Here's a theory about the effect of the bomb that's a little different from what I've read so far. What if the bomb collapsed the boundaries between certain time periods in the island's history within a close proximity of the Swan Station? People from the past, present, and future who were near the location of the Swan during those times suddenly found themselves in the same place, maybe 1977.
The time periods that merge are the same that our time travelers experienced in the beginning of Season 5. So now, joining Jack, Kate, Sawyer and crew are John Locke from the time he was banging on the hatch door after Boone's death, Faraday and Desmond from the time Dan asked Desmond to deliver a message to his mother, Juliet from the period when they were jumping through time, possibly Boone from a time he and Locke were trying to figure out what the hatch was, and maybe others. We don't know what was going on at that location during all of the time jumps because our time travelers were walking back and forth from the Orchid to the beach.
I'm not sure if we would have duplication of people if they were in the area at different time periods. Could make a wacky start to the new season.
The time periods that merge are the same that our time travelers experienced in the beginning of Season 5. So now, joining Jack, Kate, Sawyer and crew are John Locke from the time he was banging on the hatch door after Boone's death, Faraday and Desmond from the time Dan asked Desmond to deliver a message to his mother, Juliet from the period when they were jumping through time, possibly Boone from a time he and Locke were trying to figure out what the hatch was, and maybe others. We don't know what was going on at that location during all of the time jumps because our time travelers were walking back and forth from the Orchid to the beach.
I'm not sure if we would have duplication of people if they were in the area at different time periods. Could make a wacky start to the new season.