[RightWhale]

The most recent eye-opener for me was Greene's remark in The Fabric of the Cosmos that we can see only a portion of the universe equivalent to a grain of sand compared to the whole earth. I figure we can see about 10^-30 of the universe.

[gcruse]

Along analogous lines, I just learned that when you Google something and you get, say, 2 million hits, Google isn't really finding two million sources. It's seeing how many hits you got over an increment of time. Then it calculates how many hits you should find based on the number of pages out there. Neat.