Alternative theories being tested by Gravity probe B

[Garth]

Sorry Fred, one last time to try and get it right!

The present predictions are:

Note: mas = milliarcsec.

The geodetic N-S precession is predicted by GR to be - 6606 mas/yr, however there is a solar geodetic precession N-S component of + 7 mas/yr and the proper motion of IM Pegasi +28 mas/yr to take into account, resulting in a net expected N-S precession of -6571 LaTeX graphic is being generated. Reload this page in a moment.1 mas/yr.

The frame-dragging E-W precession is predicted by GR to be -39 mas/yr, the solar geodetic precession E-W component of -16 mas/yr and the proper motion of IM Pegasi -20 mas/yr to include, resulting in a net expected E-W precession of -75 LaTeX graphic is being generated. Reload this page in a moment.1 mas/yr.

From pages 20 and 21 of Francis Everitt's April APS talk, we find: A series of error ellipses on the N-S v E-W precession plot with centres respectively at (-6584 LaTeX graphic is being generated. Reload this page in a moment.60, -83 LaTeX graphic is being generated. Reload this page in a moment.22 mas/yr) June 2006, (-6597 LaTeX graphic is being generated. Reload this page in a moment.17, -92 LaTeX graphic is being generated. Reload this page in a moment.15 mas/yr) December 2006, (-6595 LaTeX graphic is being generated. Reload this page in a moment.12, -98 LaTeX graphic is being generated. Reload this page in a moment.7 mas/yr) March 2007 and (-6603 LaTeX graphic is being generated. Reload this page in a moment.8, -98 LaTeX graphic is being generated. Reload this page in a moment.7 mas/yr) March 2007.

It was this last reading for the geodetic precession that Francis Everitt reported at his April APS talk. If we also include that 'glimpse' of the E-W precession as well we have net values of:
(-6603 LaTeX graphic is being generated. Reload this page in a moment.8, -98 LaTeX graphic is being generated. Reload this page in a moment.7 mas/yr)
whereas GR predicts:
(-6571 LaTeX graphic is being generated. Reload this page in a moment.1, -75 LaTeX graphic is being generated. Reload this page in a moment.1 mas/yr).

In other words the actual readings are larger than GR predicts by 32 mas/yr in geodetic precession and 23 mas/yr in frame-dragging precession.

However, they reported an overall error, which is still being reduced, caused by residual gyro-to-gyro inconsistencies due to incomplete modelling of ~ LaTeX graphic is being generated. Reload this page in a moment.100 mas/yr.

This renders the present geodetic 'glimpse' as being consistent with GR to within about 1LaTeX graphic is being generated. Reload this page in a moment.%, whereas the frame-dragging precession is at present swamped by noise.

The running now stands:

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 Kaluza-Klein gravity theory (KK).
9. Jin He's Absolute Relativity theory (AR).The predictions are now:

GPB Geodetic gross precession (North-South)

1. GR = -6606 mas/yr.
2. BD = -LaTeX graphic is being generated. Reload this page in a moment. 6.606 arcsec/yr. where now LaTeX graphic is being generated. Reload this page in a moment. >60.
3. NGT = -6606 - a small LaTeX graphic is being generated. Reload this page in a moment. 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. AR = -6636 mas/yr.We await the GPB gravitomagnetic frame dragging gross precession (East-West) result.

1. GR = -39 mas/yr.
2. BD = -LaTeX graphic is being generated. Reload this page in a moment. 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. AR = -59 mas/yr.We continue to wait for Christmas!

Garth

 

[henryco]

Sorry Fred, one last time to try and get it right!

The present predictions are:

Note: mas = milliarcsec.

The geodetic N-S precession is predicted by GR to be - 6606 mas/yr, however there is a solar geodetic precession N-S component of + 7 mas/yr and the proper motion of IM Pegasi +28 mas/yr to take into account, resulting in a net expected N-S precession of -6571 LaTeX graphic is being generated. Reload this page in a moment.1 mas/yr.

The frame-dragging E-W precession is predicted by GR to be -39 mas/yr, the solar geodetic precession E-W component of -16 mas/yr and the proper motion of IM Pegasi -20 mas/yr to include, resulting in a net expected E-W precession of -75 LaTeX graphic is being generated. Reload this page in a moment.1 mas/yr.

From pages 20 and 21 of Francis Everitt's April APS talk, we find: A series of error ellipses on the N-S v E-W precession plot with centres respectively at (-6584 LaTeX graphic is being generated. Reload this page in a moment.60, -83 LaTeX graphic is being generated. Reload this page in a moment.22 mas/yr) June 2006, (-6597 LaTeX graphic is being generated. Reload this page in a moment.17, -92 LaTeX graphic is being generated. Reload this page in a moment.15 mas/yr) December 2006, (-6595 LaTeX graphic is being generated. Reload this page in a moment.12, -98 LaTeX graphic is being generated. Reload this page in a moment.7 mas/yr) March 2007 and (-6603 LaTeX graphic is being generated. Reload this page in a moment.8, -98 LaTeX graphic is being generated. Reload this page in a moment.7 mas/yr) March 2007.

It was this last reading for the geodetic precession that Francis Everitt reported at his April APS talk. If we also include that 'glimpse' of the E-W precession as well we have net values of:
(-6603 LaTeX graphic is being generated. Reload this page in a moment.8, -98 LaTeX graphic is being generated. Reload this page in a moment.7 mas/yr)
whereas GR predicts:
(-6571 LaTeX graphic is being generated. Reload this page in a moment.1, -75 LaTeX graphic is being generated. Reload this page in a moment.1 mas/yr).

In other words the actual readings are larger than GR predicts by 32 mas/yr in geodetic precession and 23 mas/yr in frame-dragging precession.

However, they reported an overall error, which is still being reduced, caused by residual gyro-to-gyro inconsistencies due to incomplete modelling of ~ LaTeX graphic is being generated. Reload this page in a moment.100 mas/yr.

This renders the present geodetic 'glimpse' as being consistent with GR to within about 1LaTeX graphic is being generated. Reload this page in a moment.%, whereas the frame-dragging precession is at present swamped by noise.

The running now stands:

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 Kaluza-Klein gravity theory (KK).
9. Jin He's Absolute Relativity theory (AR).


The predictions are now:

GPB Geodetic gross precession (North-South)

1. GR = -6606 mas/yr.
2. BD = -LaTeX graphic is being generated. Reload this page in a moment. 6.606 arcsec/yr. where now LaTeX graphic is being generated. Reload this page in a moment. >60.
3. NGT = -6606 - a small LaTeX graphic is being generated. Reload this page in a moment. 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. AR = -6636 mas/yr.


We await the GPB gravitomagnetic frame dragging gross precession (East-West) result.

1. GR = -39 mas/yr.
2. BD = -LaTeX graphic is being generated. Reload this page in a moment. 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. AR = -59 mas/yr.


We continue to wait for Christmas!

Garth

That's OK

Thank you Garth

Fred

 

[yogi]

Garth - this question was posed by Jonathan in post 210:

"The wider question this has bearing on is what possible interpretations for the geodetic effect do we have, now that it has been measured directly. Is curvature the only one?

