I came up with this theory soon after watching the premiere of season 5. Daniel has told us that our heroes won’t be able to change the past, and that they won’t be able to contact people who they didn’t know in the past. But we don’t know what will happen if they try. I believe that if they try to talk to themselves or try to talk to the people in the past they will fail but will show up as The Whispers.
It does make a lot of sense, The Whispers always seemed to know a lot about the characters, there were times when they seemed to be trying to tell the characters something. And it’s true that The Whispers never seemed to succeed. If they were trying to tell the survivors something then it didn’t work. They scared them, but they never managed to tell them anything.
I don’t believe that The Whispers were only our people (Sawyer, Juliet, Locke etc.) I don’t think that there’s any way that they could have been around during every scene when the Whispers occurred. So, to address this obvious weakness in the theory, I believe that it is possible that The Whispers could be other people who were traveling through time. I doubt that this is the first time that it has happened.
(Note: I don’t believe that The Whispers should be disected. There are transcipts of The Whispers, and they are very interesting, but I don’t think they are meant to be analyzed. It’s supposed to be possible to watch the show without looking up this kind of info, so if it’s necessary to record and replay The Whispers over and over until you figure out exactly what they are saying… I think that’s counter-intuitive.)
I really liked this theory better than the old one, and it might have worked, if Sawyer and co. continued to Skip around in time for three moe years. But they didn’t so this theory is done for.