Grant that the universe is filled with atomic-size billiard balls. Then, with a few insightful definitions and some mathematical gymnastics, physicists can provide you with a near-perfect explanation of our everyday world. The theory is called statistical mechanics .
Many people know that it limits the amount of work a machine can deliver.
But it actually goes much further. Statistical mechanics describes the engines that drive the earth's weather. It governs the temperatures and pressures inside stars and constrains the evolution of the cosmos . Indeed, Albert Einstein and Richard Feynman saw the theory as the highest achievement of classical physics. Sadly, many amateurs have avoided this important subject because, in this case, the highest plateau is also the hardest to reach.