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Gravity Probe B
is a "relativity gyroscope" experiment designed to test two unverified predictions of Albert Einstein's general theory of relativity (1916): that the presence of a mass in space, such as the Earth, would warp local spacetime, creating a dip or curve in spacetime, and that the rotation of a mass in space would twist or drag the local spacetime frame around it. An educator's guide and space science activities are included. (National Aeronautics and Space Administration)
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