Alternative theories being tested by Gravity probe B

[Garth]

my point in as much as I have one is that you can't really learn anything about this from the words in a press release.

Yes, of course, but frustrating all the same!

To make my point though of the uniqueness of the experiment, today's physics arXiv has this paper A Search for New Physics with the BEACON Mission, which makes the following points:

However, there are important reasons to question the validity of Einstein’s theory of gravity. Despite the beauty and simplicity of general relativity, our present understanding of the fundamental laws of physics has several shortcomings. The continued inability to merge gravity with quantum mechanics,⁸ and recent cosmological observations that lead to the unexpected discovery of the accelerated expansion of the universe (i.e., “dark energy”) indicate that the pure tensor gravity field of general relativity needs modification. It is now believed that new physics is needed to resolve these issues.⁸

Which I agree with, and:

The Eddington parameter \gamma whose value in general relativity is unity, is perhaps the most fundamental PPN parameter, ² in that \frac{1}{2}(\gamma−1) is a measure, for example, of the fractional strength of the scalar gravity interaction in scalar-tensor theories of gravity.¹ Currently, the most precise value for this parameter, \gamma−1 = (2.1±2.3)×10^-5, was obtained using radio-metric tracking data received from the Cassini spacecraft ⁷ during a solar conjunction experiment. This accuracy approaches the region where multiple tensor-scalar gravity models, consistent with the recent cosmological observations, predict a lower bound for the present value of this parameter at the level of \gamma−1 ~ 10^-6−10^-7 (see discussion in Ref. 1,8 and references therein). Therefore, improving the measurement of this parameter would provide crucial information to separate modern scalar-tensor theories of gravity from general relativity, probe possible ways for gravity quantization, and test modern theories of cosmological evolution.

Which I pointed out in #296 above.

However:

The BEACON mission architecture is based on a formation of four small spacecraft placed in circular Earth orbit at a radius of 80,000 km (Fig. 1). Each spacecraft is equipped with three laser transceivers in order to measure the distances to the other spacecraft in the formation.

The experiment is simply a refined measurement of the geodesic orbits of test particles (the spacecraft ) in Earth orbit and will therefore fail to discriminate between GR and any conformally equivalent scalar field theory in which the conformal transformation of the Action into the Einstein frame is simply canonical GR, as I explained in #296.

GP-B could resolve such a degeneracy.

Garth

 

[CarlB]

It probably doesn't help that they can't reproduce Einstein's GR. I hope that they publish their raw data so that other people can comb through it.

 

[Garth]

It probably doesn't help that they can't reproduce Einstein's GR.

You might be onto something there...

Just to show you what I mean:
Seeing General Relativity Directly[/url], from Francis Everitt's lecture slides http://colloquia.physics.cornell.edu/11-12-2007/cornellpres_files/v3_document.htm

GP-B DATA ARCHIVE TO BE AVAILABLE THROUGH NSSDC IN JULY

During the past few weeks, while our science team continues to analyze the data, our GP-B data processing team has also been quite busy, compiling an archive of the GP-B raw data—both science data and spacecraft /payload status data, as well as an archive of associated documents, drawings, photos and other information about the GP-B mission. We are currently in the process of transferring this entire archive to the National Space Science Data Center (NSSDC), located at the NASA Goddard Space Flight Center in Greenbelt, Maryland. Transfer of this archive will be completed in late June, and the GP-B archive will then become publicly available sometime thereafter.

Garth

 

[Garth]

"Rumors of the demise of GP-B are greatly exaggerated."

The latest update from the GP-B team:

All,

Since May 23, 2008, when I sent out our most recent GP-B email status
update and posted the same information on our webiste
(http://einstein.stanford.edu), I've received too many email
responses to reply to each one individually.

Thus, on behalf of the GP-B team, I wish to thank all of you,
collectively, who expressed support for GP-B, and assure you that, in
the words of Mark Twain, "...Rumors of the demise of GP-B are greatly
exaggerated."

Our science team is continuing to make excellent progress in the data
analysis. Members of the team, including several Stanford graduate
students, have produced detailed maps of the trapped magnetic flux in
all four gyro rotors in order to predict the time-varying signal in
the data. This mapping has resulted in a 500-fold improvement in the
determination of the polhode motion throughout the duration of the
experiment, essentially solving the time-varying polhode motion
problem in the data.

This work, in turn, has enabled the team to implement two
complementary methods of removing the disturbing effects of the
classical torques. With the classical torques properly handled,
rather convincing estimates of frame-dragging are now available, but
our team is still investigating all possible systematic disturbing
effects.

Another meeting of the GP-B Science Advisory Committee is being
planned in late August to review our progress in the data analysis
since last November. Also, GP-B will be a central contributor in an
international workshop on "The Nature of Gravity: Confronting Theory
and Experiment in Space" to be held in Bern, Switzerland, 6-10
October 2008, with the following team members as individual invited
speakers: William Bencze, Francis Everitt, Misha Heifetz, George
Keiser, Barry Muhlfelder & Alex Silbergleit.

Meanwhile, we are vigorously exploring funding sources outside NASA,
both through other agencies and private donors, to enable GP-B to
complete the data analysis, publish the final results and bring GP-B
to a conclusion by early 2010.

We very much appreciate the continued interest and support we have
received world-wide, and we will keep you apprised of our status
going forward.
Bob Kahn
GP-B Public Affairs

Any millionaires out there??

Garth

 

[Garth]

GP-B STATUS UPDATE -- September 26, 2008

GP-B STATUS UPDATE -- September 26, 2008.

PROGRAM STATUS

Since our May 23rd status update, GP-B has continued to make significant progress--fiscal and scientific. NASA funding and sponsorship of the program ends on September 30, 2008, but GP-B has secured alternative funding that will enable our science team to continue working at least through December 2009 in order to complete the data analysis and bring GP-B to a proper close.

The GP-B science team is continuing to make large strides in the data analysis. On Friday, August 29, 2008, the 18th meeting of our external GP-B Science Advisory Committee was held at Stanford to report our progress since the previous SAC meeting in November 2007. Their ensuing report to NASA states:

“The progress reported at SAC-18 was truly extraordinary and we commend the GPB team for this achievement. This has been a heroic effort, and has brought the experiment from what seemed like a state of potential failure, to a position where the SAC now believes that they will obtain a credible test of relativity, even if the accuracy does not meet the original goal. In the opinion of the SAC Chair, this rescue warrants comparison with the mission to correct the flawed optics of the Hubble Space Telescope, only here at a miniscule fraction of the cost.” —SAC #18 Report to NASA

On October 6-10, six GP-B team members have been invited to present these dramatically improved, interim results at an International Space Science Institute (ISSI) workshop on "The Nature of Gravity: Confronting Theory and Experiment in Space" to be held in Bern, Switzerland. Following the Bern workshop, these improved interim results will undergo a thorough peer-review and vetting; then towards the end of this year, we plan to announce them publicly.

We very much appreciate your continued interest in GP-B, and we will keep you posted on our progress in future status updates.

December 2009 - we continue to wait and see!

Garth

 

[JonathanK]

Hello Garth and all.