Maybe I missed your answer -

Along the same line - assuming the measurements are a confirmation of curvature - don't we still have an unanswered question of whether the curvature is the result of static mass acting upon static space ?

 

[Garth]

Garth - this question was posed by Jonathan in post 210:

"The wider question this has bearing on is what possible interpretations for the geodetic effect do we have, now that it has been measured directly. Is curvature the only one?

Maybe I missed your answer -

Along the same line - assuming the measurements are a confirmation of curvature - don't we still have an unanswered question of whether the curvature is the result of static mass acting upon static space ?

If space-time does suffer curvature as in GR then free falling gyros will exhibit geodesic precession.

You make a cone by cutting a thin slice out of a disk and glueing the cut edges together.

Geodesic precession is caused by the missing slice, there not being quite 360⁰ in the circle.

If there is no space-time curvature then the gyros in orbit will have to be suffering some type of Newtonian gravitational force perturbing them from their otherwise straight line trajectories.

They will be accelerating from their inertial frames of reference towards the centre of the Earth.

In a space-time continuum an accelerating parallel transported vector will 'lean over' in 4D as its velocity increases.

An accelerating gyro will precess due to this effect, the effect is called Thomas Precession.

However if there is no space-time curvature and all the orbital dynamics is caused by a Newtonian attractive gravitational force then the amount of Thomas precession is precisely half the GR prediction of geodetic precession. Already the first results of GP-B have confirmed the GR geodetic prediction to within 1\frac{1}{2}%.

Other theories have postulated different causes of N-S precession for the GP-B, you will have to read the individual papers as so far I have been unconvinced.

Garth

 

[JonathanK]

Hello Garth and all,

Yogi has mentioned what I said about interpretations for the geodetic effect. I've found a way to generalise the calculation I did about this, and put it into an equation. It's easy to check, and shows clearly that curvature is not the only interpretation for the measured effect.

If matter near a mass is slowed (in flat space) by (1 - [2GM/rc^2])^1/2, then different parts of an orbiting spherical object (such as a GP-B gyro) travel at different speeds, resulting in a slight turning of the object in the plane of the orbit, which mimics the geodetic effect. In PSG minor corrections are made to an orbital speed that's the same across the whole object.

The angle of precession θ in degrees for one (circular) orbit arising from this local slowing of matter can be arrived at with

θ = 2 arctan

2[pi]r ( ([1 – (2GM/rc^2)]^1/2) – ([1 – (2GM/r'c^2])^1/2) )
----------------------------------------------------------
r' – r

(or if preferred, tan (θ / 2) = …etc), where r is the distance from the centre of the Earth to the centre of the object, and r' is the distance to a point on its upper edge, equal to r plus the radius of the object.

This gives the curvature component of the geodetic effect (in the case of GP-B 4.4 arcsecs/yr). It gets there in a very different way from GR, and uses only basic gravity parameters.

Sorry about how the above equation is set out, couldn't do sqrt boxes etc. Garth, I'd appreciate it if you'd set it out better, thank you.

The component of the geodetic effect generally thought to be due to curvature is 2/3 of the total effect. The other 1/3 has been explained in ways that apply whether space is curved or flat (for example Shapiro et al, '88).

So this provides an alternative flat space interpretation, which means the measurement of what is known as the geodetic effect doesn't prove the curved space interpretation, it simply proves that the effect exists.

I also now have a better way of explaining why like in GR, PSG has no acceleration in freefall, in reply to your point about the Thomas precession. As in GR, the very nature of space and matter provides an explanation so fundamental that no later 'adjustments' to the description are needed. It can't be gone into here, but the freefall equation (published as equation 4 in the first paper) gives the right speeds to 12 decimal places, all along the trajectory. This came directly from this conceptual basis, so the point I'm making works in more ways than one.

Thanks, good wishes, Jonathan Kerr

 

[Garth]

Jonathan I think you had better learn LaTex, at least the tex and itex version used in these Forums!

Your calculation uses the same equations as GR but interprets them differently therefore it comes up with the same prediction, but it will be impossible to test the one theory against the other using this experiment. If all the equations are the same in every prediction then I would say you are simply restating the standard GR theory in unfamiliar and perhaps unhelpful and confusing terminology.

I should have made clear in my 'missing slice' explanation of geodetic precession in post #254 that that argument only explains the spatial part of space-time curvature, which in the GR calculation accounts for \frac{2}{3} of the total.

The other component is the time part of space-time curvature, time dilation, which accounts for the remaining \frac{1}{3} of the total.

There is no need for this to be "explained in ways that apply whether space is curved or flat", it is already accounted for in the curvature of space-time.

Note in GR gravitation is described by the curvature of the space-time manifold, not just by the curvature of space.

Garth

 

[JonathanK]

Sorry that I don't know the Latex system you use.

Your calculation uses the same equations as GR but interprets them differently therefore it comes up with the same prediction, but it will be impossible to test the one theory against the other using this experiment.
Garth

You seem to agree with my main point, which is that there is more than one possible interpretation. As I'm sure you realize, I arrived at that equation purely from the concept of matter in flat space being slowed by a certain factor. I could easily show the simple steps that led there, but they're not what matters. They show a general principle, and one that can be verified in other parallel ways. 2/3 of the geodetic effect can definitely be interpreted in this surprisingly simple way, without curvature.

So all that remains is the question of the other 1/3. There are different interpretations within GR for that (I sent you two papers about it early this year, the Shapiro et al one from '88, and a NASA funded study that puts forward more than one interpretation - to both of our surprise, including SR as one of them!)

The Shapiro et al paper described 1/3 of the geodetic effect as being due to "a gravitational analogue of spin orbit coupling". That's what I meant by an explanation that applies whether space is curved or flat.

You can look at exactly how GR interprets the effect, and I acknowledge that as you say this involves the curvature of spacetime, not just of space. But for this flat space interpretation, 2/3 is as I've interpreted it above, and the other 1/3 can be various things, such as (for example) a flat space effect like that described by Shapiro et al.

It's worth pointing out that PSG seems to mimic GR over the motion of both light and matter well in other areas. If it didn't there'd be less point in looking at the geodetic. If anyone would like to help with a more accurate calculation, let me know. (Might even explain the 32 mas/yr, though the error margins may make that impossible.) And any comments would be welcome.

Thanks again for your help Garth. It'd be great if you'd acknowledge that this alternative interpretation works, in this small corner of GR at least. Outside that there's a long way to go of course. J

 

[Garth]

Sorry that I don't know the Latex system you use.

Try How To LaTex.

You seem to agree with my main point, which is that there is more than one possible interpretation. As I'm sure you realize, I arrived at that equation purely from the concept of matter in flat space being slowed by a certain factor. I could easily show the simple steps that led there, but they're not what matters. They show a general principle, and one that can be verified in other parallel ways. 2/3 of the geodetic effect can definitely be interpreted in this surprisingly simple way, without curvature.

Yes, but my point is your expression for motion being "slowed down by a certain factor" is exactly the same as in GR. The question is therefore: "can you physically justify using that equation, or are you just copying it?" As you are using it you were bound to get the same result as GR for the spatial component.

