Thirst for physics: Leonard Susskind's popular series of lectures for the general public have been compiled in this book. (Courtesy: Linda A Cicero/Stanford News Service) The mantra for ...

These higher-degree equations are much more difficult, of course; but part of the reason solutions didn't come easily was that algebra was tied to words and concrete images for such a very long time.

Our physics expert picks his top-five equations, plus a scheme to supply US power needs with a bucket of baseballs. Thanks, Einstein!