Einstein, Albert (1879-1955)

Albert Einstein is widely agreed to have been the greatest physicist of the twentieth century and probably its greatest scientist. After a distinguished (although not brilliant) career at school in Germany and at University in Zurich, he was appointed in 1902 to the post of Technical Expert (third class) at the Swiss Patent Office in Bern. He continued academic work in his spare time, inside and outside the office, and in 1905 this work bore fruit when he published four of the most influential papers in the history of physics. In his first paper, he explained Brownian motion (the apparently random motion of pollen grains that are suspended in liquid) in terms of the bombardment of the grains by molecules of the liquid. The success of this explanation established beyond reasonable doubt the very existence of molecules, which until then had been doubted by many physicists. In the second 1905 paper, he formulated a theory of the photoelectric effect (the interaction of light with matter) using the revolutionary idea that light can be modelled as a gas of particles. It was mainly for this piece of work that he was awarded the Nobel Prize for Physics in 1921. His third and fourth 1905 papers concerned the special theory of relativity, which entailed a radical modification to Newtonian ideas of space, time, matter and energy for observers in uniform relative motion. It was in the fourth paper that he provided eloquent justification for the famous equation which connects energy mass and the speed of light in a vacuum

Although these brilliantly original papers established Einstein as a physicist of the first rank three years elapsed before he obtained his first academic post, at the University of Bern. He continued to work on quantum ideas, together with a variety of other topics, but his attention gradually focused on his desire to find a general theory of relativity, which would apply to observers in a state of general relative motion. Following his 1907 discovery of the principle of equivalence (which states, loosely speaking, that there is an equivalence between gravitational and inertial forces), it became clear that a general theory of relativity would also be a new theory of gravitation. The general theory of relativity, one of the greatest intellectual achievements of the century and the cornerstone of modern cosmology, was finally published in 1916. Soon after he completed this theory, Einstein worked on the quantum theory of electromagnetic radiation and postulated the existence of the stimulated emission of radiation (later to be the theoretical basis of the operation of lasers). In 1919, two British teams of experimenters vindicated his prediction that starlight grazing the Sun is bent by twice the amount accounted for by Newton's theory. Einstein immediately became a celebrity, fêted all over the world as a pre-eminent genius.

By the early 1920s Einstein's best scientific work was done: he wrote in 1921 'Discovery in the grand manner is for young people ... and hence for me is a thing of the past'. He was nonetheless extremely influential in the physics community and he did much to sow the seeds of, for example, the Heisenberg uncertainty principle and Born's interpretation of the quantum mechanical wavefunction. He was nonetheless deeply dissatisfied with the quantum theory formulated by Heisenberg, Schrödinger and Dirac. Although he admired the theory, he did not believe that it gives a truly fundamental account of natural phenomena. Owing to the Nazis' persecution of the Jews, Einstein left Europe in 1933 and settled in Princeton, USA, in 1935. In his later years, he became an internationally respected figure on the world's political stage while working to produce a unified theory of gravity and electromagnetism. Although this work was unsuccessful, this did nothing to diminish his extraordinary achievements. An important figure in world Zionism, he was offered the presidency of the newly founded state of Israel, but declined the invitation.