As well as working on until at least the end of next year, looks like they might announce some interim results towards the end of this year.. though you never know. Garth, are you going to redo the list? There were several updates to be made a while ago.

best wishes, Jonathan

 

[Garth]

Garth, are you going to redo the list? There were several updates to be made a while ago.

I have included PSG as it is accepted for publication, and I have taken your statement that its predictions are the same as those of GR, but note therefore that GP-B will not actually test it against GR. Note also my personal reservations previously expressed!

1. Einstein's General Relativity(GR)
2. Brans-Dicke theory (BD)
3. Moffat's Nonsymmetric Gravitational Theory (NGT)
4. Stanley Robertson's Newtonian Gravity Theory (NG),
5. F. Henry-Couannier's Dark Gravity Theory (DG).
6. Alexander and Yunes' prediction for the Chern-Simons gravity theory (CS).
7. Kris Krogh's Wave Gravity Theory (WG)
8. Hongya Liu & J. M. Overduin prediction of the http://www.journals.uchicago.edu/ApJ/journal/issues/ApJ/v538n1/50681/50681.text.html?erFrom=5252751197746712308Guest#sc8 gravity theory (KK).
9. Kerr's Planck Scale Gravity: Predictions of Experimental Results from a Gravity Theory (PSG)

The predictions are now:

GP-B Geodetic gross precession (North-South).

1. GR = -6606 mas/yr.
2. BD = -(3\omega + 4)/(3\omega + 6) 6.606 arcsec/yr. where now \omega >60.
3. NGT = -(6606 - a small \sigma correction) mas/yr.
4. NG = -6606 mas/yr.
5. DG = -6606 mas/yr.
6. CS = -6606 mas/yr.
7. WG = -6606 mas/yr.
8. KK = -(1 + b/6 - 3b² + ...) 6606 mas/yr. where 0 < b < 0.07.
9. PSG = -6606 mas/yr.

GPB gravitomagnetic frame dragging gross precession (East-West).

1. GR = -39 mas/yr.
2. BD = -(2\omega + 3)/(2\omega + 4) 39 mas/yr.
3. NGT = -39 mas/yr.
4. NG = -39 mas/yr.
5. DG = 0 mas/yr.
6. CS = -39 mas/yr. + CS correction
7. WG = 0 mas/yr.
8. KK = -39 mas/yr.
9. PSG = -39 mas/yr.

You can see for yourselves the present state of the results in a series of slides of a lecture given by Francis Everitt at Cornell University on the 12th November 2007. http://colloquia.physics.cornell.edu/11-12-2007/cornellpres_files/v3_document.htm .

The pertinent slides are slide 3: http://colloquia.physics.cornell.edu/11-12-2007/cornellpres_files/v3_slide0341.htm
and the slide: http://colloquia.physics.cornell.edu/11-12-2007/cornellpres_files/v3_slide0426.htm

These last two slides clearly show an inconsistency with the GR prediction at the 1 \sigma confidence level.

Einstein expectation:
-6571 \pm 1* mas
4-gyro result (1 \sigma) for 85 days (12 Dec 04 -- 4 Mar 05)
-6632 \pm 43 mas

(* -6606 mas + 7 mas (solar geodetic) + 28 \pm1 mas (guide star proper motion))

We note that this 07 November 1\sigma confidence level result is inconsistent with all the above geodetic predictions except KK, but nobody takes any notice until at least 3\sigma!

Garth

 

[JonathanK]

Thanks Garth,

I appreciate being back on the list. The relevant link is to the second paper published, not the first, as it has the equation that directly produces the geodetic effect curvature component, so vindicating PSG and leading to the prediction you quote above. (And showing that matter could be being affected by a kind of refractive medium at the Planck scale, as light is affected). It's at

http://journalgp.awardspace.com/journal/0202/020203.pdf

If I'm not mistaken, wasn't Jin He's Absolute relativity due to go back on as well? Anyway, it'll be interesting to see what the GP-B team have to say.

best wishes, Jonathan

 

[brightmatter]

Gravity Probe B 2009 interim results are arived!

 

[Garth]

Current Mission Status

MISSION UPDATE — February 16, 2009
PROGRAM STATUS
Observation of Frame-Dragging

Geodetic Effect Graph--All Gyros Processed data showing geodetic effect in all four gyroscopes.

Frame-Dragging Effect Graph--All Gyros
Processed data indicating frame-dragging effect in all four gyroscopes

The latest GP-B results, detailed in the papers and NASA report described below, show substantial improvement over the preliminary results announced at the April 2007 meeting of the American Physical Society (APS). At that time the geodetic effect was measured with a total uncertainty of 1%, but evidence of the frame-dragging effect as inconclusive.

The latest data analysis that includes a model for the "roll-polhode resonance torque" yields a 15% statistical uncertainty for the Frame-Dragging effect. This 15% uncertainty does not include all systematic effects. Click on the thumbnails at right to view these extraordinary results.

The data analysis leading up to this important result proved more subtle than expected. ‘Patch-effect’ anomalies on the gyro rotor and housing have complicated the gyro behavior in two ways:

1. A changing polhode path affecting the determination of the gyro scale factor.
2. Two larger than expected Newtonian torques.

Put simply, while mechanically both rotor and housing are exceedingly spherical, electrically they are not. Steadily advancing progress, reported to NASA directly and via successive meetings of the SAC, has brought a rather complete understanding of these effects. A turning point came last August with the incorporation of an elegant approach or computing the detailed history of the “roll-polhode resonance” torques discovered a year earlier by Jeff Kolodziejczak of NASA MSFC. The result was a large reduction in previously unexplained discrepancies between the four gyroscopes.

Much further work remains to bring the analysis to completion. To date, limits in computational power have bounded the processing to essentially one point per 97-minute GP-B satellite orbit. The driving period of the roll-polhode resonance torques is at the difference between the 77.5 sec roll period of the spacecraft and a harmonic of the gyroscope polhode period. High-speed computing techniques now in development will lead to more detailed analyses, and allow GP-B to approach the intrinsic limit of the gyro readout.

ISSI Presentations/Publications & Final NASA Science Report

GP-B Science Results--Final NASA Report

Early last October, five members of our GP-B team presented papers on various aspects of the GP-B data analysis at the International Space Science Institute (ISSI) workshop in Bern, Switzerland on “The Nature of Gravity: Confronting Theory and Experiment in Space.”

The five papers summarize the interim results of the GP-B experiment, as also reported to our GP-B external Science Advisory Committee (SAC) at their 18th meeting on August 29, 2008. Following the ISSI meeting, the papers were submitted for publication in the international, refereed journal, Space Science Reviews. They will be reprinted in a hardcover book in the Space Sciences Series of the ISSI, both to be published by Springer later this year.

The papers, along with an introductory preface, comprise the contents of a document entitled “Gravity Probe B Science Results—NASA Final Report,” now posted on our website. Click on the text link or thumbnail at right to view/download it.
GP-B Funding

Richard Fairbank
Richard Fairbank

We are profoundly honored that in January, 2008 Richard Fairbank (founder, Chairman and CEO of Capital One Financial Services Company and one of the three sons of GP-B co-founder, William Fairbank) made a private donation of $512K to Stanford, specifically to support GP-B’s continuing data analysis work. Fairbank’s generous offer was subsequently matched by both Stanford and NASA. This support carried the program until 30 September 2008. All of us here at GP-B are most grateful to Mr. Fairbank for his generous support.

