Unknown subtleties of gravity—depends on where it's measured on Earth

Discussion in 'Physics & Math' started by common_sense_seeker, Sep 21, 2013.

  1. common_sense_seeker Bicho Voador & Bicho Sugador Valued Senior Member

    Messages:
    2,623
    This is a possible conclusion of a recent 10 year experiment to find the precise value of the Gravitational Constant, Big "G".

    Puzzling Measurement of "Big G" Gravitational Constant Ignites Debate


    Please Register or Log in to view the hidden image!

     
  2. Google AdSense Guest Advertisement



    to hide all adverts.
  3. Aqueous Id flat Earth skeptic Valued Senior Member

    Messages:
    6,152

    Even if we settle on 450 ppm it's only 0.045%. I can't think of any application that hinges on knowing the value of G to that many digits of precision.

    One highly accurate tool at NIST is their most recent clock technology, which can detect small variations in gravity as a function of its height from a table. That's not the same thing as measuring G, but it's related.
     
  4. Google AdSense Guest Advertisement



    to hide all adverts.
  5. common_sense_seeker Bicho Voador & Bicho Sugador Valued Senior Member

    Messages:
    2,623
    Apparently it is a big deal. The fact that a Constant is actually not a constant puts a big spanner in the mainstream theory of gravity.

    The NIST aluminium-ion clock experiment was an interesting read although the opening statement is technically incorrect imv; it's atomic motion which increases in a lower gravitational field or a lower flux of gravitons. Pendulum clocks run slower at higher elevations. So the use of the word "time" is erroneous.

    Perhaps they should take their table-kit to various places on Earth and see if there's a detectable difference. I'm predicting a greater value for G in Equatorial regions compared to Polar regions.
     
  6. Google AdSense Guest Advertisement



    to hide all adverts.
  7. OnlyMe Valued Senior Member

    Messages:
    3,914
    The article did not give information detailing any time period over which the experiment was repeated. Since it is mentioned that variations may be due to how and where the measurements are made, it would be interesting to know whether differences would be detected if the experiment was repeated in a manner similar to that of the M&M experiments... Or the same experiment repeated in different physical locations, or laboratories.

    The article describes what would seem to be two methods which agree, conducted in one location. Would they agree if conducted in a different location and/or would a different experiment which does not agree with the current results, produce agreement if conducted in the same lab?
     
  8. common_sense_seeker Bicho Voador & Bicho Sugador Valued Senior Member

    Messages:
    2,623
    Yes, it would make sense if they travelled around the globe to test the hypothesis. The single experiment with two measuring devices makes it more likely that it isn't an error in the apparatus or human error, but a genuine fundamental problem in how we think the world works. It isn't as precise and constant as the maths based models it was built on. A complete overhaul of physics is needed. It's quite plain to see for thousands of professional and amateur scientists alike.
     
  9. brucep Valued Senior Member

    Messages:
    4,098
    You shouldn't be posting your brand of nonsense in the science threads. What's plain to see is you're scientifically illiterate. You don't even know anything about what you think needs an overhaul. Read about the Dunning-Kruger effect and see if you can make a move to release the hold this effect [the lack of metacognitive skills] has on you.
    Here's the last paragraph of the Scientific American article you linked

    "If the true value of big G turns out to be closer to the Quinn team’s measurement than the CODATA value, then calculations that depend on G will have to be revised. For example, the estimated masses of the solar system’s planets, including Earth, would change slightly. Such a revision, however, wouldn’t alter any fundamental laws of physics, and would have very little practical effect on anyone’s life, Quinn says. But getting to the bottom of the issue is more a matter of principle to the scientists. “It’s not a thing one likes to leave unresolved,” he adds. “We should be able to measure gravity.”

    The measurement is technically difficult. It's always been so. You don't need to rewrite physics because the measurement of this constant has a larger than acceptable [for some scientists] error bar. You wouldn't be making such a calamitous prediction if you understood this. Do some research before you stick your foot in your mouth.
     
  10. wegs Matter & Pixie Dust Valued Senior Member

    Messages:
    6,731
    bolded for emphasis, by me...

    a little dramatic to suggest that...

    Please Register or Log in to view the hidden image!



    The article states:

    If the true value of big G turns out to be closer to the Quinn team’s measurement than the CODATA value, then calculations that depend on G will have to be revised. For example, the estimated masses of the solar system’s planets, including Earth, would change slightly. Such a revision, however, wouldn’t alter any fundamental laws of physics, and would have very little practical effect on anyone’s life, Quinn says.

    Interesting article, nonetheless--thanks for sharing.
     
