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Gravity probe?
What happened to Gravity Probe B, the Stanford
experiment to test GR? They sent their detector into orbit 3 years ago, but since then, no word. Anybody here connected to that? Could be prime grist for the conspiracy intellectuals - -- Rich |
#3
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Gravity probe?
Interesting paper, but a little dry and inconclusive.
"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 with the GR predictions of -6,606.1 mas/yr and -39.2 mas/yr, respectively (`mas' is milliarc-second; 1mas = 4.848 x 10-9 rad). " So ... why the 4.3 mas/year discrepancy in geodetic frame drift rate and 2.0 mas/year discrepancy in frame-dragging drift rate? Systematic errors? Error bars? Flaws in GR? Did you even read the paper, or just skim the abstract? A mere confirmation of GR to within the limits of confidence in the data constrained by the engineering of the machine? In short, GP-B was a failure? Confirming a prediction of GR now counts as failure? |
#4
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Gravity probe?
On Sat, 03 May 2014 00:03:53 +0100, John wrote:
On Fri, 2 May 2014 20:09:52 +0000 (UTC), Greg Hennessy wrote: On 2014-05-02, wrote: What happened to Gravity Probe B, the Stanford experiment to test GR? They sent their detector into orbit 3 years ago, but since then, no word. Anybody here connected to that? Could be prime grist for the conspiracy intellectuals - The final results were released in May 2011. The results were published in Physical Review Letters. A copy can be found at http://arxiv.org/abs/1105.3456 Cool, thank you for this. I managed to miss the results and I forgot to look for them. Interesting paper, but a little dry and inconclusive. "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 with the GR predictions of -6,606.1 mas/yr and -39.2 mas/yr, respectively (`mas' is milliarc-second; 1mas = 4.848 x 10-9 rad). " So ... why the 4.3 mas/year discrepancy in geodetic frame drift rate and 2.0 mas/year discrepancy in frame-dragging drift rate? Systematic errors? Error bars? Flaws in GR? The passage you quote shows the discrepancy is within the error bars. |
#5
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Gravity probe?
On 02.05.14 22:09, Greg Hennessy wrote:
On 2014-05-02, wrote: What happened to Gravity Probe B, the Stanford experiment to test GR? They sent their detector into orbit 3 years ago, but since then, no word. Anybody here connected to that? Could be prime grist for the conspiracy intellectuals - The final results were released in May 2011. The results were published in Physical Review Letters. A copy can be found at http://arxiv.org/abs/1105.3456 Thanks! A nice set of results. |
#6
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Gravity probe?
Did you even read the paper, or just skim the abstract?
Both, why? Because several of your questions were answered in the paper. Confirming a prediction of GR now counts as failure? Yes, insofar as it advances the scientific base very little, gains us no new physics, doesn't allow us a new technology like the WWWeb and costs us a satellite and some man-years of highly educated scientists and trying-to-get-educated PHD students. Oh, the horror, those poor Ph. D. students who had to work on a FAILED mission, one that gave the best verification of GR to date! They'll never get jobs now with that stain on their resume. |
#7
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Gravity probe?
On Friday, May 2, 2014 10:12:55 AM UTC-7, wrote:
What happened to Gravity Probe B, the Stanford experiment to test GR? They sent their detector into orbit 3 years ago, but since then, no word. Anybody here connected to that? Could be prime grist for the conspiracy intellectuals - -- Rich They ran out of public loot, and once again managed to not advance nor improve anything. |
#8
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Gravity probe?
On Fri, 2 May 2014 20:09:52 +0000 (UTC), Greg Hennessy
wrote: On 2014-05-02, wrote: What happened to Gravity Probe B, the Stanford experiment to test GR? They sent their detector into orbit 3 years ago, but since then, no word. Anybody here connected to that? Could be prime grist for the conspiracy intellectuals - The final results were released in May 2011. The results were published in Physical Review Letters. A copy can be found at http://arxiv.org/abs/1105.3456 Gravity probe B Is a disgraceful example of bad science passed off as the real thing. The 4 gyroscopes were nothing but perfectly round quartz spheres, which possess zero gyroscopic properties. Check your Goldstein. This fundamental fact seems to have escaped the sponsors of this experiment, also the 70 Phd's who earned their stripes trying to straighten out the errors. The balls did not have one point of support but floated in space. Any sidewise pressure on the spin vector would simply add to the spin vector without any resistance normally supplied by precession. The gyroscopic property depends on the difference between moments of inertia on the 3 axes. In this case they are all equal. When supported by one point, such as a top, it will precess and resist toppling, because I did my own testing. But when supported by 1 point there is another set of equations that appliesbut of course not here. John Polasek |
#9
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Gravity probe?