Photo of signing of Stanford-KACST Agreement in October 2008
Signing of the Stanford-KACSTAgreement
in Ocober 2008

Discussions begun last summer with Dr. Turki al Saud, Vice President for Research Institutes at the King Abdulaziz City for Science and Technology (KACST) in Saudi Arabia, have led to the creation of an important Stanford-KACST collaboration, with Professor Charbel Farhat of the Stanford Aero-Astro Department as Co-PI for GP-B data analysis. (The photo at right shows the Stanford-KACST collaboration signing last October.)

As part of this agreement, a team of research scientists from KACST will join the Stanford team to help with the data analysis as well as participate in future projects being developed. Additionally, KACST provided funding for GP-B from October 2008 through December 2009. To maximize the benefit to the scientific and engineering community, we plan to make the capstone of the GP-B program a conference on Fundamental Physics and Innovative Engineering in Space, in honor of William Fairbank.

We thank NASA for forty-four years of continued support since issuing the first research Grant NSG-582 to the program in March 1964. The March 2007 "GP-B Post-Flight Analysis—Final Report" contained an extensive history of GP-B and the NASA personnel who guided it. It is appropriate here to express further special thanks to three individuals, the MSFC Manager Mr. Anthony T. Lyons, the HQ Program Scientist for Physics of the Cosmos Dr. Michael H. Salamon, and the HQ Program Executive Dr. Alan P. Smale. Lastly, we are most grateful to the GP-B Science Advisory Committee (SAC) for their continuing advice and support.

Note the results shown in Figure 13 from Page 21 of the GPB Final NASA Report (Dec 2008).

Garth

 

[Garth]

Okay - now closing in on the GR prediction;

Closing in on Einstein: Frame-Dragging Clearly Visible

The accuracy of the GP-B experimental results has improved seventeen-fold since our preliminary results announcement at the American Physical Society annual meeting in April 2007. At that time, only the larger, geodetic effect was clearly visible in the data. Over the past two and one half years, we have made extraordinary progress in understanding, modeling and removing three Newtonian sources of error—all due to patch potentials on the gyroscope rotor and housing surfaces. The latest results, based upon treatment of 1) damped polhode motion, 2) misalignment torques and 3) roll-polhode resonance torques, now clearly show both frame-dragging and geodetic precession in all four gyroscopes (see figure at top right).

The figure at lower right displays the science estimates as of September 2009, with the gyroscopes analyzed individually and combined. The estimates are indicated with colored "X"s, and the statistical uncertainty associated with each estimate is plotted with a corresponding colored ellipse.

The combined four-gyro result in the figure gives a statistical uncertainty of 14% (~5 marcsec/yr) for the frame-dragging (EW). The gyroscope-to-gyroscope variation gives a measure of the current systematic uncertainty. The standard deviation of this variation for all four gyroscopes is 10% (~4 marcsec/yr) of the frame-dragging effect, suggesting that the systematic uncertainty is similar in size (or smaller) than the statistical uncertainty.

EDIT - This was deleted somehow from my original post - thank you sylas below.
MISSION UPDATE — November 12, 2009
Click on the diagrams to see the present measurements, especially the 'Individual and 4-gyro combined estimates.' and note only 50% error ellipses are plotted.

They have certainly made heavy weather of it...

Garth

 

[Ich]

Well, closing in after modeling away ~95% of the initial uncertainty. I'd say, they needed a result, now they have one.
Better wait for some independent data.

 

[sylas]

They have certainly made heavy weather of it...

Oh yeah... thanks for the heads up. The link is as before, but with new content: MISSION UPDATE — November 12, 2009; Closing in on Einstein: Frame-Dragging Clearly Visible.

The GR prediction lies just outside the 50% error ellipse of the 4 combined gyros.

At this point, I wonder if they learned more about Newton and gyroscopes than about GR! The confirmation is nice even if not to the accuracy they had originally hoped.

Cheers -- sylas

 

[Polestar101]

The GP-B folks have made so many adjustments and re-adjustments of the data I have no confidence they can really tell the difference between polhode noise, aberration of light from a moving solar system or other unquantifiable effects. NASA was right to pull the plug on this one. Bad science.

 

[Garth]

Two unexpected errors have crept into the data, misalignment torques and a varying polhode motion.

A constant polhode motion (wobbling) was to be expected, as each sphere was not perfectly symmetrical, however these motions were found to be damped out and that meant removing the effect from the data proved more difficult.

However, adding the variation in spin-down rates to the analysis, the GP-B team currently believes that the underlying reason for both these errors is a single effect caused by "patch effect charges" on the gyro rotors and on the inside surfaces of their housings.

The team are confident that they are modelling these sources of noise in the data accurately because they are using two independent methods, algebraic and geometrical, and the results of each method are being compared for consistency.

The aberration of starlight is clearly observed as predicted and provides the natural system calibration, over both orbital (the satelite's) and annual (the Earth's) orbits.

However the problem is that, given the noise has to be modeled and extracted from the data to find the relativistic signal, should the final signal deviate from GR then few would find the result convincing. Others would be say that they had just modeled the noise incorrectly.

Having come this far it would be madness not to complete the data reduction, which is being done through private funding, and the published raw data could provide a mine for others to dig into for years to come - that is if anybody else will be bothered to do so!

Garth

 

[Polestar101]

The aberration of starlight is clearly observed as predicted and provides the natural system calibration, over both orbital (the satelite's) and annual (the Earth's) orbits.

Garth – It is true that the steady signal from the ~5” aberration of light from the spacecraft ’s 91 minute orbit around the Earth served as a useful calibration tool. The less frequent ~20” aberration (due to the earth’s orbit around the sun) was hardly helpful at all because the periodicity during the allotted time for the experiment was less than 2x and because the incoming GP-B data was broken up so many times (with stops and starts and recalibrations along the way).

But perhaps the biggest blunder of the experiment was failure to account for the moving frame of the solar system. The aberration of light from this effect is large (larger than the diurnal or annual figures and larger than the relativity effects) but looks like drift and is still unquantified because there is still large uncertainty about the exact speed and exact motions of the SS (it may have several). I do not blame the current program scientists for this problem as it was unforeseen by the original designers of the experiment (note the complete absence of any mention of this effect in the literature).

Having come this far it would be madness not to complete the data reduction, which is being done through private funding, and the published raw data could provide a mine for others to dig into for years to come - that is if anybody else will be bothered to do so!

I agree it would be great to thoughtfully take apart and quantify every single signal recorded by GP-B. However, the current team is so focused on finding the relativity effects I believe they are missing the discovery of some very important science about the motion of the solar system. Unintentional bias is hard to get away from in an experiment of this type.

Polhode motion is an extremely tricky thing to quantify and predict (no paper supports its prediction with this many variables). In their attempts to cancel it out the GP-B team is probably throwing out vital information about the moving solar system (all in an effort to find the relativity effects). Personally, I doubt if there was any meaningful polhode motion (think about it - those gyros were pretty darn perfect – and polhode is exactly the sort of thing they were designed to avoid!). Most of the “noise” is likely motion of the frame of the SS, and possibly, motion of our local star group relative to the guide star.

