The First Law of Thermodynamics (conservation of energy)

Robert Mayer discovered the first law of thermodynamics in 1842 (conservation of energy)

Historical Formulation:
Heat is a form of energy. Energy (the capacity for work) can only be converted into various external forms, and it cannot be created from nothing or destroyed (Robert Mayer, 1842; James Prescott Joule, 1843; Hermann von Helmholtz, 1847). A "perpetuum mobile," i.e. a machine capable of continuously producing work out of nothing, is impossible.

Original apparatus for determining the mechanical equivalent of heat, invented by Robert Mayer, 1868

 

The Second Law of Thermodynamics

Sadi Carnot, 1796-1832, discovered the "Second Law of Thermodynamics" in 1824.

Historic Formulation:
The work of a heat engine whose driving parts always return to the same position in a regular sequence is always associated with a transfer of heat from a higher to a lower temperature (Sadi Carnot, 1824). A heat engine in which this was not the case would, for example, be able to exhaust the vast amount of heat stored in the oceans and convert it into work (thereby cooling off the seas). This type of "mark 2 perpetuum mobile" is impossible.
 

The Third Law of Thermodynamics

Walther Nernst, 1895

The physicist Walter Hermann Nernst (1864–1941) formulated the Third Law of Thermodynamics in 1906. The formulation became known as the "Nernst heat theorem."

This states that entropy (i.e. the measure of the degree of disorder in processes of chemical mixing) also approaches a value of zero as the temperature approaches absolute zero (–273 °C).

This implies that absolute zero can never be reached. Nernst is regarded as one of the founders of physical chemistry. He received the Nobel Prize for Chemistry in 1920 for his discovery.

Thermodynamics (theory and practice)