So it's up to geeky Brandon, who shows off a little intra-universal coffee mug disappearing act. He explains that going "over there" is a bit of a misnomer, since the two universes overlap. Which I think the team knows, but "The Two Universes are Overlapping" is a much less catchy episode title. "To get to the other side, our universe needs to pass through you, literally, like... like water passing through a cheesecloth." Walter's studying Brandon intently. This is Walter's racket, Brandon! Don't you fuck this up for Walter Bishop! Brandon explains that the cells need to separate on an atomic level. "The problem is, when they come back together, they don't come back together with the same cohesion." Shielding himself with his hand, he taps the reconstituted coffee cup with a pen and it vaporizes in a blinding flash of light, like, THANKS FOR THE WARNING, BRANDON. He says Bell managed to cross back and forth, but they don't know how. "But I suspect that whatever methodology, he crossed so many times that he's become like this coffee cup: molecularly unstable." And also proclaiming its user as the World's Best Grandpa? "As many atoms in each of us, there are stars in the sky," says Walter, who asks Nina if that's why Bell never came back -- because he was scared the same thing happened to him. Nina says she doesn't know: "I've sent him communications, but if he got them, he hasn't been able to communicate to me." Maybe he just doesn't dig you anymore. Olivia says there has to be a way, though, and asks Walter about how he crossed over when he got Peter. "The last time I opened a door, it set in motion the ripples that weakened the very fabric of our reality. To do so again could instantly shatter both worlds. And likely would," he says. Well, except for Newton and the shapeshifting buddies who keep coming over.
Nina asks Brandon to give them the room for a moment, and then she tells Olivia that she has the ability to cross over safely. Olivia protests that she can't, not on her own; Bell's pulled her over, or she's flashed over for a few seconds, but that's it. "Not on your own, but if there were two or three of you, a larger power supply, as it were," says Walter, warming up to it. "I'm not following," says Broyles, because Peter isn't around to put everything in layman's terms. Walter babbles on about the collective psychic energy and how he and Belly always agreed that the primal part of the brain is responsible for paranormal activities like pyrokinesis, thought control, etc. "And that we all had these abilities, until there was a moment in history when something was done to us, and... and it was shut down. I suspect aliens," says Walter. But that's a whole 'nother episode. Anyway, it's a moot point, right? Because all the other Cortexiphan children they've found have "failed or worse," says Walter, and Olivia's the only one left.