William Thomson, 1st Baron Kelvin OM, GCVO, PC, PRS, PRSE, (26 June 1824 - 17 December 1907) was a Belfast-born British mathematical physicist and engineer. At the University of Glasgow he did important work in the mathematical analysis of electricity and formulation of the first and second laws of thermodynamics, and did much to unify the emerging discipline of physics in its modern form. He worked closely with mathematics professor Hugh Blackburn in his work. He also had a career as an electric telegraph engineer and inventor, which propelled him into the public eye and ensured his wealth, fame and honour. For his work on the transatlantic telegraph project he was knighted by Queen Victoria, becoming Sir William Thomson. He had extensive maritime interests and was most noted for his work on the mariner's compass, which had previously been limited in reliability.
Lord Kelvin is widely known for determining the correct value of absolute zero as approximately -273.15 Celsius. A lower limit to temperature was known prior to Lord Kelvin, as shown in "Reflections on the Motive Power of Heat", published by Sadi Carnot in French in 1824, the year of Lord Kelvin's birth. "Reflections" used -267 as the absolute zero temperature. Absolute temperatures are stated in units of kelvin in his honour. Wikipedia, William Thomson