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Gravity, something specific

  1. May 30, 2012 #1
    Hi , I have a question that arose in mind.
    If gravity is a spacetime curvature just like GR says it is the I guess the only way to altering it is from the physical size/density of the object curving the space fabric, like sun being bigger having higher gravity and so on.
    But if we find that gravity is like electromagnetic force , could we be able to adjust it just like we can make different kinds of strenghts of the electromagnetic force like in an electromagnet.
    In the case of the existance of graviton I guess.

    Please explain this to me , because i feel like getting something wrong here or maybe not...?
    Thanks in advance for your 2cents of input :)

  2. jcsd
  3. May 30, 2012 #2


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    The sources of electromagnetism are charges and currents. Charges can be either plus or minus, and currents can be reversed. Therefore charges can cancel each other out. And likewise for currents, you can put magnets in opposition and their fields will at least partially cancel.

    The source of gravity is mass/energy, which is always positive. You can't cancel one mass with another mass, they always add. And the equivalence principle tells us that the gravitational field for a given mass is always the same. So it can't be "adjusted"!
  4. May 30, 2012 #3
    Yes, the behaviour of gravitational and electromagnetic force is very different.
    Both their quanta: the photon and the graviton(if exists) must behave differently
  5. May 31, 2012 #4
    But if mass gets to big, like after a star burns out its fusion fuel, the gravity overcomes and all the mass shrinks to a point where it can be compresssed no more and that point or sphere is the black hole right? a place with concentrated mass.

    but when a thermonuclear two or more stage weapon is detonated basically as i understand one of the factors that makes fusion possible is the enormous pressure upon the secondary stage made by the primary stage of a fission bomb?

    proton/proton charge repulsion is a headache to fusion engineers I guess:)
  6. May 31, 2012 #5


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    Too big and too cold, right (burning stars can be more massive than small black holes, as long as radiation provides enough pressure to counter gravity). The black hole is the whole object.

    Thermonuclear weapons are not related to gravity or black holes. Fission usually provides the energy to ignite fusion, right. Without proton-proton repulsion, we wouldn't have any regular atoms.
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