Lunar Laser Ranging - is G constant?

[john hunter]

The purpose of this post is to summarise discussion about LLR and to try to decide whether or not it has provided evidence for, or against, a variable G (depending on the proximity of other matter).
A couple of years ago, physicists at the McDonald Observatory (which does the LLR) were contacted by email about the conjecture that G depends on the proximity of other matter.
It was put to them, that if the conjecture was true then there would be an annual sinusoidal variation in the earth-moon distance of 6cm (due to the earth-sun distance changing, and altering the earth and moon G).

...Their reply was 1) that this has been ruled out because G has been shown from approx 40 years of LLR data to be
changing by less than 4cm/year.

It was emphasised that the variation predicted was sinusoidal, not a continual increase of the earth-moon distance.

...Their reply was 2) that there was no annual sinusoidal variation in the moons orbit.

Upon further investigation it was found from puplished papers, that there is an enormous (order km) annual sinusoidal variation in the moons orbit.

...Their reply was 3) that there was no unmodelled annual sinusoidal variation in the moons orbit.

From paper "Effect of General Relativity on a Near Earth Satellite in Geocentric and Barycentric Reference Frames" - Physical Review Letters 22nd Aug 1988 - Ries, Huang, and Watkins pg 903-906 - equation 1) it seems as though their modelling process includes the transformation: r(geocentric) = r + (U/c^2)r, where r is the position of the satellite relative to the earth, U is the suns gravitational potential.
Which gives exactly the 6cm annual sinusoidal variation predicted by the conjecture.

...Their reply was 4) that this effect was a time dilation effect from General Relativity.


It seems as thought this position was reached only after much protracted probing. This attitude was due to there being an inherent assumption that the conjecture was false.

Now it seems as though there is evidence for a 6cm oscillation, and its a matter of interpretation of GR, whether its a time dilation effect, or due to a reducing G.

John Hunter.

[captain swoop]

So i don't need to eat less pies to lose weight? cool!

[john hunter]

Dear Captain,

So i don't need to eat less pies to lose weight? cool!

True!, just weigh yourself at the beginning of January each year - your weight should be lowest then - someone will probably give the exact date, when the earth is closest to the sun.

John Hunter.

[captain swoop]

I would say that just after Xmas and new Year my weight will be at its greatest!! :(

[hhEb09'1]

It was put to them, that if the conjecture was true then there would be an annual sinusoidal variation in the earth-moon distance of 6cm (due to the earth-sun distance changing, and altering the earth and moon G).I forget, how much is that distance changing? According to the theory.From paper "Effect of General Relativity on a Near Earth Satellite in Geocentric and Barycentric Reference Frames" - Physical Review Letters 22nd Aug 1988 - Ries, Huang, and Watkins pg 903-906 - equation 1) it seems as though their modelling process includes the transformation: r(geocentric) = r + (U/c^2)r, where r is the position of the satellite relative to the earth, U is the suns gravitational potential.
Which gives exactly the 6cm annual sinusoidal variation predicted by the conjecture.

...Their reply was 4) that this effect was a time dilation effect from General Relativity.So, the moon is 6cm farther from the earth (after the km level effects are accounted for) during July when it is farthest from the sun? Is that how I interpret that?

[captain swoop]

how does that = a variable G though?
it's a coincidence that G varies at exactly the same frequency as the Earths orbit around the sun!

[hhEb09'1]

how does that = a variable G though?
it's a coincidence that G varies at exactly the same frequency as the Earths orbit around the sun!No I think he's saying that the growth of the earth's distance from the sun adds an oscillation to the moon's distance.

[korjik]

How much difference in lunar orbit is there from 1/r^2 differences during the year? seems to me that that could be a much larger signal

[hhEb09'1]

How much difference in lunar orbit is there from 1/r^2 differences during the year? seems to me that that could be a much larger signalThe OP says that the distance varies by kilometers, but the models account for things down to the centimeter. We don't know G that close, but I think in this case all we need is GM, which we can get down fairly precisely.

