Her is one of the great cinematic sci-fi films. It may seem narrowly confined to a few characters and locations, but it is grand in philosophical scope, interrogating big questions like the nature of human relationships, the nature of consciousness — really the entire nature of humanity, come to that.

Joaquin Phoenix is Theodore Twombly, a lovelorn writer who activates a new computer interface, Samantha (Scarlett Johansson, dubbing over Samantha Morton, who performed the role live on set). Samantha begins as a servile Siri-like AI but soon becomes very human. For many intents and purposes (love, comfort), the arc of Theodore’s relationship with Samantha is indistinguishable from his previous relationship with his estranged wife (Rooney Mara). Meanwhile his neighbor (Amy Adams) is experiencing a deep friendship with another “conscious” OS.

The OSes at first are jealous of the people they interact with, wishing they could inhabit physical space. Eventually, they embrace the otherness of their form, moving to places beyond what Theodore and his fellow humans can understand.

All this is told with beautiful, very digital-looking cinematography (Hoyte van Hoytema with additional scenes by Spike Jonez regular lance Accord). The imagining of a future world and it’s design elements is impeccably done, but all nicely tucked away in the background while characters and their emotional lives take the foreground.

The soundtrack choices are as impeccable as impeccable the design elements. I’m sure there are some who will find them, like the film itself, too twee. But not me. Other than a short sequence involving a character played by Olivia Wilde, I can think of nothing about the film that could be profitably altered. It’s a remarkably sincere film that is nonetheless often hysterically funny.

As a bonus, it proves that grand, romantic sci-fi need not be a baffling slog. (I’m looking at you, Solaris.) Her should be seen immediately. I’m worried something this fragile and beautiful will evaporate — or suffer the fate of most sci-fi, falling into retro kitschiness. The idea of falling in love with a talking OS seems so on the cusp of both possibility and absurdity at this very moment. Eventually it will teeter and fall to one side, leaving this film but a fraction of its former self.