I can't help but wonder : where is that bloody bomb ? We are to think that Juliet didn't detonate it, since the white flash that concluded season 5 was a time flash, and not an explosion flash ( and the island wasn't turned into a nuclear wasteland )… So Jughead should still be there … But when Sawyer finds Juliet in the Swan debris in « LAX », there's no sign of it. Here's the theory : as Sayid pointed out, Dharma built concrete walls « like Chernobyl » in the Swan … We were led to think these walls contained the island's electromagnetic forces … but what if they contained a leaking Jughead ? Juliet didn't detonate it, but perhaps she caused it some damage anyway. Which would explain why Dharma left it where it was : if it was leaking, it couldn't probably be relocated safely somewhere else. And the button ? Possibly the strong electromagnetic forces at the Swan threatened to detonate the bomb, hence the button, that released some of the electromagnetic pressure on the bomb, so to speak. When Desmond activated the fail-safe key, perhaps it allowed these forces to crush the bomb completely, making it implode instead of exploding. And then, no more Swan, but no more Jughead either. So in a sense, the Swan inhabitants WERE saving the world : Jughead exploding would probably have meant the end of the island, the end of the Light, the end of the world. How could Dharma know about the worldwide consequences of what happens on the island, do you ask ? Ah, but the people who claimed to « save the world » were Inman and Desmond, and both came to the island quite late … so maybe they didn't take orders from Dharma, but the Others posing as Dharma ( like the dudes in « The New man in charge » ). Heck, Inman could BE an Other, for all we know !