I have come up with what I believe may be a possible way around the problems with time travel and the version of the Grandfather Paradox (GFP) that has been set up at the end of Season 5. It is based on the Quantum Suicide Quantum Immortallity (QSQI) thought experiment, which is a version of the Schrodinger’s Cat thought experiment from the perspective of the cat. Hang on because this will be a little lengthy.
At the end of Season 5 we see a situation that is apparently going to set up a version of the GFP. The Losties have set off a nuclear bomb in the hopes that the end result is the prevention of the building of the Swan. Here are the posibilities that I see:
1) The nuclear blast results in the death of the Losties and the destruction of the Island. This results in the Swan not being built because there is no one left to build it and no Island left to build it on. This in turn results in 815 not crashing and the Losties don’t go back in time to stop the swan from being built. End result: the GFP is set up with the endless time loop that comes along with it.
2)The nuclear blast interacts with the electromagnetic pocket (EMP) in a way that it is negated and the EMP is destroyed. Everybody lives and there is no need for DHARMA to build the Swan. 815 doesn’t crash in the future and we end up with the GFP again.
3)The nuclear blast interacts with the EMP, the Island isn’t destroyed, and the Losties are somehow thrown back to the present. Initially the EMP is contained but then starts to exhibit the build up of energy. So DHARMA builds the Swan (knowing now to be extremely careful) in a way that they can regulate it easily and go ahead with the planned experiments. There is another incedent at the Swan that results in the 108 protocol and the story unfolds as we know it. I am assumming a second incedent based on a notaion on the Blast Door Map that mentions the escape conduits being blocked after an incedent. To me this notation only makes sense if something happened after the Swan was built.
So which scenario plays out? This is where the QSQI is applied. What happens is that due to the special and strange properties of the Island all three scenarios happen at the same time but in different universes. What actually happens is that three copies of the Island are created and each scenario plays out. However, each universe is unaware of the existence of the other universe, each copy of the Losties only percieve the one they are in. Since the first two scenarios result in a timeloop due to the GFP, a version of the Losties are always traveling back to ensure that the nuclear bomb explodes. The third scenario is free to continue on. Now we already know that the Island is shrouded from the rest of the world due to the fact that it exists roughly 36 minutes behind the rest of the world. As long as nothing happens to bring the Island in sync with the world the timeloops will continue around and around thus ensuring that the tird scenario plays out. If the Losties trapped in the timeloops ever figure out that they are in a timeloop and somehow escape everything collapses.
The way that the QSQI was set up was with a man isolated in a room with a gun to his head. there was also a particle in the room and a detection device that the gun was hooked up to. the detection device was set up in a way that if it detected the particle was spining clockwise the gun would fire and kill the man. If the particle spun counterclockwise the man would hear a click from the gun but no bullit is fired. As long as no one from the outside looks in on the man both versions will happen in two different universes that are created when the particle is detected.
I know there are some problems with what I just presented and I know your comments will be very insightful in the matter. I consider this to be just one way the writers could go and it is something that I consider to be plausible although far fetched. I hope you enjoy it.