So all that remains is the question of the other 1/3. There are different interpretations within GR for that (I sent you two papers about it early this year, the Shapiro et al one from '88, and a NASA funded study that puts forward more than one interpretation - to both of our surprise, including SR as one of them!)

I disagree, there is only one interpretation within GR, it is the time component of the effect of space-time curvature.

The Shapiro et al paper described 1/3 of the geodetic effect as being due to "a gravitational analogue of spin orbit coupling". That's what I meant by an explanation that applies whether space is curved or flat.

They are either misinterpreting the time component of curvature OR they are giving an alternative flat space-time explanation. In the latter case I want to know what happens to the Thomas Precession, which must be taken into account if space-time is flat and the orbiting gyros are not in an inertial frame of reference. Each separate effect must be taken into consideration and correctly accounted for to get a valid prediction.

Thanks again for your help Garth. It'd be great if you'd acknowledge that this alternative interpretation works, in this small corner of GR at least. Outside that there's a long way to go of course. J

You're welcome.

If you want your Planck Scale Gravity (PSG) theory to be included on this thread you will have to give a refereed or Physics ArXiv link to a paper on it that makes a distinct prediction that can be falsified by the GP-B experiment.

If you have a link to a PSG paper published in a refereed journal you can discuss it on these Forums otherwise you can submit it to the Independent Research Forum having first observed their submission rules.

Garth

 

[JonathanK]

Well, it doesn't matter, and no need to put PSG back on the list, unless you want to. In fact the paper you kindly endorsed, which was published in a refereed journal (linked to in post #126), has a frame dragging prediction, the same as GR. So it does fill the criteria, but I'll let you get on with other things, and thanks again.

The original geodetic prediction was null, but the above equation (post #255), which you've acknowleged as giving the right result, vindicates the theory. It shows that the prediction, not the theory, was wrong, as the measured geodetic effect is in fact mimicked by the original theory, without any changes. I only found this out later, but luckily was able to show it to be true. Vindicating the theory has been my main aim here.

The equation I found is not a GR equation (as far as I know), but as you say, the factor sqrt (1 - [2GM/rc^2]) is of course an expression from GR. PSG is the gravity part of a theory of time, and in it not only is time 'slowed' by this factor, the motion of light and matter are as well. Yes, I can physically justify this - the conceptual basis does just that. According to it GR is largely right, but incomplete in its interpretation - and something in effect very similar to curved space happens in flat space. (And in it GR is of course right about that expression giving the local time rate. I believe I'm allowed to use it in that context…!)

Interestingly, the spatial calculation gave 2.2 arcsec/yr. I then allowed for time rate differences to the two points on the gyro in question, which doubled the difference to their speeds, so they ended up twice as far apart. The trigonometry then gave 4.4 arcsecs/yr, and there's a factor of 2 in the equation, reflecting this doubling. So I assumed I was uncovering an alternative interpretation from a GR one in which space is 1/3 and time is 1/3. But I’m sure you know the GR interpretation.

I disagree, there is only one interpretation within GR, it is the time component of the effect of space-time curvature. They are either misinterpreting the time component of curvature OR they are giving an alternative flat space-time explanation. In the latter case I want to know what happens to the Thomas Precession, which must be taken into account if space-time is flat and the orbiting gyros are not in an inertial frame of reference.
Garth

You’re right, I misused the word "within", when I said "for the other 1/3 there are different interpretations within GR". I'm sure that "surrounding GR" is more accurate. But Shapiro is a well-known GR supporter as far as I know. You'd have to ask him about the Thomas precession - I have no idea what he'd say. My aim has really been to interpret only the first 2/3, and say that the other 1/3 has enough controversy surrounding it for this flat space interpretation to be a possibility. It seems very reasonable to me - thank you for acknowledging that the mathematics for that 2/3 works. It seems not impossible that matter actually is slowed by that factor. Anyway, good wishes, and good luck all for December! Jonathan

 

[hejin]

GPB Decembe 2007 update!

GPB final result, 6 more months, no kidding!

 

[Garth]

Unfortunately you are not kidding!
From the GP-B update

MISSION UPDATE - DECEMBER 2007PROGRAM STATUS

Over the past three months, GP-B has continued to make outstanding progress.

In our September 25, 2007 status update, we reported that the trapped flux mapping technique had resulted in a dramatic improvement in the determinations of the polhode phase and angle for each gyroscope throughout the entire 353-day experiment period. Applying these results to a central 85-day stretch of data, from December 12, 2004 through March 4, 2005, we obtained a robust and stable measurement of the frame-dragging effect with a reasonable (~30%) error level. We are in process of progressively extending the analysis to increasingly long time intervals in order to reach the full experiment accuracy, potentially to an error margin of less than 5%. Also important is the completion of the study of -- and if necessary elimination of -- any remaining systematic effects that may bias the results of the experiment.

Our progress and results were intensively reviewed by the GP-B Science Advisory Committee (SAC) at its 17th meeting on November 2, 2007. In its subsequent report, the SAC commented on "the truly extraordinary progress that has been made in data analysis since SAC-16 [March 23-24, 2007]" and unanimously concluded "that GP-B is on an accelerating path toward reaching good science results."

It is anticipated that approximately another six months until May 2008 will be needed to complete this full coverage and arrive at a definitive final result. We believe the results will be truly significant and will withstand scrutiny at the deepest scientific level. We agree with the SAC that: "This phase must include an adequate opportunity for the SAC to review the final result in some detail before publications are prepared and public announcements are made."
To this end, we are planning on this review for the May 2008 time frame.

 

[hejin]

Geodetic result in December update

On the right collumn of the December update there is a graph showing

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

 

[Garth]

On the right collumn of the December update there is a graph showing

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

That http://einstein.stanford.edu/cgi-bin/highlights/showpic.cgi?name=GR-85-day_result.jpg is showing that to a 1 sigma error confidence level the results for the geodetic precession are inconsistent with GR.

This is at about a 68% confidence level, we wait for the 3\sigma 4-gyro results next year, but so far it does look interesting!

It will be especially interesting to see what happens to the frame-dragging result, which is at present swamped by noise.

Garth

 

[fasterthanjoao]

Despite having kept up-to-date with this thread since the beginning, I have no productive input except that the recommendation that this thread and the work of the contributors should be entered into a PF cosmological hall of fame. Very good.

 

[Garth]

That http://einstein.stanford.edu/cgi-bin/highlights/showpic.cgi?name=GR-85-day_result.jpg is showing that to a 1 sigma error confidence level the results for the geodetic precession are inconsistent with GR.

This is at about a 68% confidence level, we wait for the 3\sigma 4-gyro results next year, but so far it does look interesting!

As I posted in the We are in a Schwarzschild black hole--T or F? thread:

Now that is interesting, the GP-B website has withdrawn that diagram and replaced it with one that makes no such claims!

Garth

 

[Garth]

If you want to see for yourselves you can still find the original intriguing diagram 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

That last one clearly shows the inconsistency with the GR prediction to the 1 \sigma confidence level.

Again we wait for the 3 \sigma confidence level results with interest!

Garth

 

[Garth]

Impossibility of GP-B reliable measurement?

