Store bits in thin air [Resources_Hands On]

Recently, I moved from Boston to New York City, which necessitated a purge in order to fit into our inevitably smaller apartment. One of the things I tossed out was an old Electronics Learning Lab from RadioShack, which consisted of a breadboard surrounded by commonly used electronic components such as potentiometers, buttons, and LEDs. "You can throw this out," I thought. "What are the odds you're ever going to need it again?" The glow of decluttering lasted until I saw a project by Joseph Allen, who used the Electronics Learning Lab to re-create an acoustic version of an ancient form of computer memory: the delay line.