A Matter Of Solidity - Science News

A Matter Of Solidity - Science News: "The breakthrough came after John Goodkind of the University of California, San Diego reported that sound waves traveled in an unexpected manner through solid helium. Intrigued, Moses Chan of Pennsylvania State University in University Park decided to launch a new study of solid helium using a device called a torsional oscillator. This machine oscillates a sample back and forth around a central axis, like a merry-go-round spinning first one way and then the other at 1,000 times a second.

Such oscillators had been used to hunt for superfluidity because quantum materials, when placed in a spinning container, don’t spin along. Imagine rotating a bucket of water. If the water were a superfluid, it wouldn’t slosh around with the rotation but would instead sit unmoving, decoupled from the bucket’s moving sides. Supersolids, if they exist, would do the same thing. Thus, as a solid transitions to a supersolid state at low temperatures, the period of time it takes for the oscillator to rotate back and forth would drop — because less mass would be sloshing around."