A critical analysis of the GP-B mission. I: on the impossibility of a reliable measurement of the gravitomagnetic precession of the GP-B gyroscopes by a Gerhard Forst.

In this paper we discuss the impossibility for the Gravity Probe B (GP-B) experiment to provide a clean and undisputable test of the gravitomagnetic precession of its four gyroscopes and of the Lense-Thirring effect. Lense-Thirring effect and geodetic precession have already been measured by Lunar Laser Ranging (LLR), laser ranged satellites, binary pulsars and accretion disks of black holes and neutron stars. In this paper we show that in the GP-B experiment there are critical problems for measuring Lense-Thirring effect and geodetic precession by the GP-B data analysis. The GP-B data analysis is extremely model dependent and relies on the assumptions about the unknown quadrupole moment induced by the gyroscopes rotation, both: (I) its size and (II) its direction with respect to the quadrupole moment due to fabrication and (III) its unknown rate of change due to variations of the gyroscopes rotation rate. The huge systematic biases in the GP-B data amount to about 1000 milliarcsec/year, but the GP-B team has claimed to be able to model 90 % of this signal, thus leaving the systematic biases at the level of about 100 milliarcsec per year, that is $\sim 300 %$ of the Lense-Thirring effect effect of the GP-B gyroscopes; any further modelling will result in a rough test of Lense-Thirring effect that will be highly model dependent and extremely affected by other huge unknown systematic biases. In this paper we show that such claims are necessarily highly model dependent and then are very much affected by huge unknown systematic biases. We give an important example of these systematic biases of which there is no mention in the discussions of the GP-B team.

Has GP-B all been a waste of time and money?

Firstly, it must be said that the team have recognised that there were two unexpected sources of error that almost render the results too inaccurate to test the two precessions, especially the much smaller frame-dragging or gravitomagnetic precession effect.

However, the team are also confident that they can, and are, modelling these errors accurately by using two cross checking independent methods.

I specifically asked the question at the April Conference about whether these methods were genuinely independent in a 'double-blind' way or whether they used the expected GR results in their derivation.

Francis Everitt was quite adamant that that was what one mustn't do and their error reduction modelling was quite independent of the expected results.

Gerhard Forst is disputing this independence, which is a serious charge to make. However I note that his email is a private not an academic address (but then so is mine...), that he isn't an endorser on the ArXiv, which is suspicious, this is his only eprint and he has no papers published in referred journals, which does not say much about his academic credibility.

Given the immense amount of experience and expertise on the GP-B team, at this stage I would rather trust them, although of course when the results are finally published so also is all the data for others to check and dispute.

I can see an undisputed result being a long way off...

Garth

 

[Kris Krogh]

Hi Garth,

I think your suspicions about Gerhard Forst are well justified. Here is a message I sent the moderator of ArXiv:


Dear arXiv-moderation,

This concerns the authorship of http://arxiv.org/abs/0712.3934 , "A critical analysis of the GP-B mission. I: on the impossibility of a reliable measurement of the gravitomagnetic precession of the GP-B gyroscopes." This paper may represent an anonymous attack.

The author's name is given as "Gerhard Forst," with the email address g.forst@yahoo.com . He has no prior ArXiv papers, and seems to have no peer-reviewed publications. His affiliation and address are given as:

G. Forst
FGP
Behrenstr. 1
10117 Berlin

Whatever FGP stands for, there is no mention on the web of such an organization at the given address. Was this paper endorsed? If so, can the endorser show "Gerhard Forst" is the author's real name?

There is an interesting similarity to papers by another author, who has a history of tit-for-tat disputes on ArXiv:

"On the impossibility of measuring a galvano-gravitomagnetic effect with current carrying semiconductors in a space-based experiment," http://arxiv.org/abs/gr-qc/0308053

"On the impossibility of using the longitude of the ascending node of GP-B for measuring the Lense-Thirring effect," http://arxiv.org/abs/gr-qc/0404107

"On the impossibility of using certain existing spacecraft for the measurement of the Lense-Thirring effect in the terrestrial gravitational field," http://arxiv.org/abs/gr-qc/0508012

"On the impossibility of measuring the general relativistic part of the terrestrial acceleration of gravity with superconducting gravimeters, http://arxiv.org/abs/gr-qc/0602005

"On some critical issues of the LAGEOS/LAGEOS II Lense-Thirring experiment," http://arxiv.org/abs/0710.1022

In addition to the titles, there are many other similarities. Comparing the most recent of these to the paper in question, there are these sequences:

"...no other tests performed by independent teams, without connections with Ciufolini and coworkers...have been so far reported in literature."

"...no independent team, without connections with the GP-B team, will be able to repeat the GP-B data analysis..."

In the former there are 4 sentences beginning with the word "Indeed." Such a sentence is also found in the latter. I could list further examples.

That author has himself claimed increasingly accurate measurements of the Lense-Thirring effect, which I've discussed here:

http://arxiv.org/abs/astro-ph/0701653

Both those claimed measurements and his reputation would be seriously threatened by a contrary result from Gravity Probe B. I hope the reasons are clear from my paper.



Kris Krogh

 

[Garth]

Kris,

Thank you, that is very interesting!

Actually I have read Lorenzo Iorio's papers with interest, I shall be even more critical from now on!

Happy New Year
Garth

 

[henryco]

That last one clearly shows the inconsistency with the GR prediction to the 1 \sigma confidence level.

Again we wait for the 3 \sigma confidence level results with interest!

Garth

Hi Garth

Your comments on these results make me consider more seriously another possible prediction in my framework which i had eliminated because it is already ruled out by the 1% precision test of the geodetic effect by LusarLaserRanging. However the DG theory make it possible for a rare event, the appearance or disappearance of a discontinuity of gravity in the neighbourhood of our earth, to occur. If this happened after the LLR tests and before the GP-B data taking, the physics of gravitomagnetism might have changed so that the geodetic test by LLR is no more relevant now!
If so, my prediction would still be:
- no frame dragging (no influence of the Earth rotation!) on GP-B gyros
- the same geodetic effect as in GR where enters the speed of GP-B relative to the earth

but now i can consider a preferred frame effect which i did not take serious before.
The formula is the same as the geodetic effect one except that it involves the speed of the Earth relative to a preferred frame which is not attached to the Earth as i assumed up to now. Whever this preferred frame is attached to the CMB, the galaxy or more locally to our sun does not matter since in all cases the dominant effect comes from that part of the speed which is the speed of the Earth relative to our sun.

Thus the additional effect for GP-B is a periodic angular precession with roughly 40 mArcsec amplitude and one year period which should give a contribution on projection to both N-S and E-W GP-B signals.
May be the 85 days represent a favorable period to see these contributions (may be the reason why GP-B has announced a E-W effect on this period and at the sametime there is as you say a strange one sigma inconsistency with GR on th NS effect ) but then
i expect it to disapear on a one year integration.



So may be could you add a second possible prediction for DG :
If preferred frame is not the Earth (sun or galaxy or CMB)

Frame dragging 0
Geodetic as in RG
Preferred frame effect: 40marcsec-amplitude one_year-periodic angular precession

Regards

Fred

 

[Garth]

Fred, we could all add in extra adjustments in an ad hoc way to make our predictions fit any set of results. On this thread I have limited the discussion to predictions made in published papers or at least to those in eprints on the physics ArXiv.

