Researchers in the US have used an artificially-structured "metamaterial" to build a device that can control highly-elusive terahertz (THz) radiation. The modulator is claimed to be ten-times better at switching a THz beam than previous designs and could pave the way for the use of the radiation in a wide range of applications in chemistry, astronomy and even airport security (Nature 444 597). Sandwiched between the microwave and infrared regions of the electromagnetic spectrum (at about 300 GHz to 10 THz), THz radiation is notoriously difficult to work with. It is too high frequency to be manipulated electrically like microwaves...