“Worlds Apart” is episode twenty of season four of Fringe.
Walter has called a meeting of both Fringe teams. He tells them he thinks David Robert Jones is trying to collapse both universes into a singularity, in order to create a Big Bang. Olivia asks why and Walter says that Jones wants to create another universe where the laws of physics and nature are designed and controlled by him. Broyles asks how Walter came up with this. In a dream. Fauxlivia suggests that maybe it was just a dream, but Walternate thinks it shouldn’t be overlooked. Peter asks how.
In different countries, people, one of them in Manhattan is Nick Lane from “Bad Dreams”, are using countdown timers and maps to get to specific coordinates. Once there, they close their eyes and the ground starts shaking.
Fauxlivia asks how Jones would survive the destruction of both universes. Peter mentions how, when both Westfields were destroyed in “Welcome to Westfield”, one area was still standing. He thinks Jones will have built a safe zone for him and his creations. Walternate is told there is a message as Walter is being asked if there’s any way to stop this. Then Olivia, Fauxlivia and Broyles are all contacted. There have been quakes all over both worlds.
In his lab, Walter tests items from Manhattan’s epicentre. He says that they vibrate at a different frequency from either universe. Jones is trying to tune both universes to the same frequency, weakening the barrier between the universes. Done enough times in the right places and they will collapse.
Over there, and that universe’s Nick Lane comes to see Lincoln. He had a vision of the quakes before he even knew there had been any.
Astrid has found a photo of the woman who was in Sydney. Lincoln calls Olivia and explains about Lane. Olivia says she will call him back. Astrid is going to run facial recognition on the woman, but Olivia says it’s Sally Clarke. They were in the cortexiphan trials together. Olivia thinks Jones is using the cortexiphan subjects.
Walter says they are using their psychic abilities to link to the other versions of themself. Peter asks if the Bridge could facilitate the link, and if they close the Bridge, if that would stop it. It would, but Walter doesn’t know if they’d ever be able to restart the machine. The link is causing the other universe to heal. If severed, the healing will stop, though the other universe won’t get any worse. The alternative is to find Jones and stop him.
Olivia has an idea, which is using AltLane to try and make a link between her and her world’s Lane. This is used to find and catch Lane, but doesn’t stop the next set of quakes. And Walter is surprised that the universes haven’t already collapsed. This means they have very limited time to stop Jones, otherwise the link will have to be severed.