AN EXCITED ATOMIC STATE WITH A 10-YEAR LIFETIME has been discovered in the ytterbium atom, raising hopes for atomic clocks 1000 times more accurate than now possible. The Heisenberg uncertainty principle states that the longer a system can be observed, the smaller the uncertainty in its energy can be; therefore, it is extremely desirable to tune an atomic clock to a long-lived high-energy (excited) state. Researchers at the National Physical Laboratory in the UK laser cool and trap a single ytterbium ion. They then use a laser photon to boost the atom's outermost electron to the long-lived state. With additional laser light, the researchers subsequently induce the electron to return to its lowest-energy (ground) state. By noting the characteristics of the laser light interacting with the electron, the researchers determine a 3700-day lifetime for the state. In addition to being the longest living excited energy state yet detected in an atom, it is the first observed "octupole" transition, a very rare transition in which the electron changes its angular momentum by a relatively large amount of three units. Once in this state, the electron (in the absence of external perturbations) can only decay via the octupole transition, which is why the state lasts so long. An atomic clock based on the transition would be very precise but requires much additional development. (M. Roberts et al., Physical Review Letters, 10 March 1997; see also Nature, 20 March 1997.)