Soon after publishing the

**special****theory****of relativity**in 1905, Einstein started thinking about how to incorporate gravity into his new relativistic framework. In 1907, beginning with a simple thought experiment involving an observer in free fall, he embarked on what would be an eight-year search for a relativistic**theory**of gravity.From

**special**to general**relativity**. In September 1905, Albert Einstein published his**theory**of**special****relativity**, which reconciles Newton's laws of motion with electrodynamics (the interaction between objects with electric charge).**Special****relativity**introduced a new framework for all of physics by proposing new concepts of space and time