# Alternative theories being tested by Gravity probe B

by Garth
Tags: alternative, gravity, probe, tested, theories
 Sci Advisor HW Helper P: 1,204 Polestar 101, I loved your website. What I would like to see is more detailed explanation of why the usual calculations are incorrect.
 P: 27 Carl - Your point is well taken. While I do not have any good theory as to why the current model fails we do have pretty good observable evidence that the earth hardly wobbles at all relative to local objects within the solar system. In other words, our best calculations are that we see about 4"p/y of precession relative to the Moon, Venus and the Persieds (which we are using as local markers) while at the same time we can observe a full 50"p/y of re-orientation relative to the fixed stars and quasars far outside the SS. This tells me there must be a logical explanation to allow the two simultaneous observables but we have not focused on flaws with the current local dynamics model - as of yet. One simple guess is the Moon tugs on the earth and this is responsible for the nutation observable (the 18 year Saros cycle signature reflects the known motions of the Moon). But the much longer precessional cycle (which is slowly speeding up) does not reflect any known motion of the Moon. Perhaps the unaccounted for dynamic is the SS motion through space (possibly offsetting the tendency towards local precession). Anyway, there are a lot of issues. We hope to address some of them in a new paper once we have access to the GPB public data. Until then...you take a crack at it, and if it stands the test of time, I will nominate you for the Galileo Award. Walter
 P: 27 Hi Garth – It is not really my theory as others have mentioned it for years. And you’re right the precession of the equinox has been observed for thousands of years, and yes, that is the ~50”p/y observable we are discussing. It has long been assumed to be the result of strictly local forces acting upon the oblate earth producing a gyroscopic motion. Traditionally, it has been measured (by VLBI and others) relative to very distant reference points (stars or quasars far outside the SS) because distant points obviously move less than local points. However, in recent studies of the motion of the equinox relative to objects within the SS it turns out the earth wobbles very little compared to local points of reference (like the Moon). At BRI we have been working to better understand this seeming paradox: an earth that wobbles ~ 4”p/y relative to objects “inside the SS”, while at the same time showing ~ 50”p/y relative to objects “outside the SS”. One possibility is that part of the total observable, that we have attributed to local forces, might actually be due to the geometric effect of the SS's angular motion through space. This of course brings up the question of what it could be moving around, and hence several astronomers are examining companion star scenarios. As you aptly noted, one of those is a brown dwarf concept, like Nemesis, but there are other Newtonian scenarios that run from blackholes to unknown planet like masses, as well as non-Newtonian scenarios such as MOND, that would raise the far out possibility that it could even be a nearby visible star. Please understand I am not advocating any particular solution on this board, I am just trying to obtain more data at this time to better understand the precession observable. Can hardly wait until the GPB data is released - so please keep us posted! Walter
 Sci Advisor PF Gold P: 3,273 Walter, what prediction of the East-West and North-South precessions does this theory make? I still find it difficult to believe that a substantial object with SMA ~ 877 AU would not have already been discovered. And yes I agree that Francis Everitt and team are doing a marvellous job and roll on April 14th! Garth
 P: 27 Garth - No prediction as I do not believe SS motion would affect the GR part of the experiment. It is my understanding that just as the GPB team has to remove the effect of the motion of the spacecraft around the earth (~5"), and remove the effect of the motion of the earth around the sun (~20"), so too would they need to remove any signal from the motion of the solar system curving through local space as all of these affect the abberation of light relative to the guidestar. For a graphic see: http://www.binaryresearchinstitute.o...avprobeb.shtml Your calculation sounds about right for a brown dwarf scenario. And I agree it is doubtful that we would not have seen that type of object by now. Consequetly, if SS motion is confirmed in the ~ 50"p/y range, as the precession data leads me to believe, and we do not find anything in the 500-1000AU range, we need to condsider more exotic scenarios. Mid April is probably optomistic. My guess is that due to the sheer volume of data (including possible unexpected signals) and the need to better understand and crunch that data, the GPB team will likely need more time. With an experiment this profound we should probably expect the unexpected. Walter
