Like the Tardis, the small television box is far larger on the inside; it's our passport to a kind of tourism, our window on wonders. Our control over the time flow of TV has increased tremendously since Doctor Who's first broadcast in November 1963, when we were helplessly subject to the linear direction of scheduled programmes. Back then, if you missed an episode there was rarely a second chance to see it; and indeed, a whole era of Doctor Who is lost, the flimsy materials of its film and video imperfectly stored, often taped over and never intended for posterity. Now the TV set has transmuted into various forms - tablet, PC, phone - and we can pause the show as it plays live, dip into YouTube or iPlayer archives of its past, and watch previews weeks before their terrestrial transmission.
Up to a point. Because the BBC - specifically, Doctor Who showrunner Steven Moffat - has decided to retain some of the old-fashioned suspense of Saturday night television by keeping the final instalment of this season strictly under wraps until its broadcast. Fans can revisit the most recent episodes, contextualise them through online and DVD holdings of previous series and painstakingly study the trailers, but the finale - the future of Doctor Who - still lies stubbornly ahead, retaining its enigma, and we, the viewers, can travel towards it only one day at a time.
It's about time, of course. The show is inherently about time. But while superficially its plots are built around the science fiction devices of temporal paradox and historical jumps, Doctor Who's underlying themes are simpler and more universal, transcending genre conventions. Doctor Who is a family show, with all the love and loss, the irritation and in-jokes that "family" implies and involves. It's about ageing, growing up, death and departure; it's about being both a child and a parent, about falling in love and losing friends. Despite its alien protagonist, Doctor Who is, at heart, about understanding what time means to humans.
It's not about its SF trappings, although they also carry a charge of heritage now and rely on cultural memory for their power. For example, the 2005 reboot made us wait for a glimpse of the Doctor's most feared and hated enemy, and then offered only a single iconic figure in the sixth episode of the season, titled simply Dalek.
The thrill of spotting Cybermen in the trailer for the 2011 season stems not from their design or production - despite improved special effects, they still look like a cheap cross between C-3PO and the Tin Man - but the fact that they first faced off against William Hartnell, the First Doctor, in 1966. For perspective, consider that the leading academic expert on Doctor Who, Cardiff University's Matt Hills (author of the 2010 book Triumph of a Time Lord: Regenerating Doctor Who in the Twenty-first Century), wasn't born until five years later. Hills, like so many others of his generation, grew up with these monsters: he first saw them from behind the sofa.
While it constantly reinvents itself with new talent, assistants and effects, Doctor Who is more about nostalgia and reflection than shiny, whizz-bang novelty. 2005 saw the franchise revived by Christopher Eccleston with a buzz-cut and leather jacket, and pop star Billie Piper as his sidekick Rose Tyler, but the most memorable scenes of "New Who" are the simplest: the Tenth Doctor saying a final, tearful goodbye to Rose on Bad Wolf Bay, as poignant a farewell across parallel worlds as anything in Philip Pullman's His Dark Materials trilogy.
Similarly, 2006's Rise of the Cybermen may look like a science fiction story, but its mood is more Sliding Doors than H.G. Wells: like the Gwyneth Paltrow movie of 1998, it uses the device of parallel worlds as the pivot to contrast what is with what could be, and to offer Rose another bittersweet opportunity to see her dead father again, in an alternative timeline. Time travel granted her this second chance once before, in the 2005 story Father's Day, which whisks her back to his death in 1987: she saves his life and causes a paradox, so to repair the rift, he sacrifices himself. Rose cannot stop his passing, but can witness it as a young adult, and comfort him as he goes. Again, it relies on a generic SF trope, but the emotional heft of the story is similar to Audrey Niffenegger's 2003 novel The Time Traveller's Wife, which despite its title placed more stress on the "wife" - the central romantic relationship - than the time travel.
Doctor Who has a reputation for scares, but it's no more horror than Hamlet, no more a ghost story than A Christmas Carol: it's no accident that both Shakespeare and Dickens have already guest-starred in the show's historical jaunts. It draws on childhood fears and folk tales for its most haunting imagery - a giant doll's house, a grotesque statue, a sinister nursery rhyme - but like Dickens, while it toys with the spiritual, it can never resist sentiment.
The penultimate episode of the 2011 season, Closing Time, is ostensibly about the Cybermen's return, but its real narrative is young father Craig Owens' (James Corden) rescue of his baby son. The Eleventh Doctor (Matt Smith) offers a pseudo-scientific rationale for Owens' ability to resist the cyborg process, but abandons it for a simpler explanation: "You blew it up with love," he gently concludes.
The dominant note in Doctor Who is melancholy, an awareness of passing time and the loss that it inevitably brings. The Doctor goes on, regenerates and survives multiple series; but actors grow older, move on and die. Perhaps the saddest scene of all is the Doctor's goodbye to Sarah Jane Smith, played by Elisabeth Sladen. She was Jon Pertwee's assistant in 1973, stayed on during Tom Baker's first two years in the role, and returned in 2006; she, of course, was 30 years older, while the Doctor was a new, younger man, played by David Tennant. In April 2011, Sladen died, aged only 65. The Doctor continued, played by another, even younger actor in the shape of Matt Smith.
Earlier Doctors and assistants pass away, and the character - like the show itself - is passed down from parents to children, engaging a new generation. But immortality is a lonely journey. Always surviving as a cultural icon means saying painful goodbyes to those with normal lifespans and ultimately remaining alone, and the series increasingly reminds us of that.
Rose was replaced by Martha Jones (Freema Agyeman); Martha was replaced by Donna Noble (Catherine Tate); and Sarah Jane's role is now held by Amy Pond (Karen Gillan), cheerfully dubbed "The Girl Who Waited" by the Doctor, who dips in and out of her life from childhood to middle age.
One episode of the current series saw her trapped in time for 36 years, then breezily "rescued" by the Doctor, who has little sense of what she had lost by being left alone for so long. The scene where Amy meets her younger self can be admired for its make-up, its digital trickery and for Gillan's startling performance as the same woman at different ages and with different experiences, but on a fundamental level the episode isn't about Amy at all. It's about Sarah Jane and Elisabeth Sladen, the girl who stays forever young in the 1973 videotapes and the woman who passed away in 2011.
In the following episode, the Doctor says goodbye to Amy, telling her he'd rather leave her while she's still alive than wait until he gets her killed.
On the surface, it's about time. But at heart, Doctor Who isn't interested in science. It's about heart.
Will Brooker is the head of film and television research, Kingston University.