Adam and Eve

I have started to rewatch Lost, and I get to the episode that we first see Adam and Eve. Jack says that they have ben there for forty to fifty years, so I think that this info support that they are going back in time. Right now there are only 27 years before the crash and if they were to stop the crash both Rose and Bernard would not be in the past. If they are not going to have flashes anymore then they also haveto go to the past to see what happend.