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How would Elizabeth Cabot Putnam, Class of 1910, react if she were to come back to life and enter the house that carries her name? A nurse who served in the First World War, Putnam was the first director of the Radcliffe Bureau of Occupations, later called Radcliffe Career Services. The house that's named for her, a modest clapboard on the edge of Radcliffe Yard, is today divided into offices and meeting rooms, sprinkled with blackboards and whiteboards that are covered with mathematical equations. The place is alternately noisy and dead quiet. Scientists are working here, laboring in fits and starts, as they make new discoveries.

The scientists in Putnam House are engaged in trying to understand the outermost edges of our universe. How are stars and planets formed? How was the surface of Mars shaped? Group members work together and alone, drawing scientists from the Harvard faculty and other universities into their orbit. At the Radcliffe Institute, the group known as "the cosmology cluster" was created by Barbara J. Grosz, Radcliffe's dean of science and the Higgins Professor of Natural Sciences in the Faculty of Arts and Sciences' Division of Engineering and Applied Sciences. Grosz worked with faculty from three departments in the Faculty of Arts and Sciences to form the cluster.

The first of the Institute's research clusters, the cosmology group--comprising four women and two men and including planetary scientists and theoretical physicists--began to take shape when Grosz encouraged scientists from around the country to apply to the Institute's fellowship program. One faculty member with whom she collaborated in this process was Lisa Randall '83, PhD '87, RI '03, a Harvard professor of physics and a Radcliffe fellow this year. "We wanted a group that would have exciting interactions," Grosz says. "One purpose of the cluster is to foster interactions that wouldn't otherwise occur."

That goal appears to have been achieved, if you listen to Radcliffe fellow Amanda Peet RI '03, an assistant professor of physics at the University of Toronto, who spent the fall semester with the cosmology cluster. "Putnam House has been a focal point, bringing together the geographically disparate physics and astrophysics people at Harvard. I've talked with people I wouldn't otherwise have easily had the opportunity to speak with," she says.

Andrew Strominger '77, a Harvard physics professor who participates in cluster meetings, agrees with Peet about the group drawing people together from Harvard departments. He says the cluster's focus, cosmology--the astrophysical study of the history, structure, and dynamics of the universe--"is one of the most exciting frontiers in science right now." Robert Brandenberger PhD '83, a physics professor at Brown University, comes up from Providence, Rhode Island, to attend seminars sponsored by the cluster. "The focus of cosmology research in the Boston area has completely shifted to Harvard this year," he says.

In fact, the cosmology cluster has caused a proliferation of activities at the Radcliffe Institute. In addition to weekly meetings organized by Lisa Randall and held in Putnam House, cluster members hold breakfast powwows and, every three weeks, attend lectures sponsored by the Harvard-MIT-Tufts cosmology lecture series. Along with the Harvard-Smithsonian Center for Astrophysics, the Radcliffe Institute is cohosting Harvard's part of this series.

The magnetic force of the cluster reaches well beyond the Boston area, to as far away as Taiwan. One spin-off from the cosmology cluster is a series of public lectures--the "supercluster lecture series"--that Radcliffe launched under Grosz's leadership. Speakers have been John Bahcall PhD '61, a visiting professor of astrophysics at Princeton and the Richard Black Professor of Natural Sciences at the Institute for Advanced Study in Princeton; Frank Shu, a theoretical astrophysicist and president of the National Tsinghua University in Taiwan; and Alan Guth, the Victor F. Weisskopf Professor of Physics at MIT. A cluster member, Maria Zuber RI '03, will also present a supercluster lecture, on April 28.

Perhaps Elizabeth Putnam would react to the work being done at Putnam House the way most of us do, with a mix of wonder and curiosity.

Following is a description of each cluster member's research and information about the work of a colleague, Eve Ostriker '87, who collaborated with the group.

Katherine M. Benson PhD '91, RI '03, a theoretical physicist and an assistant professor of physics at Emory University, works at the interface of particle theory and cosmology. Her research concerns how models of the fundamental forces of nature and of the dynamics governing their symmetries affect the early history of our universe--and conversely, how our universe's evolution explains the forces we see today, while revealing their past dynamics.

"Major scientists on my topic are in the Boston area, so it's a great place for me to be," says Benson. "I've also enjoyed working with a bright undergraduate, Sophia Domokos '03, my Radcliffe research partner."

Raphael Bousso RI '03, a theoretical physicist and an assistant professor of physics at the University of California at Berkeley, is investigating the holographic principle, which states that the world is, in a sense, only two dimensional. He has found that the maximum complexity of any physical system seems to be very precisely related to the size of its surface area and not, as one might expect, to its volume.

