William Rowan Hamilton

Sir William Rowan Hamilton (born August 4, 1805, in Dublin, Ireland; died September 2, 1865) was an Irish mathematician, physicist, and astronomer who made numerous major contributions to algebra, classical mechanics, and optics. He reformulated Lagrangian mechanics into Hamiltonian mechanics, a framework that later proved essential to the development of quantum theory. In 1843 he invented quaternions, an extension of the complex numbers to four dimensions that abandoned the commutative law of multiplication, a radical step for the time. He also introduced foundational vector algebra concepts and terms including tensor and scalar, and contributed to the Hamilton-Jacobi equation, the theory of conical refraction, Fourier analysis, and graph theory through the Icosian game.