[Nereid]

You might want to check it out, john hunter - he revised it (http://relativity.livingreviews.org/Articles/lrr-2006-3/index.html) in March (?) this year, so it's pretty much up to date.

If you search for "LLR", you'll see that it comes up in many places in the document, but the section you will be most interested in, I think, is 3.6.

I had planned to take your ATM ideas, as presented in this section, work out the extent to which the material in Will's paper may test your idea, and ask you a series of open questions about the consistency. But, I've been busy with other things, and, in any case, if you're serious about your idea, you'll have to go through something like Will's paper, and tick off every relevant set of good observational and experimental results against the predictions from your idea. (Of course, any other BAUT member could do something like I just outlined, and several of our stalwarts, as well as some of the BAUT newbies, I'm sure could that!)

[john hunter]

Dear Nereid,

you'll have to go through something like Will's paper, and tick off every relevant set of good observational and experimental results against the predictions from your idea.

OK, just a quick reply for now.

Firstly, a lot of evidence in the paper is against a time varying G - and the paper often makes the implicit assumption that evidence against a time varying G, is also evidence that G dosn't depend on the proximity of other matter.

That is, they are assuming the redshift is evidence of an expanding universe in the traditional 'Big Bang' sense.

The theory which leads to the conjecture that G depends on the proximity of other matter, is the 'rescaling theory'. This theory 'explains' the redshift as being due to a changing value of Plancks constant with time. The evidence in favour for 'Big Bang' e.g helium abundancies is (in the new model) due to smaller 'bangs' e.g. at the centres of galactic clusters, which give the spherical void, large scale structure. (www.gravity.uk.com/cosmological_model.html and links redshift, and gravitation )
In this model the whole universe is not expanding, and G would not vary with time.

So to rule out this theory - G needs to be shown not to vary with distance - not time.


Secondly, There is no reason why the new proposals should violate the equivalence principle. The earth and moon system would still fall equally towards the Sun, because their motion is due to the curvature of space-time caused by the Sun. In fact the new proposals are intended to incorporate GR, but just reinterpret the expansion of the universe predicted by GR, with the consequence that G reduces for dense objects.

John Hunter.

[Peter Wilson]

Will results from gravity probe B, when they are done "analysing data," settle this?

[john hunter]

Dear Peter,

Will results from gravity probe B, when they are done "analysing data," settle this?

Not sure, but for an experiment measuring 'frame dragging' for the first time, its unlikely to measure it to one part in 10^10, which is the required accuracy needed to measure the change in G, with earth-sun distance.

For anyone else interested a link is: http://einstein.stanford.edu/

The most sure way of testing the conjecture seems to be from LISA. If the solar oscillations change the suns m/r ratio, the solar G will vary at the same frequenct to which LISA is sensitive. LISAs satellites orbits will vary slightly, giving a change of micrometers in the arm length.

This was discussed in:http://www.bautforum.com/showthread.php?t=38392

John Hunter.

[nutant gene 71]

How much difference in lunar orbit is there from 1/r^2 differences during the year? seems to me that that could be a much larger signal

This was discussed on BAUT about a year ago, as per Why G changes... I submit (http://www.bautforum.com/showthread.php?p=616194&highlight=%22Axiomatic+Equation%22#post616194), where I once upon a time formulated a hybrid Planck-deBroglie-Einstein equation dubbed the “axiomatic equation” showing Newton’s (universal constant) G changes (increases with distance from Sun) by about 1G per 1 AU. At the time of those discussions, the idea of a variable G were well challenged though not rejected entirely (except for my claim of 1G per 1 AU) and has found some interest especially regarding the Pioneer Anomaly, where the acceleration (towards the Sun) might be due to a variable (increasing) G with distance from the Sun.

