Set your phasers on "miniature medical sensor." We're so used to lasers that it's easy to forget that the word is an acronym for "light amplification by stimulated emission of radiation." As its name explains, lasing is all about powerful light beams made of photons with tightly controlled energies. It's easy to forget too that the laser's invention changed the modern world, particularly in the case of tiny semiconductor laser diodes like those in your DVD drives. Now Japanese scientists have invented the equivalent semiconductor device but for sounds. These are devices for making very controlled vibrations, making vibrations with...