Dear Mr. Scientist,
Alright, I know how regular clocks work now, but how does an atomic clock work?
—Doug F.
In a way, an atomic clock is like a normal clock with a pacemaker. At the heart of the clock is still a vibrating piece of quartz, but this vibrating quartz very gradually slows down. After a couple thousand years the clock may be off by as much as a second. This is not an issue in everyday life, but researchers often need accuracy to multiple decimal places, so this slowing down is unacceptable.
To keep the quartz vibrating at a constant rate, an atomic clock uses cesium atoms in a somewhat complicated process. In their natural state, cesium atoms exist in either a high energy state or a low one. A stream of atoms is passed through a magnet to get rid of any high energy atoms. The remaining atoms are bombarded by microwaves to convert them into high energy atoms which then flow into a detector. This detector then generates a current when hit by the high energy atoms.
If the vibrations of the quartz begin to slow down, high energy atoms stop being produced, so no more atoms hit the detector, which now no longer generates a current. This lack of a current alerts another part of the clock to zap the quartz to speed it up again, and time keeps on ticking.
Ask Mr. Scientist is written by Michael Leitch. If you have a burning science question you want him to answer, tweet it @DC_Science or email it to science@dailycardinal.com.
