2025-26 Frederick L. Hovde Distinguished Lecturer

David Nolte

Edward M. Purcell Distinguished Professor of Physics and Astronomy

Life is Motion:
Doppler Spectroscopy at the Speed of Life

Abstract

The idea of disease as a dynamical system arose from research into complex systems, including networks of intracellular signaling in which receptors create a cascade of downstream proteins that affect cellular dynamics. We use Doppler light scattering spectroscopy of intracellular dynamics to track the effects of drugs and disease on intracellular motions. The ultra-low-frequency Doppler effect generates phase drifts that can be measured with high sensitivity using interferometry and digital holography. This talk reviews the current state of digital holographic optical coherence tomography (DH-OCT) used for quantitative phase analysis of intracellular dynamics. Applications include drug development, in vitro fertilization, developmental biology, and cancer therapy selection. In addition, the phase sensitivity of holography enables the quantitative measurement of phase excursions that may be related to anomalous transport inside cells, introducing “Levy-alpha spectroscopy” to diagnose infections and other diseases. This talk illustrates how physics can help bridge the wide gap from principles of fundamental physics to improved health care for patients.
Recently, our group achieved a new record for ultra-low-frequency Doppler spectroscopy of living tissue by pushing the low-frequency detection limit down to a relative frequency shift of 3 parts per ten quintillion (3e-19), corresponding to intracellular speeds of 30 picometers/second associated with ultra-slow cellular shape changes and membrane motions. This relative sensitivity approaches the direct detection limits set by LIGO for gravitational wave detection and by JILA for atomic clock precision. The interferometric physics behind this new record, set using $1k optical elements, will be explained and compared to the $1B price tags for LIGO and JILA. (Spoiler Alert: It’s the difference of relative detection versus direct detection.)

Bio 

David D. Nolte is the Edward M. Purcell Distinguished Professor of Physics and Astronomy at Purdue University. After receiving his degrees in physics from Cornell and Berkeley, he worked at AT&T Bell Labs before joining the faculty at Purdue. He is the author of three trade science nonfiction books: Mind at Light Speed (Free Press, 2001), Galileo Unbound (Oxford, 2018) and Interference (Oxford, 2023), and actively writes science blogs. He is a Fellow of the National Academy of Inventors (NAI), the American Association for the Advancement of Science (AAAS), the American Physical Society (APS), and the Optica society. He received a research fellowship from the Alfred P. Sloan Foundation, a Presidential Young Investigator Award from the NSF and the Hubert Newby McCoy Award from Purdue University. He holds 25 US patents, is the technical founder of two biotech start-up companies, and has been interviewed on public radio and TV on the physics and applications of optical interferometry and holography.