Scientists make atomic clocks more accurate by using laser beams.
If you've ever seen that scene in the movie "Goldfinger" during which the villain threatens to slice James Bond in half with a laser, you're probably wondering why a laser wouldn't burn a hole through an atomic clock, instead of making it run more precisely. But it actually can do the latter. Bear with us because this gets pretty complicated.
Atomic clocks essentially bombard cesium atoms with microwaves to stir up some action, which scientists can then measure. The limitation of conventional atomic clocks has been that they can only catch a small portion of the cesium atoms with the microwave. By subjecting the atoms to a laser beam -- a process called laser optical pumping -- you can slow down the atoms' speed, which gives the microwaves more chance to hit them. That, in turn, makes for a more precise signal, which enables scientists to use the cesium oscillation to mark off time even more accurately. Oddly, the process also cools down the cesium atoms, right down to a few millionths of a degree above absolute zero on the Kelvin Scale [source: Buell and Jaduszliwer].