Lorentz, Hendrik Antoon

 Hendrik Antoon Lorentz (1853–1928), a Dutch physicist and pioneer in formulating the relations between electricity, magnetism, and light. He explained the Zeeman effect—a change in spectrum lines in a magnetic field—for which he shared with Pieter Zeeman the 1902 Nobel Prize in Physics. 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 Danish physicist Lorenz, is known as the Lorenz-Lorentz formula. He extended the hypothesis of G. F. Fitzgerald that the length of a body contracts as its speed increases, now known as the Lorentz contraction. He also formulated the Lorentz transformation, in which the space and time coordinates of one moving system can be correlated with the known space and time coordinates of any other system. This work influenced and was confirmed by Einstein’s special theory of relativity.