PF Gold
P: 3,273
Latest news on the publication of GP-B results:
 Now that the gyro polhode behavior is well understood, we have been able to shift our focus to identifying and addressing some subtle systematic sources of noise and interference that are buried in the data, along with the relativity signals. Identifying and removing as many of these subtle systematic effects as possible is critically important for reducing the margin of error in our final results—especially the frame-dragging result. While we have been making steady progress in these efforts, it has proven to be a slow and painstaking process, and it is now apparent that several more months of data analysis will be required to achieve the lowest possible margin of error. At the SAC meeting #15 last September, committee members anticipated this situation and recommended that we ask NASA to create a contingency plan, and budget for an extension of the data analysis phase for several months past our scheduled results announcement at the American Physical Society (APS) meeting on 14-17 April 2007 in Jacksonville, FL. To this end, following a meeting with NASA in mid January, NASA has requested a proposal for extending the GP-B data analysis phase through December 2007, and this is in progress. Consequently, we are now planning a two-phase announcement of the GP-B results. Our first announcement will be made at the April APS meeting, as planned for some time now. (For more information about our presentations at this meeting, see this month's GP-B Mission News story below.) In conjunction with this announcement, NASA is planning a press/media event at NASA Headquarters in Washington DC just prior to the APS meeting. The experimental results in this first announcement will have been presented to and vetted by our Science Advisory Committee during SAC meeting #16, which is scheduled for 23-24 March 2007. These will be preliminary results, representing the lowest margin of error obtainable by that date. Concurrent with this preliminary results announcement in April, we will be releasing an initial science data set to the National Space Sciences Data Center (NSSDC) at Goddard Space Flight Center in Greenbelt, MD. The remainder of our science data, along with a complete archive of GP-B documents, images, video, and related program information will be released to the NSSDC by the end of May. All GP-B data and information archived at the NSSDC will be publicly available. Following the APS meeting, our science team is planning to spend several more months removing further systematic sources of noise and interference, with the goal of reducing the margin of error in the result to the lowest possible level. These results will still be relative to the position of our guide star, IM Pegasi, which changed continually throughout the experiment. This proper motion of the guide star has been measured on our behalf by the Harvard-Smithsonian Center for Astrophysics (CfA). Thus, the final step in the analysis will be to combine our gyro spin axis orientation results with data mapping the proper motion of IM Pegasi relative to the unchanging position of a distant quasar. In late fall, 2007, playing the role of our own harshest critic, our science team will perform a careful and thorough final review of the analysis and results, checking and cross-checking each aspect to ensure the soundness of our procedures and the validity of our outcomes. We will then convene a final SAC meeting to obtain the committee's independent review of the final results. Moreover, we will seek independent reviews from a number of international experts. We intend to announce the final experimental results of GP-B through a NASA press/media event towards the end of 2007. At that time it is also our intention to have submitted a number of papers on the GP-B results for publication in peer-reviewed scientific and technical journals.
(emphasis mine)
I knew it!