I find it highly contrived to require your idea of using a "the appearance or disappearance of a discontinuity of gravity in the neighbourhood of the Earth" to fit both the LLR results and the latest GP-B glimpse.

That notwithstanding, if you publish on the ArXiv with a definite falsifiable set of predictions for GP-B then I shall be happy to include them in the 'list'.

Garth

 

[Garth]

I have also recently found that Jin He's "Absolute Relativity" has been removed from the physics ArXiv, I shall therefore remove it from the list of viable theories being tested by GP-B.

To remind ourselves, that list now stands:

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).

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.

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.

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 November 1 \sigma confidence level result is inconsistent with all the above geodetic predictions except KK!

We continue to wait for the 3 \sigma confidence level results in the "final" review now scheduled for May 2008!

Happy New 2008 Year
Garth

 

[hejin]

Hi, Garth,
You made a second mistake!
Instead of removal, my paper stands there sound on Arxiv.

I studied the origin of your mistake. If not true, please forgive me.
You posted my paper directed to 5th version as
http://arxiv.org/PS_cache/astro-ph/pdf/0604/0604084v5.pdf
Such kind of link fails if the original paper is updated. This is because Arxiv let you directly link to PDF ONLY IF the required PDF version is current version!

My updated version is
http://arxiv.org/abs/astro-ph/0604084
or
http://arxiv.org/abs/astro-ph/0604084v8

If you want to post my fifth version, that is OK if you choose:
http://arxiv.org/abs/astro-ph/0604084v5
but you choice of PDF post failed as I explained above!

 

[JonathanK]

I have a correction to the equation in post #255, it's 'arctan' rather than '2 arctan', and the positions of the second r and the r' are reversed above the line. I'd only just found it at the time - there's also a slightly more accurate version of the equation, but both give the same numbers for GP-B, which are almost identical to those from GR.

And having thought about it, I would appreciate it if you'd put PSG back on the list Garth - which it seems you'll be posting again anyway. I'm sure you agree the theory hasn't been falsified, and there's a prediction for frame dragging in a peer reviewed journal, of - 39 mas/yr. Like NG, PSG gives the same as GR for both effects - as you pointed out (so acknowledging the basic mathematics), the experiment can't distinguish between the two interpretations for the geodetic. But unlike GR, PSG hasn't been fully worked through yet, and other smaller effects may later be taken into account. At present, PSG has recovered better than other theories, where changes and extra adjustments have been made - the geodetic equation arises simply from applying the main postulate of the original theory, exactly as it was.

Thank you, Jonathan

 

[henryco]

Fred, we could all add in extra adjustments in an ad hoc way to make our predictions fit any set of results. On this thread I have limited the discussion to predictions made in published papers or at least to those in eprints on the physics ArXiv.

I find it highly contrived to require your idea of using a "the appearance or disappearance of a discontinuity of gravity in the neighbourhood of the Earth" to fit both the LLR results and the latest GP-B glimpse.

That notwithstanding, if you publish on the ArXiv with a definite falsifiable set of predictions for GP-B then I shall be happy to include them in the 'list'.

Garth

Hi Garth,

It appears that my preferred frame effect is actually not ruled out by LLR data (it is not Lorentz violating)! So i cannot exclude this possible prediction. The theory has a preferred fram effect and th predictions crucially depend on it: The prediction for DG that i gave here (0 frame dragging + same geodetic as in GR) is valid in case my preferred frame is attached to the earth.
If it is attached to the CMB or sun or the galaxy the prediction is the same for frame-dragging and geodetic effect but i have an additional preferred frame effect that you did
mention on this site sometime ago: This effect has no free parameter and gives a clear signature: it would appear as an extraoscillation with1 year period and 40 mArcsec amplitude giving a contribution in both direction (N-S and E-W).

Since you gave here the KK prediction which has a free parameter, it would not be chocking to add this extra preferred frame contribution multiplied by a parameter equal to
zero or one (corresponding to the two possible preferred frames) which makes my theory already much more predictive than KK!
I put this in my latest arXiv version. (gr-qc/0610079)

best regards

Fred

 

[henryco]

Since you gave here the KK prediction which has a free parameter, it would not be chocking to add this extra preferred frame contribution multiplied by a parameter equal to
zero or one (corresponding to the two possible preferred frames) which makes my theory already much more predictive than KK!


Fred

Hi Garth,

Rethincking about it, i realize that since you give the prediction for the integrated drift on one year on this forum, my one year oscillation integrated preferred frame effect will anyway not contribute.
So the better is to keep the predictions as they are and just mention that the drifts may not be steady ones and this may provide another discriminating info.

Is that possible?
regards


Fred

 

[Garth]

Hi Garth,

Rethincking about it, i realize that since you give the prediction for the integrated drift on one year on this forum, my one year oscillation integrated preferred frame effect will anyway not contribute.
So the better is to keep the predictions as they are and just mention that the drifts may not be steady ones and this may provide another discriminating info.

Is that possible?
regards


Fred

Fred, you have already done so!

Theories are only considered here if they make a falsifiable prediction, or pair of predictions to be tested against the published results.

Predictions have to take into account all factors that influence the result and not just tailored to match results as they come in.

Garth

 

[henryco]

Fred, you have already done so!

Theories are only considered here if they make a falsifiable prediction, or pair of predictions to be tested against the published results.

Predictions have to take into account all factors that influence the result and not just tailored to match results as they come in.

Garth

I have already done what ?

Fred

 

[Garth]

I have already done what ?

henryco: "to keep the predictions as they are and just mention that the drifts may not be steady ones and this may provide another discriminating info."

Remember others will need convincing that your theory's predictions are being verified or falsified by the results of the experiment. So a clear set of predictions would be good.

Garth

 

[notknowing]

Hi, Garth,
You made a second mistake!
Instead of removal, my paper stands there sound on Arxiv.

I studied the origin of your mistake. If not true, please forgive me.
You posted my paper directed to 5th version as
http://arxiv.org/PS_cache/astro-ph/pdf/0604/0604084v5.pdf
Such kind of link fails if the original paper is updated. This is because Arxiv let you directly link to PDF ONLY IF the required PDF version is current version!

My updated version is
http://arxiv.org/abs/astro-ph/0604084
or
http://arxiv.org/abs/astro-ph/0604084v8

If you want to post my fifth version, that is OK if you choose:
http://arxiv.org/abs/astro-ph/0604084v5
but you choice of PDF post failed as I explained above!

It is interesting to observe that you can reference an arxiv paper which is not published in a refereed journal. Recently, I also referenced my arxiv paper :
http://arxiv.org/abs/0712.1110 (on the same subject) and I was banned for this because I "tried to distribute a personal theory". The paper mentioned above is in addition an extension of a previous paper which was published in a refereed journal. I'm curious whether I will be banned again. Furthermore, I have noticed many posts which contain references to un-refereed Arxiv papers without these persons being banned.

Rudi Van Nieuwenhove

 

[Garth]

Hi Rudi!

