Robert Kirshner, a Harvard University astrophysicist and author, will discuss how the light of distant exploding stars could validate one of Einstein's most controversial theories during a March 30 lecture at the University of Colorado at Boulder.
"A Blunder Undone: The Accelerating Universe" will be held in Macky Auditorium at 7:30 p.m. The event is free and open to the public.
Kirshner's presentation is the 39th George Gamow Memorial Lecture, an event that has brought prominent scientists to campus since 1971. The series is intended for a general audience of nonscientists and is named for the late CU-Boulder physics professor who was pivotal in developing the big-bang theory of the creation of the universe.
Kirshner's talk will focus on the apparent acceleration of cosmic expansion, mysterious "dark energy" and Einstein's hotly debated cosmological constant -- a theory Gamow called Einstein's "greatest blunder."
Kirshner frequently presents public lectures on astrophysics and teaches a popular course for nonscience majors at Harvard called "Matter in the Universe." His book, "The Extravagant Universe: Exploding Stars, Dark Energy, and the Accelerating Cosmos," was published for a general audience by Princeton University Press in 2002.
With better data from modern detectors, Kirshner and his colleagues have evidence that the expansion of the universe is speeding up. A modern version of Einstein's cosmological constant might be the "dark energy" causing this acceleration, he said.
Kirshner explains that the history of cosmic expansion can be traced using the faint light from distant stellar catastrophes, and with the help of computers, scientists are now getting better views of exploding stars billions of light years from Earth.
"We've developed a pipeline system that pops out the supernova candidates about an hour after we take the images," Kirshner said. "This is important because supernovae are like fish -- after about three days, they begin to lose their freshness. If you want to see the peak of the light curve, prompt action is essential."
Now scientists are searching for supernovae 9 billion light years from Earth using the Hubble Space Telescope. They hope to learn more about the dark energy that not even Einstein could explain.
"Better measurements will show whether the dark energy comes from a source that is constant, or one that changes subtly as the universe expands. Either way will be very interesting," Kirshner said.
A Clowes Professor of Science at Harvard University, Kirshner graduated from Harvard College in 1970 and received a doctorate in astronomy from Caltech in 1975. After postdoctoral work at Kitt Peak National Observatory in Arizona, he joined the faculty at the University of Michigan for nine years before moving to the Harvard astronomy department in 1986. He served as chairman of the astronomy department from 1990 to 1997 and as associate director for optical and infrared astronomy at the Harvard-Smithsonian Center for Astrophysics from 1997 to 2003.
Kirshner has authored more than 200 research papers dealing with supernovae, the large-scale distribution of galaxies, and the size and shape of the universe. His work with the "High-Z Supernova Team" on the acceleration of the universe was dubbed the "Science Breakthrough of the Year for 1998" by Science magazine. A member of the American Academy of Arts and Sciences, he was elected to the National Academy of Sciences in 1998. He was elected president of the American Astronomical Society in 2003.
For more information on Kirshner's lecture or the George Gamow Memorial Lecture Series at CU-Boulder visit or call (303) 492-6952.