Like others here have said, the human brain is not equipped to handle the perplex nature of the answer. With 100% certainty - we all know there IS an answer to this question - we just cannot comprehend it.
For example, a bug knows survival, hunger, and the need to breed - not much more. Ask a bug a question in English. Do you get a response? They aren't even equipped to hear us. Their brains are wired for what they need to live - just like us. No matter how hard you try, you will never be able to teach a bug how to read. But they must be able to read in order to understand how to boil water. Luckily for bugs, however, they probably aren't bent on answering that question.
However, we're smart enough to raise the question "how far does the universe go".
But just like the bug, we're an animal. And just like the bug is not equipped to understand boiling water, we're not equipped to answer how far the universe goes.
If you can "understand that there are some things the human brain is simply not equipped to understand" - then you are far smarter than those actually looking for the answer itself.
Using the bug example - it makes perfect sense. We want an answer. Actually it's probably right in front of us. But you put a book in front of a bug and they couldn't read it. But WOW, at least we're smart enough to know we're not smart enough.
Knowing this, I hope I've saved you from the sleepless nights trying to understand how far the universe goes.
By the way - the theories of loops, starts, and "nothing" are admirable - but they are all within the grand picture. Perhaps they are a part of the answer. But you still have to explain them - and even "nothing" is outside something. It all leads back to the fact that as smart as we think we are, we just aren't smart enough to understand.
Some people absolutely need to have an answer. Many turn to religion. Many shut out the fact that this question persists because it makes them feel so small that they want to curl up and hide. Many are scared to face the question so they block it out. But there is nothing to be scared of. We live in a physical universe bound by physics. You'll wake up tomorrow and start your day. Fish will always live in the sea.
There's an "easy" answer to how far the universe goes - the 2006 model human just doesn't come with processor strong enough to compute it. No worries - when we upgrade to the 21,2006 model, our hyper-great grandchildren will make fun of us for questioning it.
The fun part begins here - imagine the possibilites. This isn't the only question we can't comprehend. Imagine the questions we can't even imagine to ask...it's all around us. We're like bugs crawling over the cover of an encyclopedia we don't even recognize as a source of information....feel even smaller?
Guess what - just because we can't put an answer to this question, humans are still maximized for survival on Earth. We dominate this place. We have everything we need to run marathons and billion dollar computer firms - and everything in between. We virtually exhaust the capacity of what we're capable of accomplishing...or at least the best ones do. The rest get eaten, just like the slower and dumber bugs that weren't smart enough to realize they were sitting on an encyclopedia.
Or at least that's the way I look at it. What do you think of that?
high school, college, and a mad desire to understand everything