born July 18, 1853, Arnhem, Neth.
died Feb. 4, 1928, Haarlem
Dutch physicist.
He taught at the University of Leiden (18781912) and later directed Haarlem's Teyler Institute. In 1875 he refined James Clerk Maxwell 's theory of electromagnetic radiation so that it explained the reflection and refraction of light. Aiming to devise a single theory to explain the relationship of electricity, magnetism, and light, he later suggested that atoms might consist of charged particles that oscillate and produce light. In 1896 his student Pieter Zeeman (18651943) demonstrated this phenomenon (see Zeeman effect ), and in 1902 the two men were awarded the second Nobel Prize for Physics. In 1904 Lorentz developed the Lorentz transformations (including the so-called Fitzgerald-Lorentz contraction), mathematical formulas that relate space and time measurements of one observer to those of a second observer moving relative to the first. These formed the basis of Albert Einstein 's special theory of relativity .