Maryam Mirzakhani, the first and only woman to win the prestigious Fields Medal, called the Nobel Prize of math, died on Saturday. Mirzakhani was a professor at Stanford University, which made the announcement, saying she had breast cancer that spread to her bones. She was 40.

Mirzakhani won the distinguished award, given every four years, in 2014 for her work on geometry and dynamical systems. Much of her work was highly theoretical, and Stanford’s statement said it could read like “a foreign language”  to those outside the field—“moduli spaces, Teichmüller theory, hyperbolic geometry, Ergodic theory and symplectic geometry.” In practice, her body of work may change theoretical physicists’ understanding of how the universe was formed, as well as quantum field theory. Her Fields Medal marked not only the first time a woman won since the award since its inception in 1936, but also the first time an Iranian had won.  

Mirzakhani was born in Tehran, and in 1994 she became the first female to compete with Iran’s International Mathematical Olympiad team. That year she won a gold medal, and the following year she won two. After she graduated from university, she left her home country for the U.S., where she studied at Harvard University. For her dissertation at the university she finished two problems that had never before been solved. “The majority of mathematicians will never produce something as good,” Benson Farb, a mathematician at the University of Chicago said. “And that’s what she did in her thesis.”

More recently, her work focused on the trajectory of a billiards ball going round a polygonal table, a problem that has stumped mathematicians for a century. That work inspired a lengthy paper that when published in 2013 was called “the beginning of a new era” in mathematics. Mirzakhani described her method for solving problems like writing a novel with “different characters, and you are getting to know them better. Things evolve, and then you look back at a character, and it’s completely different from your first impression.”

On Saturday, Iranian President Hassan Rouhani said Mirzakhani’s death would cause “great sorrow” for the country, and called her an “eminent Iranian.”

Both in Iran and and internationally, Mirzakhani became a heroic figure for women in the sciences. Colleagues described her as very modest, and hesitant to take credit. But when she won the Fields Medal in 2014 she acknowledged her impact by saying, “I will be happy if it encourages young female scientists and mathematicians.”