The next day, Peter is still working on the clear blackboard and starting to get really frustrated. "I can't balance the equation. There's too many variables and not enough constants," he says. Olivia's not much help in that department, but she does point out that there have been sixty-five time slips reported in the past seventy-two hours, all within a forty-mile radius of downtown Boston (she's a little disconcerted when Peter leans a little too close, a little familiar) and given that most people don't report déjà vu to the FBI, they can assume there have been at least twice as many unreported ones. She's going over her categorization system with Peter -- fascinating stuff, really -- when Walter comes to stiffly say that he was going to make a baloney sandwich, and would she care for one. He's also expressly not offering one to Peter.
Olivia politely declines, and brightly says, "I'm working on the case with Peter," adding that they could really use his help. Walter: "I'd be happy to join you, as soon as my lab is available to me again." Good god, what a baby. Not only that, he takes the reference book Peter's holding -- Caroll's Cosmology -- by pretending he just happened to be looking for it, and stomps off back to his room.
Olivia gives him a disappointed "Walter," but Peter says it's OK, and tells her to let him go. Once Walter's closed the door, though, Peter says, "He can't even look at me."
Olivia asks if Peter can blame him -- the look on Peter's face suggests that yeah, there's an argument to be made for blaming him -- because the visions Walter was having were unsettling enough, let alone seeing the adult version of the son that he lost. The visions, though, are new to Peter, who had no idea he'd been appearing to Walter.
Olivia's quiet for a moment, I imagine deciding if she really wants to share this next bit, and then decides to: "You were also showing up in my dreams, almost every night. How is that possible when I'd never even seen you before?" The smirk on Peter's face suggests he's got some idea on that one. He just says she can believe whatever she likes, but this is where he's supposed to be, so maybe she and Walter were seeing echoes of the other timeline.
They're interrupted by Lincoln Lee, who comes in to tell them about the ghost train that unfortunately didn't smash into the teenagers discussing their awful music. Olivia and Peter get up to go, with Peter saying that if he's causing some sort of cosmic disruption, he's going to need a bigger boat. I mean... more specific readings. He grabs some sort of Ghostbusters-tech and is babbling about "full-spectrum of EM waves," when, mid-sentence, he is suddenly not in the lab anymore but at the railroad crossing. The police are there, the CSI unit -- Peter looks around, disoriented, but nobody else seems to notice anything amiss. Olivia and Lincoln are interviewing the teenage driver, who says they had no warning that the train was coming. Olivia asks what he means when he says it disappeared. "I know it sounds crazy, but I could only see part of it, like it was passing through a window. Curved, like looking through a bubble," he says.