Einstein published four world-changing papers in 1905

Person: Albert Einstein
Lived: 1879–1955
Field: Physics
From: German-American

The story

In 1905 Albert Einstein was 26 and held no university post. After graduating from the federal polytechnic school in Zurich in 1900 he had struggled to find academic work, and since 1902 he had worked as an examiner at the Swiss Patent Office in Bern, judging applications for devices such as gravel sorters and electric typewriters. He did physics in his spare time, discussing ideas with friends in a small circle they jokingly called the Olympia Academy and with his colleague Michele Besso, whom he later called the best sounding board in Europe.

That year he published four papers in the journal Annalen der Physik, each of which would have made a scientific career on its own. The first, received in March, explained the photoelectric effect by proposing that light arrives in small packets of energy, or quanta, a key step toward quantum theory. The second, received in May, explained Brownian motion, the jiggling of tiny particles suspended in a liquid, and gave experimenters a way to count atoms through an ordinary microscope, strong evidence that atoms and molecules are real.

The third, "On the Electrodynamics of Moving Bodies", received at the end of June, set out the special theory of relativity. Starting from two principles, that the laws of physics are the same for all observers moving at constant speed and that the speed of light is the same for every observer, it showed that measurements of time and space depend on motion and that the aether was unnecessary. The fourth, published in November, showed that mass and energy are equivalent, the idea expressed as E = mc². The same spring Einstein also completed his doctoral dissertation on determining the size of molecules for the University of Zurich.

The papers were not all accepted at once. Jean Perrin's later experiments on Brownian motion persuaded even sceptics such as Wilhelm Ostwald that atoms exist, and it was the work on the photoelectric effect that the Nobel committee singled out when it awarded Einstein the 1921 Nobel Prize in Physics.

Together with quantum mechanics and Einstein's later general theory of relativity, the four papers form a foundation of modern physics. A century later, the International Union of Pure and Applied Physics marked the anniversary by declaring 2005 the World Year of Physics, an initiative endorsed by the United Nations.