There had been notions of the possibility of an absolute minimum temperature since Robert Boyle's discussion of the concept in 1665, but no-one had been able to determine what exactly this would be. Laplace and Lavoisier conjectured in a 1780 treatise that it might be as low as -3000 degrees Celsius. In 1848, however, William Thomson (later to become Baron Kelvin) published the results of his researches which approached the problem from a different angle, calculating in terms of basic thermodynamic principles. He therefore discovered that the lowest possible temperature - one at which entropy reaches its minimum value - was -273.15 degrees Celsius. This became known, in honour of its discoverer, as 0 Kelvin.
Editors. "Absolute zero point of temperature discovered by Lord Kelvin". The Literary Encyclopedia. First published 30 August 2013
[http://www.litencyc.com/php/stopics.php?rec=true&UID=6302, accessed 28 November 2015.]