GP-B is a unique experiment. No doubt some day someone will look at the data with a completely virgin mind and reveal key information about the moving solar system. Until then I hope the data is well preserved for future generations.

Walter

 

[sylas]

But perhaps the biggest blunder of the experiment was failure to account for the moving frame of the solar system.

I don't think that can be right. The motion of the solar system and of the guide star IM Pegasi was considered and taken into account in the analysis. Not only that, the accuracy of motions was carefully measured and determined to have only a small effect on the uncertainty of the final result.

See: Bartel et. al. (2007) VLBI astrometry for the NASA/Stanford gyroscope relativity mission Gravity Probe B, in Proceedings of the International Astronomical Union, 3, pp 190-191; doi:10.1017/S1743921308019005.

Cheers -- sylas

 

[Ich]

However the problem is that, given the noise has to be modeled and extracted from the data to find the relativistic signal, should the final signal deviate from GR then few would find the result convincing.

Garth, no matter what the outcome is: it is not convincing.
I understand that the published result does not support scc (correct me if I'm wrong), but I wouldn't see it as confirmation or rejection of anything. It is not reproducible, nobody will go down that road again in the foreseeable future, and nobody can follow their corrections without doubt.
It's sad, but I'd say: the experiment failed in this aspect. That's ok, it is bound to happen every now and then.

 

[Garth]

Walter, would not motion of the Solar System frame be subsumed into the guide star IM Pegasus' proper motion? This was measured independently by the astrometry team at the VLBI and a report found here: Proper Motion of the GP-B Guide Star.

I was at the 2007 APS meeting in Jacksonville to hear the first results of the experiment and asked the question of Francis Everitt specifically about the desire to find the GR effects affecting the modelling of the noise and hence not finding new physics. Francis emphatically stated that that was what they were not doing but modelling the errors in an independent (actually two independent) ways.

The annual aberration of light effect is described here:The Annual Aberration Signal. It seemed to confirm the orbital aberration effect.

As far as the difficulty of modelling polhode motion, and no real sphere is ever perfect and free from such effect, they have spent four years now on the problem and so they would probably agree with your statement

Polhode motion is an extremely tricky thing to quantify and predict !

I actually have a vested interest in the GP-B team getting it wrong (see SCC earlier in this thread, which is falsified by the results), so I am playing Devil's Advocate in supporting their results, and I find no reason at present to think otherwise, but if you have a serious alternative solution to their data analysis I shall be very interested!

Edit: Crossed post with both sylas and Ich.

Garth

 

[Polestar101]

Walter, would not motion of the Solar System frame be subsumed into the guide star IM Pegasus' proper motion? This was measured independently by the astrometry team at the VLBI and a report found here: Proper Motion of the GP-B Guide Star.

It is certainly useful to exactly define the proper motion of the guide star but remember the reference point has nothing to do with the motion of the instrument that is doing the measuring. The spacecraft that is doing the measuring moves in its regular orbit, and it moves with the Earth in its orbit around the sun, and it moves with the Earth and solar system as the solar system moves through space – thereby changing orientation relative to the guide star independent of any proper motion of that reference point.

The annual aberration of light effect is described here:The Annual Aberration Signal. It seemed to confirm the orbital aberration effect.

The GP-B team properly describes the orbital aberration and the annual aberration but notice there is no mention of the little known aberration that results from the motion of the solar system. I doubt that it was considered when the experiment was conceived. Even today neither the speed nor exact motion of the SS is known for certain. The Voyager 1 and 2 data suggest the SS is moving at a high rate of speed in a general southwesterly direction. But we need more than two data points before we can match it to the GP-B data.

I actually have a vested interest in the GP-B team getting it wrong (see SCC earlier in this thread, which is falsified by the results), so I am playing Devil's Advocate in supporting their results, and I find no reason at present to think otherwise, but if you have a serious alternative solution to their data analysis I shall be very interested!

Hopefully the GP-B data when juxtaposed against the data from other experiments will be useful to several generations to come – even if not to test Einstein. I will be presenting a poster at the upcoming AGU meeting in SF that looks at how much the SS might be moving and why it may be artificially constrained by current lunisolar precession theory. This could have a bearing on the interpretation of the GP-B data but I freely admit I cannot make full sense of the GP-B data at this point.

 

[sylas]

The GP-B team properly describes the orbital aberration and the annual aberration but notice there is no mention of the little known aberration that results from the motion of the solar system. I doubt that it was considered when the experiment was conceived.

It is known and it is tiny. No offense, but at this point it is clear that you have no empirical basis for your interesting personal suppositions, and claims about what the team is ignoring are pure speculation; and not actually based on any understanding of the analysis.

[strike]The Sun is not part of a binary star system.[/strike] Analysis of GP-B does not give you the data you would like to support this hypothesis (of a stellar companion to the Sun). Speculations based on pure supposition that they've somehow failed to notice this are not really acceptable by forum guidelines.

Cheers -- sylas

 

[Polestar101]

If it is known - please tell me how it is known.

The fact is the motion of the solar system is not known - it is assumed. The major assumption is that its only motion is around the galactic center in a period of about 240 million years resulting in a change in orientation of about .005" p/y (within the precession observable), but no one really knows if this is correct. In fact, this assumption itself lies on the assumption that all changes in Earth orientation are local in nature and there is no accounting for the motion of the frame of the solar system relative to the VLBI reference points. This has nothing to do with a possible stellar companion. Good science simply requires that we not make too many unfounded assumptions. Unfounded assumptions is what got GP-B into its current mess.

 

[Garth]

The experiment measured the angular displacement of the four gyros against a distant quasar, the core of 3C 454.3. Which, being at z=0.859 was seen to be a 'fixed direction in space'.

The satellite itself measured the angles between the gyros and the guide star IM Pegasi, a VLBI team independently measured the Proper Motion of the guide star, relative to the quasar. Both IM Pegasi and the quasar are radio objects.

The actual data being measured were the angles between an gryos' axes and the distant quasar. The Earth is orbiting the Sun, the Sun is orbiting the Milky Way and the Milky Way is moving through intergalactic space. The total velocity of these motions is approximately 10 ^-3c.

Using ball-park OOM estimates z = 0.859 converts into a distance of about 10¹⁰ light yrs and the galaxy moved about 10 ^-3 lgt yrs in the ~year data were collected, similarly with the quasar, so the proper motion of the quasar would be OOM 10 ^-13 rad i.e. ~ 10 ^-5 milliarcsecs. They hope to measure the displacement angles to an accuracy of about 1 milliarcsec, they have achieved an accuracy of about 10 milliarcsecs so far, so as the proper motion of the quasar relative to the Earth is 5 or 6 OOM smaller than this it can be disregarded.

