The kid / my theory of Qohen
Don't you think the kid (Bob) stole the show? His interactions with Qohen are to me, much more interesting then the girl and Qohen's. I really like how their relationship develops towards the end.
Also I think Qohen is an agnostic theist, he gave up searching for zero theorem when he realized the answer is unattainable, but he still waits for "the call" which I think signifies his belief that there is some purpose for existence after all. He also opposes Bob's view which is a sort of Atheism/Nihilism. He asks Bob why would you believe the worst possible outcome.
As for why Qohen called himself we and than changed it to I near the end, I got no idea what that's about, could be number of things. What do you think?