excerpt: "An important mistake in Newton's lunar computations, not hitherto detected, is the overestimation of the Moon's mass by 100%. The Moon : Earth mass ratio is inferred to be 1 : 40 (Principia Book III Prop. 37, Cor. IV) when in fact it is 1 : 81; and the mean lunar density to be 1-5 times that of Earth (System of the World', 56) whereas it is 0-6 that of Earth's mean density.
In what follows, the means by which Newton arrived at the erroneous estimate is first described by way of a comparison of the solar and lunar tideraising components. Then, the effect of the error upon his estimation of the barycentre of the EarthMoon system is examined, and it will be seen how his error in positioning the barycentre affected his gravity computation. Lastly, it is asked why such a prominent error has not hitherto been detected."
Modern calculations of the Moon's mass come from lunar orbits of space craft. They are accurate.
marengo
Re: the absurd implied density of moons kills gravity
meemoe_uk wrote: Watch the As and the THEs, they make all the difference. My OP was about the rocky moons of Saturn, some of which have an assumed density less than water.
Our own moon is assumed denser, but its surface is much more dense than Earths, which is interesting.
OK, but what great significance to gravity does one obtain from moons less dense than water? I cant see it.
marengo
Re: the absurd implied density of moons kills gravity
meemoe_uk
Yes I have been sidetracked to the Moon instead of moons.
The mass of a moon is calculated from orbits around it, not from reference to planets which that moon is orbiting.
CharlesChandler
Re: the absurd implied density of moons kills gravity
marengo wrote:
CharlesChandler wrote: Ummm, you said, "There is no such thing as inertia." Are you familiar with the First Law of Motion?
Yes. There is no point to the First Law. The second Law states F = ma. Thus if F = 0 then there is no acceleration. That is not inertia. It is merely a consequence of no force. I repeat; the word inertia is pointless.
What??? If you push on a heavy object, it pushes back. If you push it hard enough, it will move. Once moving, if you push in the other direction, it will push back. If you push hard enough, it will stop. When you apply force, the force that pushes back is inertia. I don't know what you're ever going to do without that concept. You can rename it if you want. But it will still be the same thing.
marengo wrote: You are forgetting Gravitational Redshift. You are also forgetting that my theory predicts these effects.
No, you have it backwards. The Scientific Method is as follows:
observe
hypothesize
experiment
conclude
You don't come up with a theory that predicts such effects, and use the theory to prove that the observations just have to be real. Good science is predicated on theory-independent observation.
marengo wrote: It is not good enough to doubt observations without providing a theory which predicts what you alternatively suggest is happening. You have not done that.
Yes I did. I said that the deflection of light near a massive object can be attributed to the mirage effect, which can be easily demonstrated here on Earth, so we know that it's real.
marengo wrote: You seem to have forgotten that you were once predicting the density of the Moon to be less than 1 when it is given by Wiki at 3.35.
I wasn't predicting anything — I was just suggesting that the discussion get back to the OP.
marengo
Re: the absurd implied density of moons kills gravity
CharlesChandler wrote: What??? If you push on a heavy object, it pushes back. If you push it hard enough, it will move. Once moving, if you push in the other direction, it will push back. If you push hard enough, it will stop. When you apply force, the force that pushes back is inertia. I don't know what you're ever going to do without that concept. You can rename it if you want. But it will still be the same thing.
Yes,the Third Law states that for every action there is an equal and opposite action. But I dont consider that to be inertia. The problem with the First Law is that it is merely a special case of the Second Law when force equals zero. The other problem with the First Law is that it refers velocity to an inertial reference frame and where do you find one of them?
CharlesChandler wrote: No, you have it backwards. The Scientific Method is as follows:
observe hypothesize experiment conclude You don't come up with a theory that predicts such effects, and use the theory to prove that the observations just have to be real. Good science is predicated on theory-independent observation.
Sorry, you are wrong here. Take Einstein's Special Relativity. He thought up his theory which predicted Relativity effects before any such effects had been observed. Furthermore, if a theory based upon unrelated postulates predicts a certain observation about which there is some doubt as to its accuracy then that is evidence to substantiate that observation. You may take Eddingtons eclipse observations as an example of that effect as General Relativity predicted such a result.
CharlesChandler wrote: Yes I did. I said that the deflection of light near a massive object can be attributed to the mirage effect, which can be easily demonstrated here on Earth, so we know that it's real.
I accept the mirage effect occurs but does it explain Eddingtons observations of light bending near the Sun. I think that you will find it does not.
