I think that space is allways changing because of dark energy and dark matter. Dark energy is a force that push's the universe apart.Dark matter is the force that hold's every thing together so you realy cant say exactly where the end of space is,because it is allways changing.
Scientist's belive that parallel universe's are stacked on top of each other like some one stacking CD's, and that every universe has a membrane that keeps them apart.
Some belive that two parallel universe's smashed in to each other which could of caused the Big Bang.