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Instantaneous accuracy: How do atomic clocks achieve an astonishing accuracy of only one second in three million years?
In the long history of time measurement, the emergence of atomic clocks is undoubtedly a revolution. They measure time with extreme accuracy, benefiting every aspect of modern technology. Whether it is the global satellite navigation system or time management in daily life, the accuracy of atomic clocks enables us to achieve unprecedented precision in the use of time.
Atomic clocks operate by monitoring the frequency of atomic energy levels, a phenomenon that is setting a new standard for measuring time accuracy.
Traditional time measurement methods are often restricted by environmental factors, which affects the accuracy of measurement. In contrast, atomic clocks measure time with extremely high accuracy by monitoring the ultra-fine shifts in the positions of cesium atoms cooled to near absolute zero. To date, the NIST (National Institute of Standards and Technology) cesium atomic well clock NIST-F2 has an error of only 1 second over a period of 3 million years. This data is of epoch-making significance in the history of time measurement.
Background of the Birth of the Atomic Clock
The concept of atomic clocks was first proposed by Scottish physicist James Clerk Maxwell in the 19th century, who advocated defining time by the vibration of light waves. With the advancement of science and technology, this theory was put into practice in the 20th century. In 1949, scientists used ammonia to realize the first practical atomic clock. In 1955, they successfully developed an atomic clock based on cesium atoms.
The cesium atomic clock created by Louis Essen, the "father of atomic timekeeping", and his colleagues at the National Physical Laboratory in the UK ushered in a new era of time measurement.
Definition of time and international standards
In 1968, the International System of Units (SI) defined one second as 9,192,631,770 vibrations of the ultra-fine transition frequency of cesium-133 atoms in their undisturbed ground state. Over time, the development of atomic clocks has gradually formed a complete set of international standards, making time measurement in countries around the world unified and standardized.
The future of scale: the rise of optical clocks
With the advancement of science and technology, especially the development of laser technology, researchers have begun to develop optical atomic clocks, which can achieve higher frequency accuracy. Optical frequency comb technology greatly improves the accuracy of the measurement process. Currently, scientists are actively exploring the possibilities of optical clocks based on elements such as yttrium, mercury, aluminum and strontium, and the prospects for these clocks are very exciting.
Modern optical atomic clocks could redefine the fundamental unit of time by 2030 or 2034.
The birth of the miniature atomic clock
In addition to improved accuracy, the development of miniature atomic clocks has greatly expanded the application range of atomic clocks. In 2004, scientists at the National Institute of Standards and Technology demonstrated a miniature atomic clock that was 100 times smaller than an ordinary atomic clock. This breakthrough made the commercialization of atomic clocks a reality. Since then, more chip-based atomic clocks have appeared on the market, further ushering in a new era of time measurement.
Technological breakthroughs to ensure accuracy
In the operation of atomic clocks, the frequency adjustment of microwave radiation is crucial. By effectively manipulating the state of atoms, researchers can adjust the accuracy and reliability of atomic clocks under the influence of microwave radiation. Using continuous monitoring protocols currently under investigation, these new generations of atomic clocks are expected to be more competitive than existing technologies and even resilient to external environmental variables.
State-of-the-art atomic clocks no longer rely solely on traditional testing methods, but instead employ a range of new technologies to ensure their stability and accuracy.
The development of atomic clocks has changed our understanding and application of time. From clocks in daily life to deadly accurate satellite navigation, all demonstrate the power of science and technology. However, the measurement of time in the future will not stop here. As new technologies continue to mature, will we rethink the nature and meaning of time again?
