Wendy Freedman

Wendy Freedman Wendy Laurel Freedman (born July 17, 1957) is a Canadian-American astronomer and one of the world’s leading experts on observational cosmology. Her many honors include the Gruber Cosmology Prize (2009), the Dannie Heineman Prize for Astrophysics (2016), and the National Medal of Science (2025). (Her husband and longterm collaborator Barry Madore is known for the Arp-Madore Catalogue.) Quotes The Hubble's law Hubble constant, which measures the Expansion of the universe#Measuring the expansion rate expansion rate, together with the total energy density of the Universe, sets the size of the observable Universe, its age, and its radius of curvature. Excellent progress has been made recently toward the measurement of the Hubble constant: a number of different methods for measuring distances have been developed and refined, and a primary project of the Hubble Space Telescope has been the accurate calibration of this difficult-to-measure parameter. The recent progress in these measurements is summarized, and areas where further work is needed are discussed. Currently, for a wide range of possible Physical cosmology cosmological models, the Universe appears to have a Age of the universe kinematic age less than about 14±2 billion years. Combined with current estimates of stellar ages, the results favor a Observable universe#Estimates based on critical density low-matter-density universe. They are consistent with either an open universe, or a flat universe with a non-zero value of the cosmological constant. Physics Reports 333–334 August 2000 13–31 The Hubble constant and the expansion age of the Universe https://doi.org/10.1016/S0370-1573(00)00013-2 10.1016/S0370-1573(00)00013-2 We are at an interesting juncture in cosmology. With new methods and technology, the accuracy in measurement of the Hubble's law Hubble constant has vastly improved, but a recent tension has arisen that is either signaling Physics beyond the Standard Model new physics or as-yet unrecognized uncertainties.Just under a century ago, Edwin Hubble revolutionized cosmology with his discovery that the Expansion of the universe universe is expanding. Hubble found a relationship between radial velocity and the distance to nearby galaxies, determining the proportionality constant Ho (=v/r), that now bears his name. The Hubble constant remains one of the most important parameters in cosmology. An accurate value of Ho can provide a powerful constraint on the cosmological model describing the evolution of the universe. In addition, it characterizes the expansion rate of the Universe at the current time, defines the observable size of the Universe, and its inverse sets the Age of the universe expansion age of the Universe. Cosmology at a Crossroads: Tension with the Hubble Constant arXiv:1706.02739 [astro-ph.CO] 2017 https://arxiv.org/abs/1706.02739 (preprint for article 2017 Cosmology at a crossroads Nature Astronomy 1 5 0121 10.1038//s41550-017-0121) ... after finishing my postdoc, I became a faculty member at Carnegie Institution for Science Carnegie, and then ended up being the scientific leader of this project to measure the rate at which the universe is expanding. ... when that project finished, .. we .. resolved the issue. We went from a factor of 2 uncertainty — we measured an uncertainty of 10%. Our Expanding Universe: Wendy L. Freedman 2023 Ryerson Lecture June 5, 2023 University of Chicago, YouTube https://www.youtube.com/watch?v=7IqCGN5Z3lg&t=830s (quote at 13:50 of 58:54 in video) External links Freedman, Wendy Laurel Encyclopedia of World Scientists Oakes, Elizabeth H. Facts on File Science Library revised Infobase Publishing 2007 9781438118826 https://books.google.com/books?id=uPRB-OED1bcC&pg=PA251 251–252 (869 pages) Drapa, Michael January 7, 2025 Wendy Freedman awarded National Medal of Science. UChicago cosmologist honored for pioneering research on Hubble constant UChicago News https://news.uchicago.edu/story/wendy-freedman-awarded-national-medal-science Category:1957 births Category:Living people Category:Astronomers from Canada Category:Astronomers from the United States Category:Cosmologists Category:Fellows of the Royal Society Category:Jews from Canada Category:Jews from the United States Category:Members of the United States National Academy of Sciences Category:Members of the American Philosophical Society Category:People from Toronto Category:University of Toronto alumni Category:Women born in the 1950s Category:Women scientists from Canada Category:Women scientists from the United States Category:National Medal of Science laureates