Garth

 

[sylas]

Using ball-park OOM estimates z = 0.859 converts into a distance of about 10¹⁰ light yrs and the galaxy moved about 10 ^-3 lgt yrs in the ~year data were collected, similarly with the quasar, so the proper motion of the quasar would be OOM 10 ^-13 rad i.e. ~ 10 ^-5 milliarcsecs. They hope to measure the displacement angles to an accuracy of about 1 milliarcsec, they have achieved an accuracy of about 10 milliarcsecs so far, so as the proper motion of the quasar relative to the Earth is 5 or 6 OOM smaller than this it can be disregarded.

Garth

Or put it another way: 1 milli arc second is about 5 * 10^-9 radians. To let actual lateral movement of the solar system distort directions by this amount would require movement of the order of 50 light years over the year or so that data was collected.

Cheers -- sylas

 

[Polestar101]

If the solar system changes "orientation" we are not just talking parallax.

VLBI does not account for changes in the solar system’s orientation to reference points outside the moving frame. Quote from NASA VLBI website:

“Changes in the Earth’s orientation in inertial space have two causes: the gravitational forces of the Sun and Moon and the redistribution of the total angular momentum among the solid Earth, ocean and atmosphere. VLBI makes a direct measurement of the Earth’s orientation in space from which geoscientists then model such phenomena as atmospheric angular momentum, ocean tides and currents, and the elastic response of the solid Earth.”

Please note the present methodology is only concerned with local changes - within the frame of the solar system – thereby effectively employing a static solar system model. Yet measurements are made to points far outside the moving frame – without accounting for any motion of the frame relative to the reference points. If the solar system curves through space we would never know it under current methodology because all changes in Earth orientation are attributed to local causes.

If the total precession observable includes some component of solar system motion then even though GP-B is be far above the precessing Earth it would still pick up some component of precession (due to SS motion) but think it was noise.

A careful reading of the press releases suggests this is exactly the type of “noise” that GP-B has been bothered with since inception.

http://www.space.com/businesstechnology/technology/gravity_probe_b_031231.html

 

[Garth]

Polestar, as the measurement is that of the change of angle between the axis of a gyro and the distant quasar, are you claiming the changes in the solar system orientation also changes to orientation of the gyro?

The changes in the Earth's orientation you mention, its change of axis, would not affect the satellite.

The early Space.com site you linked to does accurately predict

Several members of the review at the time voiced a minority skepticism about the large extrapolations required from ground testing to GP-B's performance in space. Furthermore, this same minority thought it likely that some "as yet unknown disturbance" may prevent the spacecraft from performing as required.

Why does the build up of electrostatic patches not seem to you to be "exactly the type of “noise” that GP-B has been bothered with since inception."?

Garth

 

[Polestar101]

As the SS curves through space the spacecraft , in orbit around the earth, must move with it. Just as GP-B will detect a change in orientation due to the spacecraft s orbit around the Earth (seen as a 97 minute wave), and due to the earth’s orbit around the sun (a longer waveform), so too will it detect a change due to the solar system’s change in angular velocity relative to the guide star. I don’t see how it could be any other way. Of course, the later signal probably looks like noise (thought to be polhode or something else) because the short period of the experiment relative to the long wave makes that form difficult to see. All I’m saying is don’t throw out the baby with the bathwater until we know what is hiding in that bathwater.

Re: electrostatic patches. I don't know enough about this to offer an opinion. But I would start with the assumption that those $800 million gyros have done their job and probably picked up real signals far more subtle than we can imagine. EOP is still a science in progress.

 

[Garth]

As the SS curves through space the spacecraft , in orbit around the earth, must move with it. Just as GP-B will detect a change in orientation due to the spacecraft s orbit around the Earth (seen as a 97 minute wave), and due to the earth’s orbit around the sun (a longer waveform), so too will it detect a change due to the solar system’s change in angular velocity relative to the guide star.

The "solar system’s change in angular velocity relative to the guide star" will be caused by its motion around the galaxy, I have dealt with the motion of the galaxy itself above (it is negligible).

Orbiting the galaxy would cause a geodetic precession of

(\frac{M_G}{M_E})^\frac{3}{2}(\frac{R_E}{R_G})^\frac{5}{2} \times 8 \text{arcsecs/yr }

(See MTW 'Gravitation' page 1119 eq 40.35)

i.e. about 10^-8 arcsecs per year.

I think this can also be safely ignored!

Garth

 

[Garth]

The is a general point here that is being overwhelmed by the discussion of a hypothetical solar companion star.

To save further confusion and time wasting I will re-iterate it.

It is this. If other effects such as poholde and perturbing forces are eliminated then gyros 'point in a constant direction' in space. The curvature of the space-time around the Earth cause two effects on that 'constant direction' that was measured by GP-B, the geodetic and frame-dragging precessions.

The direction of the GP-B gyros axes was referenced to a distant quasar.

All motions of the Earth around the Sun, the Sun around a possible companion, the Sun around the galaxy and the galaxy through space would add up to around 10^-3c, as that guide quasar is approximately 10¹⁰ light years away then all motions create a parallax of no more than OOM 10^-13 rad i.e. ~ 10 ^-5 milliarcsecs, far smaller than those caused by the curvature of the Earth and Sun's gravitational field that were measured by the experiment.

They can be safely ignored as negligible.

Garth

 

[maurol2]

It is this. If other effects such as poholde and perturbing forces are eliminated then gyros 'point in a constant direction' in space. The curvature of the space-time around the Earth cause two effects on that 'constant direction' that was measured by GP-B, the geodetic and frame-dragging precessions.

So, the direction at which the gyroscopes point is not constant, but subjected to, at least, two effects: geodetic and frame-dragging precessions.

Now, imagine for a moment that the movement of the solar system towards the solar apex has an actually unknown characteristic that causes precession in the same way as either geodetic or frame-dragging. I'm not saying that these are geodetic/frame-dragging effects, just that they behave similarly, affecting the orientation of the gyroscopes, that of the earth, and that of the rest of the solar system.
Suppose that this precession is a small component of what we consider to be the known axial precession due to lunisolar causes, as Polestar101 suggested.
Now, when you send a probe to the space to measure small precession effects predicted by GR, your gyroscopes start behaving in an unexpected way.
That's what Polestar101 is saying, if I understood correctly. And I think that that's a possibility that clearly deserves a closer scrutiny.

All motions of the Earth around the Sun, the Sun around a possible companion, the Sun around the galaxy and the galaxy through space would add up to around 10^-3c, as that guide quasar is approximately 10¹⁰ light years away then all motions create a parallax of no more than OOM 10^-13 rad i.e. ~ 10 -5 milliarcsecs, far smaller than those caused by the curvature of the Earth and Sun's gravitational field that were measured by the experiment.

Those are the known, small effects, predicted by GR. Imagine for a moment that there actually are unknown effects, whose causes are being mistaken in the GP-B experiment.

Mauro

 

[sylas]

You can't simply eliminate polhode and other perturbing forces to save the experiment without first being able to exactly quantify these effects. And to try and measure them by eliminating anything that does not get to the GR goal is circular reasoning and bad science.

This doesn't make any sense at all. They DO quantify the podhole effect. It was quantified and understood and taken into account from the start. There is an additional effect which was stronger than anticipated; from a tiny residual change on the gyroscopes, which gives an additional effect on the motions. There is no doubt at all that this effect exists. Most of the work of the extended data analysis phase HAS been to quantify this effect -- and not by assumption. When quantified, it can be extracted to reveal any underlying signal.