The April APS meeting:
 GP-B will have a strong presence at the American Physical Society (APS) meeting in Jacksonville, Florida, on 14-17 April 2007. During this meeting, we will emphasize three main themes: * Successful completion of most challenging space-based experiment in NASA's history * First scientific results from this historic mission * Public release of Level2 science data (via NSSDC) Four members of the GP-B team have been invited to speak at the APS meeting, beginning on Saturday morning, April 14th, with GP-B Principal Investigator, Francis Everitt, giving the plenary conference talk, entitled First Results from Gravity Probe B. In addition, on Saturday afternoon, two papers related to GP-B will be delivered in Session C12: Experimental Tests of Gravity. * C12.00004: " Lessons Learned from Gravity Probe B for STEP, LISA and other experiments" by GP-B team members Paul Worden and Sasha Buchman * C12.00005: "Proper Motion of the GP-B Guide Star" by the Harvard-Smithsonian Center for Astrophysics Gp-B guide star tracking team: Irwin Shapiro, Daniel Lebach, Michael Ratner, Norbert Bartel, Ryan Ransom, Michael Bietenholz, Jerusha Lederman, and Jean-Francois Lestrade On Sunday morning, April 15th, three members of the GP-B team have been invited to give special talks on three aspects of the GP-B program: * H7.00001: "The Gravity Probe B Science Instrument," by GP-B Co-Principal Investigator, John Turneaure * H7.00002: "The Development Challenges of Gravity Probe-B—an ongoing partnership between Physics and Engineering" by GP-B Co-Prinipal Investigator, Bradford Parkinson * H7.00003: "Gravity Probe B Data Analysis Challenges, Insights, and Results" by GP-B Co-Investigator and Chief Scientist, George (Mac) Keiser Finally, on Sunday afternoon, April 15th, a large part of the GP-B team and associated scientists and engineers will present 22 poster sessions on a host of scientific and technology topics, as listed below. Session L1: Poster Session II L1.00011: GRAVITATION * L1.00012: "Radio Imaging of the Gravity Probe B Guide Star IM Pegasi" by Michael Bietenholz, Ryan Ransom, Norbert Bartel, Daniel Lebach, Michael Ratner, Irwin Shapiro, Jean-Francois Lestrade * L1.00013: "The 'Core' of the Quasar 3C454.3 as the Extragalactic Reference for the Proper Motion of the Gravity Probe B Guide Star" by Norbert Bartel, Ryan Ransom, Michael Bietenholz, Jerusha Lederman, Daniel Lebach, Michael Ratner, Irwin Shapiro, Leonid Petrov * L1.00014: "Performance of the Gravity Probe B Inertial Reference Telescope" by Suwen Wang, John Goebel, John Lipa John Turneaure * L1.00015: "Gravity Probe B Timing System and Roll Phase Determination" by Jie Li , Jeffery Kolodziejczak * L1.00016: "The Gravity Probe B SQUID Readout Detector" by Barry Muhlfelder, Bruce Clarke, Gregory Gutt, James Lockhart, Ming Luo * L1.00017: "SQUID Control, Temperature Regulation, and Signal Processing Electronics for Gravity Probe B" by James Lockhart, Barry Muhlfelder, Jie Li, Bruce Clarke, Terry McGinnis, Peter Boretsky, Gregory Gutt * L1.00018: "Gravity Probe B Science Instrument Assembly (SIA)" by Saps Buchman, Barry Muhlfelder, John Turneaure * L1.00019: "Polhode Motion of the Gravity Probe-B Gyroscopes" by Michael Dolphin, Alex Silbergleit, Michael Salomon, Paul Worden, Daniel DeBra * L1.00020: "Evidence for Patch Effect Forces on the Gravity Probe B Gyroscopes" by Dale Gill, Saps Buchman * L1.00021: "Gravity Probe B Orbit Determination" by Paul Shestople , Huntington Small * L1.00022: "Simulator Technology of the Gravity Probe-B Mission" by David Hipkins , Robert Brumley , Yoshimi Ohshima , Thomas Holmes * L1.00023: "Achievement of the Magnetic Environment Requirements for Gravity Probe B" by John Mester, James Lockhart, Michael Taber * L1.00024: "The Gravity Probe B Gyroscopes" by Saps Buchman, Bruce Clarke, Mac Keiser, Dale Gill, Frane Marcelja, Robert Brumley * L1.00025: "Gravity Probe B Gyroscope Electrostatic Suspension System (GSS)" by William Bencze, David Hipkins, Tom Holmes, Saps Buchman, Robert Brumley * L1.00026: "The Gravity Probe B Relativity Mission (GP-B)" by C.W. Francis Everitt * L1.00027: "Gravity Probe B Experiment Error" by Barry Muhlfelder, G. Mac Keiser, John Turneaure * L1.00028: "Gravity Probe B Science Data Analysis: Filtering Strategy" by Michael Heifetz, Thomas Holmes, David Hipkins, Alex Silbergleit, Vladimir Solomonik * L1.00029: "Performance of the Gravity Probe B Cryogenic Sub-System" by Michael Taber, David Murray * L1.00030: "The Gravity Probe B Drag-free and Attitude Control System" by Michael Adams, Daniel DeBra * L1.00031: "Features of the Gravity Probe B Space Vehicle" by William Reeve, Gaylord Green * L1.00032: "Classical Torques on Gravity Probe B Gyroscopes" by Alex Silbergleit, G. Mac Keiser, Yoshimi Ohshima * L1.00033: "Trapped Flux Mapping for the Gravity Probe B Gyroscopes" by Michael Salomon, John Conklin, Michael Dolphin, G. Mac Keiser, Alex Silbergleit, Paul Worden
Patiently waiting!