If mean average distance from the Sun for Earth’s 1 AU = 149,597,890 km, then the eccentricity between perihelion and aphelion is only 0.01671, which means 1 AU ranges about 0.008355 from the mean, or about 1,250 km either way from a true 1 AU distance. This is a very small difference. Translated into the above ‘hypothetical’ change in Newton’s G, then 6.67E-11 m^3 kg^-1 s^-2 ranges only by about (plus or minus) 0.005573E-11 m^3 kg^-1 s^-2, which is a very small value, perhaps too small to measure. However, the original idea was that such a small deviation from the mean average G should be detectable eventually. If found, it would involve a ‘slightly’ weaker gravitational pull on our moon when Earth is at perihelion, and slightly stronger pull while at aphelion from the Sun.

What I think the OP is pointing out here is that there seems to be evidence that 40 years of LLR data may be showing, in the form of lunar orbital deviation, that such a G disparity exists even at such close range as + 1 AU, hence making it a variable rather than a ‘universal constant’ as postulated by Newton et al. That said, I have no way of translating (hypothetical) eccentricity in G into the ‘sinusoidal eccentricity’ of lunar orbit measured in cm. So it is interesting, though perhaps not a proof. Variable G is something that should be looked for, perhaps with the help of LISA, even in such close range as our 'known' 1 AU, in my humble opinion.

[trinitree88]

This was discussed on BAUT about a year ago, as per Why G changes... I submit (http://www.bautforum.com/showthread.php?p=616194&highlight=%22Axiomatic+Equation%22#post616194), where I once upon a time formulated a hybrid Planck-deBroglie-Einstein equation dubbed the “axiomatic equation” showing Newton’s (universal constant) G changes (increases with distance from Sun) by about 1G per 1 AU. At the time of those discussions, the idea of a variable G were well challenged though not rejected entirely (except for my claim of 1G per 1 AU) and has found some interest especially regarding the Pioneer Anomaly, where the acceleration (towards the Sun) might be due to a variable (increasing) G with distance from the Sun.

If mean average distance from the Sun for Earth’s 1 AU = 149,597,890 km, then the eccentricity between perihelion and aphelion is only 0.01671, which means 1 AU ranges about 0.008355 from the mean, or about 1,250 km either way from a true 1 AU distance. This is a very small difference. Translated into the above ‘hypothetical’ change in Newton’s G, then 6.67E-11 m^3 kg^-1 s^-2 ranges only by about (plus or minus) 0.005573E-11 m^3 kg^-1 s^-2, which is a very small value, perhaps too small to measure. However, the original idea was that such a small deviation from the mean average G should be detectable eventually. If found, it would involve a ‘slightly’ weaker gravitational pull on our moon when Earth is at perihelion, and slightly stronger pull while at aphelion from the Sun.

What I think the OP is pointing out here is that there seems to be evidence that 40 years of LLR data may be showing, in the form of lunar orbital deviation, that such a G disparity exists even at such close range as + 1 AU, hence making it a variable rather than a ‘universal constant’ as postulated by Newton et al. That said, I have no way of translating (hypothetical) eccentricity in G into the ‘sinusoidal eccentricity’ of lunar orbit measured in cm. So it is interesting, though perhaps not a proof. Variable G is something that should be looked for, perhaps with the help of LISA, even in such close range as our 'known' 1 AU, in my humble opinion.


nutant gene 71. Interesting, in that if G varies with distance, and is increasing, then stars orbiting galaxies on their peripheries, should appear to be bound more strongly than could be accounted for in invariant-G kinematics. Detection of anomalies in the excess velocities of such objects measured in galactic rotational velocity curves, (Vera Rubin) would indicate then that we are then somehow "missing" the majority of the mass in the G-invariant system,creating a cosmological conundrum....what you see is not what you get, and most of the universe is missing.
Sensitive G measurements would seem to be very interesting to all. :shifty: Pete.

