Josiah Willard Gibbs, American scientist (born 1839)

Josiah Willard Gibbs was an American mechanical engineer and scientist who made fundamental theoretical contributions to physics, chemistry, and mathematics. His work on the applications of thermodynamics was instrumental in transforming physical chemistry into a rigorous deductive science. Together with James Clerk Maxwell and Ludwig Boltzmann, he created statistical mechanics, explaining the laws of thermodynamics as consequences of the statistical properties of ensembles of the possible states of a physical system composed of many particles. Gibbs also worked on the application of Maxwell's equations to problems in physical optics. As a mathematician, he created modern vector calculus and described the Gibbs phenomenon in the theory of Fourier analysis.

April 28 is the 118th day of the year in the Gregorian calendar; 247 days remain until the end of the year.