Professors Make Headlines in a Year of Discovery

Harvard professors juggle myriad activities. When they are not in class or at their office hours, they are often conducting groundbreaking research in their academic fields. This year yielded a range of significant and eclectic findings—some professors studied hate with economics and medieval history with science, while others found new ways to analyze antimatter and manipulate light.

LOVING HATE

Scholars have often claimed that hatred defies comprehension, but 37-year-old Professor of Economics Edward L. Glaeser says the opposite. According to Glaeser, who was recently appointed co-director of the Taubman Center for State and Local Government at the Kennedy School, the market for hate is open to economic analysis.

Glaeser’s specialty is studying cities, but his interests are no means constrained to their boundaries and include obesity, city planning, transportation and religion.

Falling under a subfield of economics called behavioral economics, his work draws heavily on psychology and incorporates threads of various other disciplines including history and political science.

David M. Cutler, dean of the social sciences and professor of economics, praised Glaeser’s “provocative” work for its incorporation of many different disciplines and says that it “creates steam” for this reason.

“Ec 10 teaches that people have preferences...behavioral economics is about trying to understand where those preferences come from,” Cutler says. “Ed’s stuff...goes a step beyond and tries to understand why leaders do what they do.”

In a paper entitled “The Political Economy of Hatred,” which will be submitted to a journal this year, Glaeser explores the economics of hatred, putting forward several economic models to describe historical examples of hatred.

“Ed shows how economics can be used very constructively to think about racial and ethnic hatred not as some historical given, but as a phenomenon instigated by political entrepreneurs who used hatred for their own ends,” says Andrei Shleifer ’82, the Jones professor of economics. “It’s some of the most innovative research in economics done in a long time.”

Glaeser argues that hatred is a simple product of supply and demand.

The supply of hatred, or the willingness of political entrepreneurs to spread lies about minority groups, is governed by the wealth of the party who benefits from hatred, the electoral power of the hated party and the improvement of communications, he suggests.

Whereas, the demand, or the willingness of people to accept these lies (or truths, depending on the case), is a product of the costs and private benefits of information about the minority group.

“The central message of this paper is that hatred is particularly likely to spread against groups that are politically relevant and socially isolated,” Glaeser writes in a draft of the paper.

“[This] model helps us understand...why anti-American hatred in the Middle East has become so important,” he says. “The most important policy decision in Middle Eastern countries is how they’re going to treat the U.S.—we’re enormously salient and policy relevant.”

However, the U.S. is socially absent from the Middle East, he said. Therefore, average people in the Middle East have no contact with Americans and no incentive to understand the truth, he says.

Glaeser’s model also offers an analysis of hatred toward 19th-century European Jews and 19th-century blacks, he says.

“I write a lot of quick and dirty papers,” Glaeser says. “But this is unquestionably the work in my life that I have loved most and cared about getting right...I have reconfigured the model 14 different ways; it has been a huge amount of work for a 45-page paper.”

Glaeser teaches urban and social economics and microeconomic theory in the Faculty of Arts and Sciences.

And he has won the respect of his colleagues.

“I think there’s a good chance Ed will win a Nobel Prize,” Cutler says.

Glaeser is the author of dozens of articles on cities, economic growth, and law and economics and the editor of the Quarterly Journal of Economics. He recently co-authored the book Fighting Poverty in the U.S. and Europe with Alberto Alesina, the Ropes professor of political economy and chair of the Department of Economics.

PROBING THE PLAGUE

Michael McCormick, Goelet professor of medieval history, is exploring new horizons of medieval history by applying biological science to historical problems.

“[McCormick] is known as the elaborator of one of the genuinely grand theories of medieval history,” says professor of history James Hankins.

In his 2002 book, Origins of the European Economy: Communications and Commerce, AD 300-900, which was 10 years in the works, McCormick challenged the long-standing theory that the unexpected rise and advance of Islam led to the downfall of the Roman Empire.

McCormick argues that Europe was richer than had been believed and that the economy was driven primarily by the exportation of slaves on a massive scale.

“This grand theory…alone gives him the claim to being the greatest medieval historian now living,” Hankins says.

Largely as a result of this work, McCormick was a recipient of one of the 2002 Distinguished Achievement Awards celebrating the humanities, which are given by the Andrew W. Mellon Foundation. The award includes a $1.5-million grant.

