By Erika VillaniPosted 10.14.2010 at 4:06 pm 0 Comments
For most of history, people have divided the Earth’s motion around the sun into finer and finer units in pursuit of more accurate timekeeping. In 1967, humanity officially adopted a new method: counting atomic oscillations. Specifically, this means measuring the frequency of the photons absorbed or emitted by an atom’s electrons as those electrons gain or lose energy. These photons oscillate as reliably as Earth orbits the sun, but at much higher frequencies than once a year.