On this thread I (not being a Moderator) have allowed to be included brief references to papers on the ArXiv that have not been published in refereed journals, yet that do make some sense, and which make a definite falsifiable prediction.

This seems to have been allowed by the Moderators as the predictions will soon be able to be falsified, or just possibly otherwise.

As you can read some rough edges have been left...

Roll on May (??)!

Garth

 

[Kris Krogh]

Hi Garth,

I see today ArXiv has taken down the paper "A critical analysis of the GP-B mission. I: on the impossibility of a reliable measurement of the gravitomagnetic precession of the GP-B gyroscopes," by Gerhard Forst:

http://arxiv.org/abs/0712.3934

The comment field says: "This submission has been withdrawn by the arXiv administrators because 'G.Forst' is a pseudonym of a physicist based in Italy who is unwilling to submit articles under his own name, in violation of arXiv policies"

It's gone now, but I didn't see anything of substance in the paper. The references it cited did not show what was attributed to them.

Kris

 

[wolram]

Problems getting to KK paper, known compatibility problem, it may be a fault this end.

 

[lucien86]

Hi Gath you asked for theories that can be tested via Gravity probe B.


I have half of one that is not yet fully published or finished but I would like to mention it as it is an alternative or rather a modification to GR.
My work is based primarily on looking at what might exist beyond the light velocity barrier so it obviously involves particles with imaginary mass. My real problem is that I don't yet have the precision to make many exact predictions. What is clear though is that the model doesn't easily allow curved space times. At the moment I have gravity mapped as 'accelerating inertial frames' - the frame itself never sees the acceleration.
As far as I'm aware the model should give pretty much identical results to standard GR with one big exception - there should be tachyonic 'shadows'.
Another thing my model predicts is that gravity may be purely classical and have no lower quantum limit - in other words it can never exhibit interference patterns.

Obviously Gravity Probe B isn't going to answer many questions for my theory, but it wasn't designed to - my answers only really deviate from GR above the speed of light. (My theory forbids the folding of space)

I am working on designing a verifiable experiment that can detect tachyonic behavior but I am only an amateur with a tiny budget and other priorities so it is years away.

 

[Garth]

lucien86 we have strict guidelines here about not discussing personal theories except on the Independent Research Forum, unless they have already been published in a peer reviewed journal.

In this thread I am including theories already published on the physics ArXiv as well if they make falsifiable predictions for the GP-B experiment.

I suggest you submit your theory to the IR Forum having first followed their guidelines for submission.

Garth

 

[lucien86]

Sure - my whole point is that my theory is not ready to publish there. Half finished means exactly that. As for the IR forum the rules there are so strict that it is actually easier to get published in a big magazine like Nature. I am nowhere near getting published anywhere at the moment - sorry to bother you. - Lucien

 

[Garth]

Data Analysis Extended Again!

The GP-B website has had a revamp - although there are no new results to report.

GP-B Program Extended Through September 2008, and Possibly March 2010

On November 2, 2007, we convened the 17th meeting of our external Science Advisory Committee (SAC) to review our progress in the refinement of the GP-B experimental results. The subsequent SAC report noted "the truly extraordinary progress that had been made in data analysis since SAC-16 [March 23-24, 2007]" and unanimously concluded "that GP-B is on an accelerating path toward reaching good science results."

Following a peer-reviewed bridging proposal to NASA's Science Mission Directorate (SMD) and actions by Stanford and a private donor, the GP-B program has been extended at least through September 2008. Furthermore, SMD opened the opportunity for GP-B to submit a proposal this month to its Senior Review process. This is a bi-annual event in which ongoing NASA science programs undergo a peer-review to determine which of those programs NASA should continue and/or extend in order to achieve the greatest scientific gain. Assuming a successful Senior Review, GP-B will be extended one final time, from October 2008 through March 2010.

There are two unexpected experimental errors that are being reduced.

1. A time variation in the polhode motion of the gyroscopes, which creates complications in the gyro scale factor calibrations (conversion of electrical signals to angles).
2. Much larger than expected classical misalignment torques on the gyroscopes, attributable to “patch effect” (contact potential difference) interactions between the gyro rotors and their housings.

Although these anomalies reduced the best precision obtainable from the 1% goal they still hope to achieve about 2% for the frame-dragging effect and 0.02% for the geodetic effect.

During 2006-early 2007, we made good progress understanding the cause of these complications (and developing sound methodologies for working through them, culminating in an announcement of first results at the annual meeting of the American Physical Society in April 2007. Since that time, the team has continued to improve the results in a number of ways. As experimentalists, we make no assumptions about Einstein’s theory being right or wrong; rather, we collected data, and we are doing everything humanly possible to maximize the precision and accuracy of the final results—whether or not they agree with Einstein’s predictions.

For newbies to this thread a basic explanation of the experiment is given in a slide show on their website.

We note the Seeing General relativity Directly slide remains the replaced one, which does not give the game away. Remember the http://colloquia.physics.cornell.edu/11-12-2007/cornellpres_files/v3_slide0341.htm gave some interesting results inconsistent with GR at the one \sigma (68%) confidence level!

Garth

 

[JonathanK]

Hello Garth and everyone,

well, it seems GP-B may be a long road. My paper on the geodetic effect got through peer review, it's at

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

PSG gives the same predictions as GR and NG, hope to see it on the list with them, presumably along with Jin He's absolute relativity. Does anyone have a guess as to when the 3 sigma results will be announced? J

 

[Garth]

Well first of all Jonathan congratulations on having your paper published!

I do have a problem in including it in the list because in that paper you say:

PSG has the same values as GR for both effects being measured by Gravity Probe
B (for frame dragging it is - 39 mas/yr, using more recently released orbit figures). But
unlike GR, PSG has not been fully worked through, and it may be able to explain this
∼ 61 mas/yr anomaly when various smaller effects have been taken into account.

So what hard and fast prediction are you making for the results of this experiment? It seems that you are hedging your bets. The sign of a good scientific theory is that it can be falsified! As indeed my 2002 SCC proved to be! (darn!)

Although this isn't the place to discuss the detail of your theory, and you might like to start a new thread on PSG, as a published alternative theory, to do just that, my initial reaction is to be suspicious of your "time slowing" concept. Time on any particular world-line passes at the tautological rate of "one second per second". Time dilation between two clocks on different world-lines reveals a warping of the space-time continuum otherwise known as curvature and we are back to GR again.

Secondly I have a query about your actual calculation. If there is no curvature then orbital mechanics have to be explained by some type of Newtonian gravitational force accelerating the orbiting masses off their geodesic straight line trajectories. Such an acceleration would produce a Thomas Precession, that is unless you are denying SR as well, which acts to reduce the geodetic effect. I see no mention of that in your paper.

If you like, as it is published, I will include PSG giving a prediction equal to GR.

And I fully expect we will have to wait until 2010 to get the 3 \sigma results!

Garth

 

[JonathanK]

Thanks Garth,

I have the same predictions as GR, but if the anomaly found in the early geodetic results remains (and the delaying of the May announcement perhaps makes it slightly more likely that it is still there) I don't think that everyone will say "Ah well, GR was falsified, too bad". In that instance things would be on hold until some very good clear explanation for the 61 +/- 43 mas/yr turns up. By then the value of the anomaly would be known more accurately, so something might eventually explain it, either from analysing the experimental setup or from theory.

