Albert Einstein (March 14, 1879 – April 18, 1955) was a human who lived on Earth during the 19th and 20th centuries. Einstein would later become one of the most well known physicists in human history.
Einstein was born in Germany, and lived most of his life in that nation. Einstein traveled to the United States of America in late 1932 to work as a guest lecturer. With the rise of Adolf Hitler's Nazi party, as Einstein was an Austrian member of the Jewish faith he decided not to return to Southern Germany, and spent the rest of his life living in the United States.
Einstein was particuarly famous for the equation E = mc², and for his work on the Theory of General Relativity, and his work became the basis for development of technologies such as nuclear fission and fusion reactors, warp drive, and transporters.
When Lieutenant Reginald Barclay's intelligence was drastically increased by the Cytherian probe, Barclay felt a need to explore some aspects of advanced physics. Using the holodeck, he used a recreation of Einstein to discuss his ideas. Losing all track of time, Barclay spent the entire night talking to Einstein. When La Forge saw this he realized that something had happened to Barclay in their encounter with the Cytherian probe. (TNG episode: "The Nth Degree")
Several years later, Lieutenant Commander Data played poker with a holographic recreation of Albert Einstein, along with recreations of Sir Isaac Newton and Stephen Hawking to see how the three men would interact with each other in such a setting. In the final hand before the bridge ordered a red alert, Einstein was confident that Hawking was bluffing, but soon learned that Hawking had a stronger hand than he did. (TNG episode & novelization: Descent)