The Gravitational Constant, G

Discussion in 'Astronomy, Exobiology, & Cosmology' started by nero, Dec 3, 2004.

  1. nero Banned Banned

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    Hiya'll

    Do any of you learnered and web crawling sciency folk know of any derivation of a theoretical value for Newton's gravitational constant G ?

    Thank you just so much
     
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  3. blobrana Registered Senior Member

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    2,214
    Hi,
    The calculations are here

    http://www.nikhef.nl/~t32/newton.dir/newton.html

    G = 6.673(10) x 10<sup>-11</sup> m<sup>3</sup> /kg s<sup>2</sup>

    < whoops >
    but have a look here
    http://www.btinternet.com/~ugah174/gil31.html
    (G as Quantum Coupling Constant)

    NG ≈ 3.1095 × 10<sup>41</sup>.


    Though it must be mentioned that the two most accurate measurements of Newton's constant (G) contradict each other.
    <b>
    Sevres, France 6.67559(±0.00027)
    Wuhan, China 6.6699 (± 0.0007)
    </b>

    Newton's constant, which describes the strength of the gravity, is the most poorly determined constants of nature. The two most accurate measurements have experimental errors of 1 part in 10,000, yet their values differ by 10 times that amount.

    So physicists are left with no idea of its absolute value.

    http://www.newscientist.com/news/news.jsp?id=ns99992814
     
    Last edited: Dec 3, 2004
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  5. nero Banned Banned

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    Thank you blobrana, heart felt!!!


    so no theoretical value has been determined

    G is an empirical value at present ?
     
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  7. Facial Valued Senior Member

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    2,225
    So the average of those two values is where we get the 6.673 from... yikes.
     
  8. James R Just this guy, you know? Staff Member

    Messages:
    39,397
    G is entirely an empirical value at present. Just like h and the electron charge, and all the particle masses, etc. etc.

    There's a lot still left to do in physics.

    (Note: these days, c, the speed of light, is defined, not measured.)
     
  9. nero Banned Banned

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    Ok, it is an empirical value, but "what" is Gnewton supposed to represent.

    And just as an exercise explain why there is one G and not two (2 masses) in

    F = G M1 M2 / r^2


    just as an exercise
     
  10. blobrana Registered Senior Member

    Messages:
    2,214
    Hum,
    <b>G</b> is the curvature of space-time.

    It’s supposed that the Higgs boson gives particles their mass.

    The reason why G is the number it is, is probably because the universe is here today.
    Too big, a value and the universe wouldn’t expand and would collapse immediately after the Supersymmetry breaking process that split off the gravitational force from the other three.
    Too little and the matter created may not have formed stars etc. (??)

    However, I imagine that the amount of mass is <b>exactly</b> balanced by the expansion of space. So that the curvature of space-time has to be G…

    Just as i suppose that Pi <b>has</b> to be that amount; it cannot be anything else (in our type of universe)
     
  11. nero Banned Banned

    Messages:
    26
    Hiya blobrana

    >> G is the curvature of space-time. >>>

    if this is so, then a theoretical value for G should be easy.

    >> However, I imagine that the amount of mass is exactly balanced by the expansion of space. So that the curvature of space-time has to be G? >>>

    funny how the empirical value is so suspect.

    >> It's supposed that the Higgs boson gives particles their mass. >>

    What is the 'Higgs boson' ?
     
  12. James R Just this guy, you know? Staff Member

    Messages:
    39,397
    Actually, G is just a constant of proportionality whose value depends on our choice of basic units. G has the value of 6.67 x 10<sup>-11</sup> in SI units, where the masses are measured in kilograms, distance is in metres, and force is in Newton. Choose different units and the value of G changes.

    G has nothing to do with curvature of space. Even in general relativity, it is still a constant of proportionality.
     
  13. nero Banned Banned

    Messages:
    26
    >> it is still a constant of proportionality. >>


    A constant of proportionality between what and what ?

    and why do you say that ?

    If you have no theoretical idea what it is, how can you just make up such comments ?

    LOL
     
  14. James R Just this guy, you know? Staff Member

    Messages:
    39,397
    Between force, the two masses and the distance squared.

    Because that's what it is.

    I told you what my theoretical idea of it is.
     
  15. blobrana Registered Senior Member

    Messages:
    2,214
    @James R
    Hum,
    Yes, tnx for correction.
    In special relativity, the space-time is flat…
    what I mean was that G is <b>related</b> to the curvature of space-time created by mass as proposed by General Relativity .

