What do we really know?

I could have sworn I wrote about this topic in this blog before, but for the life of me could not find it with the search tool, so here it is (again?):
How much do scientists really know about the universe? Virtually, everything we do know has to do with visible matter. We can measure, weigh, compute motion, etc. for this bit that we can observe, but what about dark matter? All we know, pretty much, is that it acts in a similar way as visible matter in relation to gravity, but none of the other features of matter we are familiar with apply to it. Not the least of which is that light doesn't bounce off it. Yet 85% of all matter is dark, and only 15% is our visible familiar kind. But that's not all. Both kinds of matter only make up 32% of the universe's mass. 68% of the mass of the universe is dark energy. And we know even less about it. So we can observe a little bit about 5% of the mass of the universe and the other 95% is a huge (literally) unknown.
http://science.nasa.gov/astrophysics/focus-areas/what-is-dark-energy/