Researchers have released a study in the journal Science describing what they believe is the world's most precise clock.

The rate of ticking of this timepiece -- known informally (and awkwardly) as the ytterbium optical lattice clock -- does not change by more than one part in 10^18, Ludlow said. In other words, if there is any variation in how a second is measured, it would be in about the 18th decimal place.