  11. nbernardini Registered Member

    Messages:
    8
    i would be willing to bet that a satellite at the edge of the solar system but still orbiting the sun could use the center of the Milky Way (black hole) as the most accurate clock.

    Sensing the change in the force of gravity from the black hole on the satellite as this satellite orbits the sun should produce the smallest quantum of time.

    All you would need to do is make sure the suns gravity is first subtracted and then assume that as the satellite is at its closest to the center of the Milky Way, the gravitational pull would be greater. Of course a quantum computer would need to exist on this satellite to sense and calculate this and be entangled with a quantum computer on Earth where similar measurement would be made simultaneously...

    the difference in measurements should turn out to be the smallest unit in time, which would be so small that if you could see this clock ticking, the majority of the decimals on the smaller side of a second would be a blur and only a quantum computer would be able to make decisions as fast anyway... so whoever had a quantum network would basically be a pretty cool fella.
     
  12. common_sense_seeker Bicho Voador & Bicho Sugador Valued Senior Member

    Messages:
    2,623
    Thanks wegs. A little dramatic if based on this one article alone, agreed. I'm also basing the statement on the problems with the LHC and the Higgs particle Is Nature Unnatural?

     
  13. Aqueous Id flat Earth skeptic Valued Senior Member

    Messages:
    6,152
    G is constant; it's just difficult to measure it to more than about 4 decimal places. There's no spanner, nothing in controversy between academics and non-academics concerning the Newton's laws or Einstein's relativity--certainly nothing you've developed here.

    You're referring to this statement, which is true and correct:

    BOULDER, Colo. – Scientists have known for decades that time passes faster at higher elevations—a curious aspect of Einstein's theories of relativity that previously has been measured by comparing clocks on the Earth's surface and a high-flying rocket.

    It's not motion of the atoms which the atomic fountain is measuring, certainly not as you imagine it. So your assumption is incorrect.

    That's a statement about Newtonian mechanics, whereas the NIST cite is discussing the slight increase in speed of the clock at higher elevations, since it's sensitive enough to detect the relativistic effects. They are two completely different things.

    So far the only errors are your misunderstanding of how the atomic fountain works, what emission spectra are, and the difference between mechanical and relativistic effects on a device or system.

    You're confusing Big G with little g. You can consult a gravity map of the Earth - it's already been done. The Earth is an oblate spheroid which is what you're referring to, but the density is not homogenous, so the distribution is quite erratic.

    It's a conclusion, not a hypothesis, arrived at by the search for the explanation to Kepler's laws. There is no need to go anywhere, since the constancy of G is reflected in the constancy of planetary orbits, constancy of the length of an Earth year and the constancy of seasonal variations on Earth.

    So far all of the thinking errors are yours. To improve on that, you would want to enroll in some science classes in order to begin to learn how to distinguish natural law from intuition and opinion.

    It may appear that way to you since you don't know the history of the discovery of mathematical relationships in nature, and because you are unfamiliar with the actual writings of folks like Euclid, Newtown or Poincare. You would therefore be surprised to discover that you have it backwards. All math began with observing nature. It's analysis, not synthesis. Geometry followed observations about the measuring angles, length, area and volume. Calculus was invented in the course of pursuing Kepler's quest to understand planetary motion. Maxwell's equations are the concise statements of observations of electromagnetic interactions, and so on. Again, G isn't based on any model. It's entirely a consequence of studying planetary motion.

    So far you've only advocated for overhauling nature. It won't happen--you're as much a slave to it as Euclid, Newton or anyone else.

    I think the current number is around ten million professionally trained people. So far the only thing you've demonstrated is the vast difference between their productivity and the counter-productive nature of abject cynicism. The real question that you haven't addressed here is what is driving you in that direction. Is it religion? Did you have a bad experience during your early education? I am curious what actually motivates you since a normal person would assume that the experts are correct until proven otherwise.
     
  14. common_sense_seeker Bicho Voador & Bicho Sugador Valued Senior Member

    Messages:
    2,623
    No, it's not religion or a "bad experience" just common sense. I thought it since I was around 13. The professors of MOND also think on the same lines as I do, so don't try and make out someone has to be a "crank" to believe in significant changes in the mainstream theory of gravity being necessary.
     
  15. AlphaNumeric Fully ionized Registered Senior Member

    Messages:
    6,702
    Depends on the precise nature of the variation and how that feeds through to the kinematics of systems. As pointed out in one of the links, we know that the overall effect of gravity has not changed for centuries, because the motion of the planets is so precisely measured and modelled the 0.045% variation would be obvious to us by now.

