First, you should rest assured that even the worst atomic clock will not explode and is not considered a nuclear device in the traditional understanding of the word.</br></br>So, what’s the big deal about atomic clocks and how are they different from the normal, non-atomic ones?</br></br><strong>The Science of Timekeeping</strong></br></br><a title="Clocks" href="http://www.atgstores.com/furniture/living-room-furniture/clocks/" target="_blank">Clocks of any kind</a> achieve precision by relying on some type of object that generates a consistent frequency, and that object has changed over the years. In the very beginning it was a sundial and the object was the sun.</br></br>One of the earliest known mechanical clocks was called a water clock and there were several different designs. A common design, called an outflow, measured water levels as it drained through a hole in the vessel’s bottom. Eventually, this led to using water to rhythmically power more complex mechanical timekeeping machines.</br></br><strong>The ‘Oscillating Mass’</strong></br></br>Water was used to drive mechanical clocks for hundreds of years before spring-driven devices came along. But, it was the arrival of the pendulum in the 17th century that introduced the concept of the “oscillating mass” – a new and improved object that could produce a continuous and accurate frequency.</br></br>The oscillating mass quickly evolved into a highly sophisticated idea, and today that “mass” is often a sliver of quartz crystal or even a collection of atoms. How does that even work? Well, it's very science-y, but it has to do with the natural vibration of these objects; a kind of subatomic hum produced by the movement of electrons.</br></br><strong>The Atomic Clock</strong></br></br>Atoms – or, more accurately, their subatomic particles – oscillate at a specific frequency that is more precise than quartz oscillation (yep, crystals really do vibrate) or pendulum movement. And, this is why the most accurate clocks use atomic movement to keep time.</br></br>To do that, <a title="Atomic Wall Clocks" href="http://www.atgstores.com/furniture/living-room-furniture/clocks/wall-clocks/wall_clock_features/atomic/" target="_blank">atomic clocks</a> funnel atoms through radio waves adjusted to a certain frequency. The frequency causes the atoms’ electrons to shift energy states, and this shift can be measured by a detector.</br></br>Of course, the whole process is powered by electricity, so if the battery dies the clock stops, but while the system remains intact it provides the most accurate timekeeping possible, down to the nanosecond.</br></br><strong>Buying ‘Atomic Clocks’</strong></br></br>If you’re thinking it must be really hard to build an atomic clock you’d be right. And, if you think it’d cost a lot of money to buy one, you’d be right again. So, what does it mean when you see “atomic clocks” for sale?</br></br>On all but the rarest and most expensive of occasions, it means those clocks self-set by receiving a signal from the National Institute of Standards and Technology (NIST) atomic clock in Boulder, Colorado. They are not actual atomic clocks.</br></br>Even so, it’s still pretty cool because the NIST atomic clock is <a title="Wired" href="http://www.wired.com/2014/04/nist-atomic-clock/" target="_blank">accurate to within one second every 300 million years</a>, which should keep you running on schedule for quite some time.