“Fringe”s first season concluded with the introduction of a parallel universe in which the WTC Towers still stand.  This parallel universe is fondly being nicknamed ‘Over There’ by the show’s producers and it will be the only alternate dimension featured this coming season.

Jeff Pinkner, executive producer of “Fringe” lends a peek into season two:

“We have decided that though science acknowledges a multiverse, we’re only going to tell a story about two, here and what we’re referring to internally as Over There.  They are two versions of reality. It’s not time travel.”

How will the show handle two realities?  Pinkner explains:

“It takes place predominantly over here, but what’s happening Over There is impacting what’s happening over here,”

Roberto Orci, “Fringe” co-creator, writer, and executive producer adds his two cents in regards to ‘Over There’:

“Thematically, the other universe exists [as] a foil to what might have been different in this universe.  In this other place, Kennedy lived. It’s more wish fulfillment and riffing on our world than ‘We have to follow the rules of two universes.'”

[Source] Scifi