[nutant gene 71]

nutant gene 71. Interesting, in that if G varies with distance, and is increasing, then stars orbiting galaxies on their peripheries, should appear to be bound more strongly than could be accounted for in invariant-G kinematics. Detection of anomalies in the excess velocities of such objects measured in galactic rotational velocity curves, (Vera Rubin) would indicate then that we are then somehow "missing" the majority of the mass in the G-invariant system,creating a cosmological conundrum....what you see is not what you get, and most of the universe is missing.
Sensitive G measurements would seem to be very interesting to all. :shifty: Pete.
The flattening of rotation curves for outer galaxies would fit the idea that G increases with distance from 'hot' energy, i.e., the Sun or galaxy mass of hot stars. If this is found to be so, empirically not yet confirmed, then it would explain a lot of things that are now 'anomalous', everything from Pioneers to so-called 'dark matter', which would default (per equivalence) to baryonic mass 'out there' being in higher G and acting as if more massive gravitationally. I think we are at a very exciting juncture in modern physics today, and I can't wait for empirical confirmation. I think it's forthcoming. People are beginning to look that way, so stay tuned. :)

[Nereid]

The flattening of rotation curves for outer galaxies would fit the idea that G increases with distance from 'hot' energy, i.e., the Sun or galaxy mass of hot stars. If this is found to be so, empirically not yet confirmed, then it would explain a lot of things that are now 'anomalous', everything from Pioneers to so-called 'dark matter', which would default (per equivalence) to baryonic mass 'out there' being in higher G and acting as if more massive gravitationally. I think we are at a very exciting juncture in modern physics today, and I can't wait for empirical confirmation. I think it's forthcoming. People are beginning to look that way, so stay tuned. :)That may be so, but I think the huge variety among galaxy rotation curves, not to mention the variation in the DM signals in rich clusters, would require quite a bit of work to show, in detail, that this idea has legs.

[nutant gene 71]

That may be so, but I think the huge variety among galaxy rotation curves, not to mention the variation in the DM signals in rich clusters, would require quite a bit of work to show, in detail, that this idea has legs.
Until we find real empirical evidence for a variable G, the idea doesn't have a 'leg to stand on'. :)

For now there is only anecdotal 'evidence' of sorts:

1. Galaxy flattening rotation curves
2. Pioneer Anomaly
3. Large gas giant atmospheres in outer solar system
4. Deep space 'cold' hydrogen gas fusion into stars
5. 'Dark matter' galaxies and lensing
6. Cometary outgasing at about Jupiter's still cold region

Now, these do not constitute a theoretical model, but they do point to something going on out there we may not have modeled correctly. The next possibility, most damning of all for a 'universally constant' G, is the possibility that a very high G in deep cold intergalactic space is causing distant cosmic light to redshift naturally gravitationally as it passes through the very thin gaseous hydrogen molecules of space 'vacuum', if G is that much higher out there. If so, this may mean that redshift is non-Doppler, so space expansion may be no more than an optical illusion. So a lot of stuff rides on this 'variable G' presented here by John Hunter. I agree with you totally, a lot of work needs to be done to model a variable G. But first before we embark on some fancy theory, let's get the empirical data down pat. The streaming data from new observations are giving us new clues, which we cannot discount if they increasingly fail to match our theoretical models. Curve fitted at first, like MOND, but eventually we should see a clearer pattern of what is happening out there.

That said, it appears to me the real crux of John's idea is the matching equality of Einstein's Energy equation and Gravitational force Potential, as in:

mc^2 = GMm/R

I am not sure how to take this, since it seems to be equating two very different types of Energy, one being electromagnetic in nature, while the other is gravitational in nature. Perhaps John can give us some greater clarity on this?

Thanks, Ivan

[john hunter]

Dear nutant gene 71:849279



That said, it appears to me the real crux of John's idea is the matching equality of Einstein's Energy equation and Gravitational force Potential, as in:

mc^2 = GMm/R

I am not sure how to take this, since it seems to be equating two very different types of Energy, one being electromagnetic in nature, while the other is gravitational in nature. Perhaps John can give us some greater clarity on this?



