Radio gets rubble-rousing

摘要

Huge buildings could be conjured up in space using nothing more than focused radio waves to push individual components into place. Radio-controlled construction would get around one of the obstacles to colonising space―the need to ferry heavy construction equipment into orbit and support the people who will operate it. Narayanan Komerath, an aeronautical engineer from the Georgia Institute of Technology, got the idea from a technique called "acoustic shaping", in which sound waves are used to build solid objects in weightless environments (New Scientist, 1 September 2001, p 32). Speakers in a closed chamber transmit sound waves that can push, say, plastic beads around. The beads come to rest in acoustic dead spots called "nodes", which they can't easily escape from because the air pressure at all surrounding points is higher.