The Surprisingly Practical Reason Behind Doctor Who's TARDIS Design

Regardless of whether you're a "Doctor Who" fan, you must know about the TARDIS — the blue police box that can travel through space and time, and is bigger on the inside. The TARDIS is a mainstay of "Doctor Who" and perhaps the sci-fi show's most recognizable object; it is a time travel device used by the show's Time Lord to go on his adventures. Whenever anyone steps into the TARDIS, their jaws usually drop upon seeing how large it is on the inside.

But have you ever wondered why the TARDIS (an acronym for Time and Relative Dimension in Space) looks the way it does? Why it looks nothing like a car that speeds up to the point of time travel, a cosmic treadmill, or a flying, UFO-resembling device? It's just a regular old police phone booth. The Doctor's adventures span across eras — from the days when Vincent Van Gogh was a disgraced painter to the end of the world. So why not give him a cooler-looking spaceship?

There's actually a pragmatic reason why the time-traveling protagonist uses a police phone box to jump back and forward in time.

Budget is a universal issue, apparently

"Doctor Who" was imagined as a different show altogether — it was meant to be an educational family program. The main characters were intended to be science and history teachers, and they'd tell stories entirely based on historical events sans aliens and the possibility of time-traveling across eras.

The TARDIS was conceived as an object that would take the form of an article belonging to the period the episode would focus on. For instance, in an episode that took viewers to Ancient Greece or Egypt, the TARDIS would be redesigned as a column (representing Greek's pioneering architectural style) and a sarcophagus (a stone coffin), respectively. Part of me can't help but envision how hilarious it would be to see the Doctor emerge from a coffin ... it's wild to imagine what we could've had.

Anyway, when the show's budget was being calculated, it was discovered that giving the TARDIS a make-over for every episode was expensive and not at all becoming. So the makers of "Doctor Who" came up with a strategy to give the time-traveling machine a suitable appearance — one that was inexpensive and had the potential to evolve into something symbolic for the show. Thus, the police telephone box was born!

All about the malfunctioning chameleon circuit

In the "Doctor Who" universe, the TARDIS was equipped with a "chameleon circuit," allowing it to hide in plain sight. The time machine blended in with its surroundings. So, when the show was released in 1963, the time travel machine took the form of one of London's many police phone boxes.

In a mini-episode from the season 5 DVD box set that explains the workings of the TARDIS, the Doctor explains (via Den of Geek): 

"Every time the TARDIS materializes in a new location, within the first nanosecond of landing, it analyzes its surroundings, calculates a twelve-dimensional data map of everything within a thousand mile radius, and determines which outer shell would blend in best with the environment... And then it disguises itself as a police telephone box from 1963."

Naturally, with the popularity of "Doctor Who" today, the budget isn't a problem anymore. They could transform it into a spaceship or a car ... or a coffin. But despite looking like a regular old police telephone booth, the TARDIS has become one of the most popular sci-fi time machines of all time. And now the ironic thing is, the police telephone boxes (once an incredibly common sight in the '60s) have all but disappeared from the streets of London, and the anachronistic blue box is now associated largely with "Doctor Who." The Doctor might regenerate now and then, so a new face may lead the sci-fi series, but the shape and form of the TARDIS remain the same.