Listen to the (quantum) whistling gyros!(Research & Developments)

An auditory phenomenon discovered by UC Berkeley physicist Richard Packard could lead to superfluid gyroscopes that operate at a relatively toasty 2 kelvin rather than the near-zero kelvin required by liquid helium-3. Packard's research team forced helium-4, a superfluid, through an array of apertures on the order of [10.sup.-3] mm dia. until it reached critical velocity. At that point, a minuscule quantum vortex surged across each aperture, carrying away some of the energy of the flow. As the fluid accelerated and decelerated, it created vibrations that produced a whistling sound with a falling frequency. (You can listen to this "quantum whistle" online at …