Cover of the October 1920 issue of Popular Science magazine, painted by American illustrator Norman Rockwell. It depicts an inventor working on a perpetual motion machine. For millennia, it was not clear whether perpetual motion devices were possible or not, but the development of modern theories of thermodynamics has indicated that they are impossible. Despite this, many attempts have been made to construct such machines, continuing into modern times.

Cover of the October 1920 issue of Popular Science magazine, painted by American illustrator Norman Rockwell. It depicts an inventor working on a perpetual motion machine. For millennia, it was not clear whether perpetual motion devices were possible or not, but the development of modern theories of thermodynamics has indicated that they are impossible. Despite this, many attempts have been made to construct such machines, continuing into modern times.