- Professor, University of Pennsylvania (1998-)
- Associate Professor, University of Pennsylvania (1992-1998)
- Assistant Professor, University of Pennsylvania (1988-1992)
- Assistant Professor, Boston University (1987-88)
- Dennis M. Deturck Award for Innovation in Teaching (U Penn) (2018).
- Emily Gray Award of the Biophysical Society, "for far reaching and significant contributions to the teaching of biophysics, developing innovative educational materials, and fostering an environment exceptionally conducive to education in Biological Physics" (2009).
- Fellow of the American Physical Society, "For contributions to the understanding of soft biomaterials, quantum fields, and superstrings, using geometrical and topological methods" (2003).
- Ira Abrams Memorial Award for excellence in undergraduate teaching (U Penn) (2001).
- National Science Foundation Presidential Young Investigator Award (1988).
- Alfred P. Sloan Foundation Fellow (1988).
- Junior Fellow, Harvard University Society of Fellows (1984-87).
Ph.D., Harvard University (1984).
Master of Advanced Study, University of Cambridge (1981).
A.B., Princeton University (1980).
I'm currently studying the physics of artificial biomembranes, biopolymers such as DNA, and other "soft" condensed matter systems. There is a great cultural gap between physics, which seeks to understand extremely simple systems, and biology, which is obliged to study the overall behavior of extremely complex systems. I think that one area where simplicity and life intersect is the study of biomembranes and biopolymers, both in isolation and as active elements of cells. Membranes and polymers display the sort of universal behavior amenable to the powerful tools of statistical physics, thus making these systems are a bit more inevitable, less accidental, than more complex architectural elements of life. Nature has made extensive use of these generic properties in constructing useful materials and molecular machines; moreover, artificial analogs of biomaterials are subjects of intense investigation for a wide variety of bioengineering applications. Of course, physicists have been studying membranes and polymers for much of this century. Much physical research on these systems has concerned bulk systems, in thermal equilibrium. But the activities of many molecular actors are obscured when we look at them in bulk; new, single-molecule techniques reveal much that was previously hidden. Also, life processes take place far from equilibrium. So we have been studying mainly experiments involving the manipulation of single molecules of DNA, and dynamical phenomena involving membranes. I have some interest as well in general nonlinear dynamics (including pattern formation), self-assembly, electrostatics at the colloidal level, and the general area of geometrical methods in physics.
Phys 280: Physical Models of Biological Systems
Phys 516: Electromagnetic Phenomena
- My book: A Student's Guide to Python for Physical Modeling (Princeton University Press, 2018, ISBN 9781400889426) (with Jesse M. Kinder). Translated into Korean and Chinese. Chapter 1 is freely available.
- My book: From Photon to Neuron: Light, Imaging, Vision (Princeton University Press, 2017, ISBN 9780691175195). Chapter 1 is freely available.
- My book: Physical Models of Living Systems (W.H. Freeman and Co., 2015, ISBN 9781464140297). Translated into Chinese.
- My book: Biological Physics: Energy, Information, Life with new art by David Goodsell (W.H. Freeman and Co., 2014). Translated into Spanish, Portuguese, and Chinese.
- The Role of Quantum Decoherence in FRET, Biophys. J. 115: 167–172 (2018).
- Old and New Results About Single-Photon Sensitivity in Human Vision, Physical Biology 20: 025001 (2016).
- The Syncytial Drosophila Embryo as a Mechanically Excitable Medium PLoS ONE 8: e77216 (2013) (with Timon Idema, Julien O. Dubuis, Louis Kang, M. Lisa Manning, Tom C. Lubensky, and Andrea J. Liu).
- Transformation of Stimulus Correlations by the Retina, PLoS Computational Biology 9: e1003344 (2013) (with Kristina D. Simmons, Jason S. Prentice, Gasper Tkacik, Jan Homann, Heather K. Yee, Stephanie E. Palmer, and Vijay Balasubramanian).
- Three-dimensional Orientation and Dynamic Wobble of Myosin V by High Time Resolution Single Molecule Polarized Fluorescence, Biophys. J. 104: 1263 (2013) (with John F. Beausang, Deborah Y. Shroder, and Yale E. Goldman).
- The Role of Microtubule Movement in Bidirectional Organelle Transport, PNAS 105: 10011 (2008) (with I. Kulic, A.E.X. Brown, H. Kim, C. Kural, B. Blehm, P. Selvin, and V. Gelfand).
- High flexibility of DNA on short length scales probed by atomic force microscopy, Nature Nanotechnology, 1: 137 (2006) (with P. A. Wiggins, T. van der Heijden, F. Moreno-Herrero, A. Spakowitz, R. Phillips, J. Widom, and C. Dekker).
- Electrostatic Repulsion of Positively Charged Vesicles and Negatively Charged Objects, Science 285: 394 (1999) (with H. Aranda-Espinosa, Y. Chen, N. Dan, T. C. Lubensky, L. Ramos, and D. A. Weitz).
- Torsional Directed Walks, Entropic Elasticity, and DNA Twist Stiffness, Proc. Natl. Acad. Sci. USA 94: 14418 (1997) (with J. D. Moroz).
- Global Color is not Always Defined, Phys. Rev. Lett. 50: 943 (1983) (with A. Manohar).