When the Oceanic 815 survivors travel back in time to 1977, they attempt to negate the release of this energy by detonating the plutonium core of a hydrogen bomb, causing a massive explosion that returns all of the time travelers back to 2007.
They attempt to negate the release of this energy by detonating the plutonium core of a hydrogen bomb, causing a massive explosion. This massive explosion returns all of the time travelers back to 2007. The Oceanic 815 survivors travel back in time to 1977.