Garth
P: 2,043
 Quote by Garth Patiently waiting!
Agreed!

And it is to be hoped that we won't find 50 years from now that "the reduction of the margin of error" was done with the same kind of "enthusiasm" as Eddington did in 1919.
 P: 27 Well that prediction did't take long to come true! Here is another: At least one of their unexpected signals (that they have to seperate out) is magnitudes larger than the GR effects they are looking for. Walter
PF Gold
P: 3,273
 Quote by Polestar101 Well that prediction did't take long to come true!
Too true!

However I take their statement above:
 The experimental results in this first announcement will have been presented to and vetted by our Science Advisory Committee during SAC meeting #16, which is scheduled for 23-24 March 2007. These will be preliminary results, representing the lowest margin of error obtainable by that date.
to mean that they will be publishing the gross geodetic N-S and gravitomagnetic E-W precessions at the April meeting. It seems that we will have to wait until the end of 2007 for the high precession measurements.
 Quote by Polestar101 Here is another: At least one of their unexpected signals (that they have to seperate out) is magnitudes larger than the GR effects they are looking for.
Will not the ~50"/yr proper motion caused by the Earth's 26,000 year period precession show up in the tracking of the guide star, and will be well modelled, rather than in the movement of the satellite borne gyroscopes?

Garth
P: 38
 Quote by Polestar101 Well that prediction did't take long to come true! Here is another: At least one of their unexpected signals (that they have to seperate out) is magnitudes larger than the GR effects they are looking for. Walter
Dear polestar101,

these days). Your idea looks very interesting also from the point of view of the
expectations in the framework of my dark gravity theory. Indeed, in this theory
i assumed my preferred frame to be the sun frame and then i got an anomalous
angle deviation related to the motion of earth (and GP-B) around the sun.
But if the preferred frame is defined by a larger group of stars, then the
effect should be much larger and may be, as you say, related to the equinoxe
precession. All this is very exciting. I will try to attend the april meeting
where the first announcement of GP-B results is expected.

Unfortunately i cannot access the URL you give. I'm also convinced that the GP-B
results will be a major breakthrough in our understanding of gravity.
Could you please let me know why i'm not able to access your website...may be
its secured isn't it.

best regards

F Henry-couannier
PF Gold
P: 3,273
 Quote by henryco I'm also convinced that the GP-B results will be a major breakthrough in our understanding of gravity.
They certainly seem to be making a meal over producing the results!

Garth
P: 27
 Quote by Garth Too true! Will not the ~50"/yr proper motion caused by the Earth's 26,000 year period precession show up in the tracking of the guide star, and will be well modelled, rather than in the movement of the satellite borne gyroscopes? Garth
Hi Garth - Since the spacecraft is floating free above the so called wobbling earth it should NOT mimic the earth's general precession. However, if the cause of this precession observable is actually and mainly due to the solar systems motion through space in a binary frame (as we suspect), then this motion (relative to the guidestar) should be detectable.

Just as GPB will pick up the 5"+ per orbit signal as an aberration of light between the spacecraft and the guidestar, and just as they pick up the 20"+ p/y signal due to the earth's orbit around the sun, so too should they pick up a nearly 50"p/y signal if we are correct the precession observable is mainly the geometric effect of a solar system in motion.

