Imagine tuning a guitar: each string's vibration creates a unique sound. Now, envision the same concept at a microscopic scale, with tiny vibrations transmitting heat instead of sound.

Researchers from the Paul M. Rady Department of Mechanical Engineering at CU Boulder have made a groundbreaking discovery about these microscopic thermal vibrations, called phonons. They found that phonons can harmonize or clash just like musical notes, shaped by how molecules are constructed.

Published in *Nature Materials*, this research marks the first observation of phonon interference at room temperature on a molecular scale. A new technique developed by the team enables them to unveil these tiny thermal interactions.

Led by Assistant Professor Longji Cui, this collaboration includes experts from Spain and Italy, and the findings could reshape the understanding of how phonons—the primary energy carriers in insulating materials—function. This opens a potential pathway for revolutionary advances in managing heat dissipation in future electronics.

The Quest for 'Molecular Ears'