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Lord Kelvin and His Scale

The Kelvin scale was conceived after the concept of "absolute zero" was discovered. Zero on the Kelvin scale coincides with the very lowest degree of temperature that scientists believe is possible. This is the point at which there is no kinetic energy, no vibration, within a substance or system. This coincides with -273.15°C. Therefore, the freezing point of water is about 273 K, and the boiling point a hundred degrees beyond that.1 Strangely enough, a different notation was adopted for the Kelvin scale than other scales. The 13th General Conference on Weights and Measures in 1967 determined that the degree symbol (°) would not be used for Kelvin, and that the degrees would not be called "degrees Kelvin", but merely "kelvins" (in the lower case). However, the capital K would be used as the symbol for the lower case kelvins. Since one kelvin is based on 1/100th of the distance between the freezing and boiling of water, one kelvin is equal to one degree of Celsius.

Freehand drawing of Lord Kelvin based on several photographs.

In 1848 William Thomson (later to be made Lord Kelvin), based on his research in thermodynamics at the University of Glasgow, proposed a new temperature scale that took into account "absolute zero". The actual precise temperature of "absolute zero" was not precisely determined until several years later.2

William Thomson is the name of Lord Kelvin. He was born in Belfast, Ireland on the 26th of June in 1824. His father had intended on becoming a Presbyterian minister. However, he embarked on a university career in mathematics, in Glasgow, Scotland instead. William Thomson was raised largely by his father because his mother died when he was six years old. He learned mathematics at the knee of his father, who had him delving into advanced subjects at a very early age. At the age of 14 he began college level work at the University of Glasgow.

In 1841, Thomson went to Cambridge. There he diligently studied mathematics and science. Upon graduation in 1845, he went to Paris to work for Henri-Victor Regnault in his physical laboratory. He studied magnetism, electricity and the relationship between mathematics and science. In 1846, he returned to Glasgow to take the Natural Philosophy chair at the University. Here he struck up a relationship with George Gabriel Stokes, they worked together on many projects, including a study of the relationship between temperature and fluids.

Thomson developed theories of temperature and gasses (noticing that as a gas was expanded in a chamber that it cooled - also the basis for the idea of refrigeration). He went on to develop theories on magnetism and electricity. He was instrumental in developing devices that would enable the transatlantic cable between Newfoundland and Ireland. It was this work on the cable that earned him his title as Lord Kelvin (1866). It also made him wealthy.

Lord Kelvin died in 1907.

<-- Celsius and His Scale | How Thermometers Work -->

  1. UCAR on the Kelvin Scale
  2. MCS Bio of Lord Kelvin

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