Exactly Marty! You've read the letter, didn't you? They say our universe was destroyed and they saved us! You and I being here can only mean we were the source of the destruction, through the alteration of the space-time continuum!

[ Now to live with the guilt, Marty! Well, Doc is already over it apparently. It's not like... If there's a lot they can do about it right now. ]

Now remains the question: what is this tower. Is it a product of the destroyed universes? Is it afterlife? Is it a pocket dimension existing in the multiverse that aspired us when our universe died? Are we given a chance to save our universe?

[ OR- ]

Or maybe this is where all life started from!