In the past, 2012, forty-five years oldsince the moment when mankind decided to use atomic timekeeping for the most accurate time measurement. In 1967, in the International SI system, the category of time ceased to be determined by astronomical scales - they were replaced by the cesium frequency standard. It was he who got the popular name today - the atomic clock. The exact time that they allow to determine has an insignificant error of one second over three million years, which makes it possible to use them as a standard of time in any corner of the world.
A bit of history
The idea is to use atom vibrations tosuper-precise time measurement was first expressed in 1879 by the British physicist William Thomson. In the role of the emitter of resonant atoms, this scientist proposed to use hydrogen. The first attempts to implement the idea in practice were undertaken only in the 40s. twentieth century. And the world's first operating atomic clocks appeared in 1955 in the UK. Their creator was the British experimental physicist Dr. Louis Essen. These watches worked on the basis of oscillations of cesium-133 atoms, and thanks to them, scientists were finally able to measure time with much greater accuracy than before. The first Essen device allowed an error of no more than a second for every hundred years, but subsequently the accuracy of measurements increased many times and the error per second could reach only for 2-3 hundreds of millions of years.
Atomic clocks: the principle of operation
How does this ingenious "device" work?Atomic clocks use the energy levels of molecules or atoms at the quantum level as a resonant frequency generator. Quantum mechanics establishes a connection between the atomic nucleus and electrons system and several discrete energy levels. If such a system is affected by an electromagnetic field with a strictly specified frequency, then the system will move from a low level to a high one. The reverse process is also possible: the transition of an atom from a higher level to a low one, accompanied by the emission of energy. These phenomena can be monitored and recorded all energy jumps, creating something like an oscillatory circuit (it is also called an atomic oscillator). Its resonant frequency will correspond to the difference of the energies of neighboring levels of transition of atoms divided by the Planck constant.
Such an oscillating circuit has undeniableadvantages in comparison with their mechanical and astronomical predecessors. For one such atomic oscillator, the resonant frequency of atoms of a substance will be the same, which is not the case with pendulums and piezocrystals. Moreover, atoms do not change their properties over time and do not wear out. Therefore, atomic clocks are extremely accurate and almost eternal chronometer.
Exact time and modern technology
Telecommunication networks, satellite communications,GPS, NTP servers, electronic transactions on the stock exchange, online auctions, the procedure for purchasing tickets via the Internet - all these and many other phenomena have long been firmly established in our lives. But if humanity had not invented the atomic clock, all this would simply not exist. The exact time, synchronization with which allows you to minimize any errors, delays and delays, allows a person to maximize the use of this invaluable irreplaceable resource, which is never too much.
