- - - - - - - - - - - - - - REFERENCE FRAME Chemistry : Blithe Sibling of Physics

As a physical chemist or chemical physicist, I've often had to react to uncomprehending or unkind re­ marks about chemistry delivered by physicists_ Typical of such remarks are "A diatomic molecule has one atom too many" and "A topic is dead when it has been turned over to the chemists." Both those dicta are attributed to Arthur Schawlow. Coming from him, though, such comments seem incon­ gruous. Not only is he otherwise ex­ ceptionally genial, but his fine book written with Charles Townes l deals largely with polyatomic molecules and with microwave spectroscopy, a field in which chemists had a major role early on. Furthermore, like much else in modern physics, the laser work of Townes and Schawlow is a lineal de­ scendant of molecular beam experi­ ments launched decades earlier by Otto Stern, a physical chemist. Squabbles between siblings are un­ seemly yet can foster mutual apprecia­ tion. Any physicist interested in mole­ cules cannot avoid chemistry, and at the least may find it offers curious historical or cultural perspectives_ A genuine symbiosis may also emerge from complementary approaches. The typical chemist wants above all to un­ derstand why one substance behaves differently from another; the physicist usually wants to find principles that transcend any specific substances. Here, I present three brief items to exemplifY these themes.