Why is the earth's crust so stable? It has supported life for billions of years, yet it is just 12 mi thick [1] and floats on top of liquid rock that extends for thousands of miles -- the part of earth we are most familiar with is a tiny fraction of what our planet really is. You could imagine that turbulence in the liquid below would cause currents that blast through the crust with catastrophic consequences, and that this would happen regularly. But it doesn't -- we have a small number of (super) volcanos, but they are pretty rare. I find this unnerving and remarkable. Our perception of reality -- in this case the earth beneath us -- is skewed.