Albert Einstein was a physicist. He was born on March 14, 1879, in the city of Ulm, in Germany. Albert grew up in Munich, a city in Germany. Albert started school in Munich. Albert Einstein had one sister, who was born after him. Albert was four or five years old. His father showed him a compass. It gave Albert a sense of wonder. That wonder lasted his whole life. The compass deeply impressed Albert as a little boy. Albert took violin lessons as a boy.

Einstein did very well in math and science at school. Albert finished his school studies at the Cantonal School in Aarau, Switzerland. After university, Einstein could not find a teaching job. He took a job at the patent office in Bern, Switzerland. He did much of his best work in his spare time. He did it while he worked there. Einstein became a Swiss citizen in 1901. In the 1920s, Einstein traveled to give lectures in Europe, America and the Far East.

Einstein first proposed his special theory of relativity in 1905. Special relativity says the speed of light in a vacuum is the same for any observer. According to special relativity, the faster you move, the slower time passes for you. The equation E=mc2 says that energy equals mass times the speed of light squared. In the photoelectric effect, light that shines on a material makes the material give off tiny charged particles. Einstein explained the photoelectric effect. He proposed that light comes in small packets of energy called quanta.

Einstein published his general theory of relativity in 1915. General relativity says that gravity is how mass warps space and time. In 1919, astronomers photographed stars during a total solar eclipse. They wanted to test whether the Sun's gravity bends starlight. Einstein predicted gravitational waves in his general theory of relativity. This was about a hundred years before they were first observed. Gravitational waves were first observed directly. It was on September 14, 2015. His ideas changed how scientists think about time, space and the universe.

Einstein became famous around the world. In 1933, Einstein left Germany for America. He never returned to Germany. In 1933, he began work at the Institute for Advanced Study in Princeton, New Jersey. Einstein became a United States citizen in 1940. He lived and worked in Princeton in his later years. Einstein's house in Princeton was an old house with a garden at 112 Mercer Street. Einstein spent his later years looking for a unified field theory. It is one set of ideas to join the laws of physics.

Words to know

• relativity: his theory
• quanta: energy packets
• eclipse: solar eclipse
• compass: shown to Albert