I hadn't read the short story, "Story of Your Life", so I decided to read it this evening. It was quite different, and less to my taste than the movie -- the story went into much greater detail on the linguistic details of language structure and language learning, and it also spent quite a bit of time on physics, which the movie barely touched on. I feel like that level of detail would have bogged down the movie, which moved as a fairly slow pace as it was. Not too slow -- it actually felt just about the right length -- but any slower and it probably wouldn't have worked. As it was, I think Arrival does a good job of taking the main ideas of the text and transforming them to film.
One change that I thought worked quite well was the ambiguity of the timeline. I didn't realize that Hannah was Louise's future daughter, as opposed to her tragic backstory, until just before the movie confirmed it. It added a level of emotion to the film that was less immediate, to me, in the short. I suppose mileage will vary on this, as with the addition of international tensions to the movie. That's a change that works for me, too, because it effectively raised the stakes. The stakes in the story feel much lower, which is fine for a story of that length (my copy was 39 pages) but would be a lot harder to pull off in a Hollywood movie. About my only quibble is the causality loop, wherein Louise saves the day because the Chinese general gives her his phone number in her future memories. I'm not a fan of causality loops; they feel like cheating to me, and also tie in too closely to the idea that everything that happens in the universe is fated and we have no free will. This one bothers me less than some others (I'm looking at you, INTERSTELLAR), but it's such a pet peeve of mine that I can't not mention it.
Good movie. Go see it. Strong contender for best SF/F film of 2016, for sure -- you can bet that this will be on my Hugo ballot.
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