View Full Version here: : Gravitational Constant
29-05-2011, 06:04 PM
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%?
29-05-2011, 06:15 PM
Wiki says …
That makes it uncertain to only 0.01%, doesn't it ?
31-05-2011, 06:36 PM
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?
03-06-2011, 08:37 AM
Well, Earth is rotating.. we have some nearby objects like Moon and Sun.. this is the reason for ~24 hour cycle.
03-06-2011, 09:43 AM
I think you need to post some references when citing things like:
.. 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.
03-06-2011, 08:03 PM
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 (http://www.uni-stuttgart.de/gi/research/schriftenreihe/quo_vadis/pdf/varga.pdf) - Quo vadis geodesia, 2002 - uni-stuttgart.de
04-06-2011, 11:49 AM
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 …
Seems like a reasonably well argued perspective.
I wasn't too enthralled with this bit though ..
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. :confused2:
(Happy to be corrected on this, however).
07-06-2011, 11:43 AM
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 (http://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
R.J.Anderton@btinternet.com 24th January 2011 The General Science Journal
08-06-2011, 08:17 AM
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...
08-06-2011, 10:13 PM
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.
09-06-2011, 12:14 AM
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.
09-06-2011, 10:05 AM
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.
11-06-2011, 12:12 PM
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.
"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 firstname.lastname@example.org (email@example.com) Meta Research, Univ. of Maryland Physics, Army Research Lab
6327 Western Ave., NW / Washington, DC 20015-2456
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)."
11-06-2011, 12:23 PM
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 (http://en.wikipedia.org/wiki/Tom_Van_Flandern#Face_on_Mars) …
.. "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 !
11-06-2011, 02:17 PM
I was going to say something similar, Craig.
11-06-2011, 07:03 PM
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?
11-06-2011, 07:27 PM
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:lol::P:rofl:
13-06-2011, 03:21 PM
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.
13-06-2011, 03:34 PM
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.
13-06-2011, 06:01 PM
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.
13-06-2011, 06:02 PM
Oh, and another thing....the Solar System doesn't orbit the Great Attractor. The Great Attractor is a massive group of galaxy superclusters in the direction of Centaurus-Hydra and about 500Mly away. The Milky Way and the rest of the galaxies in the general neighbourhood, including the Virgo Supercluster (of which we're an outlier galaxy) is streaming towards that general direction, but hardly orbiting it.
The Solar System orbits the centre of the Galaxy once every 250 million years (that's the new figure...the one you quoted (226Ma...actually 225Ma) is out of date despite still being oft quoted and in textbooks).
13-06-2011, 06:16 PM
I got the towel ready first mention of plasma and it's going in.
13-06-2011, 06:18 PM
Cosmic plasma .. cosmic plasma .. cosmic plasma !!
13-06-2011, 06:21 PM
towel towel towel:):P
13-06-2011, 07:34 PM
I think that in order to refute things as strongly supported in Astrophysics as the constancy of G, or the mass of the Earth, or the fundamentals of Special Relativity, one has to demonstrate a strong understanding of the principles upon which each of these concepts is built. A simple read on the history/thinking Einstein went through leading to his theory of SR, usually lays out the rationale underpinning SR theory (for example). Subsequent empirical testing has removed any doubts in mainstream Science.
So far, all of the reference sources you have quoted, have been clearly refuted in some shape or another and yet, I haven't yet seen any acknowledgements or attempts at interactive conversation on this from you at all.
It seems to me that you are selecting information from pseudoscientific sources, without any consideration of reputable sources or value-laden feedback on the same subject. Making no visible attempts to comprehend the bases upon which the cornerstones of modern physics rest, makes your quest look completely biased, unyielding and uninformed.
The name of the game in refutation is to demonstrate some mastery of the topic you are attempting to refute. Quoting any paper from any source on the web, which supports one's own viewpoint, means nothing thesedays, as there is so much mis-information out there, one has to develop knowledge to separate the rubbish from value.
I'm sure everyone here will help you along this path, if you choose to take it. Some attempts at conversation/feedback and sharing your views along these lines, wouldn't go astray here.
15-06-2011, 02:15 PM
You are right; I have been selective because I do not see agreement amongst the physicists. Perhaps I should have used relative velocity with the Earth's velocity relative to the Sun as 30 kps and relative to Sagitarrius A( as Renormalised Reminded me) as 250 +/-30. I don't have the expertise to take this any further, but there is a very good discussion on the subject on the net, reference below. I assure you I have learned quite a bit from our discussions.
www.sciforums.com/showthread.php?t=47515Cached (http://webcache.googleusercontent.com/search?q=cache:Gj9SlimvkZkJ:www.sci forums.com/showthread.php%3Ft%3D47515+absolute +velocity&cd=4&hl=en&ct=clnk&gl=au&source=www.google.com.au) - Similar (http://www.google.com.au/search?hl=en&biw=853&bih=586&q=related:www.sciforums.com/showthread.php%3Ft%3D47515+absolute +velocity&tbo=1&sa=X&ei=xif4TcW6NczWiALGucT9DA&ved=0CEcQHzAD)
20 posts - 7 authors - Last post: 25 Jul 2005
Absolute Velocity - Meaningful but Useless Physics & Math.
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