Science Friday The Surprising Science Of Why Sneakers Squeak
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Mar 9, 2026 Dr. Adel Djellouli, an experimental physicist at Harvard who studies friction, explores why basketball shoes squeak. He describes using clever lab setups to watch contact and uncover supersonic slip pulses. He links these fast ripples to earthquake-like dynamics and even tiny lightning discharges that trigger squeaks. The conversation celebrates curiosity-driven experiments and surprising cross-scale physics.
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Curiosity Sparked By A Celtics Game
- Adel Djellouli went to his first NBA game and was struck by the omnipresent squeaking of basketball shoes.
- That curiosity about a simple stadium sound launched a research project into why shoes squeak.
Supersonic Wrinkles Drive The Squeak
- High-speed imaging of a used basketball shoe on acrylic revealed traveling wrinkles in the sole that move at supersonic speeds.
- Those fast ripples set the repetition frequency of the audible squeak by producing localized slip pulses instead of uniform sliding.
Shoe Quakes Mirror Earthquake Ruptures
- The slip pulses observed in shoes mirror rupture dynamics seen in geophysics, like earthquakes, despite huge scale differences.
- Adel Djellouli compares inches-long shoe quakes to continental plate ruptures because both show traveling rupture fronts.