Atoms swing to their own precise rhythm, setting a reference pace for the universe.
Measuring time with high precision has led to many hi-tech advances, an impressive one being the GPS. At the heart of every clock is a cyclical phenomenon: from the orbit of the Sun to the oscillations of a pendulum, our solutions have evolved with us. A pendulum, however, is neither precise nor reliable, since it is strongly influenced by its environment. This is why scientists learnt to control highly regular, natural oscillators: the atoms. Atoms only become excited when they absorb light of a specific frequency. By cooling and trapping them with lasers, scientists can measure that frequency and monitor time with unmatched precision.
Why do we need atomic clocks to understand the universe around us?
The basics of atomic clocks.