If you want to know how season six will begin i think all you need to do is watch the season three episode entitled "Flashes Before your Eyes". In this episode we are shown what happened to Desmond as a result of turning the fail-safe key inside the hatch. After Desmond turns the key there is a white flash, which i believe is the same type of white flash we saw when the hydrogen bomb went off at the end of the season five finale. After the white flash occurs desmond is all of a sudden laying on the floor of his apartment, he is now off of the island and reliving his past. He still retains his memories of his time spent on the island, as well as events that will occur in his future off of the island. There is a scene where Desmond is at a bar with his friend trying to explain to him that he has traveled back in time and that he knows what will happen next. He goes on to tell his friend that he knows what the ! outcome of the soccer game they are watching will be and also that a man they know from the neighborhood is going to come into the bar and attack the bartender. After niether of these things happen Desmond is left confused and begins to doubt whether or not these memories hes having are actually real. A few nights later though, Desmond returns to the same bar and realizes that this was actually the night he was telling his friend about. The soccer game ends the way he remembers and a man walks into the bar planning to attack the bartender but Desmond intervenes and is knocked out, which results in him instantly being back on the island, laying naked in the jungle and with the capability of remebering the future because he has already lived it. I believe that once Desmond was able to mentally accept what was happening to him in that moment in the bar, it caused him to consciously return to the island. Also, i think that the begining of season six will show Jack and the r! est of the group that set off the bomb, off of the island in t! heir pas t, just like what happened to Desmond. They will all have memories of their futures off of the island as well as on the island and when each of them are able to mentally accept this they will be returned to the island just as Desmond was. The key to this theory is that i believe the white flash caused by the turning of the fail-safe key and the detonation of the Hydrogen bomb are the same, and that the result of both instances will be the same. If this theory is too rediculous to understand i recommend just watching the episode.