https:\/\/youtu.be\/eOti3kKWX-c?t=291<\/a><\/p>\nIn the splitting of the frequencies in the D line of the cesium atom we will see 9.192631770 GHz<\/b>, this is one second exactly, (or what humans have chosen to be precisely a second). Remember this goes back to the earlier part in this unit about Egyptions choosing to break the day into 24 parts, which led to minutes, and seconds later on.<\/p>\n
So, we know that the second comes from measuring the frequency of the very fine transition of the D2 line ground state of the neutral cesium atom at rest. With this enormous precision we can do amazing things such as GPS, physics experiments and develop better technology all around!<\/p>\n
Portable Atomic Clocks:\u00a0<\/b><\/p>\n
In 1971 the first portable atomic clocks were used in the Hafele-Keating Experiment to test Einstein’s theory of relativity, both special relativity and general relativity. This clock was about the size of a toaster oven, before the clocks were the size of a large long table. Engineers at Hewitt Packert managed to make the microwave cavity smaller.\u00a0 Below are the parts of the first portable atomic clock:<\/p>\n
Key Parts of an HP 5061A 1968 Cesium Clock:<\/b><\/p>\n
Cesium tube<\/b> – cavity with 6 grams of cesium, heats and creates a beam
\nMagnet<\/b> – changes outer electron spin state as the beam goes through it, sorts them
\nMicrowave cavity<\/b> – send the beam through this, and it’s fed by radiation from a quartz oscillator. If you hit the atom with the precise frequency, it will flip the atom.
\nMagnet<\/b> – select the flipped atom again here, and see how many you get
\nHot wire ionizer<\/b> which gets rid of outer electron, charging it for later use
\nWith a charged cesium atom you can now direct it with an electromagnet<\/b> to form a electron spectrometer.<\/b> The atoms eventually hit a plate and kicks off electrons, and this makes the output we can convert into time using some other parts. The absorption point of an atom is naturally occuring so it’s repeatable. Whether someone creates an atomic clock at high altitude, sea level or in space, it’s basically the same frequency.<\/p>\n
Atomic Clocks Today:<\/b>
\nWe have achieved very portable atomic clocks with the CSAC (chip scale atomic clock). It uses a low power semiconductor laser as a light source. The current size of the world\u2019s smallest atomic clock is 4×3.5×1 cm and 35 grams. This clock also uses Caesium-133.<\/p>\n
Below is our short and easy explanation of the atomic clock from John Lowe of NIST (National Institute of Standards and Technology) :<\/b><\/p>\n
on point of an atom is naturally occuring so it’s repeatable. Whether someone creates an atomic clock at high altitude, sea level or in space, it’s basically the same frequency.<\/p>\n
We interviewed John Lowe from the National Institute of Standards and Technology about how the atomic clock works and a little about the development of the devices.<\/p>\n