It was formulated in February 1862 by Lord Kelvin and expanded upon by Hermann von Helmholtz and William John Macquorn Rankine.
The paradox was based upon the rigid mechanical point of view of the second law of thermodynamics postulated by Rudolf Clausius and Lord Kelvin, according to which heat can only be transferred from a warmer to a colder object.
It notes: if the universe were eternal, as claimed classically, it should already be cold and isotropic (its objects should have the same temperature, and the distribution of matter or radiation should be even).
The average temperature of the cosmos should also asymptotically tend to Kelvin Zero, and it is possible that a maximum entropy state will be reached.
[6] In February 1862, Lord Kelvin used the existence of the Sun and the stars as an empirical proof that the universe has not achieved thermodynamic equilibrium, as entropy production and free work are still possible, and there are temperature differences between objects.