Boltzmann made major contributions to the field of the kinetic theory of gasses, lending his name to the Boltzmann constant, which relates the average relative thermal energy of the particles in a gas to the thermodynamic temperature of that gas.
The Boltzmann equation is a first-order partial differential equation that describes the statistical behaviour of a fluid not in equilibrium.
The use of statistics to model the microscopic paved the way for physicists such as Max Planck and Boltzmann’s doctoral student Paul Ehrenfest to continue his work and its relation to quantum mechanics.
Ehrenfest went on to produce his own theorem, coined the term spinor, and was denied a professorship in spite of Einstein’s recommendation that Ehrenfest succeed him in his position in Prague because he was a self-professed atheist.
Both Boltzmann and Ehrenfest took their own lives, seemingly plagued by depression. A state of mind that continues to rob us of loved ones at a rate of 700,000 every year.