Relativity vs. The Newtonian Universe

l Michelson and Morely (1887) Velocity of light
l Einstein (1905)
Special Relativity (E = mc²)
l Einstein (1915)
General Relativity

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Isaac Newton developed theories and equations to explain the relationships of velocity, acceleration, time, and gravity with regard to the earth. These equations were sufficient to explain the measurable universe (which was restricted almost exclusively to the earth) through the 18th century. As science progressed, scientists attempted to apply these equations to measurements of the universe. Newtonian physics suggested that the velocity of light would be constant with respect to a fixed point in space. Albert Michelson and Edward Morely (1887) thought that they could be measure the absolute velocity of the earth by measuring the speed of light from different points on the earth and from different directions. By subtracting the differences in the speed of light, they should be able to show the absolute speed of the earth in space. To their surprise, these experiments suggested that the earth was not moving at all. What they didn't realize was that the velocity of light is constant with respect to all observers, whether they are moving or not.

In 1905, Albert Einstein derived the equations of special relativity that involved measurements of length, velocity and time from moving observers. These equations led to the now famous equation E = mc², which describes how matter and energy can be converted from one form to another.

In 1915, by applying relativity to Newtonian physics, Einstein derived the equations  of general relativity which describe the relationships between gravity, the speed of light, mass, and other factors in regard to the universe as a whole.