Michael Lucibella at the website of the American Physical Society:
Albert Einstein changed our view of the universe in 1915 when he published the general theory of relativity, in which he set forth the notion of a four-dimensional spacetime that warps and curves in response to mass or energy. The geometric foundation for his work was laid some 60 years earlier, with the work of a German mathematician named Georg Friedrich Bernhard Riemann.
Born in what is now the Federal Republic of Germany in 1826, Riemann was the second of six children of a Lutheran pastor, who taught his son until he turned ten. The young Riemann was shy and nervous, but gifted in mathematics–so much so that while attending high school in Hannover, his knowledge sometimes surpassed that of his teachers. In 1846, his father scraped together sufficient funds to send his son to the University of Göttingen, where Riemann initially intended to study theology so that he could help support his family. But then he attended lectures by Carl Friedrich Gauss and Moritz Stern, who inspired him to switch his studies. With his parents’ blessing, Riemann transferred to the University of Berlin the following year, studying under some of the most prominent mathematicians of his time.