The Historic Redefinition of the Kilogram
The Kilogram's New Definition
In 2018, a significant milestone in the field of metrology occurred with the redefinition of the kilogram. This change moved away from the physical standard, the Le Grand K, a platinum-iridium cylinder that had been the reference since 1889. The new definition is based on the Planck constant, a fundamental physical constant that relates energy and frequency for photons.
Importance of the Change
This shift not only enhances precision but also ensures that the definition of the kilogram is constant and accessible, independent of a physical object that can change over time. This change reflects the need for units of measurement to be based on unchanging constants of nature rather than on a physical object, which can degrade or vary.
Additional Redefinitions at the Conference
Ampere and Kelvin Redefined
At the same conference in Paris, held by the General Conference on Weights and Measures (CGPM), the definitions of the ampere and the kelvin were also updated. The ampere is now defined using the elementary charge, and the kelvin is based on the fixed numerical value of the Boltzmann constant. All of these changes aim to tie the definitions to universal constants that will stand the test of time.
The Significance for Science and Industry
The redefinitions enhance consistency in science and technology, impacting fields such as physics, engineering, and everyday measurements. These constants allow for greater precision in measurements that are crucial for accuracy in research and applications, reinforcing the reliability of scientific data worldwide.
Fun Fact
The New Definition's Unique Feature
Interestingly, the redefinition of the kilogram not only changes how we perceive weight but also highlights the parallel evolution of measurement units alongside advancements in technology and science.
Additional Resources
Recommended Reading on Measurement Standards
For those looking to delve deeper into the topic, consider the book "The Science of Measurement: A Historical Survey" by Peter Z. B. Kahn. This resource gives insight into how historical developments have shaped modern measurement standards.
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