About the slowing of time - I put the word "slowing" in inverted commas in the paper to make it clear that it's not literal, either in GR or PSG. But as I'm making the point there that in PSG it happens by the same factor as the slowing of the motion of light and matter in the field, the word "slowing" is justified.

Though you say it doesn't, the paper actually does mention the question of a Newtonian type force. The conceptual basis removes the need for one, just as curvature does - an orbiting object is in freefall. If one conceptual basis can make an orbiting object be in freefall, then another can, as you'll see when it's published in full (or we can argue about it then! but I think you'll agree). But meanwhile it would be odd to rule out all possible conceptual pictures other than curvature as capable of that.

Anyway, best wishes,

Jonathan

 

[JonathanK]

Ps

PS. To clarify the first point above, the anomaly is too small to falsify everything at the GR value instantly, making KK theory the new standard view. Both GR and PSG could potentially survive that, but both could be falsified if the final results contained figures further from the GR values.

In the paper I've speculated briefly about the anomaly, but it's too small to be major issue, and doesn't detract from the prediction pair I've given, with mathematical backing for the geodetic prediction. After the equation, the paper says

"This means that PSG is so far consistent with experiment, as a geodetic effect of similar value to that in GR and PSG has been measured."

The final results may change that preliminary measurement, but "of similar value" relates to the same thing. J

 

[Garth]

Though you say it doesn't, the paper actually does mention the question of a Newtonian type force. The conceptual basis removes the need for one, just as curvature does - an orbiting object is in freefall.

The question is not whether the gyro is in free-fall, a satellite in Newtonian theory is falling freely, but whether the free-fall state is one where the gyro is accelerating away from its geodesic path, i.e. is it on a 'straight' geodesic trajectory, or not?

If it is on a 'straight' geodesic trajectory, as in GR, then the shape of the orbit is explained by the curvature of space-time and there is no intrinsic acceleration or Thomas precession; if it is not, as in Newtonian gravity, then there is an accelerating force, the Newtonian gravitational force, with the consequence that the gyro suffers a Thomas precession, which in Newtonian gravity (+ SR flat space-time) produces a precession equal to one third of the GR geodetic precession.

As an aside, because of this the initial geodetic result of GP-B has falsified Newton to a high confidence level! For the same reason I am also sure that it has falsified PSG, if that theory does not include space-time curvature.

So my question Jonathan is, "Does PSG include curvature? And if not, how does it produce an elliptical orbit without accelerating the gyro away from its 'straight' geodesic trajectory?"

Garth

 

[JonathanK]

There's no acceleration, for the same reasons as there's none in GR. The conceptual picture is one that is surprisingly like curvature, and yet it comes from flat space - it involves a small cluster of lateral jumps. An orbiting object thinks it is traveling in a straight line, and follows a curve only because the nature of space has been changed in a fundamental way.

I have a book on the theory of time, of which PSG is the gravity part ("Motion through time"), also hope to publish a longer paper with the whole conceptual basis - have wondered whether it can be a series of papers, but the concepts are so interdependent that it's difficult to find a dividing line. At present I have published some of the predictions, but not all of the theory.

In the book the concepts explain very much from very few starting assumptions, but the "smoking gun" evidence provided is an explanation of exactly how equation 4 of the first published paper was derived. It directly gives all the speeds on the path of a falling object from infinity, from knowing the speed at a given point. It agrees with numbers from Newton's theory to 12 decimal places, and goes to zero at the Schwartzchild radius of a black hole. I've hoped to show you the theory for some time, look forward to hearing your opinion. Thanks, J

 

[JonathanK]

Ps

PS perhaps I can give some indication of the kind of thing I mean, using an analogy. When light is refracted around a curve, for example when traveling through an index gradient refractive medium on Earth, does the light undergo an acceleration? No, instead it thinks it is traveling in a straight line, but what it is traveling through has been changed in a fundamental way (without curvature into an extra dimension), and this makes it follow a curve. PSG has something analogous to a refractive medium, which matter responds to at the Planck scale as light does.

Jonathan

 

[Garth]

The latest GP-B website Update:

================================
GP-B STATUS UPDATE -- MAY 23, 2008
================================

NASA's 2008 SENIOR REVIEW OF GP-B

In March 2008 at NASA's invitation, we submitted a proposal to the Science Mission Directorate, Astrophysics Division Senior Review of Operating Missions (Sr. Review), requesting a final 18-month (October 2008 through March 2010), $3.8M extension of GP-B to complete the data analysis and publish the results. In April, as part of the Sr. Review process, GP-B Principal Investigator, Francis Everitt, and Program Manager, William Bencze, made a presentation to the Sr. Review Committee at NASA Headquarters, where it appeared to have been favorably received.

Thus, we were greatly surprised last week to discover that the Sr. Review had recommended that NASA not grant our final funding extension, particularly since another NASA committee--the GP-B Science Advisory Committee (SAC -- http://einstein.stanford.edu/MISSION/mission2.html#sac), chaired by relativistic physicist Clifford Will--stated in its report following the November 2007 meeting: "The SAC was impressed with the truly extraordinary progress that has been made in data analysis since SAC-16 [Mar 2007] Š and we now agree that GP-B is on an accelerating path toward reaching good science results."

The Sr. Review evaluation is an unexpected setback, but we are determined to push ahead and drive to the very best possible result within the resources available.

THE PLIGHT OF FUNDAMENTAL PHYSICS RESEARCH AT NASA

While the Sr. Review outcome has ramifications for GP-B, in broader terms, it points to the challenge of finding support for fundamental physics experiments within the NASA culture of observational missions. This has been an ongoing issue within NASA for decades. In the 1990s, fundamental physics research experiments were scattered over several divisions of NASA, which led in 1999, to the blue-ribbon NASA Advisory Council (NAC) recommending to the NASA Administrator that the agency create a "single home room" for physics missions in space so that these missions would be given the support and visibility they deserved.

The 1999 NAC committee's advice was never heeded. Furthermore, during the 2004 restructuring and consolidation of NASA divisions, the already small budget for fundamental physics research was cut to zero in the NASA Exploration Directorate, entirely eliminating fundamental physics research from that division. This left the Science Mission Directorate (SMD) as the only home for fundamental physics experiments like GP-B. However, in the SMD, physics experiments had to compete directly with the NASA Great Observatories and other astrophysics missions for pieces of an already-decimated research budget. It is no criticism of the SMD Sr. Review to say that of the ten missions under review, GP-B as a physics experiment rather than an observatory was quite unlike the rest and almost impossible to fit within a common intellectual framework. Regrettably, since NASA has failed to establish a fundamental physics research division, several missions besides GP-B have suffered. If such a division existed, we believe the agency's support for the proper completion of GP-B would continue to be strong.

