Obituary

Eugenio Calabi, who died on September 25, conceived of novel geometric objects that later became fundamental to string theory.

When Steven Weinberg died last month, the world lost one of its most profound thinkers.

A former graduate student reflects on how Isadore Singer, who died on February 11, brought together mathematicians, physicists and anyone else interested in the deeper connections between diverse fields.

The legendary mathematician, who died on April 11, was curious, colorful and one of the greatest problem-solvers of his generation.

Freeman Dyson — physicist, mathematician, writer and idea factory — died on February 28, but his vitality lives on.

The theoretical particle physicist Ann Nelson, who died on August 4 at age 61, was a font of brilliant ideas and a champion of ending discrimination in the field.

The renowned British physicist, who died at 76, left behind a riddle that could eventually lead his successors to the theory of quantum gravity.

The theoretical physicist Joe Polchinski, who died February 2, left a tremendous professional and personal legacy, says a friend and collaborator.

Voevodsky’s friends remember him as constitutionally unable to compromise on the truth — a quality that led him to produce some of the most important mathematics of the 20th century.