Gravity Probe B: final results of a space experiment to test general relativity.

King Abdulaziz City for Science and Technology, Riyadh, Saudi Arabia(Dated: May 18, 2011)Gravity Probe B, launched 20 April 2004, is a space experiment testing two fundamental predic-tions of Einstein’s theory of General Relativity (GR), the geodetic and frame-dragging e ects, bymeans of cryogenic gyroscopes in Earth orbit. Data collection started 28 August 2004 and ended14 August 2005. Analysis of the data from all four gyroscopes results in a geodetic drift rate of 6;601:8 18:3 mas/yr and a frame-dragging drift rate of 37:2 7:2 mas/yr, to be compared withthe GR predictions of 6;606:1 mas/yr and 39:2 mas/yr, respectively (‘mas’ is milliarc-second;1mas= 4:848 10