Recently a 'sister website' has been made, to clarify where this comes from, and to show more clearly why it gives
omega(matter) = 1/3

It's www.rescalingsymmetry.com and is just 3 short web pages.

John Hunter.

[Nereid]

Until we find real empirical evidence for a variable G, the idea doesn't have a 'leg to stand on'. :)

For now there is only anecdotal 'evidence' of sorts:

1. Galaxy flattening rotation curves
2. Pioneer Anomaly
3. Large gas giant atmospheres in outer solar system
4. Deep space 'cold' hydrogen gas fusion into stars
5. 'Dark matter' galaxies and lensing
6. Cometary outgasing at about Jupiter's still cold region

Now, these do not constitute a theoretical model, but they do point to something going on out there we may not have modeled correctly. The next possibility, most damning of all for a 'universally constant' G, is the possibility that a very high G in deep cold intergalactic space is causing distant cosmic light to redshift naturally gravitationally as it passes through the very thin gaseous hydrogen molecules of space 'vacuum', if G is that much higher out there. If so, this may mean that redshift is non-Doppler, so space expansion may be no more than an optical illusion. So a lot of stuff rides on this 'variable G' presented here by John Hunter. I agree with you totally, a lot of work needs to be done to model a variable G. But first before we embark on some fancy theory, let's get the empirical data down pat. The streaming data from new observations are giving us new clues, which we cannot discount if they increasingly fail to match our theoretical models. Curve fitted at first, like MOND, but eventually we should see a clearer pattern of what is happening out there.

That said, it appears to me the real crux of John's idea is the matching equality of Einstein's Energy equation and Gravitational force Potential, as in:

mc^2 = GMm/R

I am not sure how to take this, since it seems to be equating two very different types of Energy, one being electromagnetic in nature, while the other is gravitational in nature. Perhaps John can give us some greater clarity on this?

Thanks, IvanI'm not even sure I know what several of these 'observations' are, so could you start by clarifying please?

"3. Large gas giant atmospheres in outer solar system
4. Deep space 'cold' hydrogen gas fusion into stars

6. Cometary outgasing at about Jupiter's still cold region"

And as for MOND, well, as I noted earlier (http://www.bautforum.com/showpost.php?p=823074&postcount=215), even its most ardent supporters seem to have been, shall we say, somewhat selective in choosing which spiral galaxies' rotation curves to analyse.

Finally, per john hunter's posts here (http://www.bautforum.com/showthread.php?t=46507&page=2), it may be that there are some consistency problems, with "Gravitational force Potential", as on the one hand it's supposed to be a (nearly) pure GR idea, but on the other hand, this seems to be defined in a purely classical way.

[Squashed]

... The next possibility, most damning of all for a 'universally constant' G, is the possibility that a very high G in deep cold intergalactic space is causing distant cosmic light to redshift naturally gravitationally as it passes through the very thin gaseous hydrogen molecules of space 'vacuum', if G is that much higher out there. If so, this may mean that redshift is non-Doppler, so space expansion may be no more than an optical illusion. ...

This sort of talk makes me wonder if gravity is not the start of it all and somehow "gravity" condensed or was absorbed by the creation of matter and so the gravity is least inside large bodies and greatest the farthest away - a pushing type scenario. So we are pushed towards the lesser gravity areas by the greater gravity areas.

This type of scenario would lend credence to the GR view of gravity where gravity is viewed as a geometric structure of space.

Just a thought I had.

[Tassel]

If mean average distance from the Sun for Earth’s 1 AU = 149,597,890 km, then the eccentricity between perihelion and aphelion is only 0.01671, which means 1 AU ranges about 0.008355 from the mean, or about 1,250 km either way from a true 1 AU distance.
The Earth-Sun distance varies by much more than that. It's about 147 million km from the sun in January versus 152 million km in July. Using your proposed rate of change for G means G should vary between roughly 6.5E-11 and 6.8E-11 as the Earth orbits the sun which of course would be easily detectable.