My concern is what that signal looks like in the data. The spacecrafts orbital motion has a waveform in synch with the spacecrafts orbit periodicity, which will show many waves during the experiment period, so this known signal will be easy to spot. The orbit of the earth around the sun should also be clear since it is a known motion and the experiment period allows time for both an ascending and descending phase. However, the binary motion (if it exists) would only reveal about 1/26,000ths of its waveform during the experiment period. Since it is completely unexpected, and no one is looking for it, it might just be attributed to anomalous drift or assumed to be part of the pollhode motion?? I just don'y know. Fortunately, the controls on this experiment are so tight and the people involved so professional I am encouraged they will take all precautions to carefully identify every signal before announcing the final GR results.

Time will tell.

Walter Cruttenden
PF Gold
P: 3,273
Well Walter, as I said, I find it hard to believe that:
1. The Moon does not induce the observed 26,000 yr period precession on the Earth as all the models of the geoid predict and,
2. There is an unobserved ~ stellar mass object, which is a binary companion to the Sun with a SMA of ~ 877AU that is responsible for the said observed precession.

On the other hand the Abstract for Francis Everitt's paper to be given at the APS Jacksonville conference in April reads.
 The NASA Gravity Probe B (GP-B) orbiting gyroscope test of General Relativity, launched from Vandenberg Air Force Base on 20 April, 2004, tests two consequences of Einstein's theory: 1) the predicted 6.6 arc-s/year geodetic effect due to the motion of the gyroscope through the curved space-time around the Earth; 2) the predicted 0.041 arc-s/year frame-dragging e®ect due to the rotating Earth. The mission has required the development of cryogenic gyroscopes with drift-rates 7 orders of magnitude better than the best inertial navigation gyroscopes. These and other essential technologies, for an instrument which once launched must work perfectly, have come into being as the result of an intensive collaboration between Stanford physicists and engineers, NASA and industry. GP-B entered its science phase on August 27, 2004 and completed data collection on September 29, 2005. Analysis of the data has been in continuing progress during and since the mission. This paper will describe the main features and challenges of the experiment and announce the first results.
Let's hope those first results will be able to resolve the gross different predictions of the competing theories mentioned in this thread:

Einstein's General Relativity(GR)
Barber's Self Creation Cosmology (SCC),
Moffat's Nonsymmetric Gravitational Theory (NGT),
Hai-Long Zhao's Mass Variance SR Theory (MVSR),
Stanley Robertson's Newtonian Gravity Theory (NG),
Junhao & Xiang's Flat Space-Time Theory (FST).
R. L. Collin's Mass-Metric Relativity (MMR) and
F. Henry-Couannier's Dark Gravity Theory (DG).

The predictions are:

1. GPB Geodetic precession (North-South)
GR = 6.6144 arcsec/yr
SCC = 4.4096 arcsec/yr
NGT = 6.6144 - a small $\sigma$ correction arcsec/yr
MVSR = 6.6144 arcsec/yr
NG = 1.6536 arcsec/yr
FST = 4.4096 arcsec/yr
MMR = -6.56124 arcsec/yr
DG = 6.6144 arcsec/yr

2. GPB gravitomagnetic frame dragging precession (East-West)
GR = 0.0409 arcsec/yr
SCC = 0.0409 arcsec/yr
NGT = 0.0409 arcsec/yr
MVSR = 0.0102 arcsec/yr
NG = 0.0102 arcsec/yr
FST = 0.0000 arcsec/yr
MMR = -0.01924 arcsec/yr
DG = 0.0000 arcsec/yr

But first, as I said, these alternative theories have to also pass all the other tests of GR as detailed in Clifford Will's paper The Confrontation between General Relativity and Experiment.

