Well, we're not missing abstract objects that must necessarily exist, such as arithmetic and arguably reason. Arithmetic, or mathematics, is what we use to explain our reality scientifically (which is philosophically amazing). Your question depends on what you mean by 'missing'. Are we missing an asteroid that could, literally, possible hit the earth tomorrow and destroy life as we know it? Or are we missing some fundamental mathematical formula/principle that would contradict everything we think we know about the universe? And if that's the case, then we have to define mathematics. If it is the case that we're missing some fundamental principle or law, then does that mean that mathematics is a natural entity that would exist even if humans never began to exist? That we discover these principles, rather than create them? If they are discovered, then this is an objective truth about the universe and reality (for example, the fact that there is something rather than nothing). This would entail that we have some standard by which to measure and examine the universe - and that standard is mathematics, which we use to design our theories and laws to explain the world. Two + 2 equals four. And a mathematical formula that sufficiently describes some natural phenomenon, and contains no errors, [i]must[/i] be true. But this is assuming that the laws we find present in our galaxy are the same across all galaxies. Which leads to the [i]Copernican Principle[/i]. Which leads to the second abstract idea I brought up, which is reasoning - the more philosophical realm. We can use reason to determine many truths about the world. Like the one I pointed out above, we reason that there is something rather than nothing, and this is true no matter how you try to spin it. Even if we were living in the matrix, that entirely speculative (and therefore can not be proven) theory implies that there is still something that exists - namely, the matrix. Belief in the reality of the world around us is what philosophers call a properly basic belief (you'll find this a lot in theist arguments for the existence of God). Lacking a sufficient defeater for this belief, it's reasonable to think that our reality is as we perceive it to be. The same thing applies to the cosmogony enterprise as a whole. I'm gonna cut this short due to time constraints so I can't get fully into it, but the bottomline is that [b]of course[/b] we're missing something, in the sense that there is something that we have yet to discover. Science would cease to exist if this weren't the case. There is still plenty of knowledge that we don't have, but this doesn't mean that the knowledge we already have is incorrect. It most likely will need some revising in the future, but there's no reason to think that 1k years from now, astronomers/astrophysicists will come to discover that the sun is in fact rotating around the earth, rather than the earth rotating around the sun. There just isn't any good reason to think that our 'missing something' could potentially lead to metaphysical contradictions in the way that we understand the world.