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Whats the effect of universal/absolute gravity?

  1. Oct 22, 2009 #1

    Can someone explain the effect of gravity of an object on the same object?
    We pretty much know the effect of gravity of one body on another body, but is there a way to understand the effect on the same body?

  2. jcsd
  3. Oct 22, 2009 #2
    I received an email saying I have received a reply to my post from molydood, but I cannot see it here.

    Here is the message that has just been posted:
    its the same theory, but you have to break it down into smaller bits, really tiny bits if you want an accurate answer.
  4. Oct 22, 2009 #3


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    All matter affects other matter via gravity. This is true right down to the atomic level where two atoms have a gravitational effect on each other.

    On the grand scale, every atom within an object has a gravitational effect on every other atom. This is why the Earth is spherical.
  5. Oct 22, 2009 #4
    I think yes that is good explanation for earth being spherical, this is one effect. Can you please tell me more such effects that absolute gravity has.

    I know relative causes acceleration, revolution of one body around another, phase locking of planets, gravitational mass, bending of light rays and many more.

    Can you name more effects of absolute gravity?
  6. Oct 22, 2009 #5


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    There is no such thing as "absolute gravity". It is gravity operating between masses. Period.

    The list of effects due to gravity is virtually boundless.
    Last edited: Oct 22, 2009
  7. Oct 22, 2009 #6
    And why do you say that?
    Last edited: Oct 23, 2009
  8. Oct 22, 2009 #7


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    I said it because it's true and it answers your question as best as possible. What are you having difficulty with?

    [ Oops. Corrected a typo. Maybe that was what was confusing you. ]
  9. Oct 23, 2009 #8
    That sounds more like a belief than a reason, how can you be so sure without citing any scientific and observational evidence?

    A body in space creates curvature around itlself that causes another body to rotate around it (GTR). If that curvature has some effect on another body why it should have no effect on the same body.
    e.g. how to understand the effect of universal gravity on the universe itself.
    or say the effect of earths gravity on earth itself and so on.
    Last edited: Oct 23, 2009
  10. Oct 23, 2009 #9

    Doc Al

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    What makes you think a body exerts a gravitational force on itself? Do you have a reference for this, or is this just a personal theory or belief? So far as I know, current theories of gravity include no such effect, so the burden is upon you to provide a scientific reference.

    The different parts of the earth (or other composite body) certainly exert gravitational forces on each other, but an element of mass does not exert a gravitational force on itself.
  11. Oct 23, 2009 #10
    OK, in that case let me start with an assumption. Can I?
  12. Oct 23, 2009 #11


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    Sure - then you have to build a theory around it and test it. But you haven't - you're just making this up as you go along!

    So to echo: There is no such thing as "universal/absolute gravity". That's just a term that you made up.
  13. Oct 23, 2009 #12
    Easy folks, it looks kind of defensive here. In schools we are always allowed to start with an assumption like "lets assume the price of a lether jacket is X", and it doesn't draw such flaks.

    I don't understand why do you say 'period' or 'to echo...' when you have no evidence for it. Do you think your approach is right?
  14. Oct 23, 2009 #13


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    "lets assume the price of a lether jacket is X"

    That would be right in the maths department, not the physics department.
  15. Oct 23, 2009 #14


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    We're not getting defensive, we're taking umbrage with your loosey-goosey thinking.
    You cannot invent terms and then expect other people to accept them.

    Stating an assumption is not the same as making up something out of whole cloth.

    You can't start with "lets assume the price of a lether jacket is red" and get away with it.

    This is our current understanding of physics.

    The onus is on you to show otherwise.
  16. Oct 23, 2009 #15
    "your loosey-goosey thinking" using such statements is what is called defensiveness.

    I don't ask you to accept, I only ask you to make an assumption.

    With due respect, defensiveness again.

    Correct! I cannot make an assumption like that because red is known to be a colour, it has a value that is measured in terms of mixture of RGB and not in terms of monetary currency.

    That is exactly the question. Whats the effect of universal/absolute gravity?

    I don't think the content itself would have taken more time than this kind of defensive deadlock, honestly!
  17. Oct 23, 2009 #16
    What do you mean by universal/absolute gravity? These are terms you made up?

    You're the one being defensive, when you asked for sources for what can be found in textbooks published 30 years ago? Surely those are good enough sources? Study Gravitation by Weinburg, everything people say here is based on the theory which is extremely comprehensively covered in that book.

    Can I ask you one question: if you are postulating that a body exerts a gravitational force on itself, in what direction do you think the force vector points?
  18. Oct 23, 2009 #17

    Doc Al

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    Once again: "universal/absolute gravity" is just some word salad that you've made up! You haven't provided a reference or even a coherent expression of what that might mean, except for some vague notion of bodies attracting themselves. You just keep asking the same question, as if it had some recognized meaning.

    This thread is done.
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