Gravitational Constant

[Ernest Wilson]

Why does measurement of the Gravitational Constant have a 1% accuracy, the same as achieved by Cavendish in 1798, when measurement of most physical constants have an accuracy of 0.01%?

[CraigS]

Hi Ernest;

Wiki says …

The gravitational constant is perhaps the most difficult physical constant to measure to high accuracy. In SI units, the 2006 CODATA-recommended value of the gravitational constant is:

G=6.67428 x 10^-11 N(m/kg)^2

with relative standard uncertainty 1 part in 10^4.

That makes it uncertain to only 0.01%, doesn't it ?

Cheers

[Ernest Wilson]

Hi CraigS,

Thanks for showing up my poor maths!! The range of the readings is significant because when measurements of gravity are made continuously, the results show a sinusoidal pattern over 24 hours that is repeated day after day. That would suggest that gravity may not be constant. Why so?

Have fun.

[bojan]

Well, Earth is rotating.. we have some nearby objects like Moon and Sun.. this is the reason for ~24 hour cycle.

[CraigS]

Ernest;

I think you need to post some references when citing things like:

Originally Posted by Ernest Wilson

The range of the readings is significant because when measurements of gravity are made continuously, the results show a sinusoidal pattern over 24 hours that is repeated day after day.

.. otherwise, all we have is opinions to discuss.

I can think of heaps of reasons as to why someone may come to this conclusion, all or none of which, may be relevant to the measurements made in your source material.

For example, the length of day measurement is also not a straight-forward issue as atmospheric drag, etc has been shown to have significant effects on the measurement of a day. If this is so, have the researchers in your source material taken this into account ?

It appears to me, that the biggest issue in precisely measuring the Gravitational Constant lies in precisely characterising the errors in the mechanical behaviours of the test apparatus. There are many techniques developed over the 300 years (since Newton), to measure it. these have culminated in the results mentioned in my post #2.

Cheers

[Ernest Wilson]

Herewith references:

Tidal Accelerometry: Exploring the Cosmos Via Gravitational Correlations By T Datta, M Yin, M Wescott, Y Jeong, P Morawiec,

J Gambrell, D Overcash, H Zhangand G Voulgaris
- Arxiv preprint arXiv: …, 2010 - arxiv.org

Geophysical Geodesy beyond 2000 by Petert Varga Geophysical Geodesy Beyond 2000[PDF] from uni-stuttgart.de - Quo vadis geodesia, 2002 - uni-stuttgart.de

[CraigS]

Ok thanks for the references, Ernest.

Had a read through the Datta et al paper, and I think you have your purported answer right there …

Here we reason that water tide clearly is not the way to go, nevertheless tidal or geodesic deviation signals can be an accurate source of astronomical quantities that may provide a double check on standard methods. More importantly gravitational tide can reveal information that cannot be accessed via conventional observational techniques.

Seems like a reasonably well argued perspective.

I wasn't too enthralled with this bit though ..

Etymology of the condition “lunacy” is another empirical evidence of celestial effects on human psychology. Furthermore, for a long time there has been at least anecdotal evidence, which is beginning to be scientifically substantiated about a credible connection between significant geophysical events such as earthquakes and tides.

Whilst I've heard the 'lunacy' inferences being cited in mainstream media, I've never researched the topic and I remain sceptical about this. (Which doesn't necessarily rule it out as a possibility, mind you).

Also, they should clarify that the 'credible connection between earthquakes and tides', doesn't lead to any useful long term predictive capabilities. Invoking tides as a trigger for relieving fault stress, I see is credible, but using it as a sole method for prediction, places it back into the unlikely category (for lots of reasons).

Using such examples in their Introduction also raises alarm bells with me, when it comes to the credibility of other aspects of their arguments/rationale.

Also, perhaps I haven't read it closely enough, but are they actually saying that: 'the results show a sinusoidal pattern over 24 hours that is repeated day after day.' ??
Figure 10 in this paper is a "synthetic tidal signal". Can't seem to find where they actually come out and say say a 24 hour cycle is statistically evident from the results.
(Happy to be corrected on this, however).

Cheers

[Ernest Wilson]

Bojan makes the point that diurnal variation of G could be due to the effect of the Sun and the planets. Methinks that I am out of my depth in this, but there may be a physicist out there who could care to question the validity of the following papers. Ernie.

Unified Theory Foundations© Engineer Xavier Borg - Blaze Labs Research 2009 (www.blazelabs.com)

"Mass varies with its absolute velocity..and together with gravitational constant G, over 50 other scientific units depend on stars position!" Final Demystification of the gravitational constant variation

Einstein Gravitation and Newton Gravitation
Roger J.Anderton

R.J.Anderton@btinternet.com 24th January 2011 The General Science Journal

[bojan]

Originally Posted by Ernest Wilson

Bojan makes the point that diurnal variation of G could be due to the effect of the Sun and the planets.

