Jens Ickler/Alamy
How do you check the accuracy of an atomic clock that “will lose less than 1 second every 40 billion years”, as per a recent Â鶹´«Ã½ article?
Pat French
Longdon-upon-Tern, Shropshire, UK
Atomic clocks are based upon quartz crystals. These crystals vibrate at a very uniform rate when an electric current is passed through them. By measuring minute variations in those vibrations over months or years, scientists can predict a clock’s accuracy.
The value of those variations is so small that it needs to be projected over tens of billions of years in order to be stated in seconds…
