  Erwin Louis Hahn was one of the most innovative and influential physical
scientists in recent history, impacting generations of scientists through his
work in nuclear magnetic resonance (NMR), optics, and the intersection of these
two fields. Starting with his discovery of the spin echo, a phenomenon of
monumental significance and practical importance, Hahn launched a major
revolution in how we think about spin physics, with numerous implications to
follow in many other areas of science. Students of NMR and coherent optics
quickly discover that many of the key concepts and techniques in these fields
derive directly from his work.
