How do we know this was an alternate universe? There was a poster on young Peter's wall, celebrating the "Challenger 11 Mission" on "June 28, 1984." In our universe, the 10th mission of the Challenger - not specifically named that way - tragically exploded on January 28, 1986. (My Loose Ends time travel series deals directly with that explosion.)
Although we don't yet know this for a fact, presumably Peter's alternate universe is the same one that Olivia visited, where she met William Bell. In that universe, John F. Kennedy was not assassinated, the World Trade Center stands in 2009, among other profoundly significant differences.
I find this alternate universe stuff so good that I wish - as I've said before - that Fringe would give us more of it. But the show delivered well with another science fiction nugget last night, control of minds from afar - in the case of Fringe, via computers. Sort of wi-fi for the mind.
Fringe continues to be in a strange television class of its own, which I take to be a good thing. I'm looking forward to what they serve up for us in November.
6-min podcast review of Fringe
See also Top Notch Return of Fringe Second Season ... Fringe 2.2 and The Mole People ... Fringe 2.3 and the Human Body as Bomb ... Fringe 2.4 Unfolds and Takes Wing
See also reviews of Season One Fringe Begins ... Fringe 2 and 3: The Anthology Tightrope ... 4: The Eternal Bald Observer ... 7: A Bullet Can Scramble a Dead Brain's Transmission ... 8. Heroic Walter and Apple Through Steel ... 9. Razor-Tipped Butterflies of the Mind ... 10. Shattered Pieces Come Together Through Space and Times ... 11. A Traitor, a Crimimal, and a Lunatic ... 12, 13, 14: Fringe and Teleportation ... 15: Fringe is Back with Feral Child, Pheromones, and Bald Men ... 17. Fringe in New York, with Oliva as Her Suspect ... 18. Heroes and Villains across Fringe ... Stephen King, Arthur C. Clarke, and Star Trek in Penultimate Fringe ... Fringe Alternate Reality Finale: Science Fiction At Its Best