I have maintained for a while now that we have been watching a cleverly edited jumble of scenes from different realities made to look like one continuous story. I also think that attempts to change the incident will end up so that events will ultimately turn out as we know them from series 1-5. There may be some small differences like the date of the incident and whether Chang was there or not (ie whether or not he looses his arm). The concrete will still get poured, somehow the electromagnetism in the pocket will be plugged but the plug will be like a champagne cork - wonder where that idea came from
When Desmond released the special island properties/electromagnetism after turning the failsafe key he experienced conscious time travel. So did the Dharma employees who were in the immediate vicinity of the incident. Remember the man who drilled into the pocket of electromagnetism under the Orchid who died of a brain aneurism? Well we now know that was because he most likely consciously time travelled and did not have a constant. Did he travel to a past where he did not recognise anything? Did Chang and Radzinsky travel back to a time when they DID recognise something, something important to them? When did they flash back to? That is, if Chang and Radzinsky were even at the site of the Swan when the original incident took place.
Looking at Desmond’s experience as evidence as to what happened after the incident I can guess that Chang and Radzinsky might have consciously time travelled back 8 years to 1969 or was it 10 years, or 5, or 7? It could be to anytime perhaps even the future, since Faraday said the phenomenon is unpredictable.
So if Chang and Radzinsky, for example, found themselves in a position where they knew the future, what would they do? Would they change things? They might bring their experiments forwards with knowledge of future ideas. This would be similar to how Faraday was able to short-cut his experiments by giving Desmond the correct frequency of his mind time travel machine. Perhaps the Swan was designed for physical time travel or just recording the findings from experimenting on the exotic matter. However, having found themselves in their past bodies and with this new information about how the electromagnetism works they changed the design for the Swan (Swan Orientation Film). Perhaps it was just Radzinsky whose mind went back in time, since he was so adamant to keep drilling but Chang was against it after the problem at the Orchid. Perhaps Chang was not at the Swan site for the incident but future events altered his actions and so he ended up with a damaged arm in one future reali! ty.
More importantly they were most likely able to avert the cataclysmic side affects of the incident. Would the incident have ended all of existence, or alter the space time continuum, or throw the island into another time or restart time completely to the start of all creation? Someone recently mentioned in comments that the whole of creation is a paradox. We are told however, by the writers, that the world of Lost is paradox adverse. Therefore something must happen other than a paradox. I conclude that there must be alternative timelines/universes/realities, call them what you will. Not as a result of events we’ve witnessed at the end of series 5 though. There will not be a reset in my opinion, the plan to blow up the bomb to alter the future will not succeed.
Teresa falls up the stairs, Teresa falls down the stairs. Desmond from 2004 went back in time to 1996, 1996 Desmond came forward to 2004. Did his consciousness get to see all of time? In a linear existence Desmond’s brain cannot compute the information it is given and Desmond may be in both timelines at once. Some people may say that Desmond only had flashes to the future after he turned the failsafe key but I believe that after he turned the failsafe key in 2004 this triggered his 1996 counterpart, in an alternate reality which was created from that point, to be able to flash to the future for brief moments. Therfore there is one reality where Desmond from 1996 goes about his life unaffected by anything time travelley and another reality where Desmond has been getting glimses of the future since 1996. It may very well explain why Desmond said what he said to Jack, that day at the stadium, the day he and Jack first met. “You’ve got to lift it up”. Desmond does not ge! t déjà vu, or an intuition, or a dream he gets a flash or a real memory. I talk about this in more detail here http://theoriesonlost.blogspot.com/2010/01/swans-white-light-is-conscious-time.html
This loop that everyone is suggesting could merely be the result of time travel which has indeed ripped apart the space time continuum. As soon as the electromagnetism was released everyone on the island and in the immediate vicinity was affected and time is now screwy. Rose had déjà vu, Clare had premonitions, Kate and Locke have had dreams, and then of course the lovely Desmond. So, some people more affected then others, proximity matters.