Small screen film Alien Once said: „In space, no one can hear you scream.” However, physicists Juran Keng and Ilari Masilta of the Center for Nanoscience at the University of Jyväskylä, Finland, beg to differ. Their latest research suggests that under certain conditions, sound can indeed be transmitted powerfully in a vacuum.
Their findings, recently published in the journal Contact Physics, reveal that under certain circumstances, sound waves can „tunnel” through the vacuum gap between two solid materials, those materials being piezoelectric. These specific materials produce an electrical response when subjected to sound waves or vibrations. Since a vacuum can contain an electric field, it can effectively transport these sound waves.
The requirement is that the size of the gap should be smaller than the wavelength of the sound wave. This effect works not only in the audio range of frequencies (Hz-kHz), but also at ultrasound (MHz) and hypersound (GHz) frequencies, as long as the vacuum gap becomes smaller as the frequencies increase.
In most cases the effect is small, but the entire energy of the wave jumps across the vacuum with 100% efficiency and no reflection. Therefore, this phenomenon could find applications in micro-electromechanical components (MEMS, smartphone technology) and control of heat, says Prof. Ilari Masilda from the Nanoscience Center of the University of Jyväskylä.
Reference: Juran Keng and Ilary J. Masilda, 14 July 2023, „Complete Tunneling of Sound Waves Between Piezoelectric Crystals” Contact Physics.
The study was funded by the Academy of Finland and the European Union’s Horizon 2020 programme.
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