"We are puzzled about this relation. Much evidence attests that it is true, but it has yet to be explained," he says. "My goal this year is to make some progress understanding why nature behaves this way. Radcliffe provides me with an invaluable opportunity to focus on this exciting question, in an environment where I interact with great colleagues."

Éanna Flanagan RI '03, a theoretical physicist and an associate professor of physics and astronomy in Cornell's F. R. Newman Laboratory for Elementary-Particle Physics, studies the properties and interactions of neutron stars, black holes, and the early universe. These objects can emit gravitational waves in the fabric of space-time. At Radcliffe, Flanagan is developing theoretical tools and computational methods for computing the gravitational wave signals emitted by neutron stars spiraling into supermassive black holes in distant galaxies.

"Gravitational radiation is weak," Flanagan says. "We've never actually detected it directly." He and other scientists hope that the Laser Interferometer Gravitational-Wave Observatory will detect gravitational waves, opening a new window onto the universe. The facility consists of two laser interferometers, each four kilometers long--one in Washington, one in Louisiana--that operate in unison.

Eve Ostriker '87, a theoretical astrophysicist and an associate professor of astronomy at the University of Maryland, spent one week every month this fall with the cosmology cluster fellows and Harvard colleagues. "The best thing about it was that I got a chance to talk to people whom I wouldn't usually have seen," she says.

Ostriker's main interests center on understanding the interstellar medium (the gas and dust between stars) and its dynamics. This subject encompasses star and planet formation on a small scale, galactic structure on a larger scale, and the evolution of galaxies over cosmological times and on the largest spatial scales. At Radcliffe, Ostriker was involved in work characterizing the global regulation of star formation in spiral galaxies and in developing diagnostics of turbulent interstellar clouds using computational models.

Amanda Peet RI '03, a theoretical physicist and a scholar in the Cosmology and Gravity Program at the Canadian Institute for Advanced Research (in addition to being on the faculty at the University of Toronto), says, "Harvard is one of the top places on the planet for the kind of physics that I do."

Peet focuses on string theory and its connection to early universe cosmology. This theory aims to explain the fundamental structure of matter and interactions from the subatomic to the cosmological realm. String theory posits that nature's building blocks are minuscule interacting strings--perhaps as small as 10-33 centimeters, or a million billion billion billionth of a centimeter. "If you could look deep inside every particle--electron, neutron, quarks--you would discover a tiny vibrating string," she says. Because the technology doesn't exist yet to observe strings, she studies them using mathematical modeling.

Lisa Randall '83, PhD '87, RI '03, a Harvard professor of physics, does research within the field of theoretical elementary particle physics, with some excursions into cosmology and string theory. Randall's recent work has focused on the possibility of unseen spatial dimensions. At Radcliffe, she is studying possible cosmological implications of these unseen dimensions, and whether extra dimensions yield better models of inflation and are reflected in current cosmological observations. In an article about the cluster in the November-December 2002 issue of Harvard Magazine, Randall said research in theoretical physics, astronomy, and planetary sciences is "ripe for some new developments."

Maria Zuber RI '03, the E. A. Griswold Professor of Geophysics and Planetary Sciences at MIT, studies the structure and evolution of Earth and the terrestrial planets. Her research combines the design and implementation of spacecraft laser and radio tracking investigations with theoretical modeling of the geophysical processes that shape planetary surfaces.

Zuber has been involved with several space missions, including ones to map the Moon and Mars, and has more planned. In 2004, a spacecraft will head for an orbit around Mercury; in 2005, another will lift off to orbit Mars; and in 2006, a third will aim for an asteroid belt. "My goal in my career is to have one of my students make it to Mars," Zuber says.

At Radcliffe, Zuber is studying the early evolution of the crusts of the terrestrial planets. She collaborates with Daniel Schrag, a professor of geochemistry in the earth and planetary sciences department and director of the geochemical oceanography laboratory at Harvard. "What we've just started working on is how strange perturbations in the carbon cycle may have affected Martian climate four billion years ago," Zuber says. Schrag, whose research until now has focused entirely on Earth's climate history, is thrilled with the opportunity to stretch his mind in new directions. "Maria is a superb scholar. I learn something new almost every time we speak," he says. "Having Maria at Radcliffe is a great opportunity for both of us to work on new and exciting questions that require our different skills and experiences."

Such connections between the fellows and Harvard faculty are just what Grosz had in mind when she created the cosmology cluster, and are also exciting to other Harvard faculty members. "What we hope is that people will find some new direction to move in across disciplines," Strominger says.