    Furthermore G is a dimensionful quantity, it is not dimensionless. Variations in dimensionful quantities do not necessarily imply something is actually going on. For example, varying the speed of light in terms of metres per second (or whatever units you prefer) is not a physically meaningful thing since c has units. Instead it is the dimensionless ratios c plays a part in which must vary for something to actually be going on. c turns up in the fine structure constant of QED and the proportionality constant in the Einstein field equations. Varying c but leaving those expressions unchanged (by countering the change by varying other dimensionful terms in the expressions) would result in identical physics. It is the dimensionless parameters which define the physics, not the value of the individual terms which make them up. Exactly the same principles are used in fluid mechanics with the Reynolds number, two flows are the same up to arbitrary definitions if they have the same Reynolds number because it is unchanged under said redefinitions.

    And even allowing for a varying G that doesn't necessarily mean a huge spanner. If G varies on a tiny scale then we can simply view general relativity as an effective theory of something more fundamental, which is what we already do because we know GR doesn't capture the quantum properties of gravity. In string theory and many other models with extra dimensions the variation of G is expected, since ALL of the coupling parameters we see in current physics (fine structure constant, CP breaking term, G, etc) are actually the value of scalar fields describing the extra dimensions. If the extra dimensions deform in particular ways then the values of the couplings change. This concept is also in the Higgs mechanism, the masses of particles arises from the vacuum value of the Higgs field, changing the field would change masses. In string theory the strength of gravity we observe is linked to a 'fundamental' gravity strength via a scaling induced by extra dimensions. Variations in G could be used as a test for many models of extra dimensions in fact.

    You're hardly familiar with the experiment or related models so what precisely are you basing this conclusion on? Divine inspiration?

    Would you care to provide the model from which you're extracting such conclusions or is it just a wordy guess based on nothing but "Because I say so!"?

    Firstly it is funny how quickly people such as yourself, ie those with a particular agenda against the mainstream, so quickly jump on anything to justify your position. Another example is how quickly certain people (ie Sylwester) jumped on the "Neutrinos going faster than light?" story a year or two ago. Rather than maintain a steady mentality and wait for all the checks and data to be completed it was "Aha! Told you!". Turned out the data was wrong due a fault in the equipment. Suddenly all the "See, us armchair physicists knew it!" turned into "Oh, never mind....", particularly as the proper data precisely aligned with prediction. Suddenly an experiment which was telling us how neutrinos really behave isn't important any more. Sylwester claimed his work precisely predicted the 1.005c speed and yet when it turned out the data was in error it didn't invalidate his work. He is not alone in this kind of hypocritical behaviour.

    Now such people come out of the woodwork again, with similar impatience for proper evaluation of the work. You have no knowledge of the specifics of the experiments, the method of error analysis, combining different datasets or the models involved but somehow you have insight into all of this? Yes, at some point overhauls will be needed and I'm sure on that day you'll be saying "Told you, told you!!" but the problem is you are always saying "This experiment, definitely this one, invalidates the mainstream views!", it is not like you've done a careful analysis of the work yourself and have a competing working model which you're also evaluating with the data, that would be the honest way, following the evidence. Instead you have a point of view, namely the mainstream is wrong, and you go looking for anything to try to justify that. Yes, scientists go looking for experiments which are the most likely to test a model to breaking point but they have models to test which they have developed properly.

    Your bias is obvious from how you phrase the implications. " It isn't as precise and constant as the maths based models it was built on. A complete overhaul of physics is needed.". You have no knowledge of the mathematical models and what they are or are not capable of and whether a small modification or a complete redo is needed. Extensions to general relativity to allow for a varying scalar field linked to the strength of gravity, as measured by 3+1 dimensional general relativity, date back to the 1920s, less than a decade after GRs original publication. The Kaluza-Klein model works in 4+1 dimensional space-time and upon converting the new spatial direction to being circular it provides 3+1 dimensional general relativity, 3+1 dimensional electromagnetism and an extra scalar field which relates to the size of the extra dimension and which rescales the g of the 4+1 dimensional theory into a G of the 3+1 dimensional theory. g can be constant but G can vary in time and space if the scalar field varies in time and space. KK models were not explored much further (until string theory MASSIVELY generalised them) because there was no evidence of this scalar field but now we could be seeing that, if the experiments are really saying G varies. All of that is just standard GR, you just pick a different space-time configuration to work with. In fact doing the KK compactification and computing the result fields people living in the 3+1 dimensional region would see is a nice homework problem for anyone competent in GR. String theory has generalised this concept to go far beyond just a single circular direction, allowing all sorts of additional phenomena to be handled by the framework. But you don't know that and since you have a presumed conclusion you don't bother to go out and find out whether what you say is justified or not.

