| If time is crucial to you or your office, consider investing | | | | the time from a shared location where one of the |
| in atomic clocks so that everyone knows exactly | | | | world's few of the world's atomic clocks operates. A |
| what time it is and everyone has the same time. | | | | low -frequency radio signal broadcasts the time from |
| These are the most accurate time keeping pieces you | | | | that location to all atomic clocks within its range. There |
| can get, and more and more businesses are using | | | | are currently approximately 200 atomic clocks |
| atomic wall clocks to make sure that accurate time | | | | world-wide in sixty countries. |
| sheets and appointments are kept. | | | | In the United States, most atomic clocks used for |
| But what are atomic clocks and why are they so | | | | home and offices are synchronized to the National |
| much more accurate than regular clocks? A standard | | | | Institutes of Standards and Technology atomic clock in |
| clock, whether wind-up, electric or battery operated, | | | | Boulder, Colorado. The other official atomic clock is at |
| counts time by the number of "ticks" that a resonator | | | | the U.S. Naval Observatory in Washington, D.C. and is |
| makes. The resonator is the device that actually keeps | | | | the official time clock of the Department of Defense. |
| track of time. In most clocks the resonator is either a | | | | Since both of these atomic clocks are within one |
| swinging pendulum or (in digital clocks) oscillations in the | | | | second of each other over a million years of time, it is |
| power line (which is a bit different in the U.S. and in | | | | unlikely that time displayed on atomic wall clocks at the |
| Europe). | | | | Pentagon will differ from the time displayed on an |
| Atomic clocks also use a resonator, but the resonator | | | | atomic clock in your home office! |
| counts based on the resonance frequency of atoms. | | | | How Do At-Home Clocks Get the Information from |
| Resonance is the emission or absorption of | | | | Master Atomic Clocks? |
| microwave electromagnetic radiation by an atom. It is | | | | Global positioning satellites (GPS) in the skies above us |
| very regular, and no matter which atom of cesium | | | | transmit the signals from the official atomic clocks to |
| used, the frequency of resonance is always exactly | | | | individual receivers in atomic wall clocks and desk |
| the same. This is why atomic clocks are so much | | | | clocks all over the world. In other countries, the signal |
| more accurate than other clocks - the resonators in | | | | would come from whichever clock is the official |
| other clocks can be affected by lots of variables like | | | | atomic clock for that region, just as the one in Boulder, |
| temperature, moisture and atmospheric conditions. | | | | Colorado is the one for the United States. |
| None of these affect the atoms, so the atomic clocks | | | | These amazingly accurate atomic clocks are also |
| never lose or gain time. | | | | responsible for the fact that all computers with built-in |
| Synchronization of Atomic Clocks | | | | clocks are synchronized and accurate and keep time |
| The reason all atomic clocks show the same time | | | | whether on or off. With such accurate time keeping |
| anywhere you go is because they don't each have | | | | and the use of GPS, you can be sure that your atomic |
| their own cesium atom - this would be impossible | | | | clocks will let you know exactly what time it is, down |
| because it's incredibly expensive and requires very | | | | to the nano-second! |
| precise conditions. Atomic clocks are actually receiving | | | | |