This is an extra factor influencing the gyroscopes which was larger than anticipated, and has been at the root of the limited accuracy to which results could be given.

The description by Polestar101 is very misleading. It's not bad science at all -- it is precisely what science should do to test GR as well as they can without making assumptions. They quantify all influences and obtain the residual signal, which stands then as a test of the predictions from the frame-dragging effect. There is no assumption of GR involved in that process. Without the proper quantification of the electromagnetic forces, the accuracy of the test is very weak. With proper quantification, the test will improve, though it is unlikely to get to the level of 1% which had originally been hoped.

There's a nice summary of the issues in The Gravity Probe B Bailout, IEEE Spectrum, Oct 2008. This report is describing how the team was able to secure additional funding; and their own project page gives more on the existing funding. (Gravity Probe B -- current status -- updated November 12, 2009. The work is ongoing, and primarily this is focused upon quantifying the effects of the electromagnetic influences, so that they can be properly take into account -- without just making assumption -- and so improving the accuracy of the true independent test of GR.

 

[Garth]

It is this. If other effects such as poholde and perturbing forces are eliminated then gyros 'point in a constant direction' in space. The curvature of the space-time around the Earth cause two effects on that 'constant direction' that was measured by GP-B, the geodetic and frame-dragging precessions.

So, the direction at which the gyroscopes point is not constant, but subjected to, at least, two effects: geodetic and frame-dragging precessions.

You have not understood the experiment. If other effects are eliminated then the gyro's do 'point in a constant direction' in space. It is space itself that is curved by the presence of the Earth's, and to a lesser degree, the Sun's gravitational fields. There is a further effect caused by the dilation (or 'curvature') of time.

It is this curvature of space-time that cause the geodetic precession and frame-dragging effects that GP-B measured.

Please start another thread about whether the Sun has a companion or not, it is irrelevant to this experiment.

Garth

 

[cristo]

Offtopic posts have been removed, mostly to [thread=383916]here[/thread]. Please keep this thread on the topic of comparing published theories that have made proper predictions for the Gravity Probe B experiment.

 

[maurol2]

Offtopic posts have been removed, mostly to [thread=383916]here[/thread]. Please keep this thread on the topic of comparing published theories that have made proper predictions for the Gravity Probe B experiment.

I've noticed that you've deleted my last reply to Garth, in the name of "topicness". Do as you please. I couldn't care less, except to mention that I don't see why you didn't removed Garth's last comment too. He was the one which initiated that avenue towards "offtopicness", so to speak, presuming about the geometrical migth of GR.

 

[JonathanK]

Hello Garth and all,

I just want to point out that strictly because of the very nature of this thread Garth you're not in a position to say "It is this curvature of space-time that cause the geodetic precession and frame-dragging effects that GP-B measured."

There may be other theories apart from mine, on the list of theories that are still viable in the light of the results, that give conceptual interpretations other than curvature for the measured effects.

But whether or not others do it, PSG certainly does. Equation 3 of the second paper on PSG published in a peer reviewed journal, here
http://journalgp.awardspace.com/journal/0202/020203.pdf

generates the curvature component of the geodetic effect from flat space, simply from assuming that an effect like a refractive medium slows matter in the same way as it slows light. That's 2/3 of the effect potentially explained, and because the other 1/3 doesn't require curvature, the equation works as a proof that curvature doesn't necessarily have to be the cause. (Wikipedia, nevertheless, still defines the geodetic effect as a direct result of curvature.)

You checked the equation, found it gives the right numbers, and then put PSG back on the list of viable theories, after more than a year off it. The reason it deserved to go back on the list was that the only premiss that went into the equation was the original starting premiss of PSG, ie that light and matter are slowed by sqrt(1 - [2GM/rc^2]) in a gravity field. (So the equation vindicated the theory, and showed that in the earlier prediction I was wrong, but PSG wasn't.)

Sorry to restate this, but it seems directly relevant to what you've said about the interpretation of the results. (BTW, have been hoping to get back in touch anyway.)

Best wishes, Jonathan Kerr

 

[maurol2]

But whether or not others do it, PSG certainly does. Equation 3 of the second paper on PSG published in a peer reviewed journal, here
http://journalgp.awardspace.com/journal/0202/020203.pdf

generates the curvature component of the geodetic effect from flat space, simply from assuming that an effect like a refractive medium slows matter in the same way as it slows light. That's 2/3 of the effect potentially explained, and because the other 1/3 doesn't require curvature, the equation works as a proof that curvature doesn't necessarily have to be the cause. (Wikipedia, nevertheless, still defines the geodetic effect as a direct result of curvature.)

Very interesting. Are you suggesting that this is related also to the origin of the rotation of the planets, or I misunderstood/read too much?

Talking about the likely effect of refractive mediums, you might be interested in this 2003 paper by Consoli & Constanzo:
http://arxiv.org/abs/astro-ph/0311576"

They re-analize the Michelson-Morley, Miller and other interferometry experiments, and show that in all cases a fringe shift is in fact detected, only its value is less than expected. They provide an excellent explanation for the differences, based on previous work by Kitto and Cahill, which goes back to Fresnel and the Fresnel drag coefficient.

I mention all this in this context due to a number of reasons:
- Consoli & Constanzo show that ether drag is dependant on the refractive index of the medium, and that this is the explanantion for the diverging results of the various interferometry experiments.
- They talk about a small similar effect caused by gravity, which resembles Fresnel drag, that will be equivalent to what you're proposing in your paper for 2/3 of the geodetic effect.

You might be interested also in this http://en.wikipedia.org/wiki/Aether_drag_hypothesis"
and the linked references and papers. In particular those by D. Gezari.

Regards,
Mauro

 

[JonathanK]

Hello,

Thanks for the references, if we discuss it in detail it should be elsewhere (or we'll find ourselves there anyway!). But to make something clear - I don't believe in an ether, that was disproved. The original ether was thought to behave rather like matter behaves - unconventional 'ethers' have carried on, but they're so different they shouldn't be called that. The electromagnetic field is an example.

PSG is a gravity theory that comes out of a theory of time, and has a conceptual basis that's different from others I've seen. The visual picture that led to both is in a book 'Motion through time: the missing piece of the puzzle'. Initially it looks at the question of whether the future is decided or undecided, and points out that relativity and quantum theory tell us opposite things on that. My solution does overlap with some other theories, including refractive medium theories, which according to mine are incomplete. Incidentally, my view has special relativity entirely right, except in the interpretation, which is incomplete anyway.

To answer your question about the axial rotation of the planets - although most of them rotate in the right direction, I doubt if either version of the geodetic effect could slowly spin up the planets. But if mine could then it's likely the GR version could as well, so the question lands comfortably within standard physics, and the best thing is probably to ask Garth..

Jonathan

 

[maurol2]

Hello,

Thanks for the references, if we discuss it in detail it should be elsewhere (or we'll find ourselves there anyway!). But to make something clear - I don't believe in an ether, that was disproved. The original ether was thought to behave rather like matter behaves - unconventional 'ethers' have carried on, but they're so different they shouldn't be called that. The electromagnetic field is an example.