CharlesChandler wrote: I wasn't predicting anything — I was just suggesting that the discussion get back to the OP.
I have replied to meemoe_uk on that point.
You haven't replied to my point about Gravitational Redshift as evidence that the gravitational potential is the speed of light. Have you read my paper on Gravity yet?
Aardwolf
Re: the absurd implied density of moons kills gravity
marengo wrote:
Aardwolf wrote: Then please explain why they have the SAME surface gravity?
If, as you state, only the distance from the centre matters, then why do two significantly different planets in radius, have the same surface gravity?
I have explained it. It is not my fault that you cannot understand the explanation. But here is another go, m/r^2 = M/R^2 for the two planets
Unfortunately you're too tied up with formulas to understand the reality of what you are saying. Previously you stated this;
marengo wrote: The planet with greatest mass also has a larger radius.
However, if you were to look up from you calculator you would realise that;
1) Uranus has a larger radius than Neptune yet Neptune has the greater mass and higher surface gravity; 2) Titan has a larger radius than Mercury yet Mercury has the greater mass and higher surface gravity; 3) Rhea has a larger radius than Oberon yet Oberon has the greater mass and higher surface gravity.
I hope that statement wasn't one of your unquestionable postulates.
CharlesChandler
Re: the absurd implied density of moons kills gravity
marengo wrote: The other problem with the First Law is that it refers velocity to an inertial reference frame and where do you find one of them?
Ummm... let me guess... at the mass' centroid?
marengo wrote: Sorry, you are wrong here. Take Einstein's Special Relativity. He thought up his theory which predicted Relativity effects before any such effects had been observed.
Right. And that should be the first indication that it is BS. The fact that the effects still haven't been observed is the second. Relativity is just a way of taking something simple and making it sound really, really complicated. If you want to understand Einstein, study Zeno of Elea first, and all will be revealed.
marengo wrote: I accept the mirage effect occurs but does it explain Eddingtons observations of light bending near the Sun. I think that you will find it does not.
Ummm... Eddington acknowledged the mirage effect, and that it had to be factored out, and that whatever was left was the gravitational lensing. And he acknowledged that the mirage effect was far more powerful. He even said that the mirage effect can be used as a convenient way of visualizing how gravitational lensing works. This cleverly builds the problem into the solution, making it look like it isn't a problem anymore. But the bottom line is that yes, the mirage effect bends light passing by gravitational sources (but not because of the gravity — it's because of the density gradient in the atmosphere due to gravity). But because he was in such a hurry to get on Einstein's bandwagon, he claimed to have found a few arc-seconds of discrepancy in light that had been bent several arc-minutes, and announced that he was the first to prove Relativity!!! In reality, we still don't have the instrumentation necessary to predict to arc-second accuracy the effects of light passing through atmospheres near large gravitational sources. If you actually want to pursue this, I'd suggest reviewing Dowdye's work. Here's a link to get you started:
Re: the absurd implied density of moons kills gravity
marengo wrote: I accept the mirage effect occurs but does it explain Eddingtons observations of light bending near the Sun. I think that you will find it does not.
Eddington's observations are totally inadequate as an explanation of any effect. His measurements go beyond the limits of his instrumentation and are pretty much useless for any scientific conclusions, least of all proving a deflection of light due to a gravitational field.
That announcement was one of the most influential events of 20th-century science, since Einstein's instant rise to enormous fame arose directly from it. In spite of the confidence with which the announcement was made, however, it was later realized that the accuracy of the observations was insufficient to constitute a reliable confirmation of the phenomenon that was predicted.
from the article:
The problems of interpreting the results of the eclipse expeditions have been well summarized by Guggenheimer (1925), who made the following comment on the 1919 eclipse observations: Any reader, though far from an expert astronomer or physicist, who will study the description of the apparatus used in these observations and the large margin of error possible by reason of defects therein, will readily comprehend that, in view of the required delicacy of measurement of the things observed and of the error allowances both for apparatus defects and other possible physical causes of the observed phenomena, the greatest caution in the analysis of the results is necessary. Some astronomers deny that the photographs of the eclipse observations, when compared with those taken of the same stars in the absence of the sun, show deflections approximating the amount or the direction predicted by Professor Einstein. An examination of the various tables of the deflections observed shows that many of them are far away from the quantities predicted. The quantity approximating the predicted one is obtained by averaging a selected few of the observations.
The author goes on to discuss some other questionable "verifications" of Einstein and explains the behavior of scientists as human beings operating within an historical and social context.