On Monday, May 5, 2014 8:15:47 PM UTC-7, wrote:
On Fri, 2 May 2014 20:09:52 +0000 (UTC), Greg Hennessy wrote: On 2014-05-02, wrote: What happened to Gravity Probe B, the Stanford experiment to test GR? They sent their detector into orbit 3 years ago, but since then, no word. Anybody here connected to that? Could be prime grist for the conspiracy intellectuals - The final results were released in May 2011. The results were published in Physical Review Letters. A copy can be found at http://arxiv.org/abs/1105.3456 Gravity probe B Is a disgraceful example of bad science passed off as the real thing. The 4 gyroscopes were nothing but perfectly round quartz spheres, which possess zero gyroscopic properties. Check your Goldstein. This fundamental fact seems to have escaped the sponsors of this experiment, also the 70 Phd's who earned their stripes trying to straighten out the errors. The balls did not have one point of support but floated in space. Any sidewise pressure on the spin vector would simply add to the spin vector without any resistance normally supplied by precession. The gyroscopic property depends on the difference between moments of inertia on the 3 axes. In this case they are all equal. When supported by one point, such as a top, it will precess and resist toppling, because I did my own testing. But when supported by 1 point there is another set of equations that appliesbut of course not here. John Polasek Computer science data extrapolated from that mission was revised in order to obtain anything meaningful, so there's no telling what was actually measured because Earth isn't round nor without mascon issues, not to mention what modulation our moon contributes. In other words, far too many variables taking place. |
#10
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Gravity probe?
On Tue, 6 May 2014 08:45:44 -0700 (PDT), Brad Guth
wrote: On Monday, May 5, 2014 8:15:47 PM UTC-7, wrote: On Fri, 2 May 2014 20:09:52 +0000 (UTC), Greg Hennessy wrote: On 2014-05-02, wrote: What happened to Gravity Probe B, the Stanford experiment to test GR? They sent their detector into orbit 3 years ago, but since then, no word. Anybody here connected to that? Could be prime grist for the conspiracy intellectuals - The final results were released in May 2011. The results were published in Physical Review Letters. A copy can be found at http://arxiv.org/abs/1105.3456 Gravity probe B Is a disgraceful example of bad science passed off as the real thing. The 4 gyroscopes were nothing but perfectly round quartz spheres, which possess zero gyroscopic properties. Check your Goldstein. This fundamental fact seems to have escaped the sponsors of this experiment, also the 70 Phd's who earned their stripes trying to straighten out the errors. The balls did not have one point of support but floated in space. Any sidewise pressure on the spin vector would simply add to the spin vector without any resistance normally supplied by precession. The gyroscopic property depends on the difference between moments of inertia on the 3 axes. In this case they are all equal. When supported by one point, such as a top, it will precess and resist toppling, because I did my own testing. But when supported by 1 point there is another set of equations that appliesbut of course not here. John Polasek Computer science data extrapolated from that mission was revised in order to obtain anything meaningful, so there's no telling what was actually measured because Earth isn't round nor without mascon issues, not to mention what modulation our moon contributes. In other words, far too many variables taking place. You need to come to grips with this statement: a uniform sphere has no gyroscopic properties. It is fatal. There's also the problem that in setting up this experiment, it would not have been possible to simulate it because it needs a gravity free environment to float the Gyro Ball. As I recall, the principal investigator enlightened us initiates by boasting about the "extra inch". I take this to mean that instead of going 25,000 miles around in orbit, the Einstein drag provided an extra tilt that added 1.0" to what would otherwise have been 1,584,000,000 inches. Such precision is impossible, especially read at the radius of 1 inch of the ball. It looks to me like the experiment is fundamentally impossible. John Polasek |
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