Einstein’s General Theory of Relativity Published

Illustration of the Distortion of Space-Time Caused by the Sun's Mass

In April 2004 NASA sent into space the Gravity Probe B satellite on a mission to prove a couple of postulations published 98 years ago this week by a man considered by many the greatest intellectual mind ever. On May 4, 2011, seven years after the probe was launched, the experiments finally confirmed two predictions by Albert Einstein‘s theory of general relativity: the warping, or curving, of space and time (space-time) around Earth; and frame-dragging, the amount of space-time that is dragged around Earth by its rotation. Thursday, March 20th, marks the landmark date when Einstein published those arguments, and others, under his theory of gravity in “The Foundation of the General Theory of Relativity.”

Gravity Probe BEven though Einstein worked these theories out mathematically, to get a practical sense of what these principles meant, there are two analogies most frequently used. First, with the warping of space-time around a large mass, imagine a large, heavy ball (representing the Sun) placed in the center of a thin, stretched sheet of rubber (representing space). The ball presses down in the middle of the sheet causing a depression, or curvature. When another smaller ball (representing Earth) is tossed onto the sheet it will circle and roll toward the larger ball. Einstein posited that gravity was not some mysterious gravitational force, as Isaac Newton thought, but merely smaller objects traveling through space along a curve toward the larger ones with enough mass that warps space around them. With frame-dragging, think of Earth as being immersed in honey. As the Earth rotates, the honey around it would swirl. And so it would with space and time.

Although measuring these two effects by the Gravity Probe B has led to practical applications in the improvement in aeronautics and GPS technologies, for astrophysicists and cosmologists it has fueled further interest in black holes. It is believed that objects with much more mass than our earth or sun can warp space-time fabric so much that they can create a hole where space itself falls into and where even light cannot escape.

Is gravity nothing more than the motion of objects around other, more massive objects which distort and curve the fabric of space-time?  Are there objects so massive where even light cannot escape? To dig deeper into these questions, and more on Albert Einstein and his theory of general relativity, visit eLibrary and view the resources below.

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Albert Einstein
Black Holes
Isaac Newton

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