Spoiler-ish.I was so relieved when I got to the ending and was rewarded with ambiguity and doubt rather than the heartbreak I was anticipating. Worrying about the ending did take a little away from the enjoyment of the story for me. I liked the characters, though I did notice that Calpurnia sometimes read as 11 and sometimes read as an adult recounting her adventures from a comfortable remove. Well worth reading, especially for science nerds.ETA: What I find I'm coming back to again and again is the soldier and the bat in the tent. That really worked for me in a lot of ways.