Re: Fringe 4x19 - "Letters of Transit" (Live Commentary, Spoilers)
Well no mention of either dimension or 'bridge' were made in this episode, so it's entirely possible that this is a 'third universe' that we have yet to connect to...
It was made apparent in the books that there are infinite universe out there in the Fringe Universe... so it's quite possible that this is a third universe, green perhaps, that is going to be brought into the equation...
In Russia, a 122 year old man has passed away, he credited his long life to abtaining from alcohol, tobacco and women. His last words were "I've made a huge mistake."