After Einstein presented a series of ground-breaking ideas in 1905, Einstein continued to research and expand these concepts and other ideas in physics and mathematics. In 1916, Einstein presented his general theory of relativity, proposing that gravity is a curved field in the space-time continuum created by the existence of mass.
He received the 1921 Nobel Prize in Physics for his discovery of the law of the photoelectric effect and his work in theoretical physics.
Einstein left his homeland in Germany in 1933 upon Adolph Hitler's rise to power, and accepted a position at the Institute of Advanced Study in Princeton, N.J. He became a U.S. citizen in 1940. Peaceful by nature and politics, he spoke out strongly against nationalism, war and violence. He also supported Zionism, the idea of the creation of a homeland for Jews in Palestine.
In 1939, Einstein learned that two German chemists had split the uranium atom; he wrote to President Franklin D. Roosevelt that this application of scientific knowledge could lead to Germany's development of an atomic bomb and he urged the U.S. to begin its own research. His suggestions led to the creation of The Manhattan Project -- and the first two atomic bombs it spawned -- in 1945. Einstein was saddened when he heard of the destruction in Japan, and later campaigned for a ban on nuclear weapons.
Scientists are still finding new uses for Einstein's work today. Einstein developed a refrigerator design that received a U.S. patent in 1930. Instead of cooling the interior of the refrigerator with Freon, as we do today, Einstein's design uses ammonia, butane, water -- and almost no energy. Researchers are taking another look at the design as an eco-friendly alternative to air conditioning and refrigeration.