It was something my fellow classmates had a hard time grasping in chemistry, the idea that each side of the equation must be equal or something would go terribly wrong. For Fringe, this balance exists between two universes, and when Newton – the newly re-headed bad guy – attempts to open a doorway to the other universe, the results are disastrous.
The doorway, it seems, allowed a building – and all of its occupants – to travel into our dimension, fusing with the building – and all of its occupants – already in existence in a mishmash of parts and personalities. Through the memory of an old experiment, Walter realizes that he already knows what is going to occur: Something from our universe must travel into the other to re-establish the balance that was thrown off by Newton's experiment.
Peter's eventual conclusion is that some building of equal mass must travel to the other side and the episode's main charge is finding that building and evacuating all of its occupants. The question of how falls on Walter, who presumes it can be located by someone who can see the opening window to the other side – something he is sure Olivia can do, if she can only re-activate another one of her abilities: seeing the things in our world that do not belong… the things that come from the other reality. This catapults our heroine on a journey back to the place where this ability began – the titular 'Jacksonville'.
Previously mentioned as a smaller cell of a larger study, Walter informs us that it was the only place where the Cortexiphan injected into small children worked, giving them special abilities. The strongest of those children, Olivia – then known as Olive– Dunham, arrives and observes that despite her "freakish" memory, she has absolutely no recollection of the Day Care Center in which the experiments took place.
As an aside, did the parents consent to this secret testing? Olivia had mentioned her father had been in the army, stationed for a short while in Jacksonville – if he did consent, were these trials part of some larger government testing? Creating a soldier who can destroy an enemy with their mind would be valuable to a government looking to eradicate losses, both personal and political.
The key to reconciling Olivia with her previous perceptive powers, says Walter, lies in their ties to strong emotions. With the help of another dose of Cortexiphan and Walter's special blend of drugs, Walter sends Olivia into a dream-like place where she soon finds she's not alone. A small child argues with Olivia that she doesn't want to do this anymore and that she has to make them stop. Olivia catches the child, comforting her before asking her name. "Olive."
Confronted with herself, she's lost in that fear and the child disappears from her arms, only to appear a foot away with eerily bright blue eyes, scaring Olivia enough to wake her from her dream no more able to see the things out-of-place than she was before. The emotion Walter was shooting for, he explains upon re-watching the video we previous saw of Olive sitting in the pristine center of a scorched room, was fear. Of course, Olivia isn't afraid of anything anymore and Walter presumes that without the particularly strong emotion of fear she will never see what she needs to see.
Returning to Manhattan more jarred than enlightened, the team sets out to solve the riddle of which building will be transported using the only piece of information they do have – it must be of equal mass to the building that came from the other side. Of course, the closer it draws to the moment of truth (as Walter calculates they had roughly 40 hours from the time the original building came through), the more helpless Olivia feels.
As the only known person to have had this ability, she feels responsible and approaches Peter with this fear. In comforting her, the duo lean in for their first shared kiss and Olivia realizes, she's afraid. She bolts from the room, looks out over the city, and sees a building shimmering in the distance. The occupants of the building are evacuated and the building gets sucked violently from sight, something Olivia knows the conspiracy theorists will have a field day with.
Of course, the fans can have a field day with this episode. Did Olivia's FEAR of not finding the building trigger her ability (an emotion *I* would have classified closer to disappointment, or frustration), or did her fear of what was about to occur right in front of her – being approached by Peter in a more-than-friendly capacity – flop her gut in a less than fearful and more like love kind of way. Walter only stated that it had to be a strong emotion; he assumed it was fear because of what worked with the children – particularly, Olive. For a child, a strong emotion can be anything; as an adult, it's harder to stimulate love than fear, and it is definitely the greater of the two emotions.
There's also now the question of Peter. Before departing on their first 'date', Olivia is able to see Peter shimmer in much the same way she was able to see the building in the city, clueing her into the fact that he is not part of this reality. Of course, given the information we received throughout this episode, for Peter to have come into our world, something (or someone) of equal mass must have gone into the other.
Did Walter deposit Peter's dead body into alt-Peter's bed, for his parents to find and mourn? Or, given his curiously saddened response to Astrid's proclamation that the alt-people just vanished and their loved ones would never know where they went, did he simply steal Peter, leaving alt-Peter's parents to wonder forever what happened to their son. Is that the reason for this "war" of the worlds? Alt-Walter might not have changed as much as our Walter has and his vengeance may be a great behemoth of scientific catastrophe waiting to happen.
It also begs the question, William Bell is too large to have 'replaced' Peter in the alt-world so whom did he replace? Or, as Walter mentioned, Peter was more rotund as a child, possibly Bell would have been a lanky fellow and WAS his replacement. And where does Nina fit into all of this? Did she help orchestrate Peter's substitution and 'rehabilitation'? Is travelling to the other universe how she lost her right arm?
And, given the dangers of temporal displacement, though Olivia seems pleased that they saved the occupants of the hotel in OUR universe, she gave little thought to the consequence of said building merging with its mirror in the OTHER universe. Presumably this mystery is being solved by Alt-Olivia, with or without the aid of Alt-Walter. From a previous episode we know she's still working in a 'Fringe' division with Broyles and Agent Francis.
Which brings us back to Peter, the one element that – no matter the sequence of events – increasingly seems to be at the heart of the imbalance bringing these two universes crashing into one another. Does total balance between the universes require that he be returned? Does it require that of William Bell as well? Or is there something else, some other piece of the puzzle yet to be revealed. Can Olivia's abilities seal the gateways permanently, or would it require some greater event?
I envision a finale that involves alt-Peter asking alt-Walter to let him go, to stop trying to get him back because he's made a home where he is. I also envision Olivia encircling herself and Peter in a fiery wall of protection, mirroring what happened to her as a child, but this time using her powers out of not fear, but love. But something tells me we're in for something far greater.
We just have to wait two months to get to it.