Age of the Universe
To say that we know the age of the universe is like saying that the earth is flat: we can only say that when we have insufficient informaiton.
Age of universe is determined by its expansion, which assumes we know the history of the expansion rate, density of the universe, and composition of the universe. To say that we know any of these is pure arrogance - and thus we have no clue on the real age of the universe. - Opinion of MJ. Read this for some limited insights - 
For example, if we look more closely at a small path of the sky and find oodles of new galaxies - why are we assuming that this will stop when we look at an ever smaller subsection of the observed part? To say that we can count the number of galaxies at this point is plain nonsense.