Is Gravity in the vaccum of space decelerating or exspanding? please explain why,when and how in detail, Along with a credible reference. If Science has not concluded either please give a reference as well.
closed as unclear what you're asking by Hohmannfan, HDE 226868♦, Sir Cumference, Rob Jeffries, Stan Liou Feb 21 '16 at 5:26
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The only known theoretical way to stop gravity is "antigravity", as needed to stabilize a wormhole. For this you need negative energy, which has been observed only on small scales and in small amounts. For any practically relevant scenarios gravity sums up. Observational evidence for "antigravity" is negligible compared to usual gravity.
But in some sense the accelerating universe due to dark energy limits the range of the gravity of a mass, since gravity propagates with the speed of light. For particles outside the cosmological event horizon of the considered mass, the field of gravity of the considered mass will never reach those particles.
Newton's third law is that if a body A exerts a force on body B, then body B exerts an equal (in magnitude) and opposite (in direction) force on body A. In Newtonian gravity when body A exerts a gravitational force on body B, then body B exerts an equal gravitational force on body A. As both forces are attractive they have opposite directions.
General relativity doesn't treat gravity as a force, but Newton's third law can be demonstrated in the Newtonian limit of GR.
In big bang cosmology the initial expansion is not due to gravity or any other "force", rather it comes from the initial conditions of the Universe. Matter and radiation have positive energy density and non-negative pressure which both contribute to their gravity which acts to slow down the rate of expansion (the Hubble parameter). However it has been demonstrated that the Universe's rate of expansion is in fact increasing which means that there must exist some form of dark energy which has a negative pressure which is large enough in proportion to its (positive) energy density to accelerate the expansion of the Universe.