They are always there, they are never explained, and they are (almost) always red. They are blinking tubes that don't do anything. The prop has been used in just about every science fiction movie you've ever seen, even if you don't recall them. Don't believe me? Then watch this compilation of clips that show the same tubes in science fiction stories through the spectrum of the genre.
A bit of digging revealed that this the most common of these gadgets was owned by a company called Modern Props. At one time, you could rent it for $775 a week. Modern Props went out of business last year, and most of its inventory was sold at auction. The science fiction stuff, however, may eventually be donated to a museum.
(via Geeks Are Sexy)