Oh, I don't believe either in a mechanical and material ether.
But in fact, I certainly do believe that reality is composed by more than matter. Particularly, I believe that there are fields and "forces" that have no material cause, but that interact with and affect matter.
Moreover: matter is just a manifestation of these fields and forces(a kind of condensation), under the right circumstances.
We may not know and observe these fields and forces today in a direct way, but we can start to know them by their effects. And the day will come when we'll be able to observe them directly again, in all their magnificence and harmony.
I also firmly believe that Science, in the great name and tradition that represents, must (and certainly will) study and incorporate these fields and forces into its subjects of study. And when I say Science I mean all the sciencies, from Physics to Biology, from the study of the mineral to the study of the living. Also the social sciences; and the most important study of all: the clear and real understanding of the human being and its true nature.

 

[Garth]

Just a point: the geodetic effect is tiny unless you are dealing with an intense gravitational field, when the frame dragging effects would overwhelm it in the case of a rotating black hole, for example.

It is not responsible for the spinning up of the planets; that is due to the simply the conservation of angular momentum.

Unless a theory makes a specific prediction that is being tested by the GP-B experiment please post elsewhere.

Garth

 

[maurol2]

Just a point: the geodetic effect is tiny unless you are dealing with an intense gravitational field, when the frame dragging effects would overwhelm it in the case of a rotating black hole, for example.

It is not responsible for the spinning up of the planets; that is due to the simply the conservation of angular momentum.

That can't be so simple, or it is incomplete, considering by example that Venus is slowly spinning in the opposite direction.
Electromagnetic effects will have to be taken into account, sooner or later, to explain this solar system anomaly, and also others.

 

[Chronos]

Not at all, Venus could easily have been 'flipped' as the result of a past collision. The rotational axis of Uranus is similarly goofy, it points almost directly at the sun [re: http://www.windows2universe.org/our_solar_system/planets_table.html] and also has a slightly retrograde rotation. The former planet Pluto also suffers from this condition. Their current axial orientation is unrelated to how the planets acquired spin.

 

[maurol2]

Not at all, Venus could easily have been 'flipped' as the result of a past collision. The rotational axis of Uranus is similarly goofy, it points almost directly at the sun [re: http://www.windows2universe.org/our_solar_system/planets_table.html] and also has a slightly retrograde rotation. The former planet Pluto also suffers from this condition. Their current axial orientation is unrelated to how the planets acquired spin.

"Simply". "Easily". I'm dismayed by your fondness for "easy" explanations. "Easy" meaning, of course, that you can explain things (independently of how improbable these explanations really are) using standard physics and models.

Venus has a super-rotating atmosphere. That atmosphere circles the planet in around 4 (earth) days in a westward (Earth's west) direction. That is, most likely, the cause of the planet anomalous spin. The westward(Earth) spinning atmosphere gradually slowed down, and eventually reversed, the spin of the underlying solid planet, due to friction based momentum transfer.

Now, (and this independently if it is the cause of Venus's actual spin or not), we have to explain the reason for the atmosphere's super rotation. And to explain that it will be unavoidable to reckon with and take into account electromagnetic effects.

References:
http://en.wikipedia.org/wiki/Atmosphere_of_Venus
http://www.esa.int/SPECIALS/Venus_Express/SEMYGQEFWOE_0.html
http://www.physorg.com/news194504586.html

 

[Polestar101]

You can always blame it on polhode motion : )

 

[Chronos]

'Simple' explanations are usually more reliable than 'amazing' explanations, maurol2. Avoiding the issue I raised by injecting unrelated 'facts' does not rescue your 'amazing' model.

 

[maurol2]

'Simple' explanations are usually more reliable than 'amazing' explanations, maurol2. Avoiding the issue I raised by injecting unrelated 'facts' does not rescue your 'amazing' model.

What issue do you raised? The fact that the standard model of solar system formation has a potential explanation for the anomalous rotation of some planets, involving one or multiple collisions, does not mean that other cause can be the one responsible.

Uranus, by example, could be a former extrasolar planet, acquired with that particular spin angle.
Or it could have been inclined by the combined tidal effects of Saturn and Jupiter, when they crossed their 1:2 resonance, like this paper suggests:
http://www.planetary.org/blog/article/00000553/[/URL]
[url]http://www.nature.com/nature/journal/v440/n7088/abs/nature04577.html[/url]
That would explain the migration of its satellites, by the way.

With regard to Venus, what I find amazing (without the quotes) is that Venus atmosphere is super rotating with westwards winds of around 200 m/s. Excuse me, but what's the "standard" explanation for that?

And with those continuous and extremely strong winds I find plausible(if not obvious), they can be the real cause for Venus's actual spin.

The right thing to do would be to do the calculations, assuming an initial spin in accordance with Venus's position in its orbit, and testing for various atmospheric densities, velocity gradients, Venus's estimated age, etc. etc.

I don't have the time to do that, but maybe some other guy can do it. The hypothesis deserves some serious consideration and research. By the way, I don't think it is an amazing explanation, but a simple, elegant, and pretty obvious(if you think outside the standard box) one.

Finally: As far as I know, Venus's atmospheric super-rotation should be caused by the interaction between Venus's atmosphere and the solar wind. Here are some additional papers, which show a correlation between Earth's atmospheric Angular Momentum (AAM) and Solar Activity (SA). Interestingly, Earth's AAM is also retrograde in its general tendency, and of course, variations on Earth's AAM affect Length of Day (Length of Day) due to conservation of Angular Momentum:
[url]http://adsabs.harvard.edu/abs/2004cosp...35.4731A[/url]
[url]http://www.cgd.ucar.edu/cas/adai/papers/Abarca_delRio_etal_JGeodyn03.pdf[/url]


Mauro Lacy

 

[maurol2]

What issue do you raised? The fact that the standard model of solar system formation has a potential explanation for the anomalous rotation of some planets, involving one or multiple collisions, does not mean that other cause can be the one responsible.

I meant: can't.

The right thing to do would be to do the calculations, assuming an initial spin in accordance with Venus's position in its orbit, and testing for various atmospheric densities, velocity gradients, Venus's estimated age, etc. etc.

I meant: Venus's position in the solar system (distance to the Sun)

Incidentally, a similar process can probably explain Mercury comparatively slow rotation rate.

 

[Garth]

It is nearly a year since the last update of Mission Status on the GP-B website and while waiting for a final statement we note the existing published results are homing in on the GR prediction.

The gross GR prediction, including Solar GR effects and guide star motion is:
Geodetic (N-S) –6571 +/- 1 mas/yr and
Frame dragging (E-W) -75 +/1 1 mas /yr.

The average results over the 4 gyros is Geodetic = –6565 mas /yr i.e. within 0.1%,
and Frame dragging = -81 mas /yr i.e. within 8 % of the GR predictions.
These are consistent with GR to within the present experimental error bars.

Several of the alternative theories on the list I have compiled predict the same results as GR, therefore they fall into a different category to those that can be tested against GR by this experiment.

