Gravity Probe B press conf. 4 May (any surprises? comment?)

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    Gravity Probe
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Discussion Overview

The discussion revolves around the final results of the Gravity Probe B (GP-B) experiment announced by NASA, focusing on the implications for General Relativity (GR) and the precision of the measurements related to geodetic precession and frame dragging. Participants explore the accuracy of the results and the handling of the data.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Exploratory

Main Points Raised

  • Some participants suggest that the announcement indicates a precise confirmation of GR, particularly for geodetic precession, with a measurement accuracy of within 0.2%.
  • Others point out that the press release reports a residual precession measurement of 0.039 plus or minus 0.007 arcseconds, which they argue reflects a larger margin of error than initially stated.
  • There is a claim that while the geodetic effect was confirmed to within 0.2%, the frame dragging result was confirmed with a larger uncertainty of 19%, leading to concerns about the precision of this aspect of GR.
  • Some participants express skepticism regarding the frame dragging results, citing potential issues with data handling and manipulation after funding cuts in 2008.
  • A later reply humorously critiques the interpretation of the margin of error, suggesting that calling 0.007 "almost half" of 0.039 is an exaggeration.

Areas of Agreement / Disagreement

Participants generally express differing views on the precision of the GP-B results, particularly regarding the confirmation of GR for geodetic precession versus frame dragging. The discussion remains unresolved with multiple competing interpretations of the data's implications.

Contextual Notes

Participants note limitations in the clarity of the final analysis and the handling of raw data, which may affect the interpretation of the results. There is an acknowledgment of the complexity involved in the measurements and the potential for skepticism regarding the frame dragging results.

marcus
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It certainly reads that way to me!
 
What I've read since just confirms your supposition: after a lot of hard work this is another confirmation of GR to within .2% . From eclipses to to the smoothest spheres we've ever made, GR just keeps on keeping on.
 
Misericorde said:
What I've read since just confirms your supposition: after a lot of hard work this is another confirmation of GR to within .2% . From eclipses to to the smoothest spheres we've ever made, GR just keeps on keeping on.

The press release gives 0.039 plus or minus 0.007 arcseconds for the "residual" precession. This is more like 20% than .2%. Am I missing something?
 
Daverz said:
The press release gives 0.039 plus or minus 0.007 arcseconds for the "residual" precession. This is more like 20% than .2%. Am I missing something?

The Geodetic Effect was measured to within .2%, and frame dragging to 19%, so, I was imprecise.
 
So then I guess GR was precisely confirmed for the geodetic precession and imprecisely confirmed for frame dragging: a plus or minus 20% imprecision- almost half the total value after more than five years of fine tuning the data is basically useless as far as precise confirmations of GR go.
But the real issue (wrt frame dragging) is to analyze exactly how the raw data has been handled to reach that result. When NASA cut funds in 2008 it also warned that after all the manipulation the data had been subjected to, skepticism wrt the frame dragging result was justified, so I guess it is important to see their final analysis and their methods.
 
Last edited:
TrickyDicky said:
So then I guess GR was precisely confirmed for the geodetic precession and imprecisely confirmed for frame dragging: a plus or minus 20% imprecision- almost half the total value

Calling .007 "almost half" of 0.039 is quite creative.
 
Daverz said:
Calling .007 "almost half" of 0.039 is quite creative.
I meant the total margin of error is plus/minus 0.007, so when added it approaches 40%.
 

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