In science fiction, spaceships are often powered by energy released when antimatter annihilates its matter counterpart. In the real world, physicists struggle to create even fleeting particles of antimatter. Twelve years ago they created the first antiatom, and now David Cassidy at the University of California at Riverside has joined two positronium atoms—formed by the union of an electron and its antiparticle, the positron—into the first antimolecule. The short-lived molecule may not have any direct uses, but the technique brings us closer to creating a powerful gamma-ray laser.