My news is that I have reviewed my theory (self-creation cosmology) and republished. The field equation can be cast in three forms, as explained in my paper, the Einstein conformal frame, the effective Jordan conformal frame and the true Jordan frame. The standard Brans Dicke theory is cast in the effective Jordan frame as was my 2002 version with its heterodox prediction for GP-B. Cast in the true Jordan frame (JF) it makes the same GP-B prediction as GR and therefore has not been falsified by the experiment. [Note of explanation: In SCC as I now understand it the true JF is to be used for the behaviour of massive particles, i.e. the gyros of GP-B and the effective JF for massless particles, i.e. the behaviour of light.]

1. Einstein's General Relativity(GR)
2. Brans-Dicke theory (BD)
3. Moffat's Nonsymmetric Gravitational theory (NGT)
4. Stanley Robertson's Newtonian Gravity theory (NG),
5. F. Henry-Couannier's Dark Gravity theory (DG).
6. Alexander and Yunes' prediction for the Chern-Simons gravity theory (CS).
7. Kris Krogh's Wave Gravity theory (WG)
8. Hongya Liu & J. M. Overduin prediction of the http://www.journals.uchicago.edu/ApJ/journal/issues/ApJ/v538n1/50681/50681.text.html?erFrom=5252751197746712308Guest#sc8 gravity theory (KK).
9. Kerr's Planck Scale Gravity: Predictions of Experimental Results from a Gravity Theory (PSG)
10. My Self Creation Cosmology (SCC),

The predictions are now:

GP-B Geodetic gross precession (North-South).

1. GR = -6606 mas/yr.
2. BD = -(3\omega + 4)/(3\omega + 6) 6.606 arcsec/yr. where now \omega >60.
3. NGT = -(6606 - a small \sigma correction) mas/yr.
4. SCC = -6606 mas/yr.
5. NG = -6606 mas/yr.
6. DG = -6606 mas/yr.
7. CS = -6606 mas/yr.
8. WG = -6606 mas/yr.
9. KK = -(1 + b/6 - 3b² + ...) 6606 mas/yr. where 0 < b < 0.07.
10. PSG = -6606 mas/yr.

GPB gravitomagnetic frame dragging gross precession (East-West).

1. GR = -39 mas/yr.
2. BD = -(2\omega + 3)/(2\omega + 4) 39 mas/yr.
3. SCC = -39 mas/yr.
4. NGT = -39 mas/yr.
5. NG = -39 mas/yr.
6. DG = 0 mas/yr.
7. CS = -39 mas/yr. + CS correction
8. WG = 0 mas/yr.
9. KK = -39 mas/yr.
10. PSG = -39 mas/yr.

Those theories being tested against GR by this experiment are:
BD – Brans Dicke theory; with \omega > 660.
KK - Kaluza-Klein gravity theory; with b < 1.5 x 10^-4.
NGT – Nonsymmetric Gravitational theory; it depends on how ‘small’ the \sigma correction is!

The ones falsified by the present results are:
DG - Dark Gravity theory.
WG - Wave Gravity theory.

And the ones not tested against GR by this experiment, and are still consistent with GP-B are:
SCC - Self Creation Cosmology theory.
NG - Newtonian Gravity theory.
CS - Chern-Simons gravity theory.
PSG - Planck Scale Gravity theory.

Garth

 

[JonathanK]

Thanks Garth,

Just to point out that the link you posted with PSG theory was the wrong one, it should be
http://journalgp.awardspace.com/journal/0202/020203.pdf

That's the paper (in a peer reviewed journal), "A derivation of the geodetic effect without space curvature", with the equation that shows a 'geodetic' effect with the same value as that of the GR curvature component - but being generated from flat space and using only the simple starting premiss of PSG theory. So that's the relevant link, as it shows why PSG theory is on the 'still consistent with GP-B' list, and gives the same result as GR.

Incidentally, the paper may be a first, in that it may be the first time an alternative interpretation for the geodetic effect (to the GR one) has been put forward on a mathematical basis. The generalised equation is for a single orbit around any mass.

thanks, Jonathan

 

[Polestar101]

Wish I shared your faith in the GP-B results. With so much unexpected noise (all of which needed to be properly accounted for and canceled out to have any chance of getting meaningful results) GP-B became more of an engineering project than a science experiment. Fortunately an objective panel of 15 scientists at NASA recognized the difference, pulled the funding and stated the truth; GP-B “failed to reach its goals”.

While subsequent attempts to engineer a solution were and are commendable they are highly suspect. Any methodology that relies on canceling out unanticipated “noise” by categorizing such unwanted effects as impossible to predict polhode motion (or anything else that is inherently unpredictable) negates the validity of the original science experiment. Good science relies on making and meeting predictions. Getting close to those predictions by “engineering” a preferred result is hardly science.

The only alternative theories that should be taken seriously are those that predicted the unwanted results without need to rely on cancellation of unpredictable signals.

 

[Garth]

Wish I shared your faith in the GP-B results. With so much unexpected noise (all of which needed to be properly accounted for and canceled out to have any chance of getting meaningful results) GP-B became more of an engineering project than a science experiment. Fortunately an objective panel of 15 scientists at NASA recognized the difference, pulled the funding and stated the truth; GP-B “failed to reach its goals”.

While subsequent attempts to engineer a solution were and are commendable they are highly suspect. Any methodology that relies on canceling out unanticipated “noise” by categorizing such unwanted effects as impossible to predict polhode motion (or anything else that is inherently unpredictable) negates the validity of the original science experiment. Good science relies on making and meeting predictions. Getting close to those predictions by “engineering” a preferred result is hardly science.

The only alternative theories that should be taken seriously are those that predicted the unwanted results without need to rely on cancellation of unpredictable signals.

Although I share your reservations and asked a question along similar lines to Francis Everitt about the error reduction at the April 2007 APS meeting, I have no doubt the signal did trace the GR prediction as can be seen here.

Francis Everitt's reply was that the one thing they mustn't do was perform the analysis with the answer (GR) in mind but try and make it as 'double blind' as possible. The procedure was to carry out the analysis in two teams using two different methods, an algebraic one and a geometric one, with both teams not knowing the proper motion of the guide star until they both came up with their answers. These were then compared for consistency and the proper motion then allowed for to get the result. Also the four gyros are analysed independently to help remove experimental errors by averaging.

Obviously then they have had to refine the process several times over the years to get to the latest published results so the further refinements would not have been 'double blind'.

They intended to complete all possible error reduction by this year and get a +/- 1 mas/yr accuracy ( an order of magnitude larger than originally hoped for), and unlesss they have succeeded in their aims and publish finally before the end of the year it may be that the present state of play is all they have been able to achieve, i.e. a ~ +/- 10 mas/yr (from the diagram of 50% error ellipses).

The level 2 data after preliminary processing is available here but does not mean much until "considerable further processing to calibrate the instrument, remove the effects of vehicle dynamics, aberration, guide star proper motion, small classical torques, and other systematic effects before any results about gyro orientation history can be determined".

"This refined processing of the data, which will result in a Level 3 data archive, is precisely what the GP-B team has been working on since October 2005" and they say will also be publicly available. I don't think I'll have the energy to sort through it to check it though! You might!

Garth