As the Antiworld Turns

This article focuses on the fact that a single atom of antimatter—in particular, antihydrogen—may unlock fundamental mysteries of our universe and could lead to revolutionary advances in medicine and space travel. Physicists, through experiments due to begin soon in Geneva, Switzerland, hope to produce a relatively large amount of antihydrogen on a regular basis to compare matter and antimatter. Athena and Atrap share the goal of producing antihydrogen atoms at low energies, in a magnetic trap, and comparing the energy levels and behavior of antihydrogen with hydrogen. The Athena collaboration developed out of an attempt to measure the gravitational acceleration of antiprotons toward Earth. Its experiments, which are to cover a range of considerations, will include studies of gravitational acceleration of antimatter. A tiny asymmetry in the way particles of matter and antimatter decay could help substantiate the belief that, at a somewhat later time after the Big Bang, collisions between the matter and antimatter destroyed all the antimatter but left an excess of matter, from which our universe evolved.