Albert Einstein was born in 1879 in Germany, attending public school in Munich before moving to Zurich, Switzerland to study mathematics and physics at the Swiss Polytechnic Institute. Einstein became a citizen of Switzerland in 1905, returning to work as a professor of physics at various German universities until 1930, when he and his family left Germany following the rise of the Nazis. Einstein urged U.S. President Franklin D. Roosevelt to expand nuclear research at the outbreak of World War II in 1939.
The Greek philosopher Democritus first theorized the presence of fine particles in the atmosphere of the Earth around 400 B.C. There was no actual evidence of the existence of atoms, however, until Einstein published three scientific papers in 1905 in the German science journal Annals of Physics. These three papers included Einstein's theory of relativity. The theory included the formula E=mc2, meaning energy equals mass times the velocity of light squared, which became the cornerstone of atomic theory research.
The theory proposed by Einstein extends the work of Max Planck by examining the effect of particles of light that are absorbed by a black surface. Einstein theorized the presence of electrons that are produced when a beam of light is directed onto the surface of metal -- this is known as the photoelectric effect. The release of atoms caused by the photoelectric effect was theorized to form an electrical current. This theory challenged the idea that light traveled only in waves.
The Brownian theory put forward by Einstein in the papers of 1905 defined the atomic theory of matter. The theory concerns the irregular movement of minute particles within a liquid or gas. Einstein's theory of Brownian motion was an extension of the effects seen by Scottish plant expert Robert Brown. The publishing of Einstein's research into Brownian motion is regarded by many researchers as the first real evidence of the presence of atoms, according to the Tesla Memorial Society of New York.