Often we hear the phrase that atomic clocks always show the exact time. But from their name it is difficult to understand why atomic clock is the most accurate or as they are arranged.
The fact that in the title is the word "atomic" does not mean that the clock is a danger to life, even if the thoughts of the atomic bomb or a nuclear power plant immediately come to mind. In this case, we are only talking about the principle of work hours. If in conventional mechanical clock, the oscillatory movements make gears and their movements are calculated, then in atomic clocks there is a calculation of electron oscillations inside atoms. To better understand the principle of work, recall the physics of elementary particles.
All substances in our world consist of atoms. Atoms are consisting of protons, neutrons and electrons. Protons and neutrons combine with each other in the core, which is also called the nucleon. Electrons are moving around the kernel that can be in different energy levels. The most interesting thing is that when absorbing or disposable energy, the electron can move from its energy level to a higher or low. An electron can receive energy from electromagnetic radiation, with each transition absorbing or emitting electromagnetic radiation of a certain frequency.
Most often there are hours in which atoms of the cesium element -133 are used to change. If in 1 second, the pendulum of ordinary watches performs 1 oscillatory movement, then the electrons in atomic clock based on cesium-133 during the transition from one energy level to another emit electromagnetic radiation with a frequency of 9192631770 Hz. It turns out that one second is divided into such a number of gaps if it is calculated in atomic clock. This value was officially adopted by the international community in 1967. Imagine a huge dial, where there is not 60, and 9192631770 divisions that make up only 1 second. It is not surprising that atomic hours are so accurate and have a number of advantages: atoms are not exposed to aging, not wearing, and the oscillation frequency will always be the same for one chemical element, so that you can synchronously compare, for example, the testimony of atomic watches is far in space and on Earth, Not fear of errors.
Thanks to the atomic hour, humanity in practice was able to verify the correctness of the theory of relativity and make sure that on board the ISS due to high speed, the time really flows slower than on Earth. Atomic clock is installed on many satellites and spacecraft, they are used for telecommunication needs, for mobile communications, they compare the exact time on the entire planet. Without exaggeration, it was thanks to the invention of atomic clocks, humanity was able to enter the era of high technologies.
How do atomic clock work?
Cesium-133 is heated, evaporating cesium atoms that passes through a magnetic field where atoms with the necessary energy states are selected.
The selected atoms are then passing through a magnetic field with a frequency close to 9192631770 Hz, which creates a quartz generator. Under the influence of the field, the cesium atoms change the energy states again, and fall on the detector, which fixes when the largest number of atoms falling atoms will have a "right" energy state. The maximum number of atoms with a modified energy state indicates that the frequency of the microwave field is correct, and then its value is supplied to the electronic device - the frequency divider, which, reducing the frequency by an integer time, receives a number 1, which is a reference second.
Thus, cesium atoms are used to verify the correctness of the magnetic field frequency generated by a quartz generator, helping to maintain it in a constant value.
This is interesting: Although atomic clock existing atomic clocks are unprecedented at the moment and can take millions of years without errors, physics are not going to stop there. Using atoms of various chemical elements, they constantly work on an increase in atomic clock accuracy. Of the last inventions - atomic hours on strontium, which are three times more accurates their cesium counterpart. To fall behind only for a second they will need 15 billion years - time exceeding the age of our universe ...