Hi Ernie,
What I meant by my remark was that 24-hour cycle must surely be present in the raw data and it should have been accounted for.
In no way I implied that the presence of Moon and Sun may influence the value of G in an way, except to make the accurate measurements more difficult...

[Ernest Wilson]

Thank you Bojan. A vexing question apparently even for physicists with rather robust arguments being expressed at times. I will just have to consider two conflicting assumptions, a constant G and a variable G, in my work. A constant G means that the Earth maintains its mass throughout time and is why subduction had to be invoked to counteract the expansion that is evident in formation of the oceans. A variable G means that Expansion and Contraction could have alternated throughout time, and might help geologists who believe that both expansion and contraction have taken place on Earth. At the moment, reconciling the observations is difficult and we encounter anomalies and paradoxes that seem to defy explanation. Ernie.

[sjastro]

Originally Posted by Ernest Wilson

Thank you Bojan. A vexing question apparently even for physicists with rather robust arguments being expressed at times. I will just have to consider two conflicting assumptions, a constant G and a variable G, in my work. A constant G means that the Earth maintains its mass throughout time and is why subduction had to be invoked to counteract the expansion that is evident in formation of the oceans. A variable G means that Expansion and Contraction could have alternated throughout time, and might help geologists who believe that both expansion and contraction have taken place on Earth. At the moment, reconciling the observations is difficult and we encounter anomalies and paradoxes that seem to defy explanation. Ernie.

Ernest,

Physicists have nothing to worry about given the link you have provided is pure pseudoscience nonsense. A simple examination of the G vs time plots indicates there is no "pseudo sinusoidal" variation of G.

The author refers to the works of Dayton Miller. In the history of the MM experiment no one has been able to reproduce Miller's results, so it is fairly certain there was a major flaw in Miller's experiment.

Why refer to the MM experiment in the first place? It was designed to measure differences in the speed of light as the Earth moved through the (non existent) aether and has nothing to do with G.

That is only the tip of the iceberg. The author makes many errors in his interpretation of Newtonian physics, SR and GR.

If G is assumed to vary, why is this due to a variation in the Earth's mass? You have two other "possible" variables, the mass of the other body (ie Sun or Moon) and distance between the Earth and the body.

The fact is G is a proportionality constant. As has been pointed out, the variations are due to experimental error.


Regards

Steven

[renormalised (Carl)]

Originally Posted by Ernest Wilson

Thank you Bojan. A vexing question apparently even for physicists with rather robust arguments being expressed at times. I will just have to consider two conflicting assumptions, a constant G and a variable G, in my work. A constant G means that the Earth maintains its mass throughout time and is why subduction had to be invoked to counteract the expansion that is evident in formation of the oceans. A variable G means that Expansion and Contraction could have alternated throughout time, and might help geologists who believe that both expansion and contraction have taken place on Earth. At the moment, reconciling the observations is difficult and we encounter anomalies and paradoxes that seem to defy explanation. Ernie.

What makes you think that geologist believe in either??? I am a geologists and none of the theory I was ever taught expressed a tendency of the Earth to expand and/or contract...at least not in the sense I am gathering from what you've said. The formation of the oceans has nothing to do with the Earth expanding. It has everything to do with the fact that the Earth consists of a few dozen plates which move about due to the motions of the upper mantle/asthenosphere. They form when the continents on the plates drift apart and close when they drift together.

It's quite obvious from what you wrote that you actually don't understand the science.

[Ernest Wilson]

Thanks Steven,
Perhaps we should refute pseudoscience, as you call it, rather than ignore it. I hope you find the papers from which the following quotes were taken of interest.
Ernie.
.
"The most amazing thing I was taught as a graduate student of celestial mechanics at Yale in the 1960s was that all gravitational interactions between bodies in all dynamical systems had to be taken as instantaneous." Van Flandern (Speed of Gravity)

"We conclude that the speed of gravity may provide the new insight physics has been awaiting to lead the way to unification of the fundamental forces. As shown in (Van Flandern, 1993, pp.80-85 and Van Flandern, 1996), it may also be connected with the explanation of the dark matter problem in cosmology. Moreover, the modest switch from SR to LR may correct the "wrong turn" physics must have made to get into the dilemma presented by quantum mechanics, that there appears to be no "deep reality" to the world around us. Quantum phenomena that violate the locality criterion may now be welcomed into conventional physics." van Flandern.
The Speed of Gravity - What the Experiments Say Tom Van Flandern tomvf@metaresearch.org Meta Research, Univ. of Maryland Physics, Army Research Lab
6327 Western Ave., NW / Washington, DC 20015-2456
(metaresearch.org)

