Dedicated to memory of David Schramm, report assesses research opportunities where physics, astronomy intersect

By Steve Koppes News Office

During his career at the University, the late cosmologist David Schramm used to tell his associates not to let projects fall into a black hole. Committee reports often have a habit of doing that, but not Connecting Quarks with the Cosmos, a recently published report by the National Research Council that was dedicated to Schramm’s memory.

Chairing the committee that produced the report and successfully lobbying for its acceptance in Washington, D.C., was Michael Turner, the Bruce V. & Diana M. Rauner Distinguished Service Professor in Astronomy & Astrophysics and the College.

“This study should have been chaired by David Schramm, because it was his vision, enthusiasm, energy and passion that pushed this field forward,” Turner said.

Also serving on the 21-person committee were Bruce Winstein, the Samuel Allison Distinguished Service Professor in Physics and the College, and Frank Wilczek (B.S.,’70), the Herman Feshbach professor of physics at the Massachusetts Institute of Technology.

“It is having impact. There’s no doubt about it,” Winstein said of the report. “I’m sure that David would be very pleased about this.”

Former NASA administrator Daniel Goldin asked the National Research Council’s Board on Physics and Astronomy to draft the report to assess the scientific opportunities that occur on the frontiers of research at the intersection of physics and astronomy.

The National Science Foundation and the U.S. Department of Energy joined NASA in sponsoring the study to help the Bush administration, as it took office, to formulate science planning.

Goldin saw the study as a major new initiative in the physical sciences, Turner said.

“While we’d all like to cure every known disease and know more about our own genetic makeup, there are other interesting things out there,” Turner said. “You can’t make progress in the biological sciences if you have weak physical sciences.”

One of the recommendations of Turner’s committee was to detect the signature of gravity waves in the cosmic microwave background radiation, the afterglow of the big bang. Such a discovery would help determine the underlying cause of inflation, an extension of the big bang theory.

According to inflation, the universe underwent a massive growth spurt, expanding from a volume smaller than an atom to an object measuring inches across, just a fraction of a second after the big bang.

NASA has, in fact, already approved a study design for such an experiment. One of two teams that are independently forming to pursue the experiment includes three scientists from the University’s Center for Cosmological Physics. They are Winstein, Center Director; Stephan Meyer, Professor in Astronomy & Astrophysics and the College; and Wayne Hu, Assistant Professor in Astronomy & Astrophysics.

“I think the Turner committee had something to do with getting this project going this fast,” Winstein said.

The Bush administration has included several other projects in its fiscal year 2004 budget that would support goals recommended by the Turner committee. One project, called Constellation-X, proposes using a group of orbiting X-ray telescopes to study black holes by watching the material that falls into them.

Another approved project is the Laser Interferometer Space Antenna, or LISA. Consisting of three spacecraft, LISA will observe gravitational waves generated by colliding black holes. The mission, like Constellation-X, holds promise for testing Einstein’s theory of gravity to see if it works as well when applied to distant black holes formed in the early universe as it does to the planets and other objects much closer to Earth.

A third project, the Supernova/Acceleration Probe, or SNAP, will address yet another Turner committee recommendation: to determine the expansion history of the universe and probe the nature of dark energy. Supernova measurements in recent years indicate that the expansion of the universe is accelerating. Scientists have theorized that dark energy, a form of energy with gravity that is repulsive, accounts for this phenomenon.

SNAP will be equipped with a 2-meter space telescope dedicated to finding supernovae and a giga-pixel CCD camera. Scientists affiliated with the University and Fermi National Accelerator Laboratory are interested in SNAP because it will provide several complementary methods of probing the nature of dark energy. These methods consist of measuring the distances to remote supernovae, counting the number of massive galaxy clusters as they occurred back in time, and measuring the gravitational distortion of light from distant galaxies.

“The Fermilab group is interested in all of these, though with particular focus on carrying out the latter two measurements using the SNAP wide-field survey, which will be interleaved with the deeper, narrower supernova survey,” said Joshua Frieman, Professor in Astronomy & Astrophysics and the College, and a member of Fermilab’s Theoretical Astrophysics Group.

The Center for Cosmological Physics may also become involved with the SNAP project, Winstein said.

“Working on the committee helped me appreciate the importance of studying the dark energy by as many ways as possible. SNAP is one way, maybe even the best way,” he said.