Garth
P: 38
 Quote by Garth Well Walter, as I said, I find it hard to believe that: 1. The Moon does not induce the observed 26,000 yr period precession on the Earth as all the models of the geoid predict and, 2. There is an unobserved ~ stellar mass object, which is a binary companion to the Sun with a SMA of ~ 877AU that is responsible for the said observed precession. On the other hand the Abstract for Francis Everitt's paper to be given at the APS Jacksonville conference in April reads. Let's hope those first results will be able to resolve the gross different predictions of the competing theories mentioned in this thread: Einstein's General Relativity(GR) Barber's Self Creation Cosmology (SCC), Moffat's Nonsymmetric Gravitational Theory (NGT), Hai-Long Zhao's Mass Variance SR Theory (MVSR), Stanley Robertson's Newtonian Gravity Theory (NG), Junhao & Xiang's Flat Space-Time Theory (FST). R. L. Collin's Mass-Metric Relativity (MMR) and F. Henry-Couannier's Dark Gravity Theory (DG). The predictions are: 1. GPB Geodetic precession (North-South) GR = 6.6144 arcsec/yr SCC = 4.4096 arcsec/yr NGT = 6.6144 - a small $\sigma$ correction arcsec/yr MVSR = 6.6144 arcsec/yr NG = 1.6536 arcsec/yr FST = 4.4096 arcsec/yr MMR = -6.56124 arcsec/yr DG = 6.6144 arcsec/yr 2. GPB gravitomagnetic frame dragging precession (East-West) GR = 0.0409 arcsec/yr SCC = 0.0409 arcsec/yr NGT = 0.0409 arcsec/yr MVSR = 0.0102 arcsec/yr NG = 0.0102 arcsec/yr FST = 0.0000 arcsec/yr MMR = -0.01924 arcsec/yr DG = 0.0000 arcsec/yr But first, as I said, these alternative theories have to also pass all the other tests of GR as detailed in Clifford Will's paper The Confrontation between General Relativity and Experiment. Garth
Hello,

Please also notice that DG predicts a small preferred frame effect to be seen by GP-B. It's a one year periodicity angular deviation with amplitude 0.005 arcsec...at the limit of GP-B sensitivity but i hope still detectable...and i thinck this is the "subtle effect " they need 10 more months to understand.

PLease have a look at gr-qc/0702028 the latest paper by Turyshev, Nordtvedt and co regarding gravitomagnetism and Lunar Laser Ranging.
It says something incredible! It says that the frame-dragging is seen in the frame of the observer (earth frame) where there should be nothing at all since in this frame the speed of the earth vanishes...but they keep using there (badly incorrect) the gravitomagnetic field formula of the sun rest frame. Crazy isn't it? PLease check this and tell me if i'm wrong!

Best regards

Fred
PF Gold
P: 3,273
 Quote by henryco Hello, Please also notice that DG predicts a small preferred frame effect to be seen by GP-B. It's a one year periodicity angular deviation with amplitude 0.005 arcsec...at the limit of GP-B sensitivity but i hope still detectable...and i thinck this is the "subtle effect " they need 10 more months to understand. PLease have a look at gr-qc/0702028 the latest paper by Turyshev, Nordtvedt and co regarding gravitomagnetism and Lunar Laser Ranging. It says something incredible! It says that the frame-dragging is seen in the frame of the observer (earth frame) where there should be nothing at all since in this frame the speed of the earth vanishes...but they keep using there (badly incorrect) the gravitomagnetic field formula of the sun rest frame. Crazy isn't it? PLease check this and tell me if i'm wrong! Best regards Fred
Hi Fred,

Obviously the DG prediction of zero frame-dragging precession should be a much more obvious anomaly than its predicted subtle 0.005" effect.

As far as gr-qc/0702028 is concerned, is not the frame-dragging effect on the Moon's orbit caused by the spinning Earth, not the moving Earth? Therefore should it not be effective in the inertial Earth's frame of reference?

(There is a much more subtle effect of the Earth's rotation about the Sun in the Sun's rest frame.)

Actually analysis of the Moon's orbit is very theory dependent, needing a theory of tides etc., therefore I wouldn't place too much reliance on its conclusions.

Garth
P: 38
 Quote by Garth Hi Fred, Obviously the DG prediction of zero frame-dragging precession should be a much more obvious anomaly than its predicted subtle 0.005" effect.
Sure! but the small effect would be an additional signature allowing to locate the preferred frame .
 Quote by Garth As far as gr-qc/0702028 is concerned, is not the frame-dragging effect on the Moon's orbit caused by the spinning Earth, not the moving Earth? Therefore should it not be effective in the inertial Earth's frame of reference?
Not at all the spinning earth, but the moving earth!
Actually, it is true that the first part of the paper deals with the effect of the spinning earth on a rotating body...and this is applied to GP-B just to show us that the formula applied there is the same that will be applied later on the moon orbit analysis. (They never claimed having seen the frame dragging due to the rotation of the earth on the moon orbit, only the geodetic effect, which actually should not be considered a gravitomagnetic effect, and is not the subject of this paper.)

