He was born as the son of nursery-owner Gerrit Frederik Lorentz and his wife née Geertruida van Ginkel. When he was four years old, his mother died, and in 1862 his father married Luberta Hupkes. In those days the grade school did not only have school hours in the morning and in the afternoon, but also in the evening, when teaching was more free . After the 5th form and a year of study of the classics, he entered the University of Leyden in 1870, obtained his B.Sc. degree in mathematics and physics in 1871, and returned to Arnhem in 1872 to become a night-school teacher, at the same time preparing for his doctoral thesis on the reflection and refraction of light. In 1875, at the early age of 22, he obtained his doctor's degree, and only three years later he was appointed to the Chair of Theoretical Physics at Leyden, newly created for him. In spite of many invitations to chairs abroad, he always remained faithful to his Alma Mater. He continued at Leyden as Extraordinary Professor, delivering his famous Monday morning lectures for the rest of his life. The far-seeing directors of Teyler's Foundation thus enabled his unique mind to be freed from routine academic obligations, permitting him to spread his wings still further in the highest secluded realms of science, which are attainable by so few.
In 1878, he published an essay on the relation between the velocity of light in a medium and the density and composition thereof. The resulting formula, proposed almost simultaneously by the Danish physicist Lorenz, has become known as the Lorenz-Lorentz formula.Lorentz also made fundamental contributions to the study of the phenomena of moving bodies. In an extensive treatise on the aberration of light and the problems arising in connection with it, he followed A.J. Fresnel's hypothesis of the existence of an immovable ether, which freely penetrates all bodies. This assumption formed the basis of a general theory of the electrical and optical phenomena of moving bodies.From Lorentz stems the conception of the electron; his view that his minute, electrically charged particle plays a role during electromagnetic phenomena in ponderable matter made it possible to apply the molecular theory to the theory of electricity, and to explain the behaviour of light waves passing through moving, transparent bodies.The so-called Lorentz transformation (1904) was based on the fact that electromagnetic forces between charges are subject to slight alterations due to their motion, resulting in a minute contraction in the size of moving bodies. It not only adequately explains the apparent absence of the relative motion of the Earth with respect to the ether, as indicated by the experiments of Michelson and Morley, but also paved the way for Einstein's special theory of relativity.It may well be said that Lorentz was regarded by all theoretical physicists as the world's leading spirit, who completed what was left unfinished by his predecessors and prepared the ground for the fruitful reception of the new ideas based on the quantum theory.In 1919, he was appointed Chairman of the Committee whose task it was to study the movements of sea water which could be expected during and after the reclamation of the Zuyderzee in The Netherlands, one of the greatest works of all times in hydraulic engineering. His theoretical calculations, the result of eight years of pioneering work, have been confirmed in actual practice in the most striking manner, and have ever since been of permanent value to the science of hydraulics.An overwhelming number of honours and distinctions from all over the world were bestowed on Lorentz. International gatherings were presided over by him with exceptional skill, both on account of his amiable and judicious personality and his masterly command of languages. Until his death he was Chairman of all Solvay Congresses, and in 1923 he was elected to the membership of the "International Committee of Intellectual Cooperation" of the League of Nations. Of this Committee, consisting of only seven of the world's most eminent scholars, he became the President in 1925.Through his great prestige in governmental circles in his own country, Lorentz was able to convince them of the importance of science for national production. He thus initiated the steps which finally led to the creation of the organisation now generally known under the initials T.N.O. (Dutch for Applied Scientific Research).
Lorentz was a man of immense personal charm. The very picture of unselfishness, full of genuine interest in whoever had the privilege of crossing his path, he endeared himself both to the leaders of his age and to the ordinary citizen.In 1881 Lorentz married Aletta Catharina Kaiser, whose father, J.W. Kaiser, Professor at the Academy of Fine Arts, was the Director of the Museum which later became the well-known Rijksmuseum (National Gallery) of Amsterdam, and the designer of the first postage stamps of The Netherlands. There were two daughters and one son from this marriage. The eldest daughter Dr. Geertruida Luberta Lorentz is a physicist in her own right and married Professor W.J. de Haas, Director of the Cryogenic Laboratory (Kamerlingh Onnes Laboratory) of the University of Leyden.Lorentz died at Haarlem on February 4, 1928.
