Janna J. Levin (born 1967) is an American theoretical cosmologist. She earned a PhD in theoretical physics at the Massachusetts Institute of Technology in 1993, and a Bachelor of Science in astronomy and physics with a concentration in philosophy at Barnard College in 1988. Much of her work deals with looking for evidence to support the proposal that our universe might be finite in size due to its having a nontrivial topology. Other work includes black holes and chaos theory. Since January 2004, she has been a professor of astronomy and physics at Barnard College of Columbia University.
Levin is the author of the popular science book How the Universe Got Its Spots: diary of a finite time in a finite space. In 2006, she published A Madman Dreams of Turing Machines, a novel of ideas recounting the lives and deaths of Kurt Gödel and Alan Turing.
Levin has written a series of essays to accompany exhibitions at several galleries in England, including the Ruskin School of Drawing and Fine Art and the Hayward Gallery. Levin was featured on Talk of the Nation on July 12, 2002. She appeared as a guest on Stephen Colbert's Comedy Central show The Colbert Report on August 24, 2006. She also appeared as the featured guest on the Speaking of Faith radio show on February 22, 2009, where she discussed her book A Madman Dreams of Turing Machines with the show's host Krista Tippett. Levin presented "The sound the universe makes" on TED.com on March 1, 2011. She was named a Guggenheim Fellow in 2012.
Her book Black Hole Blues and Other Songs from Outer Space was published in March, 2016. The book is about the history of the Laser Interferometer Gravitational-Wave Observatory and the 2015 discovery of gravitational waves. In a review of the book published in the Wall Street Journal, British astrophysicist John Gribbin wrote, "This is a splendid book that I recommend to anyone with an interest in how science works and in the power of human imagination and ability."
Levin is the parent of two children, a son born in 2004 and a daughter born in 2007. Levin did not officially graduate from high school, as she was in a serious car accident and hospitalized for a time.