QUANTUM MIRAGE. The scanning tunneling microscope (STM) allows one both to push individual atoms around on a surface and to image them. Especially intriguing are images of "quantum corrals," circular or elliptical arrangements on a surface inside of which the waves corresponding to electrons near the substrate surface can be revealed. The latest entry in the gallery of fine pictures comes from IBM, where physicists placed 36 cobalt atoms in an elliptical "Stonehenge" pattern on a copper surface. An extra magnetic cobalt atom was placed at one of the two foci of the ellipse, causing visible interactions with the surface electron waves. But the waves seem also to be interacting with a phantom cobalt atom at the other focus, an atom that is not really there. (Manoharan, Lutz, Eigler, Nature, 3 Feb /pnu/2000/; see figure at Physics News Graphics.)