well you want some explaination about universe and dark mattr and expanding of universe let me start form my previous theory and thanks upon thier comments
BLACK HOLE
it is consider that(till now) that whole galaxy(universe) is surrounded by a large black hole and its slowly engulfing the universe! we are currently circling around the black hole! now the question is how our universe END? well their is some suggestion by some theorist that universe is expanding like this in the speed of light and after billons and billions years from now all stars, dusts,plants are split to protons,nutrons etc and after this after millions of years these smallest partical(which is possibile that time) is also broke(split) and there is one condition arise that means NOTING!!!!!!! this is the end of our universe dude another theory is
WHITE HOLE
it also believe that if you are giving something thats means someone is taker,GIVE=TAKE understod its also suggested by some theorist that if there is black hole present then there is also possiblities of some white hole which are emmiting the energy and black hole is taking that! according to some theorist if you will cross black hole(impossible) there you may go to ANOTHER UNIVERSE!!!??? if have some quary plz do write me hope im given you all satisfactory ans im not scientist but a avverge student of science give replys to me
thanks