Assuming the universe is homogeneous (ie we are not in some special place) you only need to see a small portion of the universe to date it. https://en.m.wikipe

Assuming the universe is homogeneous (ie we are not in some special place) you only need to see a small portion of the universe to date it. https://en.m.wikipedia.org/wiki/Age_of_the_universe https://en.m.wikipedia.org/wiki/Age_of_the_universe