Mar. 11, 1998 The famous Polish astronomer, Nicolaus Copernicus (1473-1543), forever changed our world-view by arguing that the Earth is not, in fact, the center of the universe. Today, Qaisar Shafi of the Bartol Research Institute at the University of Delaware is taking that argument one step further.
"We are not even made out of the same material that makes up the bulk of the universe," says Prof. Shafi. "When we look at galaxies, clusters of galaxies and even larger-scale structures, we are seeing only a fraction of the material there. The bulk of the material in these structures, comprising in some cases as much as 90 percent of the total mass, is dark matter that does not shine."
Such revolutionary views on the formation and content of galaxies and other large-scale structures of the universe recently earned Shafi a prestigious Alexander von Humboldt Research Award. He was among 18 senior-level scientists--and only four within the field of physics--to be elected in November 1997 to receive the award from Germany's Alexander von Humboldt Foundation. The prize will make it possible for Shafi to spend a year conducting research at the Deutsches Elektronen-Synchrotron in Hamburg, one of the world's leading particle-accelerator facilities.
In a letter to UD President David P. Roselle, a Humboldt Foundation official wrote that Shafi was recognized for his past contributions to the field of theoretical physics--especially cosmology and the physics of elementary particles. But he is perhaps best known for his theories on galaxies, super-clusters, quasars and other large-scale structures.
For cosmologists, Shafi explains, "a galaxy is a basic building block, containing a hundred-billion stars." Researchers have proposed various theories to explain how such large-scale structures form. Shafi's theory, proposed in the early 1980s and subsequently developed with former Bartol research scientist R.K. Schaefer, predicts that dark matter has two distinct components. A `cold' component is believed to reside in the haloes of galaxies and their clusters, Shafi says, while the `hot' component is "gravitationally trapped by only the largest bound structures, such as superclusters and beyond."
Shafi and other theorists argue that cold dark matter consists of an entirely new kind of elementary particle, which interacts weakly with known particles such as protons, neutrons and electrons. The search for this mysterious, unknown particle is currently underway in many laboratories around the globe, Shafi notes. As for hot dark matter, the neutrino, another weakly interacting particle, is "the leading candidate," he says. With a mass almost a million times smaller than the mass of an electron, highly abundant neutrinos can comprise 20 percent to 30 percent of the total mass in the universe, according to Shafi.
"This is where cosmology, the study of the largest-scale objects, comes together with our examinations of the smallest objects in our world," he says. "The physics of the very smallest objects is innately related to the physics of the largest objects." Incorporating new ideas about dark matter into models of the universe could help guide further experimental work, Shafi says.
Bartol President Norman Ness says he is "proud of the international recognition that Qaisar Shafi's important contributions to the field of modern theoretical physics have received." In addition to his research, Ness says, Shafi "is well known for his leadership of the Summer School of Physics, held annually at Trieste, Italy, which brings together young researchers from around the world to work collaboratively with more senior faculty, frequently including Nobel Laureates." Shafi joins colleague Paul Evenson on the list of Bartol researchers who have received the Humboldt Research Award.
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