Number 235, July 28, 1995 by Phillip F. Schewe and Ben Stein A MAGNETIC MIRROR FOR CHILLY ATOMS has been demonstrated, allowing researchers to manipulate cold atoms in a new way, and possibly bringing about a novel method for exploring the wavelike nature of atoms. Edward Hinds (203-432-3826) and his coworkers at Yale built their mirror using a commonplace material: strips of audio tape recorded with a sinusoidally varying magnetic field pattern. A supply of atoms--a rubidium-85 gas--is trapped and cooled with a combination of laser light and magnetic fields in a configuration similar to that used to create Bose-Einstein condensation (Update 233). The magneto-optic trap not only helps to cool the atoms but also orients the atoms' magnetic moments (the atoms can be thought of as tiny bar magnets). Cooled to a temperature of about 30 millionths of a degree above absolute zero, the atoms are then dropped onto the tape from a height of one inch. The magnetic interaction between the atom and the tiny domains in the tape causes the atoms to bounce back up in an orderly way. In fact, the atoms can bounce repeatedly (or even be recaptured in the trap). Such mirrors are needed for carrying out "atom optics," the manipulation of atoms just as light waves are manipulated by lenses and mirrors in conventional optics. Unlike a previously demonstrated atom mirror (Update 149), the Yale mirror does not use laser light to reflect the atoms. (T.M. Roach et al, Physical Review Letters, 24 July 1995.) At a June laser spectroscopy meeting in Capri, Italy, Hinds announced that the Yale team is now using a new medium for magnetic mirrors, floppy disks, from which they made a converging mirror. The researchers sealed the disk across the open end of a tube, and evacuated the air from the tube. The suction made the disk bow inward, forming a concave surface able to focus reflected atoms into a single point. Future possibilities also include using magnetic mirrors to construct a "reflection grating" for atoms in order to study their wavelike properties. THE AMERICAN INSTITUTE OF PHYSICS HOMEPAGE (address: http://www.aip.org) is one of many starting points for finding physics information on the World Wide Web. The following is a brief sketch of what you can find there. First of all, the current Physics News Update and past issues going back through 1993 can be retrieved. Physics Today offers an extensive calendar enumerating upcoming physics meetings worldwide. Links to the homepages of various societies, such as the American Geophysical Union and The American Physical Society, include useful information on membership, meetings, journals, and jobs. Through the European Physical Society one can access national physics homepages and through these individual institutes, some with detailed updates on recent research and publications. The table of contents of this week's issue of Science can be had from the AAAS homepage. A section called "Physics Around the World Index", organized by McGill University, surveys physics research areas in branches of ever greater specificity; for example, under condensed matter physics there is a subsection about the Texas Center for Superconductivity, which in turn displays a nice tutorial on high-temperature superconductivity. More Worldwide Physics homepages lead to theoretical physics institutes worldwide, physics consulting firms, markets for secondhand instruments, lists of fundamental constants, overviews of various physics laws, a guide to graduate physics departments in the U.S. (faculties, facilities, research areas, etc.), and a section on educational resources, such as frequently asked questions in physics, a table of the nuclides, links to USENET physics bulletin boards, and other physics newsletters.