How is it possible that while Sawyer can't interact with Desmond because he never encountered Desmond in their original timeline and thus the past can't be changed, how is it possible that the Losties are able to encounter everyone else, like young Widmore, young Rousseau, when they haven't met them in their original timeline. Isn't this changing the past? I find it unlikely that somehow Jin knew Rousseau in the past. It doesn't really work. Any thoughts?