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Did you know? The definition of the international standard second is closely related to the sodium 133 atom!
In our daily lives, seconds are the basic unit of time and are everywhere. But have you ever thought that there are precise scientific principles hidden behind this simple unit? This article will give you an in-depth look at the definition of the international standard second and how it is closely linked to the sodium-133 atom.
The international standard second is based on the ultra-fine state transition frequency of sodium 133 atoms.
According to the definition of the International System of Units (SI), the second (symbol: s) is defined as 9,192,631,770 vibrations of the ultra-fine transition frequency of the undisturbed ground state of sodium 133 atoms. This precise definition has made the second the cornerstone of time measurement, a technology based on the study of atomic physics on the interaction between energy states and electromagnetic radiation.
Typically, atomic clocks measure the frequency of vibrations between atoms, which allows them to keep time with unparalleled precision. In particular, when sodium 133 atoms are cooled to near absolute zero, the transition of their energy states occurs at a very specific frequency, and this frequency helps us achieve extremely high timekeeping accuracy.
Ultra-precise time measurement technology not only affects scientific research, but also has a significant impact on navigation technologies such as the Global Positioning System (GPS).
History of the Atomic Clock
The technology dates back to the 1930s, when American physicist Isidor Ivy Rabi first constructed an atomic beam magnetic resonance frequency clock. It wasn't until 1955 that the UK National Physical Laboratory used sodium 133 atoms to create the first practical atomic clock, which was accurate to just 1 second every 3 million years.
The original inspiration for this technology came from a theory proposed by Scottish physicist James Clerk Maxwell in 1873, who advocated that time should be accurately defined by measuring the vibration of light waves. This idea gave rise to the subsequent precision clock technology.
Why is the sodium 133 atom so important?
According to current standards, the sodium-133 atom was chosen as the basis for defining the second primarily because of its stability and reliability in high-precision measurements. This provides scientists with an excellent benchmark for measuring time, allowing the time measurement standards of various countries to be unified.
In addition, the properties of sodium 133 atoms make them quite insensitive to changes in temperature and environment, a property that allows atomic timepieces to remain accurate even under extreme conditions. In the future, as scientists predict, when optical clock technology becomes more mature, newer time standards may emerge.
All these developments demonstrate the key role of precise time measurement in modern technology, and that future clock technology will rely even more on advances in atomic physics.
Advances in Modern Clock Technology
With the advancement of science and technology, new technologies such as optical clocks are constantly emerging. These clocks use lasers and optical frequency comb technology to be more precise than traditional sodium atomic clocks. The new clock may redefine the meaning of "second" to a certain extent.
For example, in 2021, JILA researchers developed an optical strontium clock with an unprecedented level of frequency accuracy, showing potential for future high-precision time measurement. Soon, we may see how new technologies shape our understanding of time.
Conclusion
Looking back at the evolution of atomic clocks, we can feel the continuous innovation and change in time measurement technology. Putting aside how accuracy affects navigation and communication, we should think about this: in an era of rapid technological advancement, should our understanding of time also change?