    Obviously, the curvature is not static but can have different values, and dependant on mass. (G is always constant)

    “<i>In General Relativity, the effect of matter on space (gravity) is taken into account. Gravity is measured as a curvature of spacetime, which is represented in several ways</i>.”
    http://physics.syr.edu/courses/PHY312.03Spring/keish-walter/project.htm

    As for the Higgs boson -well the Higgs field has yet to be discovered but they are trying to find it right now..
    http://www.exploratorium.edu/origins/cern/ideas/higgs.html
     
    Last edited: Dec 12, 2004
  16. nero Banned Banned

    Messages:
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    >> As for the Higgs boson -well the Higgs field has yet to be discovered but they are trying to find it right now..>>>>

    modern religious science

    conjecture upon irrational conjecture

    I laugh,

    LOL

    wonder where G comes into the formulae of SR or even GR ?????

    LOL

    you guys will believe ANYTHING as long as you are told so by the establishment

    again

    LOL
     
  17. nero Banned Banned

    Messages:
    26
    >>( A constant of proportionality between what and what ?)
    Between force, the two masses and the distance squared. >>>

    around and around the garden...............

    circular arguments are not given points

    LOL

    another shuffle under the carpet...


    What is the nature of this force that it needs an adjustment factor ??

    Is it like a permitivity constant in a vacuum ?

    but it is measured in air......

    This is very poor physics.
     
  18. James R Just this guy, you know? Staff Member

    Messages:
    39,397
    nero, aka Zarkov. You were previously banned from sciforums for exactly this kind of trolling. If you insist on proceeding along the same lines again, you will not be warned. You will simply be banned again.

    In telling you this, I am giving you a chance, which I hope you will use wisely.
     
  19. macx Registered Member

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    9
    "Zeldovich first suggested
    that gravitational interactions could lead to a small
    disturbance in the non-zero quantum fluctuations of
    the vacuum and thus give rise to a finite value of
    Einstein’s cosmological constant.[13] Sakharov later
    derived a value for Newton’s gravitational constant
    G using frequency w as the only free parameter.[14]


    G=c^5/h integral w dw



    where c is the speed of light and h is the Plank
    constant. The integral is carried out over all
    frequencies using the Plank frequency on observable
    electromagnetic phenomena ( p w ~ 10-33 cm) as a
    cutoff value."

    _____________________

    There are other derivations of G as opposed to empirical measurements.


    PS How many nicknames do you have Mr Zarkov/Stoic/Nero etc?

    macx
     
  20. blobrana Registered Senior Member

    Messages:
    2,214
    @nero
    Hum,
    i suppose people laughed when they tried to find the W and Z particles that describes the Electromagnetic field, and how particles interact with photons.

    (or at the wright brothers)


    But, is it just because the discovery of a Higgs field would confirm that the symmetry breaking theory is on the right path, that you object to?

    The non-discovery of it would put a spanner in the works of most current theories, and certainly worth the effort, to know either way...

    <edit >
     
  21. nero Banned Banned

    Messages:
    26
    when the going gets tough the illiterate scream

    >> If you insist on proceeding along the same lines again, you will not be warned. You will simply be banned again.
    >>

    go ahead make my day, troll
     
  22. nero Banned Banned

    Messages:
    26
    >> The non-discovery of it would put a spanner in the works of most current theories, and certainly worth the effort, to know either way... >>>


    I don't really object to anything, even discarded theories held merit, and may still do given new information.

    I do object to "patch work" science as displayed by powerful posters (gardians) here and basically on all science forum sites.

    These people really just use the muscle to ram their 'correctness"
    once discussion gets out of their league, they pull the plug

    LOL

    how's you gonnna find the truth under such sophism..

    LOL


    I piss on them.

    *gone again*
     
  23. nero Banned Banned

    Messages:
    26
    >>> Sakharov later
    derived a value for Newton’s gravitational constant
    G using frequency w as the only free parameter.[14]


    G=c^5/h integral w dw



    where c is the speed of light and h is the Plank
    constant. The integral is carried out over all
    frequencies using the Plank frequency on observable
    electromagnetic phenomena ( p w ~ 10-33 cm) as a
    cutoff value." >>>

    so what was the actual "value" obtained by this 'valid' but confused approach, Mr Macx ???

    (by valid I mean, at least he was on a reasonable (even though incorrect) approach, it is at least related to fields, but not as Sakharov envisaged..... LOL )

    not a very useful understanding though, and I am afraid Dr Sakjarov has taken his logic with him.

    Hang onto coat-tails Macx,,,,, but understanding comes first.... unless you are a high priest (like James R) of religious science then you can write the science bible.....

    History is full of such people, they come and fall, and get a BAD name, LOL
    and real science tramples upon their grave.

    LOL

    get real mate
     

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