it's sci-fi like this that make me thankful i'm a historian. I can just sit back and say 'ok' to all that science and enjoy the story without worrying about whether any of it makes sense. That being said, i'm certain a meteoroid would do more damage than that if it hit the earth, i mean, it's going pretty damn quick, right? Also wouldn't one that small burn up in the athmosphere anyw- no. shut up. Characters, plot, themes. Ignore the science.
I actually really enjoyed this story. I thought tom's emotional insanity was amusing and well explored. I liked how he was suddenly able to simulate entire universes and work out complex maths, but still couldn't manage to work out basic morality, or forgive some simple mistake for which he could clearly see she was very sorry, for several billion years. I was hoping for a slightly less depressing/unambiguous ending. I'd have liked for Mary's brain to have expanded into a universe of it's own, offering at least some hint light at the end of the tunnel.