Who formulated the theory of relavity early in th century?

The theory of relativity was formulated by Albert Einstein in the early 20th century. It consists of two parts: special relativity, introduced in 1905, which addresses the physics of moving bodies and the constancy of the speed of light, and general relativity, published in 1915, which describes gravity as the curvature of spacetime caused by mass. Einstein's groundbreaking work fundamentally altered our understanding of space, time, and gravity.