So it looks like Mommy Eloise screwed up the time-stream originally somehow and she raised her son in one time-stream to skip music for science so he could try to right her wrong (something to do with the bomb
Widmore's daughter Penny and Desmond have some special time-equation properties also because they seem to factor into the events that led everyone to the island. Desmond must intersect with Penny in all time-streams and Desmo

The whole subplot with Charlie was pretty good ... in this time-stream he's had a vision and seems to invite death by pushing limits on everything - hoping to have the revelatory moment he recounted
Desmond is Widmore's favored errand boy/dealmaker in this time-stream and he tasks him with seeing his wife to break the bad news that Charlie's band won't be performing and this will disappoint her son (Faraday). She takes the news in stride and only turns into the predicted witch when Desmond mentions trying to find Penny. Eloise tells Desmond not to look for her to just leave it all alone.
Faraday overhears and takes Desmond aside and tells him he thinks they've lived other lives and are seeing flashes of these other lives and that he, Faraday, blew up a nuclear bomb in one of these other lives. Desmond looks at him like he's a wackadoodle until he says Penny is his half-sister and he can tell Desmond where to find her.
Cool back-and-forth between time-streams and story arcs this ep - well done. And at the end when a resistant Desmond is checked, found healthy, and released from the electro-magnetic experiment Widmore had subjected him to on
Now I don't know how they are going to join up the supernatural with the science, but



























