SAS Frontiers

Into the Dark

Five billion years ago, the universe began to grow dimmer, according to Penn astrophysicist Raul Jimenez and scientists from the University of Edinburgh. That’s when star formation peaked—about the time our sun ignited. Since then, old stars have been dying faster than new ones are being born.

“ If we want to understand how structure in the universe formed and evolved, then we need to understand the history of stars,” says Jimenez, an assistant professor of physics and astronomy. “By analyzing all the light coming out of a particular galaxy…we can effectively see the entire ‘fossil record’ of that galaxy at one glance.” By tracking galactic luminosities, scientists can predict the mass and age of a star system.

Using data from the Sloan Digital Sky Survey, the researchers looked at nearly 100,000 galaxies. Previous efforts examined only 50 or 100. To do the analysis, they created their own computer program, called Multiple Optimized Parameter Estimation and Data Compression. “Our method takes into account all the stars that are present in the observed galaxies today,” notes Jimenez, “and allows us to create the most complete history of star formation yet assembled.” Given that many stars can live up to 100 billion years and the universe’s age is estimated to be 13 billion, the cosmic night will
be a long time coming.

Probing a Power Vacuum

Egyptian President Hosni Mubarak’s authoritarian government will eventually fall, says political science professor Ian Lustick, the Bess W. Heyman Professor and a researcher
at the Solomon Asch Center for Study of Ethnopolitical Conflict. Whether Mubarak steps down freely, is ousted,
or remains in power until his death doesn’t matter. The ensuing instability could reshape the Middle East.

What that new terrain will look like is anyone’s guess, but Lustick’s opinion is more highly regarded than most—especially by the U.S. government. His latest research involves examining what happens after a dictator is removed. Sophisticated software developed at Penn allows him to play out different scenarios in a virtual Middle East.

To the untrained eye, the PS-I program shows hundreds of colored squares spilling across a computer screen. Each square is an agent, representing a person, community, or organization. An agent’s color indicates its affiliation in this composite Middle Eastern society, dubbed “Virtualstan,” which features regime supporters and multiple political challengers. When the program is run and the colors change, Lustick can see where a tribal chieftain has lost power or a town has changed allegiances—all in the virtual world. The next step, Lustick notes, is deciding what this means for the real world. “We’re learning what instabilities are created,” he says, “and where there are opportunities.”

For the full story on Lustick’s research, plus how to download a
free copy of his software, go to www.sas.upenn.edu/home/news/lustick.html.

The Stories We Tell
In his latest book, Stories of Peoplehood: The Politics and Morals of Political Membership, Rogers Smith tackles traditional theories of what builds group identity. Smith is the Christopher H. Browne Distinguished Professor of Political Science and department chair.

Everyone is part of some political affiliation, he contends. “The most politically important feature of a group is the degree to which its proponents assert its priority over other associations.” Citing empires from ancient Greece to today’s superpowers, Smith points out that the strongest peoples with the widest influence tend to be the most imperialistic and most likely to engage in conflict. Moderately power-ful groups “can inspire allegiance from and participation by their members while accepting that those members simultaneously belong to a wide variety of other deeply valued communities.” The moderate form of peoplehood is more ethical, he concludes, and urges the adoption of that model in fostering international institutions to protect human rights.

Smith purports that political scientists have overlooked an important facet of people-making: storytelling. Stories “inspire trust and worth.” Whether in the pages of Thomas Paine’s Common Sense or in the defiant wartime broad-casts of Winston Churchill, stories bind people together and make an implicit claim that “membership is somehow intrinsic to the core identities of potential constituents.”

Nursery of Civilizations

Archaeologists once thought of Mesopotamia as the cradle of civilization, but art historian Holly Pittman (above, right) says that scholars are becoming more convinced the ancient Sumerians were part of a much larger nursery of civilizations that spanned the Old World from Anatolia to the Indus Valley. Pittman, the College for Women Class of 1963 Endowed Term Professor in the Humanities, spent the first three months of this year at Jiroft in southeastern Iran analyzing the remains of a long vanished culture. The artifacts are from huge excavations that are uncovering hundreds of intricately carved dark-stone vessels. The engravings suggest that monumental buildings resembling ziggurats may lie beneath some 80 giant mounds. There are also images of strange scorpion men emerging from the site. “We don’t know yet how far back it’s going to go,” Pittman says, “but I think it’s going to be yet another very important Bronze Age civilization like the Indus Valley, like Mesopotamia, like Egypt.”

The Jiroft site is one of several centers of human habitation that, 6,000 years ago, developed intensive agriculture, centralized government, institutionalized religion, and all the other complexities that characterize a civilization. Pittman has studied a few artifacts with stamp impressions that look like an unknown script—writing being a key marker of civilization. Some of the objects she handles are stamped with impressions of long forgotten gods. And the scorpion man, so abundant in Jiroft, is a prominent icon in Sumerian ideas about death. She expects the excavators will discover that some ideas and materials and cultural traditions in Mesopotamia will have been imported from Jiroft.

Thunder Lizard

In the Jurassic period, about 150 million years ago, a 50-foot plant-eating dinosaur walked among the gingkoes by the Sundance Sea, a place we now call Montana. We know this because its fossilized bones were found there.

The new sauropod was named Suuwassea emilieae, from the Native American Crow language for “ancient thunder,” a nod toward “thunder lizard,” the original nickname for the family of dinosaurs with small heads and long necks and tails. Suuwassea is the first new sauropod from the Morrison Formation, which extends from New Mexico to Montana, in more than a century, says Peter Dodson, who holds joint appointments in the Department of Earth and Environmental Science and the veterinary school. The partial skeleton Dodson and colleagues unearthed showed that it was a new species. “It has a number of distin-guishing features, but the most striking is this second hole in its skull,” says Dodson, “a feature we have never seen before in a North American dinosaur.” Other sauropods, such as Diplodocus, have a single hole in the top of the skull for a nasal cavity, but the use of this second opening is still a mystery. “For sauropods, only bigger, heavier, and denser bones like limbs are usually preserved,” notes Ph.D. student and collaborator Jerry Harris. The small sauropod skulls are made of thin, fragile bones and are rarely found. Near the excavation site of Suuwassea, the expedition team also discovered the partial skeleton of what might be a new dinosaur predator, which is under study by Penn researchers.