I think it is here that the film is really interesting. On the whole there are lots of silly things about Inception (it is the kind of film I loved as a teenager and thought terribly profound), but the idea that a) you can become consumed by your past and b) you CHOOSE to do this IS quite a profound one. The final shot of the film [spoiler here] is of the spinning top Cobb uses to test the 'reality' of his world - if it continues spinning then it is a dream. Nolan cuts the slow zoom onto the spinning top before it can fall; we actually watched this shot several times, arguing whether there was a slight tremor that indicated it was about to fall, thereby confirming Cobb had indeed returned to reality and his children. The ambiguity belies this neat ending, and therefore leaves it to the audience to decide. But does it really matter? If Cobb has chosen to live in a dream in which his wife is dead but he still has his children, what he has done is merely swap one dream for another. So the narrative seems to suggest that free will (in this sense just the freedom to choose) is the defining nature of existence.
The use of technology is linked to this self-determination. From the early days of Friends Reunited (remember them?) to the ubiquity of Facebook, a very modern preoccupation is to check out what other people (often from your past, often those you don't really see any more) are doing/what they have achieved/how fat they've got or not as the case maybe. This can become addictive, and seems quite ironic that for a society that can communicate instantly with anyone in the entire world at any time, we spend SO much time looking back. One of the most memorable scenes in the film is where Ariadne (Ellen Page) imagines the dream world folding in on itself, with the ground forming the sky. Is the Chinese-box style narrative a comment on this? Or the confines of a depressive mind-set, whose thought patterns run around and around on the same track?
Dr Who is less ambiguous in its judgement of the past (and future). Of course Rory chooses the young Amy. He had no choice; she was his future. The old Amy was stuck in the past (or future), isolated, hating, suddenly a genius capable of constructing a sonic screwdriver out of a bit of piping and a hairpin. Yet she was still Amy. Of course Amy is in a literal prison, but this has been shored up by her making a prison out of her memories ('I knew a boy who pretended to be in a band...'). The inability to move on from the past, this episode suggests, will age you, make you embittered. Existing only to survive. The technology here is designed to at once keep people alive (or at least comfortable in the passage to death), yet for the all-too-human Amy it is a living death. One touch from the (frankly slightly silly) handbots and she's a gonner. Lack of human contact, present, warm, messy, is the stuff of life in Dr Who. Interestingly Amy builds herself a Rory, with a smiley face but no hands. Now she has control. The final scene of 'The Girl Who Waited' sees old Amy and Rory touching hands through the glass door of the Tardis. They touch, but do not touch. Because old Amy cannot forgive, she cannot break through the wall she has built around herself. Technology distances, yet gives the illusion of closeness. And yes, I cried at the end of both of these. But then I'm soft.