A Spin through Space-Time
A long-planned test of Einstein's theory is poised for takeoff
Peter Weiss
A satellite designed to test one of the more twisted predictions of Albert Einstein's general theory of relativity is finally at its launch site after 40 years of preparation. The probe will look for evidence of a gravitational effect known as frame dragging. Just as a dipper drags honey along as it twirls in a honey jar, any spinning body in space, including Earth, ought to drag some space-time along with it. That was Einstein's prediction, anyway. The effect has never been convincingly observed.
That's partly because Earth's tweaking of space should barely register on even the most sensitive instruments. Yet the effects of frame dragging may prove enormous in deep space where spinning, ultradense concentrations of mass known as supermassive black holes may torque space-time vigorously enough to create the enormously powerful jets of matter and energy known as quasars (SN: 4/5/03, p. 214: http://www.sciencenews.org/20030405/fob7.asp).
FLYING THERMOS. Stacked inside Gravity Probe B's insulated tank of liquid helium, seen between the solar panels in this photo, are four gyroscopes and a telescope that can peer through the top hatch.
GP-B Project
Many relativity experts are enthusiastic about the prospects for Gravity Probe B (GP-B), as the spacecraft is known. Gathering hard evidence that "space is not the fixed fabric we think of" would be a "stunning achievement," says Clifford M. Will of Washington University in St. Louis, a gravitational physicist who served on a NASA-convened review panel that endorsed the mission's science goals last spring. He adds, "It's the kind of result that will be written in physics textbooks for years to come."
No one can say what the probe will find. Its measurements might confirm Einstein's prediction, or it might find discrepancies. Such anomalies could provide crucial clues for a model of the universe that might ultimately succeed relativity.
Other researchers, who are less sanguine about the mission, say that its scientific value has declined drastically during its long period of development. Those critics argue that the mission's estimated $700 million cost would have been better spent elsewhere.
Says physicist Kenneth Nordtvedt of Northwest Analysis in Bozeman, Mont., "The survival of GP-B through several decades . . . reveals to me how dysfunctional NASA has been in planning their strategy in this field of fundamental science."
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A long-planned test of Einstein's theory is poised for takeoff
Peter Weiss
A satellite designed to test one of the more twisted predictions of Albert Einstein's general theory of relativity is finally at its launch site after 40 years of preparation. The probe will look for evidence of a gravitational effect known as frame dragging. Just as a dipper drags honey along as it twirls in a honey jar, any spinning body in space, including Earth, ought to drag some space-time along with it. That was Einstein's prediction, anyway. The effect has never been convincingly observed.
That's partly because Earth's tweaking of space should barely register on even the most sensitive instruments. Yet the effects of frame dragging may prove enormous in deep space where spinning, ultradense concentrations of mass known as supermassive black holes may torque space-time vigorously enough to create the enormously powerful jets of matter and energy known as quasars (SN: 4/5/03, p. 214: http://www.sciencenews.org/20030405/fob7.asp).
FLYING THERMOS. Stacked inside Gravity Probe B's insulated tank of liquid helium, seen between the solar panels in this photo, are four gyroscopes and a telescope that can peer through the top hatch.
GP-B Project
Many relativity experts are enthusiastic about the prospects for Gravity Probe B (GP-B), as the spacecraft is known. Gathering hard evidence that "space is not the fixed fabric we think of" would be a "stunning achievement," says Clifford M. Will of Washington University in St. Louis, a gravitational physicist who served on a NASA-convened review panel that endorsed the mission's science goals last spring. He adds, "It's the kind of result that will be written in physics textbooks for years to come."
No one can say what the probe will find. Its measurements might confirm Einstein's prediction, or it might find discrepancies. Such anomalies could provide crucial clues for a model of the universe that might ultimately succeed relativity.
Other researchers, who are less sanguine about the mission, say that its scientific value has declined drastically during its long period of development. Those critics argue that the mission's estimated $700 million cost would have been better spent elsewhere.
Says physicist Kenneth Nordtvedt of Northwest Analysis in Bozeman, Mont., "The survival of GP-B through several decades . . . reveals to me how dysfunctional NASA has been in planning their strategy in this field of fundamental science."
Read rest of article
