Walter's walking away from Peter, ignoring him as he says this, and then he just stops short before saying he'll be in his bedroom working on the problem and doesn't wish to be disturbed.
Peter's a wee bit surprised to find out that Walter lives here since Olivia checked him out of the mental institution, but she says it's the only place he feels safe now. Then, as if Walter's a petulant teenager who went to his room after a fight with Mom and Dad, the loud rock n' rock music starts up. What's amusing is the song: "No Time Left For You" by The Guess Who. Anyway, Peter decides that if Walter won't help, he'll figure things out for himself, and asks if Walter still keeps his notes on worm holes in the bathroom, and part of me wants to ask what Walter's reasoning for that is, but most of me knows it's a bad idea to even think about asking about it.
Olivia asks Peter if he thinks this has something to do with time travel. Not time travel -- that would be bananas -- but time displacement, says Peter: "I think that, when I came back here, I somehow damaged the space-time continuum. And if that's the case, there may not actually be any rules to it," he says, as though any and all laws of physics have not been broken repeatedly over the course of this series.
But Olivia runs with it: like how in the apartment fire, the mother didn't revert to a younger age, but her daughter did (I'd like to point out that four years means something a little different to an adult than it does to a child, but in any case I'm not sure how they know she didn't revert to a four-year-younger version of herself).
Anyway, that's exactly what Peter's talking about. As far as he can tell, the anomalies are going to keep increasing exponentially, which is another observation based on nothing but a hunch, near as I can tell.
Cut to a carload of teenagers we've never seen before listening to loud music, which usually means a car accident is right around the corner. They're listening to Nine Inch Nails or some Nine Inch Nails-ripoff and arguing about the bands -- including a group called Aluminum Rain -- that they're going to go see, apparently in the middle of the woods. And they're arguing about the music to the extent that you can't wait for them all to die in a grisly collision of metal on metal.
That's not what happens, though. Instead, as they approach a railway crossing, they almost hit a train that appears actually out of nowhere. Ghost train! They get out of the car and stare at the flickering train passing through, but only within a sphere sitting atop the crossing.