectic curiosity led him to questions far astray from the ones usually asked by theoretical physicists. How does one make the most accurate maps? What makes the moon look larger when it is closer to the horizon? What design of paper money would thwart photocopying?

His friends recalled meals, full of red wine and red meat (no vegetables), at which the conversation — not just about physics but also about literature and classical music — would stretch late into the night.

Dr. Feigenbaum’s lifestyle and his Renaissance intellect were a poor fit to the demands of modern publish-or-perish academia. But by following his own path, he uncovered a pattern of chaos that is universal in math and in nature.