Only 4 percent of our universe is made of ordinary matter like atoms and molecules. The other 96 percent is in entirely unfamiliar forms we know almost nothing about. About 25 percent is dark matter, which holds galaxies and larger-scale structures together; another 70 percent is thought to be dark energy, an even more mysterious entity that appears to be driving the accelerated expansion of the universe.
In this spring’s Hans Bethe Lecture at Cornell, physicist Joshua Frieman will introduce the Dark Universe, give an overview of what we have learned about it, and describe new experiments and observatories that aim to illuminate its enigmas. The free public lecture will be held Wednesday, April 26, at 7:30 p.m. in Schwartz Auditorium, Rockefeller Hall.
“The observation that the universe is composed primarily of exotic energy forms that we do not understand, and that our familiar stars and planets are but minor players on a much stranger stage, is one of the most startling and baffling discoveries of all time,” said Jim Alexander, event organizer and professor of physics. “Joshua Frieman knows as much about the Dark Universe as anyone, and we’re looking forward to hearing his insights on the latest research.”
Frieman is a founder, and currently serves as director, of the Dark Energy Survey, a collaboration of more than 300 scientists from 25 institutions on three continents that is probing the origin of cosmic acceleration. He is a senior staff member in the theoretical astrophysics group at Fermilab and the Fermilab Center for Particle Astrophysics as well as professor of astronomy and astrophysics at the University of Chicago, where he is a member of the Kavli Institute for Cosmological Physics.
His research centers on theoretical and observational cosmology, including studies of the nature of dark energy, the early universe, gravitational lensing, the large-scale structure of the universe, and supernovae as cosmological distance indicators. The author of more than 275 publications, Frieman led the Sloan Digital Sky Survey (SDSS-II) Supernova Survey, which discovered more than 500 type-Ia supernovae for cosmology studies, served as chair of the SDSS Collaboration Council, and as co-lead of the SDSS Large-scale Structure Working Group.
Frieman earned a bachelor's degree from Stanford University in 1981 and a doctorate in physics from the University of Chicago in 1985. He is an honorary fellow of the Royal Astronomical Society and a fellow of the American Physical Society and of the American Association for the Advancement of Science.
As part of the Hans Bethe Lecture series, Frieman will also present the physics colloquium “Probing Cosmic Acceleration with the Dark Energy Survey,” Monday, April 24, at 4 p.m. in Schwartz Auditorium; and a Laboratory of Atomic and Solid State Physics and Applied and Engineering Physics theory seminar, “Cosmic Acceleration Then and Now,” Tuesday, April 25, at 3 p.m. in 120 Physical Sciences Building.
The Hans Bethe Lectures, established by the Department of Physics and the College of Arts and Sciences, honor Bethe, Cornell professor of physics from 1936 until his death in 2005. Bethe won the Nobel Prize in physics in 1967 for his description of the nuclear processes that power the sun.
Linda B. Glaser is a staff writer for the College of Arts and Sciences.