Wendy Freedman, the John and Marion Sullivan University Professor in Astronomy and Astrophysics at the University of Chicago, has been named one of TIME Magazine’s 100 Most Influential People of 2025.
Freedman was recognized for her work to measure how fast the universe is expanding, known as the Hubble constant. Different methods have yielded different results, but Freedman’s analysis is bringing us closer to an answer.
Freedman specializes in measuring the rate of expansion of the nearby universe, which requires estimating the distance of far-off galaxies by observing the brightness of their supernovae and calibrating the brightness-to-distance relationship using “standard candles”—well-studied, relatively nearby stars.
In 2001, Freedman led a team that made a landmark measurement of the expansion of the universe using this method, known as the Hubble Key Project. More recently, she pioneered two new methods to use different types of stars to cross-check the accuracy of the measurements. Last summer, she released new results based on readings from the newly launched James Webb Space Telescope.
In January, she was awarded the National Medal of Science, the country’s highest scientific honor. Her other honors include the Magellanic Premium, the Gruber Cosmology Prize and the Dannie Heineman Prize for Astrophysics.
"I am honored to be included in this year's TIME100 list of the world's most influential leaders in 2025, and very grateful for the support that UChicago has given me for my research, and for the collegial and stimulating environment here," Freedman said.
