What is space-time?

When it was first suggested that the earth was a sphere in three dimensions as opposed to a flat two-dimensional plane of sorts, the idea was largely startling at until experimental evidence proved it to be true.  The same can be said with space-time, albeit with an extra dimension involved.  It was once thought that space and time were separate, and that the universe was merely an assortment of cosmic bodies arranged in three dimensions.  Einstein, however, introduced the concept of a fourth dimension-time-that meant that space and time were inextricably linked.  The general theory of relativity suggests that space-time expands and contracts depending on the momentum and mass of nearby matter.  The theory was sound, but all that was needed was proof. 

That proof came recently courtesy of NASA’s Gravity Probe B, which demonstrated that space and time were indeed linked.  Four gyroscopes were pointed in the direction of a distant star and, if gravity did not have an effect on space and time, they would remain locked in the same position.  However, scientists clearly observed a ‘fame-dragging’ effect due to the gravity of the Earth that meant the gyroscopes were pulled very slightly out of position.  This seems to prove that the fabric of space itself can be altered and, if space and time are linked, then time itself can be stretched and contracted by gravity.

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