David A. Weitz is the Mallingkrodt Professor of Physics and Applied Physics at Harvard University, where he has appointment in both the Physics Department and the School of Engineering and Applied Sciences. He received his PhD in physics from Harvard, and then worked at Exxon Research and Engineering for nearly 18 years. He then was a professor of Physics at the University of Pennsylvania before joining to Harvard, where he leads the experimental soft condensed matter physics research group. His research efforts include soft matter physics, biophysics and biotechnology. He is a member of the National Academies of Science and the American Academy of Arts and Science.