The Gravitational Constant, the Chandrasekhar Limit, and Neutron Star Masses
S. E. Thorsett Physical review letters, 1996 - APS
Joseph Henry Laboratories and Department of Physics, Princeton University, Princeton, NJ 08544
"The Chandrasekhar mass limit sets the scale for the late evolutionary stages of massive stars,
including the formation of neutron stars in core collapse supernovae. Because its value depends on
the gravitational constant G, the masses of these neutron stars retain a record of past values of
G. Using Bayesian statistical techniques, I show that measurements of the masses of young and
old neutron stars in pulsar binaries limit ˙ G/G = (−0.6 ± 2.0) × 10−12yr−1 (68% confidence) or
˙ G/G = (−0.6 ± 4.2) × 10−12yr− 1(95% confidence)."

[CraigS]

Ahm sorry Ernie .. but I'm afraid for me, Van Flandern just doesn't make my grade for spending too much effort in refuting what he had to say.

I mean I just can't get over his quoted words on the Face of Mars …

"We've shown conclusively that at least some of the artifacts on the surface of Mars were artificially produced, and the evidence indicates they were produced approximately 3.2 million years ago, which is when Planet V exploded. Mars was a moon of Planet V, and we speculate that the Builders created the artificial structures as theme parks and advertisements to catch the attention of space tourists from Planet V (much as we may do on our own Moon some day, when lunar tourism becomes prevalent), or perhaps they are museums of some kind.

Remember that the Face at Cydonia was located on the original equator of Mars. The Builder's civilization ended 3.2 million years ago. The evidence suggests that the explosion was anticipated, so the Builders may have departed their world, and it produced a massive flood, because Planet V was a water world. It is a coincidence that the face on Mars is hominid, like ours, and the earliest fossil record on Earth of hominids is the "Lucy" fossil from 3.2 million years ago. There have been some claims of earlier hominid fossils, but Lucy is the earliest that is definite. So I leave you with the thought that there may be a grain of truth in The War of the Worlds, with the twist that WE are the Martians.

.. "a man's just gotta know his limitations" … and it would seem, Van Flandern didn't know his (or anyone else's).

Its difficult to accept anything he came up with, following the above stand.
As much as I try, its hard to take any of his more serious work, seriously !

Cheers

[renormalised (Carl)]

I was going to say something similar, Craig.

[sjastro]

Originally Posted by Ernest Wilson

Thanks Steven,
Perhaps we should refute pseudoscience, as you call it, rather than ignore it. I hope you find the papers from which the following quotes were taken of interest.
Ernie.
.
"The most amazing thing I was taught as a graduate student of celestial mechanics at Yale in the 1960s was that all gravitational interactions between bodies in all dynamical systems had to be taken as instantaneous." Van Flandern (Speed of Gravity)

"We conclude that the speed of gravity may provide the new insight physics has been awaiting to lead the way to unification of the fundamental forces. As shown in (Van Flandern, 1993, pp.80-85 and Van Flandern, 1996), it may also be connected with the explanation of the dark matter problem in cosmology. Moreover, the modest switch from SR to LR may correct the "wrong turn" physics must have made to get into the dilemma presented by quantum mechanics, that there appears to be no "deep reality" to the world around us. Quantum phenomena that violate the locality criterion may now be welcomed into conventional physics." van Flandern.
The Speed of Gravity - What the Experiments Say Tom Van Flandern tomvf@metaresearch.org Meta Research, Univ. of Maryland Physics, Army Research Lab
6327 Western Ave., NW / Washington, DC 20015-2456
(metaresearch.org)

The Gravitational Constant, the Chandrasekhar Limit, and Neutron Star Masses
S. E. Thorsett Physical review letters, 1996 - APS
Joseph Henry Laboratories and Department of Physics, Princeton University, Princeton, NJ 08544
"The Chandrasekhar mass limit sets the scale for the late evolutionary stages of massive stars,
including the formation of neutron stars in core collapse supernovae. Because its value depends on
the gravitational constant G, the masses of these neutron stars retain a record of past values of
G. Using Bayesian statistical techniques, I show that measurements of the masses of young and
old neutron stars in pulsar binaries limit ˙ G/G = (−0.6 ± 2.0) × 10−12yr−1 (68% confidence) or
˙ G/G = (−0.6 ± 4.2) × 10−12yr− 1(95% confidence)."

Ernie,

Pseudosciences are frequently refuted, through the application of logic, and by experiment and observation.

I find it intriguing that LR is based on a concept of an aether that cannot be observed or measured.
The experiments and observations that point to aether not existing however are quite overwhelming.

(1) Aberration of light.
(2) Fizeau convection coefficient.
(3) Michelson Morley test
(4) Kennedy Thorndike test.
(5) De Sitter spectroscopic binaries.
(6) Trouton_Noble experiment.
(7) Unipolar Induction.
(8) Meson decay at high velocities.

