Researchers have finally cracked the mystery behind the distinctive screeching sound produced when peeling Scotch tape rapidly from its roll. A new study published in Physical Review E reveals that the sound results from shock waves created by micro-cracks propagating along the tape at supersonic speeds, a phenomenon that has puzzled physicists for decades.

The discovery builds on earlier research into tape's unusual properties. In 1953, Russian scientists first reported detecting electrons with sufficient energy to emit X-rays while peeling tape in a vacuum, a finding confirmed in 2008 by UCLA physicists who produced low-quality X-ray images of a human finger. The same team previously identified the crucial micro-fracture phenomenon using ultra-fast imaging, observing transverse cracks traveling across the adhesive at supersonic speeds.

This latest research by Sigurdur Thoroddsen and colleagues at King Abdullah University experimentally confirmed their hypothesis that the screeching sound is directly generated by a crack's rapidly moving tip. By conducting simultaneous high-speed imaging of both the propagating fractures and the sound waves traveling in air, the team established a direct correspondence between the discrete sound wave pulses and the supersonic micro-cracks. The findings not only solve a long-standing acoustic mystery but also demonstrate how everyday materials can still yield surprising scientific insights.