[nutant gene 71]

The Earth-Sun distance varies by much more than that. It's about 147 million km from the sun in January versus 152 million km in July. Using your proposed rate of change for G means G should vary between roughly 6.5E-11 and 6.8E-11 as the Earth orbits the sun which of course would be easily detectable.
Thanks for pointing out my serious error in miscalculating eccentricity! With a 5 million km difference, the G variation would indeed be large enough to measure. Such a large disparity between '6.5E-11 and 6.8E-11' has not been detected, to my knowledge. The OP talks about a very small difference in lunar orbital deviation. A deviation of 0.3E-11 from perihelion to aphelion should have been detected, if it were so. Scratch my idea on that. :(

[Ps: On thinking on this some more, though I had never worked out Energy numbers for Earth's perihelion-aphelion and translated into resulting G (using 'axiomatic equation') in the way E was derived for the nine planets, it should be an interesting exercise to see how it works out. I need Earth's orbital velocity at both extremes of the elliptical to do that (which I don't know) and then work out G from the resulting proton mass the equation yields. There may be another factor which involves how the planet's velocity changes, which may be a 'netting out' effect, but really still don't know if this translates into a larger or smaller G. Something to do, and will report back once I have.]

[nutant gene 71]

I'm not even sure I know what several of these 'observations' are, so could you start by clarifying please?

"3. Large gas giant atmospheres in outer solar system
4. Deep space 'cold' hydrogen gas fusion into stars

6. Cometary outgasing at about Jupiter's still cold region"

And as for MOND, well, as I noted earlier (http://www.bautforum.com/showpost.php?p=823074&postcount=215), even its most ardent supporters seem to have been, shall we say, somewhat selective in choosing which spiral galaxies' rotation curves to analyse.

Finally, per john hunter's posts here (http://www.bautforum.com/showthread.php?t=46507&page=2), it may be that there are some consistency problems, with "Gravitational force Potential", as on the one hand it's supposed to be a (nearly) pure GR idea, but on the other hand, this seems to be defined in a purely classical way.
I can only answer the three blues above parenthetically, to not deviate too far from OP's original.

#6. Deeply elliptical comets range from Kuiper Belt or beyond down towards inner solar system. If variable G is real, from a larger outer G region to lower inner G, it could cause 'compacting' of loose space material on the comet in outer solar system to 'de-compact' coming into lower G region closer in. I think from reading that comets begin outgassing at about Jupiter's orbital region, which is far enough away from the Sun's energy to be considered a cold region, so temperature rise may not be large enough to account for it. The idea is that if G is less for 5 AU than for 40 AU, for example, then the difference may be enough to release materials compacted on the comet by the time it is approaching 5 AU, which might acccount for 'outgassing' of not only water molecules but dust as well. (Low elliptical comets should exhibit less outgassing, by this reasoning?)

#4. I believe there is a conundrum about deep space hydrogen gas clouds collapsing into fusion because gravity is not high enough to make such clouds being compressed enough to combust. A much higher G, orders of magnitude higher than what we know, could overcome this conundrum. However, this can be taken as conjecture only for now.

#3. Starting at Jupiter's 5 AU begins the gas giants, except for little Pluto which is smaller than our moon but has some sort of atmosphere. The idea of a larger G in outer solar system might, hypothetically, be cause for why atmospheres of gas giants are as large as they are. On another thread (http://www.bautforum.com/showthread.php?t=35380) was discussed Titan's large atmosphere, larger than Earth's though Titan is smaller. Another factor is that radar readings of Jupiter's interior core mass is only about 2-3 times Earth size (but has about 10-15 times Earth masses (http://www.nineplanets.org/jupiter.html)), yet around this small core can accumulate such large atmosphere, which is curious.