On the subject of the variation of G, I'm a bit confused. Your previous reference through Xavier Borg suggested that G varies in the short term.
Your current reference suggests a much longer time frame.

If G varies over a longer time frame how do we explain the observed type IA supernova light curves for galaxies of different z?

Regards

Steven

[renormalised (Carl)]

Steven, I've just figured out that the ether really does exist...it's the reason why all these "left of field" ideas and pseudoscience actually comes about!!!.

Their interpretations of the data they find are wonky because they've been sniffing too much of the stuff..........the ether

[Ernest Wilson]

Steven,
As I understand it, Borg states that G varies with absolute velocity, and that absolute velocity varies short term on a daily basis, yearly as the Earth orbits the Sun and over 226Ma as the solar system orbits the Great Attractor. I quote Borg now explaining the relationship of the various parameters.

"Since Newton wrongly assumed that Mass is a constant, he had later on 'hidden' Kepler's constant within his Gravitational constant G. Newton's G and Kepler's constant K, are related through:
K = GMS/4 π2.....MS = Solar system mass
So here we can see that planetary motion shows that it's not G or M that are constant, but their product GM, and that G will only be a constant as long as Mass is constant." Borg.

"From Kepler's constant and the standard gravitational parameter, we know that GM is conserved for different planetary velocities:
µ = GM = (G+DG) * (M+DM)
(G+DG) a 1/(M+DM)
DM = Dg mo and DG = D(1/g) G ..... where g= Lorentz factor, mo = rest mass

This relationship shows that any change in mass will be reflected in a change in G and that both Mass and G are functions of velocity " Borg.

As I understand it, if absolute velocity varies, then so will Mass and the Gravitatioal Constant.
Ernie.

[renormalised (Carl)]

Ernest, how can you have an absolute velocity when there are no privileged frames of reference??. In which case, Borg's equations are meaningless. To have a preferential reference frame, it must have uniquely fixed (absolute) coordinates in both time and space. If it did, that would imply that SR is a load of crock and everything else we've based our findings in science upon SR is wrong. To have an absolute frame of reference would mean SR was wrong, completely. Simple observation would tell you that Borg has approached this from a faulty premise, otherwise the speed of light would vary depending on your location and frame of reference, vis a vie the universal fixed frame of reference. Since this isn't the case, Borg must therefore by wrong.

[sjastro]

Originally Posted by Ernest Wilson

Steven,
As I understand it, Borg states that G varies with absolute velocity, and that absolute velocity varies short term on a daily basis, yearly as the Earth orbits the Sun and over 226Ma as the solar system orbits the Great Attractor. I quote Borg now explaining the relationship of the various parameters.

"Since Newton wrongly assumed that Mass is a constant, he had later on 'hidden' Kepler's constant within his Gravitational constant G. Newton's G and Kepler's constant K, are related through:
K = GMS/4 π2.....MS = Solar system mass
So here we can see that planetary motion shows that it's not G or M that are constant, but their product GM, and that G will only be a constant as long as Mass is constant." Borg.

"From Kepler's constant and the standard gravitational parameter, we know that GM is conserved for different planetary velocities:
µ = GM = (G+DG) * (M+DM)
(G+DG) a 1/(M+DM)
DM = Dg mo and DG = D(1/g) G ..... where g= Lorentz factor, mo = rest mass

This relationship shows that any change in mass will be reflected in a change in G and that both Mass and G are functions of velocity " Borg.

As I understand it, if absolute velocity varies, then so will Mass and the Gravitatioal Constant.
Ernie.

Ernie,

Borg doesn't understand what mass is.

Inertial mass = F/a.
Take an elephant, a gerbil, a ball, any object, apply a force (F) to it, measure the acceleration (a) and you find F/a is a constant.
Measure F/a 1 time, 10 times, a quadrillion times and F/a is still a constant within experimental error.

Newton did not wrongly assume that mass was constant.
SR through the equivalence principle showed that gravitational and inertial mass are also equivalent hence gravitational mass is also constant.

Borg is totally confused about relativistic mass.
As Carl has pointed out absolute velocity is a meaningless concept, but let's look at relativistic mass in an inertial frame of reference.

Relativistic mass is a measurement of total energy or more precisely inertial mass + relativistic kinetic energy. Here inertial mass mo=E/c^2.
If an object's relativistic mass increases it's because it's relativistic kinetic energy increases. The inertial mass remains the same.

This is clearly observed in particle accelerators such as the LHC. A proton's inertial mass remains constant as it's relativistic mass increases.

F=GMm/r^2. M and m are inertial masses.

If these masses were to vary, then F will vary accordingly. G being a proportionality constant will remain constant.

Regards

Steven