The Oceanic six, the Island’s constants….
This is my first time putting one of my theories out there so be gentle :).
We all know of the need for a constant when a person becomes unstuck in time. A constant that is outside of the effects of the person who has become unstuck in time. In Desmonds case he was able to use Penny because his conciousness was slipping in time and Penny was some one that was a live and known to him in the time line he was traveling thru (1996-present).
Ben has made it clear to Jack that they ALL need to go back to save the ones they left. In my opinion it is because they are connected to the group that is unstuck in time, they can be their PHYSICAL constants. It is similar to what happened to Desmond in that they are time traveling but they are physically traveling through time as opposed to just their conciousness. This is the same for the Island, Faraday said that it could be the island that is unstuck or it could be them. By the end of the first episode it seems clear that it is them BUT in my opinion its BOTH. The Island is unstuck and is only able to go into its past. It is no longer part of the PRESENT because as everyone that was off of the island when Ben turned the wheel we saw that the island literally disappeared from the present and was ‘moved’. But as Faraday said about the camp site, it’s not gone, it’s just not their yet. So the Island is currently ‘moved’ or gone but it can be returned to the present with a constant.
So for the Island and the ones left behind to be able to come back into the present they need the oceanic six to come back (since they were on the Island in the past and are connected to the ones that are unstuck in time) and be their physical constants to bring them to the present time line.