Lorentz attended primary school in Arnhem until he was 13 years of age when he entered the new High School there. He entered the University of Leiden in 1870 but, in 1872, he returned to Arnhem to take up teaching evening classes. He worked for his doctorate while holding the teaching post.
In his doctoral thesis for University of Leiden (1875), Lorentz refined the electromagnetic theory of James Clerk Maxwell to better explain the reflection and refraction of light. He was appointed professor of mathematical physics at the Univiersity of Leiden in 1878. During his time there he was primarily interested in a single theory to explain the relationship of electricity, magnetism, and light. Lorentz theorized that the atoms might consist of charged particles and suggested that the oscillations of these charged particles were the source of light. This was experimentally proven in 1896 by Pieter Zeeman, a pupil of Lorentz.
In 1895 in an attempt to explain the Michelson-Morley experiment, Lorentz introduced the concept of local time (different time rates in different locations). He also proposed that bodies approaching the velocity of light contract in the direction of motion (see FitzGerald-Lorentz Contraction). (George FitzGerald had already arrived at this conclusion.) In 1904 (one year before the publication of Einstein's paper) Lorentz extended this work and developed the Lorentz transformations. These mathematical formulas describe basic effects of the theory of relativity, namely the increase of mass, shortening of length, and time dilation that are characteristic of a moving body.
Lorentz was chairman of the first Solvay Conference held in Brussels in the autumn of 1911. This conference looked at the problems of having two approaches, namely the classical physics and quantum theory. However Lorentz never fully accepted quantum theory and hoped it would be incorporated back into the classical approach. In 1912 Lorentz became director of research at the Teyler Institute in Haarlem, although he remained honorary professor at Leiden and gave weekly lectures there. Lorentz received a great many honours for his outstanding work. He was elected a Fellow of the Royal Society in 1905. The Society awarded him their Rumford Medal in 1908 and their Copley Medal in 1918.
The respect that Lorentz was held in in The Netherlands is seen in O W Richardson's description of his funeral :
The funeral took place at Haarlem at noon on Friday, February 10. At the stroke of twelve the State telegraph and telephone services of Holland were suspended for three minutes as a revered tribute to the greatest man Holland has produced in our time. It was attended by many colleagues and distinguished physicists from foreign countries. The President, Sir Ernest Rutherford, represented the Royal Society and made an appreciative oration by the graveside.
Richardson describes Lorentz as:
[A] man of remarkable intellectual powers ... . Although steeped in his own investigation of the moment, he always seemed to have in his immediate grasp its ramifications into every corner the universe. ... The singular clearness of his writings provides a striking reflection of his wonderful powers in this respect. .... He possessed and successfully employed the mental vivacity which is necessary to follow the interplay of discussion, the insight which is required to extract those statements which illuminate the real difficulties, and the wisdom to lead the discussion among fruitful channels, and he did this so skillfully taught the process was hardly perceptible.