The Metric System
In the late 18th century, Louis XVI of France charged a group of scientists to reform the French system of weights and measures. It was widely recognized at the time that it was an inconsistent and disorganized collection of measurements that varied with location and often on obscure bases. Providing a scientifically observable system with decimally based divisions was the charge assigned to a group from the French Academy of Sciences, which included Pierre Simon LaPlace and J.J. Lagrange. They sought to create bases of measurement linked to the scientifically verifiable values such as the Earth’s circumference.
The unit of length, defined as a meter, was introduced in 1791 after careful measurement of the Earth’s radius and the recognition that the planet was not perfectly spherical but instead possessed an oblate spheroid shape. The meter was designated as one ten-millionth of the length of the Earth’s meridian through the city of Paris from the North Pole to the Equator.
The kilogram was settled upon in 1799 as the mass standard, based on the value of a platinum bar. Now the contemporary standard for the kilogram is stored at the Bureau International des Poids et Mesures (BIPM) in Sevres, France as a Platinum-iridium alloy.
Since the 1960s, the International System of Units has been internationally agreed upon as the standard metric system.
What is the Kelvin Temperature Scale?
In 1848, William Thomson Kelvin, a British physicist proposed the scale that is now named in his honor. In the design of this system, there are no negative values for temperature with the lowest value on the scale known as absolute zero. Substances at this theoretical point would display a complete absence of kinetic energy, thus atoms at absolute zero would cease all motion.