McCormick says he plans to use this money to pursue a wide range of projects on a variety of subjects ranging from saints’ lives to DNA to Carolingian coins to rats. At the root of all of these projects is a desire to create historical knowledge using the breakthroughs of natural science and the computer revolution, he says.

“He is brilliant in the use and elaboration of evidence...archeological evidence, coins, fossilized pollen,” Hankins says.

McCormick says he intends to use science’s new understanding of DNA and genomes to determine how health and disease impacted people’s lives throughout the medieval period.

“Human health is a fundamental part of human history and offers a huge window on culture,” he says.

Not too unlike the movie “Jurassic Park,” McCormick hopes to use DNA, which may survive in fragmented form in the remains of both people and animals, to determine what organisms might have had an impact of people’s health, he said.

McCormick is analyzing Roman skulls with a team at the medical school to identify the cause of the great 6th- century plague which, according to some, precipitated the fall of the Roman Empire in the West.

“We’re trying to see if we can turn up any traces of the genomes of people buried in mass graves at this time,” he says.

McCormick seems to find historical evidence in the unlikeliest of places.

For example, according to Hankins, McCormick and others have recently sought to determine how many meters the black rat, Ratus ratus—supposedly the main agent of the plague—could travel in a year. It turns out the rat can travel 200 meters a year, which suggests that the rat had to have been ship-born for the plague to have spread as fast as it did, according to Hankins.

McCormick has also studied tree owls that eat rats in Sardinia, Hankins says.

Scientists, McCormick says, are making strides towards identifying the diets of both people and animals from their bones or teeth.

According to Hankins, McCormick is currently in negotiations with the Egyptian government over second-hand mummies. Hankins added that his friend hopes to use information gleaned from these mummies to determine early settlement patterns and the ethnic make-up of Europe. “The marriage between health and history is something that has been occasionally attempted...but [McCormick] seems to be doing it really, really, really well,” Hankins says.

Yet another project McCormick will soon begin will take him to France, where scientists are going to test between 15 and 20 coins of Charlemagne to try to determine the origins of silver and possibly reveal something about the European economy based on the movement of coins.

But McCormick’s plans don’t stop there.

McCormick began this year by organizing a “test balloon of a workshop” on computational philology—the science of texts—which brought together experts in artificial intelligence, classicists and computer scientists to create software that would help historians identify and determine the origin of documents based on language, he says.

“That’s one of the things I want to do with the Mellon money,” he says, “to bring together people who would never get together.”

McCormick intends to apply the software he hopes will emerge out of this group effort to the approximately 14,000 primary sources on the Latin lives of saints, nearly 8,000 of which are completely unidentified, he says. “Historians have to know where and when [a document] comes from,” he says. “I thought that if we could give people some way of sorting through these 8,000 documents—even to say that it was written before 1,000—[that] would be fantastic.”

“Mellon just gave me the money, so I can try things that are high risk,” he says. This allows me to try as many different things as possible.”

WHY ANTIMATTER MATTERS

Scientists have long wondered how insights into the composition of the world could affect reality.

Gerald Gabrielse, Leverett professor of physics, has been searching for an answer for the past two decades.

“Why in the world do we have a matter universe? Why don’t we have an antimatter universe?” Gabrielse, who was on leave this year, says. “At the most fundamental level, we are trying to test how our reality is put together.”

The three basic particles of antimatter—positron, antiproton and antineutron—share the same masses and magnitudes of charge as those of their counterparts in matter—electron, proton and neutron, but with opposite charges. Just as a proton and electron compose a hydrogen atom, an antiproton and positron make an antihydrogen atom. When matter and antimatter particles collide, they destroy each other in a burst of energy.

Professors in the physics community are testing whether antimatter behaves identically to ordinary matter, to understand why matter mostly comprises our universe.

After 18 years of work, Gabrielse, who leads an international team of physicists at the European Organization for Nuclear Research, has already found a way to produce the slowest antiprotons on earth—an important step towards understanding antimatter since the slower the antiproton, the easier it is to measure its properties accurately.

In fact, the antiprotons that Gabrielse studies are 10 orders of magnitude lower in energy than the antiprotons produced in Geneva, the only source of antiprotons in the world.

