We Know, But We Still Don't Understand

Life seems to have many "Yeah, I know how it works, but I still don't understand how it works" things. For instance:

(a) I never understood how a railroad train stays on the tracks. The wheel flanges are only an inch or so tall and don't have a sharp edge to them. There seems to be very little to prevent the cars from leaving the tracks at high speeds and especially when bouncing over switches. I know the physics behind it, but I still don't get how it works in real life.

(b) The universe is expanding. Fine. But what's at the edge; what does it expand into? Or does it just keep getting bigger with no real edge in sight?

(c) How can clouds float across the sky so easily, when each one weighs the same as a locomotive?

(d) Why do people have to learn the hard way? Life would be so much more pleasant if we could learn from each other's mistakes and listen to the accumulated wisdom of those around us. But, no.

(e) Zero Tolerance. Never seen it work; always seen it backfire. Thank goodness that God doesn't have Zero Tolerance or we'd all end up in Hell. Maybe the ZT folks will; what goes around, comes around.