how big is our universe?
We have gotten pretty close with our instruments and now have begun to measure the left-over radiation from the Big Bang. I believe 14 billion light years away.
However, since the universe is constantly E-x-p-a-n-d-i-n-g - - - -
.. it appears that the best scenario of bigness is found in viewing the universe as a toros .. which is the shape of a donut. The universe shoots out of the bottom of the donut in a big bang, then expands in all directions (imagine a film on the skin of the donut), slowly and magically comin' round the mountain of the donut to end up in one big Black Hole at the other side of the donut.
btw .. a Light Year is a Measure of Distance, and Time.
It is the DISTANCE that a photon of light travels in ONE (EARTH) YEAR, at its constant speed of 186,000 miles per second. When you do the math, it comes to roughly 6 trillion miles. (Our Sun is 8-1/3 Light Minutes away from us; while SIRIUS, the closest star to our Sun is 8.6 Light Years away from us.)
No one knows, it is currently imeasurable. There are several theories, but nothing definite. Its...just...big...
Uncountable by normal standard, maybe bigger than infernity.