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| Joel Mobley Photo by Robert K. Jordan |
Joel Mobley and Josh Gladden have a few things in common. Both joined the Department of Physics and Astronomy as assistant professors in 2005. Both are gaining national attention for their research. And both enjoy teaching and mentoring students.
Mobley recently proved that it is, indeed, possible for sound to travel faster than light. Using microscopic plastic beads in water, Mobley’s experiments fired ultrasonic pulses lasting less than one-millionth of a second between two transducers.
“The idea that acoustic wave groups could move faster than light is not a new idea, but no one had seen it happen until recently,” Mobley said. “This work provides a novel look at the effect usually observed in experiments with light, not sound.”
Mobley said his ultrasound research could potentially be applied to microwave systems that are used for cell phones, wireless Internet and satellite TV.
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| Josh Gladden Photo by Robert K. Jordan |
Meanwhile, Gladden has been conducting experiments with viscoelastic materials — substances that share qualities of solids and liquids, but do not fall neatly into either category. Such mixtures share the properties of everyday materials including toothpaste, the Earth’s mantle, blood clots and Jell-O.
At question is how such gel-like substances respond when a rigid object moves through them at various speeds. The results of these experiments provide new insights into how such materials change from being solidlike to being liquidlike.
The opportunities to pursue such research while working with talented students attracted both professors to UM in 2005. Mobley holds degrees from Washington University in St. Louis and the University of Kentucky. Gladden graduated from the University of the South (Sewanee) and was a postdoctoral fellow at Penn State before joining UM’s faculty.
“This was a unique opportunity to be a part of the world-class acoustics facility at the National Center for Physical Acoustics,” said Mobley, who was a physicist at the Army Research Laboratory in Adelphi, Md., before coming to UM.
“I enjoy being in the classroom and interacting with students, but I also very much like thinking up and performing new experiments in the lab,” said Gladden, who also taught high-school physics in Virginia and New Mexico. “The university has a nice balance of teaching and research.”
“As a teacher, it is energizing to be around young people trying to find their way to their life’s work and to play a small part in helping them realize their intellectual and professional ambitions,” added Mobley. “As a scientist, I get to work with creative and talented people here and throughout the world who are pushing the boundaries of science and engineering.”