Sound To Power Space Probes

An anonymous reader writes "The old adage that 'no one can hear you scream in space' seems to have its own variant when Los Alamos scientists announced today their latest designs for the 'traveling wave engine', a derivative of the classic, pistonless Stirling device. Because it uses helium as an oscillating gas in a long tube, the design works kind of like a high-pitched loudspeaker at maximum efficiency. Another description combines a refrigerator and whistle to make an engine."