He has made major contributions over 40 years to the theory of the structure of water, aqueous solutions and hydrophobic-hydrophilic interactions.
In recent years, he has advocated the use of information theory to better understand and advance statistical mechanics and thermodynamics.
Unfortunately, the application of the concept of entropy to the entire universe features in many textbooks and in popular science books.
Because this temperature scale was introduced before the atomic, microscopic nature of matter was widely accepted, the Boltzmann constant was necessary.
An example of the insight that information theory can bring to statistical mechanics is the rederivation of the Sackur-Tetrode equation.