The Grandfather of Quantum Physics

H. A. Lorentz as the Grandfather of Quantum Physics

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Author: Xavier Bick

 

The first Solvay Conference in the fall of 1911 set a precedent for how leading physicists collaborate in order to solve difficult problems such as blackbody radiation and the photoelectric effect. By the end of the fifth Solvay Conference in 1927, the foundation had been laid for the theory of Quantum Mechanics. Besides featuring many prominent scientists in the field of quantum physics such as Einstein and Bohr, the first five Solvay Conferences had one very important characteristic that they all shared: they were chaired by Hendrik Lorentz. Following the first Solvay Conference, physicist Henri Poincar said this of Lorentz's importance to the beginning of quantum theory:

... at every moment [we] could be heard talking of the [quantum mechanics] which [we] contrasted with the old mechanics. Now what was the old mechanics? Was it that of Newton, the one which still reigned uncontested at the close of the nineteenth century? No, it was the mechanics of Lorentz, the one dealing with the principle of relativity; the one which, hardly five years ago, seemed to be the height of boldness.

Prior to the first Solvay Conference in 1911, H. A. Lorentz had published pioneering work concerning electromagnetism, the luminiferous aether, relativity, and the Zeeman effect. Lorentz paved the way for scientists such as Planck, Einstein, and the other participants of the early Solvay Conferences to develop the modern theory of quantum mechanics.

Hendrik Antoon Lorentz began teaching in 1878 at the University of Leiden in the Netherlands. Over the last few decades of the 19th century, he solidified then-revolutionary theories about the propagation of electromagnetic radiation which eventually led to an interested in relativity and electrodynamics by the turn of the century.

In 1904, one year before Einstein published his theory of Special Relativity, Lorentz published a paper collecting all his work over the past several years concerning the motion of bodies through the aether with a focus specifically on bodies moving slower than the speed of light. Here, Lorentz gave us his space-time transformations, along with the ideas of length contraction and time dilation, which were derived over the course of a few years in response to the failure of the Michelson-Morley experiment, saying, "... the negative result of [the Michelson-Morley experiment] has led FITZ GERALD and myself to the conclusion that the dimensions of solid bodies are slightly altered by their motion through the aether." Although Lorentz used his transformations to correctly explain experiments concerning light aberration, his paper was unsuccessful in explaining the Michelson-Morley experiment because he attempted to use the first-order ratio of velocity to the speed of light v/c rather than the second order ratio v^2/c^2 which he derived for other scenarios. A year later, Einstein used algebraically equivalent versions of the transformations mentioned in Lorentz's paper to describe his theory of special relativity.

While Lorentz's contributions to relativity were important, it was his work on the Zeeman Effect that earned him the Nobel Prize in 1902 with Pieter Zeeman. The Zeeman Effect was first observed in 1897, and Lorentz published a paper with its theoretical interpretation in 1899 based on an application of the Hamiltonian operator. Because the intrinsic spin of an electron wasn't discovered until 1925, the "Normal" Zeeman Effect is the one which involves a zero net spin. Even though it is the more unusual case, it is called the Normal Zeeman Effect because it was the only case that could be explained by Lorentz's theory without taking spin into account.

Hendrik Lorentz may be considered the last great contributor to classical physics with the ideas of Lorentz Force and the Lorentz Ether Theory. Although his early contributions to quantum mechanics were slightly off the mark, his ideas and the scientific method allowed and inspired other scientists fill in the gaps and emerge with the theory of quantum mechanics that was eventually adopted into the Standard Model. If Newton is the father of modern physics, then Lorentz is the grandfather of quantum physics.

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