294 | Addy Pross on Dynamics, Stability, and Life

153.323 - 175.455 Sean Carroll

And it's very familiar in your everyday life that if a ball rolls down a hill and it comes down to the valley at the bottom of the hill, eventually it will stop there. It might roll around a little bit, bump into some things, but it will come to rest. And if you just took your first year physics course straightforwardly to heart, it would say that that shouldn't happen because energy is conserved.