Research

Make Room on the Mantel for the Nobel

Stern School of Business

“Growth springs from better recipes,” Paul Romer once wrote, “not just from more cooking.” The Stern economics professor’s own talent for artful synthesis was recognized when he won the 2018 Nobel Memorial Prize in Economic Sciences, an award he shared with Yale University’s William Nordhaus. Romer was cited “for integrating technological innovations into long-run macroeconomic analysis” and his pioneering contributions to “endogenous growth theory,” which holds that the sharing of technology and knowledge (neither can be depleted) is central to economic growth. In addition to teaching, Romer served as the World Bank’s chief economist and is the former director of NYU’s Marron Institute of Urban Management. As founding director of Stern’s Urbanization Project, he is a proponent for the creation of charter cities, whereby one established country oversees the expansion of a metropolis in a developing nation. In all of his work, Romer has underlined the power of economic imagination, particularly when it comes to making better use of what we already have. “All we can ever do is rearrange things,” Romer said in 2007. “We've got the same amount of stuff we've always had, but the world is a nicer place to live in because we’ve rearranged it.” His own world became doubly nice on December 10, 2018—the day of the Nobel banquet as well as his marriage to Caroline Weber, a Barnard College French literature professor.
—Rollo Romig (GSAS ’08)  
(Illustration by Roberto Parada)

“All we can ever do is rearrange things. We’ve got the same amount of stuff we’ve always had, but the world is a nicer place to live in because we’ve rearranged it.”

Commuting While Female

Wagner Graduate School of Public Service

The term “pink tax” refers to the upcharge women must pay for myriad products and services—everything from razors to dry cleaning. That unfortunate reality, along with the #MeToo movement, inspired Sarah Kaufman, associate director of Wagner’s Rudin Center for Transportation, to wonder: Do women pay more to commute to and from work? Rudin Center researchers conducted an online survey of New Yorkers to find out. The results revealed that safety concerns and disproportionate caregiver responsibilities (often entailing the schlepping of kids, strollers, backpacks, etc.) prompted women who could afford it to choose ride-hailing services over mass transit more often than men do—a combination that’s responsible for some female respondents spending as much as $1,200 a year more than men to get around the city. For Kaufman, who is also an adjunct assistant professor of urban planning, the stories that emerged from the research could prove to be even more valuable than the lamentable numbers. “I hadn’t realized how few women report issues of harassment” in the transit system, she says. “Now, reading through the responses, I understand why.” The reason is, in a word, guilt; if a woman stops a train to alert authorities to an abuse, she’s delaying thousands of people on their commutes for something that seems to her relatively minor. Before launching a follow-up survey that will reach out to a wider demographic of New Yorkers, Kaufman plans to study what transit systems elsewhere in the world are doing to remedy the pink tax vexation.
—Rollo Romig (GSAS ’08)  
(Illustration by Matt Chase)

The Spectacular Science of Bubbles  

Courant Institute of Mathematical Sciences

To kids, blowing a bubble—producing a perfect orb with a mere puff of breath—is magic. To Leif Ristroph, who works with soap film in Courant’s Applied Math Lab, it’s “something that’s obvious and commonplace”—and still not completely understood. So the assistant professor of mathematics decided to take a closer look by forming bubbles underwater using a tool called a water tunnel, often employed in the study of fluid dynamics because it allows the experimenter to fill the liquid with fine glass particles that can be illuminated with colorful lasers to see exactly what’s happening with the flow. After much trial and error, Ristroph settled on using olive oil because it remained stretched across a bubble wand underwater, just as soap film does in air. His team’s findings, published in the journal Physical Review Letters, includes an equation (shown at right) that, as Ristroph puts it, “mathifies” the physics behind bubbles’ formation. “The cool thing is this formula allows you to calculate the flow speed you need to blow a bubble [given] geometric and material properties like surface tension, density of the air, size of the radius of the ring of the wand, and so on,” says Ristroph. “Maybe in a sense we’re not really saying anything that we don't already know, but now we can articulate it.” It’s something children everywhere seem to know intuitively, but the hard numbers could be useful to chemists developing a wide range of consumer products, such as sprays, foams, and emulsions—all of which contain bubbles or droplets.
—Rollo Romig (GSAS ’08)  
(Photo by Bela Zecker)