Researchers working with a type of super-cooled helium have made the frigid stuff whistle, an attribute they say might make it the crux of better global positioning systems (GPS) in submarines and airplanes among other things.
The trick, it turns out, resides in cooling a specific flavor of helium – called helium-4 – down to just two degrees above absolute zero (2 degrees Kelvin or -271 degrees Celsius), where it becomes a frictionless superfluid.
It is that superfluid, the scientists said, that whistled unexpectedly when squashed through tiny holes and could be the foundation of new superfluid gyroscopes for submersible GPS navigation and seismic measurements on Earth and in space. [Click here to hear the helium-4 whistle.]
“The fact that they do whistle coherently means that we could make a sensitive gyroscope,” explained UC Berkeley physicist Richard Packard, who led the study, in a telephone interview
The research, which was funded by NASA and the National Science Foundation, appeared in the Jan. 27 issue of the journal Nature.
With almost no moving parts, superfluid gyroscopes promise much more sensitivity to rotational motion than their mechanical counterparts, a useful trait considering that changes in the Earth’s rotation must constantly be added to the GPS system.