The Redefinition of the Kilogram in 2018

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.