Temperature Reflection

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1. Introduction We live in a special space-time even if we human-beings don’t realize what it is. With the progress of modern science and technology, we understand the wider and longer world than we used to. Men recognize space from the largest galaxy to the smallest electron. Scholars also define time between the longest origin of some celestial bodies and the shortest particle annihilation. The research and development of space and time may always be the most difficult but vital part of the whole science, including the physics. Nowadays scientists use “meter” and “second” to be the scale of space and time. A leap of these researches is the birth of atomic clock which has defined “second” in a more precise way. As far as this article concerned,…show more content…
Perhaps the most familiar frequency is the orange glow from the sodium in table salt if it is sprinkled on a flame. An atom will have many frequencies, some at radio wavelength, some in the visible spectrum, and some in between the two. Cesium 133 is the element most commonly chosen for atomic clocks. To turn the cesium atomic resonance into an atomic clock, it is necessary to measure one of its transition or resonant frequencies accurately. This is normally done by locking a crystal oscillator to the principal microwave resonance of the cesium atom. This signal is in the microwave range of the radio spectrum, and just happens to be at the same sort of frequency as direct broadcast satellite signals. Engineers understand how to build equipment in this area of the spectrum in great detail. To create a clock, cesium is first heated so that atoms boil off and pass down a tube maintained at a high vacuum. First they pass through a magnetic field that selects atoms of the right energy state; then they pass through an intense microwave field. The frequency of the microwave energy sweeps backward and forward within a narrow range of frequencies, so that at some point in each cycle it crosses the frequency of exactly 9192631770 Hertz (Hz, or cycles per second). The range of the microwave generator is already close to this exact frequency, as it comes from an accurate crystal oscillator. When a cesium atom receives microwave energy at exactly the right frequency, it changes its energy
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