On the MOND issue not fitting all galaxy rotation curves, I find this as new information, so can't comment yet, not a strong enough student of this effect. Curious though, since I always felt MOND is ad hoc, so not surprised to find 'curve fitting' not universal.

[nutant gene 71]

Dear nutant gene 71:849279


Recently a 'sister website' has been made, to clarify where this comes from, and to show more clearly why it gives
omega(matter) = 1/3

It's www.rescalingsymmetry.com and is just 3 short web pages.

John Hunter.
Thanks John, for the The Redshift of Light (http://www.rescalingsymmetry.com/redshift_of_light.html) and Value of G and Omega (http://www.rescalingsymmetry.com/value_of_G.html) referenced. It appears they're contingent on a changing Planck's constant over time to account for 'stretched' lambda over time. Interesting idea, but how to prove it?

[john hunter]

Dear nutant,

Thanks John, for the The Redshift of Light (http://www.rescalingsymmetry.com/redshift_of_light.html) and Value of G and Omega (http://www.rescalingsymmetry.com/value_of_G.html) referenced. It appears they're contingent on a changing Planck's constant over time to account for 'stretched' lambda over time. Interesting idea, but how to prove it?

Good question.

So far efforts have been mostly on trying to see if G reduces as predicted by the conjecture, for masses of high m/r ratio.

This has included all sorts of dead-end attempts, but has finished up with LLR and binary pulsar data. Dead end attempts included detecting the change of a weight of a mass, by strain guages, change in volcanic activity, when earth is near or far from sun.....the value quoted a few posts ago of 0.3x10^-11 is about 5% of G, and might cause disastor from volcanic activity on an unimaginable scale! Any weighing method would also show this change.

Another way would be to try and account for the accelerating universe q=-1, and q(z), which is mathematically very complicated, since scale factor is not related to (1+z), but sqrt(1+z).

Also to see if future measurements of omega(m) give a value closer to 1/3 or 0.3.

John Hunter.

[MaDeR]

The idea of a larger G in outer solar system might, hypothetically, be cause for why atmospheres of gas giants are as large as they are.

What it fits into Hot Jupiters? Many of them are too large, not too small.

[Nereid]

But why just LLR? Why not all the data that is available through all the projects which ILRS (International Laser Ranging Service) (http://ilrs.gsfc.nasa.gov/) covers?

For example, the recent, successfully completed, GIOVE work (http://www.esa.int/esaCP/SEM8QOKKKSE_index_0.html)?

If I read this right, accuracies are at the mm level, which is ~2 OOM better than LLR, and while there are many important differences between the Moon and satellites, there is a great deal of independent data.

And another question about the JHE (apologies if this has been asked before) - what about Gravity Probe B? Can you predict what the results will be?

[nutant gene 71]

What it fits into Hot Jupiters? Many of them are too large, not too small.
Very good point. If G in our solar system were to be distance relative to the Sun's hot energy, then same process should be expected in other solar systems. The key would then be of necessity to measure the energy output of 'hot' stars where such large hot 'Jupiters' are found. By this reasoning, large planets that are gaseous, such as our gas giants, should be further from hot stars, unless those stars are measurably cooler than our own type-2 Sun, or mass configurations are different. At this point, we still do not have a good optical ranging on what those hot Jupiters are doing, except to watch for wobble and then extrapolate orbital distance and mass by using Newton G physics, where G is a constant axiomatically, so we 'see' what we expect to see. More data needed to address very far solar systems. We can use LR here in our own solar system, but not yet for those thousands of light years away, at this time.

[Nereid]

How about we have a separate ATM thread on these? I think they are quite irrelevant wrt the JHE and lunar laser ranging!

[nutant gene 71]

How about we have a separate ATM thread on these? I think they are quite irrelevant wrt the JHE and lunar laser ranging!
I really have nothing else to add to this line of reasoning, and would rather go back to LLR discussion. As I mentioned earlier, mine was a 'parenthetical' answer, to not drive off course on OP's original. Of course, if others want to start a separate discussion, fine with me.

