The energy from the Big Bang drove the universe's early expansion. Since then, gravity and dark energy have engaged in a cosmic tug of war.
Gravity pulls galaxies closer together; dark energy pushes them apart. Whether the universe is expanding or contracting depends on which force dominates, gravity or dark energy
“Gravity dominates at distances, while antigravity is stronger than gravity; therefore, a gravitationally bound system with its mass can exist only inside the zero gravity sphere of its radius. Whereas, dark energy is effective in the outer region of the domination of gravitating mass and practically have no effect within the strong domination of gravitating mass.
The density of dark energy is high enough to affect the structure of a large rich cluster of galaxy-as a gravitationally bound physical system embedded in the perfectly uniform static dark energy background. The antigravity of dark energy affects strongly a cosmic structure at large scale.
The dark energy background produces antigravity which is stronger than the matter gravity in the present Universe as a whole. This makes the cosmological expansion accelerated. The cosmic antigravity can be stronger than gravity not only globally, but also locally on the scale of ~3.26 - 32.63 mega-lightyear (~1 – 10 Mpc).
The local weakfield dynamical effects of dark energy adequately described in term of Newtonian mechanics, and its effective gravitating density is negative, producing antigravity.”
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