THE CONTINUED RELEVANCE & IMPORTANCE OF GP-B

One of the Sr. Review Committee's main arguments supporting its recommendation that NASA not fund the final extension requested by GP-B, was that the goals of GP-B have already been fulfilled by other measurements, and that GP-B is therefore no longer relevant. This view is in stark contrast with the recommendations of the SAC (2007), NASA's Turner panel review of GP-B (2003), and NASA's Fitch-Taylor NRC review of GP-B (1995). All of these reviews concluded that the GP-B experiment is scientifically justified and should be completed.Now, in 2008, the scientific justification for completing the GP-B experiment is even more valid. During the past five years, there has been little progress on other relativity experiments, but GP-B was launched, operated, and collected all of the necessary data. After two years of intense work, the GP-B science team is very close to completing the data analysis. GP-B has made, in the view of the SAC, "extraordinary progress" in addressing two unexpected and difficult complications in analysis caused by unanticipated electrostatic patch effect fields within the gyroscope. (These have been reported previously in our Summer 2007, September 2007 and December 2007 status updates, which you can view in the STATUS tab on our Website: http://einstein.stanford.edu/highlights/hlindexmain.html)

GP-B directly studies gravity, one of the most fundamental laws of nature. Inherently, the goals of GP-B differ significantly from those of typical astrophysics missions, where natural laws--inferred theoretically and tested on the ground--are used to interpret observations of astrophysical phenomena. Furthermore, GP-B objectives and methods are qualitatively different from those underlying most astrophysical work. For this reason, the GP-B experiment begs to be evaluated with respect to criteria based on its direct experimental methodology. Direct tests of nature's laws are the foundation of physical science; such tests are the only rational basis for the belief that these laws are, in part, "understood." GP-B seeks to deepen our understanding of gravity in this way.In addition to its scientific significance, GP-B's technological heritage and operational experience is critically important for future gravity space missions, including tests of the equivalence principle (STEP) and the search for gravitational waves (LISA). NASA stands to loose much of the expertise developed on the GP-B mission if the program is not brought to a proper conclusion.

THE ROAD AHEAD

Our GP-B team has been making steady progress in analyzing the data and working through the unexpected complications discovered within the data. We are now in the home stretch. We have identified the issues that still need to be addressed, and we have prepared a sound plan for completion of the analysis. This plan, which was spelled out in detail in our proposal to the NASA Sr. Review, requires an additional 18-month investment of $3.8M from September 2008 through March 2010. If no further funds are forthcoming from NASA, the analysis efforts will likely cease by October 2008, unless other funding sources can be identified. Since February 2008, GP-B has been funded by contributions from NASA, Stanford University, and a private donor, in approximately equal shares.

We have now clearly confirmed the geodetic effect to a precision of less than 1.5% (97 milli-arcseconds/year). However, because the frame-dragging effect is ~170 times smaller, removing the sources of error from that measurement--especially the non-relativistic torques due to patch effect interactions between the gyro rotors and their housings--is a detailed, painstakingly slow process. We have yet to reach a point of diminishing returns. Until we do, it is our intention to push onward and obtain the best result possible to properly complete this landmark experiment.

We wait to see how accurate they can get their results before the plug is pulled.

However, if it just a matter of $3.8M to complete the analysis up to March 2010 it seems a waste to stop in September this year after spending $800M.
Anybody got $3.8M to spare?

Garth

 

[Garth]

The reason GP-B is a unique experiment that has not been done before is because all other tests of the geodetic precession and gravito-magnetic effect rely on measuring the trajectories of test particles through space-time. They are not directly measuring the precessions of a physical (solid) gyroscope.

A non-metric theory that is conformally equivalent to GR in vacuo (i.e. its Action reduces to GR in vacuo) will generate the same geodesic trajectories for test particles although the Robertson parameters may be different.

This is significant because in terms of the Robertson PPN parameters all other tests of GR have effectively measured \gamma in the expression:

GM(\frac{1+\gamma}{2}),

whereas the geodetic precession is given by the expression:

GM(\frac{1+2\gamma}{3}).

The \gamma is coupled to G differently, so the measurement of the geodetic precession of an actual gyroscope, rather than just the precession of an orbit, is a unique measurement that has only been carried out by GP-B. It would be a crying shame not to complete the processing of the data obtained.

Garth

 

[Chronos]

Exactly the point of rigorously crunching GP-B data, Garth!

 

[Wallace]

I guess the funding panels just didn't believe the data was salvageable and whatever result GP-B would end up claiming would always have a big question mark next to it due to the extra noise. If the funding panel didn't believe the noise could be removed with certainty what would the research community think about the results? I guess they decided not to throw good money after bad.

I have no idea myself about how salvageable the data is, but clearly that was the view of the panel, who I'm sure aren't dodo's. It's a crying shame, but maybe humpty dumpty just can't be put back together again, no matter how much glue we buy.

 

[Garth]

I guess the funding panels just didn't believe the data was salvageable and whatever result GP-B would end up claiming would always have a big question mark next to it due to the extra noise. If the funding panel didn't believe the noise could be removed with certainty what would the research community think about the results? I guess they decided not to throw good money after bad.

I have no idea myself about how salvageable the data is, but clearly that was the view of the panel, who I'm sure aren't dodo's. It's a crying shame, but maybe humpty dumpty just can't be put back together again, no matter how much glue we buy.

The Update actually claims that the drying up of the money is due to a funding crisis and the lack of a fundamental physics research division within NASA:

It is no criticism of the SMD Sr. Review to say that of the ten missions under review, GP-B as a physics experiment rather than an observatory was quite unlike the rest and almost impossible to fit within a common intellectual framework. Regrettably, since NASA has failed to establish a fundamental physics research division, several missions besides GP-B have suffered. If such a division existed, we believe the agency's support for the proper completion of GP-B would continue to be strong.

In my post above I have explained the counter argument to the Sr. Review Committee's main criticism:

the goals of GP-B have already been fulfilled by other measurements, and that GP-B is therefore no longer relevant.

The GP-B team claim that 'Humpty Dumpty' has been almost put back together and a full repair is at hand.

Now, in 2008, the scientific justification for completing the GP-B experiment is even more valid. During the past five years, there has been little progress on other relativity experiments, but GP-B was launched, operated, and collected all of the necessary data. After two years of intense work, the GP-B science team is very close to completing the data analysis. GP-B has made, in the view of the SAC, "extraordinary progress" in addressing two unexpected and difficult complications in analysis caused by unanticipated electrostatic patch effect fields within the gyroscope.

Garth

 

[Wallace]

The Update actually claims that the drying up of the money is due to a funding crisis and the lack of a fundamental physics research division within NASA:

I know what the press release said (from both sides), I'm just trying to read between the lines I guess. If the honchos in NASA thought GP-B still had great things to say, they would have found the money somewhere, regardless of structural barriers.

The GP-B team claim that 'Humpty Dumpty' has been almost put back together and a full repair is at hand.

Again, that's what they are saying. But how long have they been saying that to the funding bodies? At some point patience will wear out. I've been telling my supervisor that the paper I'm working on is 'almost done' for a few months now, does that mean it will be ready tomorrow? Probably not. I don't think I've ever seen a grant application say 'we have a lot of work to do and it might not work out after all of that effort anyway', even though that is very often the truth.

Again, I know very little about GP-B, so this could all be irrelevant, 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.