Re: the absurd implied density of moons kills gravity
marengo wrote:
viscount aero wrote: I believe you said "Newton was right" and he wasn't. He created only an approximation for calculating gravitational effects in local space. Yes it was a big discovery. Nobody denies that. Who has denied that his discovery was big? But he wasn't aware of the bigger picture for gravity. He was stuck in his time. Despite its usefulness to this day, it is time to move beyond Newton's world to new things.
I dont understand you. You say there is a bigger picture of Gravity than Newtons, yet you fail to explain what it is.
Are you serious? Galactic rotation needs mentioning? I think everyone here is aware of that discrepancy (which led to the whole fake dark matter invention).
viscount aero
Re: the absurd implied density of moons kills gravity
excerpt: "An important mistake in Newton's lunar computations, not hitherto detected, is the overestimation of the Moon's mass by 100%. The Moon : Earth mass ratio is inferred to be 1 : 40 (Principia Book III Prop. 37, Cor. IV) when in fact it is 1 : 81; and the mean lunar density to be 1-5 times that of Earth (System of the World', 56) whereas it is 0-6 that of Earth's mean density.
In what follows, the means by which Newton arrived at the erroneous estimate is first described by way of a comparison of the solar and lunar tideraising components. Then, the effect of the error upon his estimation of the barycentre of the EarthMoon system is examined, and it will be seen how his error in positioning the barycentre affected his gravity computation. Lastly, it is asked why such a prominent error has not hitherto been detected."
Modern calculations of the Moon's mass come from lunar orbits of space craft. They are accurate.
I feel that you've missed the point. The point is that Newton wasn't right about a lot of things. The Newtonian lunar mass error was not detected until the year 1985. Isn't that a bit late to be detecting an error that was assumed to be true, as written in his Philosophiæ Naturalis Principia Mathematica ("the Principia"), that was first published in 1687? That is almost 300 years of believing in a falsehood born out of the 17th century.
In addition to the Newton's Lunar Mass Error, I posted another article about the SELENE lunar mission which is a recent program sent around the Moon for conducting science--which includes lunar gravitational and mass calculations. Part and parcel to the findings is that the Moon's density and gravity varies dramatically across its surface, particularly from front to far-facing hemispheres.
meemoe_uk
Re: the absurd implied density of moons kills gravity
>Modern calculations of the Moon's mass come from lunar orbits of space craft. They are accurate.
Naw, you see that's what I wonder. If you accept the gravity derived mass and density of moons then some of the Moons of Saturn are less dense than water. But that is counter to the conventional explanation for planet and moon creation. Rocks came together and became molten, heavy stuff sinks to the core, light stuff floats to top. Yet nearly all moons have distinctly rocky surfaces, their interiors should be rocks, heavier rocks.
Gravity force could simply be electro-static force, which can vary independently from the moon's mass. The surface gravity would be an measure of the ionization of the core, but not the mass of a planet. Electrical activity does seem to be related to how dense conventional science thinks planets and moons are.
Having Oped this thread, I then wondered the opposite view : yeah gravity is only directly proportional to the mass. In which case the Moons of Saturn really are >95% ice. What then? It would seem planets grow from converting the hydrogen and oxygen into rock, via subsurface transmutation. Saturn's rings seem to be a moon factory. There are many moonlets and asteroids in Saturn's rings, and the distinction between them and recognised moons is just a arbitrary line in the sand. Saturn's rings were probably formed when its Van Allen belts reached a certain strength, enough to trap hydrogen long term and create oxygen via fusion and also retain some of it. Then water ice would form in low activity regions of the belts. This may be ongoing today.
Theres tons of stuff we just can't be sure of. We are lucky that there's a steady stream of new satellites discovering new stuff, but obviously they are not designed to answer the questions we want so its slower for us. The prob that dogs me the most is that despite over a hundred pages of thread on this site we still have no way in principle that planets can grow while obeying the 1st law of thermo. Its sort of against our principles but there's so far no way of avoiding it. But then, no-one ever has found a way to properly get round it. Bigbang theory excuses its self by sweeping all the mass-energy creation back into history a few years then pretends thats ok ( pathetic ). Steady state theory just said universe is infinite in time so mass-energy has always been there ( unsatisfactory ). creation is something every general theory has to tackle head on. There has been on this forum an effort to say galactic current energy is transferred to the core of stars and planets and this gives these objects the power to grow, but so far its seems the evidence doesn't support this idea. Creation has to be put somewhere. I say that with our current evidence, the best place seems to be inside stars, planets and moons. It's the big unknown of the universe. EU theory has already well explained the cosmos. But inside planets and stars is an absolute mystery. The evidence hints at it, and we have 1 bit of theory which supports it. The Einstein de sitter equation of 1912 says that there is a unconserved ( infinite ) energy source in the universe - Quantum uncertainty. But so far humans haven't managed to tap this energy source. It's a random jostling that on average takes as much energy as it gives. But the key point is that its unconserved. A theoretical tap on Brownian motion ( thermo-motion of particles ) could only tap the finite total energy of the subject particles, but a theoretical tap on quantum jostling could in theory produce infinite energy. While some say the reason we haven't in the last 100 years found a way of taping quantum uncertainty energy is because its fundamentally impossible, I wonder if its been because of a general stigma against perpetual motion machines. It was a solid result of 17th 18th and 19th physics that perpetual motion via classical physics was impossible. This was perhaps the most deeply engrained 'impossible' that physics ever realised. So when the 1912 uncertainty equation was published, the potential for an unconserved energy source ( perpetual motion machine ) was never properly considered due to the heritage of ideas from physics history.
