In the past, 2012, it turned forty-five years from the moment when mankind decided to use atomic timekeeping for the most accurate measurement of time. In 1967, in the International SI system, the category of time ceased to be determined by astronomical scales - the cesium standard of frequency came to replace them. It was he who got the now popular name - the atomic clock. The exact time they allow us to determine has an insignificant error of one second in three million years, which allows us to use them as a standard of time in any part of the world.
A bit of history
The very idea of using vibrations of atoms for an ultra-precise measurement of time was first expressed in 1879 by the British physicist William Thomson. In the role of the emitter of atoms-resonators, this scientist proposed using hydrogen. The first attempts to realize the idea in practice were made only in the 40s. twentieth century. And the world's first working atomic clocks appeared in 1955 in the UK. Their creator was the British physicist-experimenter Dr. Louis Essen. The clock worked on the basis of vibrations of cesium-133 atoms and thanks to them scientists finally were able to measure time with much greater accuracy than it was before. The first device of Essen allowed an error of not more than a second for every hundred years, but subsequently the accuracy of measurements repeatedly increased and the error per second can only run for 2-3 hundreds of millions of years.
Atomic clock: the principle of operation
How does this cunning "device" work? As a generator of resonance frequency, atomic clocks use the energy levels of molecules or atoms at the quantum level. Quantum mechanics establishes the connection between the "atomic nucleus-electron" system and several discrete energy levels. If such a system is affected by an electromagnetic field with a strictly specified frequency, then this system will transition from a low level to a high one. An inverse process is also possible: the transition of an atom from a higher level to a low one, accompanied by radiation of energy. These phenomena can be controlled and fixed all the energy jumps, creating something like an oscillatory circuit (it is also called an atomic oscillator). Its resonance frequency will correspond to the energy difference of the neighboring levels of the atomic transition, divided by the Planck constant.
Such an oscillatory circuit has undeniable advantages in comparison with its mechanical and astronomical predecessors. For one such atomic oscillator, the resonance frequency of the atoms of any substance will be the same, which can not be said for pendulums and piezoelectric crystals. In addition, atoms do not change their properties over time and do not wear out. Therefore, the atomic clock is an extremely accurate and practically eternal chronometer.
Exact time and modern technology
Telecommunication networks, satellite communications, GPS, NTP-servers, electronic transactions on the exchange, online auctions, the procedure for buying tickets through the Internet - all these and many other phenomena have long been firmly entrenched in our lives. But if humanity did not invent the atomic clock, it would not have happened. Precise time, synchronization with which allows you to minimize any errors, delays and delays, enables a person to make the most of this invaluable irreplaceable resource, which is never too much.