Thanks, Ivan

[nutant gene 71]

I came across Kenneth Nordtvedt's paper (2003): "dG/dt measurement and the timing of lunar laser ranging observations" (http://www.iop.org/EJ/article/0264-9381/20/11/101/q311l1.html) which makes a case for non-constant G'/G (worth) having a sinodic lunar cycle distribution. He also mentions in passing a study for solar cycle might produce similar orbital frequencies, could be revealing, though beyond present capabilities. I would agree, seeing Newton's G can vary (by as much as 1%) in various measurements without known cause, so the durability of a fixed universally constant G comes in question. If we could find cause for LLR results, or future solar LR results prove G'/G varies, it could be significant for our deeper understanding of astrophysics.

In this paper by Blaze Labs Research, which may not be the best source, it shows how G varies by anywhere from 0.6% to 1% in various studies: http://www.blazelabs.com/f-u-massvariation.asp (see pages 2-4), though for most of the rest of it, I didn't care for.

[Tensor]

In this paper by Blaze Labs Research, which may not be the best source, it shows how G varies by anywhere from 0.6% to 1% in various studies: http://www.blazelabs.com/f-u-massvariation.asp (see pages 2-4), though for most of the rest of it, I didn't care for.

And so?????? All of the results (at least as far as the ones I could check with the actual papers) are within the limits of the measuring errors of the particular experiment. That different experiments have different bias, and as a result, different results shouldn't be so suprising. I also find their claim of eliminating all possible experimental errors (on behalf of J.P. Schwartz and J.E. Faller, the actual experimenters) rather silly. J.P. Schwartz and J.E. Faller make no such claim in their paper. The do claim to have eliminated many such errors, but not all of them. The experimenters also do not claim to have found a variable g, they attribute the variability of the results to, guess what? Simple experimental variation. The authors of that page want a variable g (so it fits in with their ideas), so they are making claims on behalf of the actual experimenters who didn't make the claims the authors wanted. That page is simply a case of trying to fit data to their own ideas. You are right in saying that page may not be the best source, it's not even a sorta, kinda source.

[nutant gene 71]

And so?????? All of the results (at least as far as the ones I could check with the actual papers) are within the limits of the measuring errors of the particular experiment. That different experiments have different bias, and as a result, different results shouldn't be so suprising. I also find their claim of eliminating all possible experimental errors (on behalf of J.P. Schwartz and J.E. Faller, the actual experimenters) rather silly. J.P. Schwartz and J.E. Faller make no such claim in their paper. The do claim to have eliminated many such errors, but not all of them. The experimenters also do not claim to have found a variable g, they attribute the variability of the results to, guess what? Simple experimental variation. The authors of that page want a variable g (so it fits in with their ideas), so they are making claims on behalf of the actual experimenters who didn't make the claims the authors wanted. That page is simply a case of trying to fit data to their own ideas. You are right in saying that page may not be the best source, it's not even a sorta, kinda source.
Can't disagree with you there, Tensor. Here was the quote that (mis)led me to think the paper was onto something, along with the graph above it for three years study. This is a plot of G results using the mentioned free fall technique. Error bars represent one formal standard deviation. The 1997 data was processed daily, giving values of G from 6.66E-11 to 6.71E-11. One day's observation consisted of approximately 7200 drop measurements. Again, data consistently shows that G varies over time, with an uncertainty of over 1400ppm, despite the fact that all sources of possible experimental errors associated with the classical Cavendish setup, have been eliminated. I didn't take this paper too seriously, and have grave reservations about their conclusion that a variable G is due to relative velocities of Sun, Milky Way, etc.

[Thanatos]

This hypothesis should be testable: either the moon is receeding from earth at a velocity of 3 cm per year, or the speed of gravity is slowing down by the same relative amount. So, gravity gets stronger with redshift? Interesting concept. Observational evidence should be abundant.