Nations are rivals in soccer and international relations, but science is a unifying force. Many of our biggest achievements seem to come from international collaborations. A team from 11 laboratories in nine countries identified the SARS cor­onavirus in 2003 with unprecedented speed. Scientists come from all over to chase the Higgs boson at the Large Hadron Col­lider near Geneva. Centers of excellence dot the globe. The world of science is getting flatter.

What has gone underappreciated in this trend is the effect on science itself and how science is actually done. It has become a cliché that great discoveries come from interdisciplinary thinking—a chemist bringing insight to a discussion of a materials problem, a physicist sharing an intuition about a problem in biology, a biologist helping an engineer see how nature comes up with optimal solutions. Few realize how much science is energized when team members have different cultural approaches to problem solving. International diversity is just as important as diversity of discipline.

I have seen this phenomenon at close quarters. For years I have collaborated with colleagues from Mexico and Germany. We see eye to eye on so many things. We like one another’s cuisine, hiking, and the mathematics and physics our research involves. When we began writing out equations on a chalkboard, though, our cultural differences became apparent.

When we first started out, our approaches seemed irreconcilable. The physics problems we work on—fluid suspensions of small particles—are hard. They encompass many unknowns, and the physics bumps up against many constraints and boundary conditions—rules that cannot be broken, like conservation of matter or the impassibility of a solid wall. While working on difficult equations, my Mexican cohorts wanted to relax the rules to make the mathematics more tractable and later put them back in. This set our German friends on edge. They kept reminding us of the constraints and the boundary conditions to make sure we did not stray too far. My American training left me somewhere in the middle: I worried about the constraints but was tentatively willing to relax them.

Over the years the creative clash of viewpoints bred success. The German-Mexican teams, along with some Americans, wound up solving challenging multibody hydrodynamics problems—the complicated mathematical descriptions of the way swarms of particles squeeze the fluid between them, explaining the flow behavior of pastes and slurries.

I first got a lesson in cross-cultural dynamics during a NATO post­doctor­al fellowship in Paris in 1985. Working with French colleagues taught me a different way to simplify and clarify a physics problem. An appreciation for the beauty of the problem and the value of intuition might have led us to solutions more easily than the typical American approach: to attack the problem with loads of mathematical equations. Later in Germany, as an Alexander von Humboldt Foundation awardee, I found that approaching an experimental problem with a deliberate, tactical and strategic way reduced the need for trial and error.

The power of this diversity of thought comes alive in international conferences where there is an opportunity to listen, ask questions, think about problems, confer with and critique one another, and continue the dialogue after the meeting is over.

New institutions have sprung up to take advantage of the synergies in multinational collaborations. Singapore has created an intensely international science scene, where talent converges to contribute and compete to form some of the best research teams in the world. In December, King Abdullah University of Science and Technology graduated its second cohort of men and women receiving master’s degrees in science and engineering, who hail from Saudi Arabia, China, Mexico, the U.S. and 29 other countries. Labs, institutes and universities are hubs that gather the best scientists to tackle the hardest problems.

The need to reach across national boundaries places greater demands on scientists. While scientists become more specialized as they proceed through their studies, broadening and collaborative experiences make them better able to “think differently” and “connect the dots” to discover new things. Ultimately it leads to better science.

This article was published in print as "Boundary Conditions."