Articles by IAS Faculty
By Yve-Alain Bois
How things that look apparently very simple are in fact much more complex than they seem
Ellsworth Kelly is one of the very first artists whose work I liked. Perhaps he was second, just after Piet Mondrian. One of the things I asked Kelly after we finally met and became friends, close to a quarter of a century ago, was why he had not answered a fan letter that I had written to him in my teens. He remembered the letter. He had received it at a time when he felt isolated, bypassed by a new generation of artists, and he had been struck by the fact that it came from a French teenager living in the middle of nowhere—he thought he might even have kept it. Since Kelly is a demon archivist, he found the darn letter, and he gave me a copy of it, which, unlike him, I immediately misplaced. But I read it, and it was humbling. First, because I realized I had misdated it in my memory, placing it three years too early—probably because the main event it described, my first encounter with his works, at a show of his lithographs at the Galerie Adrien Maeght in Paris, dated from even earlier to 1965. Second, because it was sheer adolescent drivel. At the time of the letter, Kelly was for me the purest representative of pure abstraction, whatever that is supposed to be.
By Dani Rodrik
When economists skip over real-world complications, it’s as if physicists spoke of a world without gravity.
When the 2013 Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel (colloquially known as the “Economics Nobel”) was awarded to Eugene Fama and Robert Shiller, along with Lars Peter Hansen, many were puzzled by the selection. Fama and Shiller are both distinguished and highly regarded scholars, so it was not their qualifications that raised eyebrows. What seemed odd was that the committee had picked them together.
After all, the two economists seem to hold diametrically opposed views on how financial markets work. Fama, the University of Chicago economist, is the father of the “efficient market hypothesis,” the theory that asset prices reflect all publicly available information, with the implication that it is impossible to beat the market consistently. Shiller, the Yale economist, meanwhile, has spent much of his career demonstrating financial markets work poorly: they overshoot, are subject to “bubbles” (sustained rises in asset prices that cannot be explained by fundamentals), and are often driven by “behavioral” rather than rational forces. Could both these scholars be right? Was the Nobel committee simply hedging its bets?
While one cannot read the jury’s mind, its selection highlighted a central feature of economics—and a key difference between it and the natural sciences. Economics deals with human behavior, which depends on social and institutional context. That context in turn is the creation of human behavior, purposeful or not. This implies that propositions in economic science are typically context-specific, rather than universal. The best, and most useful, economic theories are those that draw clear causal links from a specific set of contextual assumptions to predicted outcomes.
By Juan Maldacena
Can the weird quantum mechanical property of entanglement give rise to wormholes connecting far away regions in space?
In 1935, Albert Einstein and collaborators wrote two papers at the Institute for Advanced Study. One was on quantum mechanics  and the other was on black holes . The paper on quantum mechanics is very famous and influential. It pointed out a feature of quantum mechanics that deeply troubled Einstein. The paper on black holes pointed out an interesting aspect of a black hole solution with no matter, where the solution looks like a wormhole connecting regions of spacetime that are far away. Though these papers seemed to be on two completely disconnected subjects, recent research has suggested that they are closely connected.
Einstein’s theory of general relativity tells us that spacetime is dynamical. Spacetime is similar to a rubber sheet that can be deformed by the presence of matter. A very drastic deformation of spacetime is the formation of a black hole. When there is a large amount of matter concentrated in a small enough region of space, this can collapse in an irreversible fashion. For example, if we filled a sphere the size of the solar system with air, it would collapse into a black hole. When a black hole forms, we can define an imaginary surface called “the horizon”; it separates the region of spacetime that can send signals to the exterior from the region that cannot. If an astronaut crosses the horizon, she can never come back out. She does not feel anything special as she crosses the horizon. However, once she crosses, she will be inevitably crushed by the force of gravity into a region called “the singularity” (Figure 1a).
By Danielle S. Allen
College campuses struggle with how to think and talk about diversity of all kinds, a struggle that has gone on for more than two decades now. Every year, there are stories from around the country about anonymous hate speech and offensive theme parties with equally offensive T-shirts as well as controversies about “political correctness.” Nor has there been a year in my roughly two decades in higher ed when I haven’t read or heard someone wondering, “Why do all the black kids sit together in the cafeteria?”
What are the stakes for how well we deal with diversity on college campuses? There are two answers to this question, one concerning the stakes for the campuses themselves, the other the broader social stakes.
First, for campuses. Social scientists have long distinguished between two kinds of social tie: “bonding ties” that connect people who share similar backgrounds and “bridging ties” that link people who come from different social spaces. Since the 1970s, scholars have been aware that “bridging ties” are especially powerful for generating knowledge transmission; more recently, scholars have argued convincingly that teams and communities that, first, emphasize bridging ties and, second, successfully learn how to communicate across their differences outperform more homogenous teams and communities with regard to the development and deployment of knowledge.