John C. Mather

John Cromwell Mather (born August 7, 1946) is an American astrophysicist and cosmologist. He shared the 2006 Nobel Prize in Physics with George Smoot for the "for their discovery of the black body form and anisotropy of the cosmic microwave background radiation".

This work helped cement the Big Bang theory of the universe. According to the Nobel Prize committee, "the COBE-project can also be regarded as the starting point for cosmology as a precision science."

Mather is a senior astrophysicist at the NASA Goddard Space Flight Center (GSFC) in Maryland and adjunct professor of physics at the University of Maryland College of Computer, Mathematical, and Natural Sciences. In 2007, Time magazine listed Mather among the 100 Most Influential People in The World. In October 2012, he was listed again by Time magazine in a special issue on New Space Discoveries as one of the 25 most influential people in space.

Mather is one of the 20 American recipients of the Nobel Prize in Physics to sign a letter addressed to President George W. Bush in May 2008, urging him to "reverse the damage done to basic science research in the Fiscal Year 2008 Omnibus Appropriations Bill" by requesting additional emergency funding for the Department of Energy's Office of Science, the National Science Foundation, and the National Institute of Standards and Technology.

Mather served as the senior project scientist for the James Webb Space Telescope (JWST) from 1995 until 2023, when he was succeeded by Jane Rigby.

In 2014, Mather delivered an address on the James Webb Space Telescope at the second Starmus Festival in the Canary Islands.