Deltanine

The universe is about 13.7 billion years old according to red-shift theory. Light reaching us from the earliest known galaxies has been traveling, therefore, for more than 13 billion years. So one might assume that the radius of the universe is 13.7 billion light-years and so the diameter is 27.4 billion light-years across.

But if, according to theory, the universe has been expanding more rapidly as time goes on then the stuff we see at a distance of 13.7 billion light-years is further away now due to this expansion.

How far? Scientist now estimate that the universe is at least 156 billion across!