Chair of the Department of Physics John Huth called Gabrielse’s work a “tour de force.” “It would be a rather tremendous discovery if he found that there were distinct differences between the properties of hydrogen and antihydrogen,” he adds.

This year, in a lab in Geneva, Gabrielse developed novel ways to produce antihydrogen atoms using lasers, map their internal structures and measure their speeds—three techniques which have never been used before.

First, Gabrielse used lasers to excite the electron in a cesium atom into a higher orbit. When the cesium atom collides with a positron, the electron binds with the positron, to create an atom that is half matter and half antimatter. When that atom collides with an antiproton, the positron binds to the antiproton, forming an antihydrogen atom.

“It’s kind of like particle promiscuity,” Gabrielse jokes. “These particles can’t decide what their permanent partners are.”

In addition, Gabrielse’s team was able to measure the distance between the positron and antiproton in an antihydrogen atom by the magnitude of the voltage required to pull the two particles apart, enabling them to better map the internal structure of the atom.

Gabrielse, who also won the Levenson Teaching Award for Science A-45, “Reality Physics,” says he plans to submit his team’s findings this week for publication in Physical Review Letters.

For his work, Gabrielse was also awarded the George Ledlie Prize by the President and Fellows of Harvard College, an award given every two years to someone affiliated with the University who has made a contribution to science or “for the benefit of mankind.”

IN THE STILL OF THE LIGHT

This year, several Harvard physicists managed to bring light, which normally travels at 186,000 miles per second, to a stop.

Assistant Professor of Physics Mikhail D. Lukin and Harvard graduate students Michal Bajcsy, Axel P. André and Alexander S. Zibrov, made history when they halted a light pulse for 10 milliseconds.

The result, with significant applications for information processing and the construction of quantum computers, builds on previous experiments, also led by Harvard scientists, which have slowed and briefly stored light.

In 1999, Lene V. Hau, McKay professor of applied physics, supervised an experiment that slowed light to about 40 m.p.h. In 2001, a team led by Lukin and Ronald Walsworth of the Harvard Smithsonian Center for Astrophysics, and independently, a team led by Hau, stopped a light pulse by storing it in the form of excited atoms to be converted back into a light pulse.

“What we have done this year is to actually store the light pulse in electromagnetic form, to actually store the light as light,” Lukin says.

Working in the Lyman laboratory, the researchers used a technique known as electro-magnetically induced transparency, in which they fired a red laser light pulse into a sealed glass cylinder containing rubidium vapor. They fired two control beams through the vapor, rather than the one beam used in previous experiments, so that their interaction simulated the effect of tiny atomic mirrors.

The photons within the light pulse in the vapor bounced back and forth so that the light pulse as a whole was frozen in space.

The study’s findings were published in the December 2003 issue of Nature.

Lukin and his team’s work has significant implications for information processing and quantum communication.

The ability to store and hold a quantum state of light without destroying it is the basis behind the idea of quantum computing.

Light must be in electromagnetic form for individual photons to interact with one another, which allows for information processing.

“The intriguing futuristic application would be processing signals that are carried by individual protons,” says Lukin, who has been on the faculty for three years. “If you could make these single photons interact or ‘talk’ with each other, you could process the signal which is carried by just one single photon. This would allow us to process information in a completely new way and to build new devices like quantum computers.”

The next step in their research, according to Lukin and André, would be to trap light in all directions and to manipulate and interact trapped light pulses.

“We’ve managed to prevent light from moving in the forward and backward directions. We’d like to also constrain light from transverse action,” says André, who has worked with Lukin for over three years.

The interaction of individual light photons facilitates computation and is the basis for the notion of quantum computers.

“We’re going to try and make two pulses of light interact with each other,” André says.

Trapping light pulses would allow them to interact and alter one another’s states, according to André, “whereas with two pulses of light that are just flying freely, because they’re moving so fast, they effectively don’t have much time to interact with one another.”

The interaction of light pulses is “the building block of anything you would want to call computation,” André says.

—Staff writer Ella A. Hoffman can be reached at ehoffman@fas.harvard.edu.

—Staff writer Tina Wang can be reached at tinawang@fas.harvard.edu.