TARDIS

The TARDIS is the name for the machine used by Dr Who for travelling through space and time. TARDIS is an acronym for Time And Relative Dimensions In Space. It is bigger on the inside than on the outside, and usually takes the form of a (British circa 1950s) blue police box, and although it is supposed to blend in inconspicuously in whatever time or environment it turns up in, it invariably shows up as a blue police box. (This was probably a ploy by the BBC to save time and money in props, but became an in-joke genre convention in its own right, particularly since there have been very few of these left in Britain for some considerable time). The rationalisation for this was given quite early in the series as a failure in the mechanism which enabled the machine to do the adaptation. Despite considerable ingenuity in other fields, and ownership of a sonic screwdriver, Dr Who has been entirely unable to rectify this problem.