Just this evening I was out pondering the Universe.
Just last evening, I was pondering Nominalism. The reason we can ponder the universe (and discuss it here) is because we have a name for it. But according to nominalists, there will always be a difference between the names of things and the actual things themselves. That might seem quite obvious to most sane people, for instance, here's a word: apple. But you can't eat that word, only a real apple. Maybe you've had to eat your words before, but that's getting off-topic.
An abstraction will always be just that, not the real thing. Apparent for things like apples, but when we start getting into ideas that are themselves very abstract in nature, the line between reality and understanding begins to get fuzzy. For most people, love is real, the universe is real, but both those things are abstractions. They're imaginations, speculations, anticipations, presumptions about what the real world might be that we live in, but they are not the real things themselves.
I'm not saying this to debunk the validity of the ponderings of the universe here, but rather the other way around. I'm trying to own up to the limitations of words. I consider myself a pretty eloquent guy, but I still buy holiday greetings cards - how do you sum up your love for someone? It's easier to just pay the $5 and have someone else do it for you!
But let's get back to words. Why challenge their validity? If you haven't noticed (and most people don't), we live in an, arguably, excessively literal society. Most people believe almost all of what they read. It's just human nature: we're wired to do most of what we're told to do, most of the time. Even as you're reading this, you're going, "Yep, that's true." But what proof do you have that that's real, other than my say-so? See? We're a pretty gullible species!
When reading was invented, we found a way to vicariously express ideas. You could read someone's mind without them even being there (or alive!). That added an extra component of abstraction to our already abstract method of thinking and sharing ideas orally. With reading, people were detached from time, from the real-time discourse over ideas, and separately people could build their own wealth of ideas. "That's not true," they started to say to each other, "It's not what's written here in the [cave, law, bible, etc]."
What might be reality started to be limited by what could be written down. That's even worse than presuming that the limits of reality are what any one person can imagine (that said, I don't have any hard evidence that any of you aren't figments of my imagination). What are the limits you put on your own understanding of the universe? What you can write down? What you're able to discuss with people? What you can imagine?
That's a lot deeper than I can fairly explore in a single post, but let's start with what's written down. What's a "universe?" What are the inherent limits of that word? What does that word mean, literally? "Universe" translates from Latin into, "turning into one." As postmodernists (as I'm guessing most who visit this forum are), though, how constrained do we feel by the strictly literal meaning of "universe?" Perhaps it's become a more general term, for some (maybe those with monotheistic inclinations) retaining it's original meaning, but for others being merely another expression for everything, infinite, etc squared.
My point is, are we really trying to determine the definition of "the universe" here, or are we perhaps exploring the limitations of human understanding itself? For some people, those might seem like incongruous ideas; for others, it might seem like splitting hairs. Both are journeys of a kind, although one certainly seems outward, and the other inward.