I guess there could be a trick that planet and star interiors are playing to cox the quantum jostling to give a bit more than it takes, at which point creation becomes viable. Until I read a better alternative to these 2 hardest ( and therefore most immediate ) problems, this is, reluctantly, my best solution to growth of planets + stars + creation.
Sparky
Re: the absurd implied density of moons kills gravity
The universe is like os95/98, which needs to be restarted when the bits clog.
We can see this as pole swaps, mass extinctions, and sudden appearances of humanoids.We have evidence that land masses moved about and took up prime spots on the crust, causing plants and animals to change their wayward ways.
The most wayward is gravity, holding us down when we want to go up, and allowing us to climb too high before reminding us that what we just did was not wise. It likes big, solid objects, which it holds in place solidly. But, does not like big animals, which were extinguished by one of it's petulant deviations. It deals in mass and that messes with the divine order, mixing the large worlds with the small. G is not G for everyone, everywhere, but it will act as a close constant, in a universe that may not have any. ...where was I? hmmmmm, somewhere within a realm of density, implied or real, comforting.
GaryN
Re: the absurd implied density of moons kills gravity
I just received my copy of "Cosmic Machinery in an Electro-Magnetic Universe", by Capt. H.A.Staples, and though not exactly what I was expecting, in light of the announcement of the Van Allen belt double-layers, his ideas may be closer to the truth than he could have suspected. I have only had a quick skim, but he proposes an EM interaction between the Sun, Earth, and Moon for the nature of the tides on Earth. He has done some very thorough studies, and the book contains many tide readings from around the world, as well as going into some complex orbital science that I'm not familiar with, and used rotating electric fields surrounding all three objects to show how the tides can be explained by the interaction of these fields. He certainly seems to know his science, so this is not some amateur publication. I'll post again if I find anything of interest relevant to this thread. I also have to keep in mind Teslas words, that we should treat the Earth, and probably all planets and moons with solid surfaces, as a conducting sphere. Hollow, multi-layered too perhaps, meaning not as massive as now believed. That way I could perhaps allow for mechanisms such as gravitational capture, which using the Newtonian model are extremely unlikely, but if gravity was to be an EM force, not so unlikely.
marengo
Re: the absurd implied density of moons kills gravity
Aardwolf wrote: However, if you were to look up from you calculator you would realise that;
1) Uranus has a larger radius than Neptune yet Neptune has the greater mass and higher surface gravity; 2) Titan has a larger radius than Mercury yet Mercury has the greater mass and higher surface gravity; 3) Rhea has a larger radius than Oberon yet Oberon has the greater mass and higher surface gravity.
I hope that statement wasn't one of your unquestionable postulates.
If you are arguing with Newtons law of acc = GM/r^2 then you will need to propose an alternative law of gravity.
So far in my comments I have taken the density as a constant. Of course if the density is much less than another planet with the same mass then its radius will be bigger and the surface gravity will then be less.
meemoe_uk
Re: the absurd implied density of moons kills gravity
>If you are arguing with Newtons law of acc = GM/r^2 then you will need to propose an alternative law of gravity.
I proposed the electrostatic force in the OP.
F= kq1q2/r2
There's obviously not straight forward as altering a bodies charge doesn't seem to affect its gravity accel. - the positive ion cores of moons and planets are highly ionized, therefore pretty much al matter is less positive, and will still be attracted - there are several double layers down thru the interior radius, this allows attraction of any matter, regardless of charge, because there will always be an opposite charge in the double layers to attract the charge of the subject body.
It's a trick of double layers I'm proposing that mimics a like attracts like mechanism.