Her is a film about a man falling in love with an operating system; it looks from outside like a technophobe’s ideal parable.* I began quite worried that Her would be overly preachy: Aren’t we all too obsessed with our phones, real communication is amazing, and that sort of thing.

It puts paid to that pretty quickly: the opening scene shows Theodore at his job, writing apparently heartfelt letters on demand for his customers’ celebrations. One of his customers supposedly misses his girlfriend’s little crooked tooth, another [something]; the results are printed out in artificial handwriting and sent away. (The company is called BeautifulHandwrittenLetters.com.) Her might look like the kind of film that would encourage us to write handwritten letters to one another, as a corrective to the wealth of humanity-less digital communication that we are continually exposed to; but Her shows that letters can’t be honest anymore.

If it does say anything about the world it’s that world that’s summoned by the anti-tech lobby is the equally fantastic — it seems, through Rooney Mara’s Catherine, Twombly’s ex-wife, that he was just as bad at dealing with real humans as he is with his operating system. (And the end of the film — which I shan’t ruin — is a warning that real stasis of the kind that might be asked for couldn’t ever happen anyway: people grow up.)

The film is kind of sci-fi: a domestic, understated take on a genre that I completely adore but admit has had trouble, since the 1980s, in trying to grow up. It has, of course, absorbed new technologies, and found a new platform to launch its speculations from as the present has changed, but its worlds have become almost backward looking: a vision of the future from the past. Her’s world is different: subdued and private. It’s sci-fi for a world that has seen technology become a friend, not an enemy; the greats of sci-fi past might not have been surprised by NSA snooping, but they’d probably have been surprised to find out that nobody is really bothered.

The attention to creating its future world is meticulous. What sci-fi has often got wrong is its belief that the world of the future will be very different from how it is now. Her avoids that: its future is one of slightly higher waistlines, emptier houses, a fondness for moustaches. It actually looks as old as it does new. It’s supposedly set in LA but its supersprawl is more like the megacities of south east Asia; its architecture, as with its set design and clothing, traces the economic vectors that exist in the world now, rather than the familiar sci-fi trick of exaggerating the present world’s most new features.

It was maybe three or four times during the film that I realised that there is only one person on the screen for roughly 90% of the time. Johannson and Phoenix do such convincing work in living what is essentially an internal monologue that it’s easy to forget that only one of them really exists. (There are arguments, there are make-ups, there are sex scenes, all between one person and a disembodied voice.) Samantha Morton was the voice during filming, re-cast after the fact by Johannson, making the achievement at once greater and more obvious.

The humanity of that acting, and the sensitivity of the whole work, lets a film about technology become a film about people, and one about people become one about technology. It could easily have been about fear, or excitement; but its biggest achievement is not being about, or saying, anything in particular.

* This happened once in the Big Bang Theory, in one of the only episodes of that show I’ve ever watched. The plot is essentially the same.