Lost, Sixth Sense and Jack's loophole by poupeta

My first reaction to the finale was SADNESS and DENIAL. Then ANGER.

Now, after being able to rewatch I have two theories-opinions to post.

1) I think the alternate timeline was something like the "living a normal life without knowing you are dead and without remembering you past life", something like Bruce Willis in the "Sixth sense".

Then someone comes to tell you you are dead and then you can let go and your spirit can go wherever it is that a spirit is supposed to go..

So, I believe that when the losties died either on island or elsewhere they "lived" this "life" until all of them could be reunited and remember.. and realize.. and let go..

2) I played the dialog between Jack and Desmond before him going down in the light few times and I have another theory that maybe will make some people really angry but kind of made me feel better about the finale..

Here it is:

Desmond:We sat next to each other on Oceanic 815. It never crashed..
Jack:I tried that once.There are no shortcuts, no do-overs.What happened happened.Trust me I know.

Well, I believe back in the Pilot, Jack was trying to make a do-over but end the same. I believe he either did that with Jughead or later with letting Desmond do the job. Then he realized that every time it ended the same, he ended in the bamboo forest and the plane had crashed. So he decided to sacrifice himself so that the others could leave and live on with their lives.

As for Desmond, how could he know about the "alternate" life?
Well I believe it's either because of his speciality concerning electromagnetism or another idea that came into my head is that maybe it's got something to do with Hurley as the new Jacob trying to fix things by using Desmond between the two worlds..

Please people post your ideas. Help me out!