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Who developed the special and general theories of relativity?

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Brian Greene sits in a living room, holding a pen, with handwritten equations m = E/c^2 and E = mc^2 on a whiteboard beside him, highlighting c^2 as the speed of light. — relativity Brian Greene kicking off his *Your Daily Equation* video series with Albert Einstein's famous equation E = mc².

The German-born physicist Albert Einstein developed both the special and general theories of relativity.12

Special theory of relativity: Einstein formulated this theory in 1905. It addresses the physics of objects moving at constant speeds in inertial frames of reference and established that the speed of light is constant for all observers.342
General theory of relativity: Published by Einstein in 1915, this theory expanded upon his earlier work to provide a comprehensive description of gravity as a geometric property of space and time.312

While other scientists, such as Hendrik Antoon Lorentz and Henri Poincaré, contributed foundational equations and concepts that preceded or paralleled the development of special relativity, it was Einstein’s axiomatic approach and clarity of thought that defined the theory.3