The Oldest Rock in the World (not even on AARP yet)

What have we learned from the 'oldest rock in the world'? Tons.

We've learned that what we think we know about early Earth is actually a patchwork of best guesses.  Most of them are probably wrong.

This period has a name; it's called the Hadean Eon, from the ancient Greek, Hades — basically, a polite term for "hellish." Hell melted all the rocks on the Earth's surface, and when it's as hot as Hades, you can't have life, either. The Earth had to wait for its first living creature until later — till things cooled and quieted down. That, anyway, is what we used to think.

Fascinating.  What we know about the universe is.. not much.  But we're learning.  More info here.