Space/Time and the theory of relativity: are they all related...
Special relativity is a theory of the structure of space time. It was introduced in Albert Einstein's 1905 paper "On the Electrodynamics of Moving Bodies"
And, because relativity calls for the curvature of space to be equal to the curvature of time, the researchers could calculate whether light was influenced in equal amounts by both, as it should be if general relativity holds true.
General Relativity: Einstein's earlier theory of time and space, special relativity, proposed that distance and time are not absolute. The ticking rate of a clock depends on the motion of the observer of that clock; likewise for the length of a "yardstick." Published in 1915, general relativity proposed that gravity, as well as motion, can affect the intervals of time and of space. The key idea of general relativity, called the equivalence principle, is that gravity pulling in one direction is completely equivalent to acceleration in the opposite direction. A car accelerating forwards feels just like sideways gravity pushing one back against his seat. An elevator accelerating upwards feels just like gravity pushing one downwards.
If gravity is equivalent to acceleration, and if motion affects measurements of time and space (as in special relativity), then it follows that gravity does so as well. In particular, the gravity of any mass, such as the sun, has the effect of warping the space and time surrounding it. For example, the angles of a triangle no longer add up to 180 degrees, and clocks tick more slowly the closer they are to a gravitational mass like the sun.
Many of the predictions of general relativity, such as the bending of starlight by gravity and a slight shift in the orbit of the planet Mercury, is quantitatively confirmed by experiment. Two of the strangest predictions, impossible ever to completely confirm, are the existence of black holes and the effect of gravity on the universe as a whole (cosmology).
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