But look at equation 17 : V is the earth speed about the sun: The second part of this
paper using the same GR formula deals with the effect of the earth rotation about the sun
on the moon orbit...an effect which should vanish in the earth reference frame where V=0 of course...and they see it: it's crazy but if this is confirmed it's eaxctly the "subtle effect expected in DG!
 Quote by Garth Actually analysis of the Moon's orbit is very theory dependent, needing a theory of tides etc., therefore I wouldn't place too much reliance on its conclusions. Garth
I was also told that the analysis is extremely complicated, but look at formula 27 and the errors they give in the last page of the article! the two effects which are the signatures of the frame dragging (in the earth rest frame!!!???) have 6.6 and 6.1 meters amplitude and the errors are 4mm!!

Please anybody have a look at this ! It's completely crazy. If you agree there is a huge anomaly in this treatment please tell this and ask around you ...then keep me informed if you have news. I could not find the emails of the authors!

regards

F H-C
 Sci Advisor PF Gold P: 3,273 Returning to the OP of marshalling as many alternative predictions of the outcome of the Gravity Probe B experiment so they can be compared with the results, which are to be published this year. It seems from their latest press release that the first results will be published at the APS Jacksonville conference in April and only towards the end of the year will the proper motion of the guide star IM Pegasi be combined with the satellite data to find the most accurate absolute precession relative to a distant quasar. This is to preserve as much as a 'double blind' element to the experiment to retain the objectivity of the results. So here again are the predictions as assembled by me and the already known details of the guide star so a rough result will be obtainable in April. Einstein's General Relativity(GR) Barber's Self Creation Cosmology (SCC), Moffat's Nonsymmetric Gravitational Theory (NGT), Hai-Long Zhao's Mass Variance SR Theory (MVSR), Stanley Robertson's Newtonian Gravity Theory (NG), Junhao & Xiang's Flat Space-Time Theory (FST). R. L. Collin's Mass-Metric Relativity (MMR) and F. Henry-Couannier's Dark Gravity Theory (DG). The predictions are: 1. GPB Geodetic precession (North-South) GR = 6.6144 arcsec/yr SCC = 4.4096 arcsec/yr NGT = 6.6144 - a small $\sigma$ correction arcsec/yr MVSR = 6.6144 arcsec/yr NG = 1.6536 arcsec/yr FST = 4.4096 arcsec/yr MMR = -6.56124 arcsec/yr DG = 6.6144 arcsec/yr 2. GPB gravitomagnetic frame dragging precession (East-West) GR = 0.0409 arcsec/yr SCC = 0.0409 arcsec/yr NGT = 0.0409 arcsec/yr MVSR = 0.0102 arcsec/yr NG = 0.0102 arcsec/yr FST = 0.0000 arcsec/yr MMR = -0.01924 arcsec/yr DG = 0.0000 arcsec/yr But first, as I said, these alternative theories have to also pass all the other tests of GR as detailed in Clifford Will's paper The Confrontation between General Relativity and Experiment. And from The stars of Pegasus from the Bright Star Catalogue, 5th Revised Ed. (Preliminary Version) (Hoffleit+, 1991, Yale University Observatory) as distributed by the Astronomical Data Center at NASA Goddard Space Flight Center. IM Pegasi RA J2000 : 22h 53m 2.3s DEC J2000 : +16° 50' 28" Proper motion in RA : -0.018 arcsec/y Proper motion in DEC : -0.024 arcsec/y mag : 5.64 MK spectral class : K1-2II-III The Proper motion in RA will affect the E-W precession and the Proper motion in DEC will affect the N-S precession. Happy hunting! Garth

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