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Featured Gravity vs Mass

Discussion in 'Science and Religion' started by Thief, Jan 15, 2020.

  1. Thief

    Thief Rogue Theologian

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    I have a question of which I will not post
    I already know.....no one can answer it

    but it does relate to this topic and so.....a redirect and a blindside
    right up front

    do you THINK you understand gravity?
    and WHAT has mass got to do with it?

    and if the Creator gets a mention
    don't be surprised
     
  2. Subduction Zone

    Subduction Zone Veteran Member

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    I have more than a sneaking suspicion that the OP does not understand either.
     
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  3. Darkforbid

    Darkforbid Well-Known Member

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  4. Mestemia

    Mestemia Advocatus Diaboli
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    What do I need to know beyond "you drop something it falls"?
     
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  5. Subduction Zone

    Subduction Zone Veteran Member

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    Don't stand underneath people dropping things.
     
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  6. Mestemia

    Mestemia Advocatus Diaboli
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    I will have to try and remember that...
    Though with all the bumps to the head, I would forget my head were it not attached.
     
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  7. Terry Sampson

    Terry Sampson Well-Known Member

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    Can I ask "rational experiences"?
     
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  8. exchemist

    exchemist Veteran Member

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    Depends what you mean by "understand".

    As with everything, there are levels of understanding. If one goes deep enough on any subject there always comes a point at which one has to say, "I don't know the answer to that".

    I understand the Newtonian model of gravity , and I know in outline how General Relativity models it. According to both, gravitation arises from mass. Why it does so is not known. But then we do not know why electric charges attract and repel either: they just do. It is just how we observe nature to behave.
     
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  9. Native

    Native Free Natural Philosopher & Comparative Mythologist

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    Well, even Newton admitted that he couldn´t explain the dynamic force of gravity . . . he just assumed it from watching an apple fall to the ground and also assumed the planets to be held in orbits by the Sun.

    If something cannot be dynamically explained, it of course cannot be fully understood.

    The Standard Cosmology idea of "mass" and "gravity" is completely out of order, right from the ideas of formation of stars and up to the strange and very speculative idea that a "Higgs Boson particle" is assumed to "give mass" to everything.

    All atoms and particles have electromagnetic properties which either attracts or repels each other, all depending of the overall existence of diverse elements and effects from cosmological sources and movements.

    Mass isn´t a question of "gravitational binding atoms and particles together". It is generally a question of electromagnetic binding of atoms and molecules - right from the microcosmic and up to the macrocosmic scale.
     
    #9 Native, Jan 16, 2020
    Last edited: Jan 16, 2020
  10. blü 2

    blü 2 Well-Known Member
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    It's a force that only acts between objects that have mass.

    So the way to be gravity-free is to have a rest mass of zero, and never to move.

    In a relativistic world, that last requirement is even harder than it first seems.
     
  11. Polymath257

    Polymath257 Think & Care
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    Gravity is the curvature of spacetime that is produced when there is energy and momentum in a region. Mass tends to be the largest concentration of energy in many situations simply because in E=mc^2, the c is so large.

    But all types of energy enter into the equation for gravity.

    The basic equation is
    G_{\mu\nu} =(8G\pi/c^2) T_{\mu\nu}

    Where the left hand side is a tensor describing the curvature geometrically and the right hand side is the stress-energy tensor. The T_{00} component of this tensor is the energy (and mass contributes to this) and is, by far, the largest contribution in most cases. But the other diagonal elements are related to pressure and the off-diagonal elements are related to momentum density.

    This equation is slightly modified in the presence of a cosmological constant, which can either be treated as an additional term on the left (representing a curvature present even when there is no stress-energy) or on the right side where it represents an energy density of the vacuum.

    Next.
     
    #11 Polymath257, Jan 16, 2020
    Last edited: Jan 16, 2020
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  12. 'mud

    'mud ~~ Life is Stuff ~~
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    Such a waste of chalk on those blackboards !

    Why do hydrogen and helium rise ?

    What else does ?

    Does the earth ?
     
  13. Native

    Native Free Natural Philosopher & Comparative Mythologist

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    You most certainly have your equations written right - but what about the cosmological explanations and it´s correctness? Are you sure you really have understood it?

    Watch this: "Why E=mc^2 is wrong" -
     
  14. HonestJoe

    HonestJoe Well-Known Member

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    Then I won’t give the correct answer the question you’ve not asked as I already know you’ll refuse to accept it. ;)

    At a very basic level, much like I understand how a car works well enough to drive one and carry out basic wear-and-tear maintenance but I wouldn’t know where to start if I was asked to build one from scratch.

    The gravitational force an object exerts is a function of its mass.

    And if mention of "the Creator" gets strongly challenged as entirely off-topic, don’t be resentful. :cool:
     
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  15. Polymath257

    Polymath257 Think & Care
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    *sigh*. Yes, that is the equation for a mass that is not moving. The more general equation that even works for massless particles is

    E^2 =m^2 c^4 +p^2 c^2

    where E is the energy, m is the (rest) mass, and p is the momentum.

    So, for photons, m=0, giving E=pc.

    For a particle with mass m and velocity v, the momentum is given by

    p=(mv)/sqrt(1-(v/c)^2 )

    As for 'cosmological explanations' and 'correctness', the correctness is determined via observation. The phrase 'cosmological explanation' is likely to be philosophical rubbish.
     
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  16. Thief

    Thief Rogue Theologian

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    in eighth grade......sooooooooooo long ago

    two classmates were given the assignment.....What if gravity failed
    and they assumed all of the large objects....and us.....
    would float off into space

    at the time I was naïve enough to ask.....
    would not the atomic structures fail?
    and we simply pop into the nothing from which reality came forth?

    kinda dropped a bomb on their science report

    but neither did I think I was right
    I was just asking
     
  17. Thief

    Thief Rogue Theologian

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    well....I guess I am two up on you
    as a body repair man...….I can take your vehicle apart and put it back together

    as a toolmaker......I can make any of the hard items
    but that would take sooooooooo much longer

    a new car would be cheaper
     
  18. Thief

    Thief Rogue Theologian

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    so.....you discount observation?

    I do find your post interesting

    particles …...of no mass

    like a ghost having form
    but no substance
     
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  19. Heyo

    Heyo Well-Known Member

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    Hydrogen and helium don't rise. They get pushed up by other molecules falling.
     
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  20. Twilight Hue

    Twilight Hue The gentle embrace of twilight has become my guide

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    I understand it based on actual experience as with everybody else.

    I think energy has a lot to do with gravity involving the characteristics and properties of atoms.

    It seems denser material has more gravity than that of less dense material and is interesting in terms of how electromagnetism works as it relates with gravity. Now with research suggesting gravitational waves now, the whole topic has gotten so much more interesting.
     
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