Much of the Doctor’s incredible ship is shrouded in mystery, but we’ve discovered that it’s far more than a machine for travelling through time and space…

FEATURE BY JONATHAN MORRIS

The Doctor (Matt Smith) shows the Van Baalen brothers the Eye in Journey to the Centre of the TARDIS (2013).

The Eye of Harmony, as it appears in the TV Movie (1996).

Barbara (Jacqueline Hill), Ian (William Russell) and Susan (Carole Ann Ford) watch as the Doctor (William Hartnell) prepares to dematerialise the TARDIS in The Mutants (aka The Daleks, 1963-64).

THE TARDIS IS CAPABLE OF MANY FEATS, NOT LEAST ITS ABILITY TO TRAVEL THROUGH TIME AND SPACE.

The TARDIS is, without doubt, the most extraordinary piece of technology in Doctor Who. The product of one of the most advanced civilisations in the universe, it’s capable of many feats, not least its ability to travel anywhere through time and space. But how does it work?

To begin with, its primary power source is the Eye of Harmony, the source of energy that gives the Time Lords mastery over time. In The Three Doctors (1972-73) we learn that solar engineer Omega created this power source by detonating a star; in The Deadly Assassin (1976) its discovery is attributed to another Time Lord, Rassilon, and the power source is named as the Eye of Harmony, the stabilised nucleus of a black hole, relocated to an area beneath the Panopticon on Gallifrey. In Hide (2013) we learn that it’s possible to create a ‘subset’ of the Eye, which may explain why the Eye is present in the TARDIS in the 1996 TV Movie and Journey to the Centre of the TARDIS (2013).

It’s a little mind-boggling to fathom how the Eye can be present in every TARDIS, until you consider that the interior of every TARDIS exists in a different dimension (as explained in The Robots of Death, 1977). Presumably, just as the interior continua can intersect with real space-time through the door, it can also intersect with wherever the Eye is too; the Eye seen in the TARDIS is like the tip of an iceberg protruding into the TARDIS interior dimension while the rest of the Eye exists in real space-time. However, the power drains in Death to the Daleks (1974), Enlightenment (1983) and Flatline (2014) imply that the TARDIS’ power supply is finite – so perhaps the TARDIS only intersects with the Eye when it needs to refuel? In The Invasion of Time (1978) we learn that the TARDIS has an ancillary power station (disguised as an art gallery); might this be how the TARDIS is powered when not relying on its primary power source?

Of course, after the Time War the Ninth Doctor believed Gallifrey to have been destroyed, which is why he refuels the TARDIS by landing on a rift in time and space, filling up the engines with rift energy. (See Boom Town, 2005; Utopia, 2007; The Doctor’s Wife, 2011.) Dialogue in The Doctor’s Wife implies that this is ‘artron energy’, although elsewhere this refers to the energy involved in Time Lord regeneration. Rise of the Cybermen (2006) seems to resolve this discrepancy when we learn that the TARDIS contains power cells that the Doctor can recharge using years of his life – ie, regeneration energy.