Concept of time

The science fiction elements of the novel include time travel. Billy leaps in time, experience his life's events out of order and repeatedly. He learns on the alien world of Trafalmadore that all time happens simultaneously; thus, no one really dies. But this permanence has its dark side: brutal acts also live on forever. Memory is one of the novel's important themes; because of their memories, Vonnegut and Billy cannot move past the Dresden massacre. Billy leaps back in time to Dresden again and again, but at critical points we see Dresden simply because Billy relives it in his memory.