  In this contribution, the Gaussian channel is represented as an equivalent
thermal system allowing to express its input-output mutual information in terms
of thermodynamic quantities. This thermodynamic description of the mutual
information is based upon a generalization of the $2^{nd}$ thermodynamic law
and provides an alternative proof to the Guo-Shamai-Verd\'{u} theorem, giving
an intriguing connection between this remarkable theorem and the most
fundamental laws of nature - the laws of thermodynamics.
