Albert Einstein's General Theory of Relativity

Gravity is one of the most mysterious forces in the Universe. Many of the greatest minds have devoted their time to try to explain this strange and yet familiar entity, but have only produced more questions: What causes gravity? In what ways does it reveal itself? Can it be explained in physical terms? In the early 1900s, Albert Einstein took a stab at the problems inherent in gravity and the Universe in general. His models, most importantly the General Theory of Relativity, led to a better understanding of the world around us, and gave way to new and previously inconceivable physical phenomena.


In mid-1905, Einstein published his Special Theory of Relativity, which stated that observers see an event occur differently if they are in different reference frames or moving at different velocities. A result of this theory is that the speed of light must be constant, and that absolute space and time do not exist. This led to such notions as time dilation and length contraction, in which an object moving at a velocity near the speed of light has a noticeably slower clock and a noticeably contracted length in the direction of motion. The problem with this theory is that it assumed the Universe to be devoid of gravity. This did not mean that the theory was wrong, but that it had yet to incorporate an understanding of gravity.