    You have shown time and time again you have no idea what common sense is. Furthermore you think you have some kind of insight into physics, yet you have no personal experience with actual data, no mathematical understanding of mainstream work, you have no models you've developed yourself, you have nothing on which to base your supposed insight. Besides, common sense is not a good guide in physics, particularly quantum or relativity stuff, since they are often highly counter intuitive.

    Sure, someone saying "I think the mainstream might be wrong" is not automatically a crank but when they have no knowledge of the data, no understanding of the mainstream models and believes common sense is a good guide, while simultaneously showing they have no common sense, then they (you) are a crank.

    Yes, one day quantum theory will be replaced. One day general relativity will be replaced. But that will happen because of diligent evaluation of their actual capabilities in the light of new data, not because everyone just presumes they cannot work and throws them into the bin. You want to bring new experiments to light for discussion here, fine. If they potentially push a model to breaking point, even better. But this wilful ignorance you show, presuming things about domains of physics you have absolutely zero knowledge of is not fine. You know you don't know any relativity or quantum mechanics yet you speak as if you know about the "maths based models", enough to know what they can or cannot do. If you want to lie to and delude yourself then go do it somewhere else.
     
  16. common_sense_seeker Bicho Voador & Bicho Sugador Valued Senior Member

    Messages:
    2,623
    This is an incorrect statement. How can this be true when we've only just found out that the moon is currently moving away from the Earth and not towards it as intuitively expected. Look how close the moon is compared to the planets. It's ludicrous to say that we know the planets haven't changed their orbits in hundreds of years. We simply can't be that certain.
     
  17. exchemist Valued Senior Member

    Messages:
    9,628
    The trouble is, you are acting like a crank.

    As Alphanumeric and others point out, a couple of measurements varying from the previous consensus value by 0.045%, in a constant that is notoriously hard to measure, does not remotely begin to justify your wild assertion that "a complete overhaul of physics is needed".

    And your remark that you have thought so since you were 13 simply adds to the impression of some nut with a bee in his bonnet, who will seize on anything.

    Let's see where this goes, if anywhere. There are far too many cases of errors in experimental technique for anyone to draw radical conclusions from such a small data sample.
     
  18. common_sense_seeker Bicho Voador & Bicho Sugador Valued Senior Member

    Messages:
    2,623
    Please read my post#9
     
  19. Aqueous Id flat Earth skeptic Valued Senior Member

    Messages:
    6,152
    That's impossible. Common sense does not attack knowledge, certainly not in the particular way you're doing it here. Common sense embraces knowledge and understanding, speaks candidly, and checks the level of the water before diving in headfirst. Your answer just leaves me more convinced that one of my assumptions is probably true--that you are attacking science from a religious motive, or that you were damaged in some way and feel the need to strike out against something that you think for some reason threatens you -- science. But why? :shrug:

    You thought the value for G was inaccurate when you were 13 ?? That's ludicrous. Maybe you're just admitting to abject cynicism of science since age 13. That indeed would reflect some kind of damage. If that's actually what you are saying, you might want to develop it for us a little more. What would cause such ideation in this very early stage of the maturing persona?

    You made a statement to that effect elsewhere, and produced some correspondence, but it doesn't support this conclusion you are making. It doesn't show that any professor thinks like you do. The item I saw has you mention your interest in what causes disk shaped galaxies, but the answer the prof gave you is not supporting anything your said as far as the physical causes are concerned. And those causes were never given in detail by the prof. You responded with what you think the causes are, and we have to assume that the prof cut off the conversation at that point, since your explanation was ludicrous.

    However, feel free to develop this idea--what is it that makes you think your idea was supported at all by anyone with any formal training in science? It speaks to your motives for this conversation, motives which remain hidden.


    No one is arguing against innocuous changes to any theory. (BTW we're mostly addressing law, not theory). Your claim is that the Universal Gravitational Constant is not actually constant, which is false--certainly within the confines of this discussion. It's not even supported by the article you cited, leaving readers to conclude you misunderstood what you read. So far the contributors here have just outlined a number of your mistakes and misunderstandings leading to the construction of these invalid grounds for claiming that science is fundamentally broken. Your belief in a mainstream that limits, manipulates, or otherwise detracts from free inquiry into truths about nature demonstrates your larger agenda. But it's all in your mind. Now the only question that remains is: what's motivating that?
     
  20. Aqueous Id flat Earth skeptic Valued Senior Member

    Messages:
    6,152
    That has nothing to do with the constancy of G. Go find out what happens to the Moon from dragging the oceans around (tides) and get back with us on your finding.
     

Share This Page