Slow light

‘‘New Problems’’ resumes this month with the first of a series of problems from Kirk McDonald of Princeton University. ‘‘New Problems’’ continues to solicit interesting and novel worked problems for use in undergraduate physics courses beyond the introductory level. We seek problems that convey the excitement and interest of current developments in physics and that are useful for teaching courses such as Classical Mechanics, Electricity and Magnetism, Statistical Mechanics and Thermodynamics, ‘‘Modern’’ Physics, and Quantum Mechanics. We challenge physicists everywhere to create problems that show how their various branches of physics use the central unifying ideas of physics to advance physical understanding. We want these problems to become an important source of ideas and information for students of physics and their teachers. All submissions are peer-reviewed prior to publication. Send manuscripts directly to Christopher R. Gould, Editor.