Comparing Gravity and Big Bang Theory

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The discussion centers on the apparent contradiction between the Big Bang Theory, which states that the universe is expanding, and gravitational forces that should pull matter together. Despite expectations that gravity would slow down this expansion, recent discoveries indicate that the expansion is actually accelerating. This acceleration is attributed to dark energy, which constitutes about 75% of the universe and is linked to Einstein's cosmological constant. The concept of dark energy remains a tentative area of research in cosmology. Understanding these dynamics is crucial for comprehending the universe's evolution.
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I don't know much about big bang theory except that it says that the universe is expanding..
What i don't understand is that why isn't the gravitational force pulling everything together ?
Is there any other force which is leading to the expansion??
 
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Once the expansion got going, the theory was that gravity would slow it down. However about fifteen years ago it was discovered that the expansion is speeding up. Since then scientists have been looking for an explanation. The current theory is that there exists something called dark energy (which makes up about 75% of the universe) which is causing the acceleration of the expansion. It is supposed to be related to Einstein's cosmological constant. This whole idea is still somewhat tentative!
 

Thread 'Matter density right after the decoupling'

https://en.wikipedia.org/wiki/Recombination_(cosmology) Was a matter density right after the decoupling low enough to consider the vacuum as the actual vacuum, and not the medium through which the light propagates with the speed lower than ##({\epsilon_0\mu_0})^{-1/2}##? I'm asking this in context of the calculation of the observable universe radius, where the time integral of the inverse of the scale factor is multiplied by the constant speed of light ##c##.
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Thread 'Hubble Constant, Dark Energy and the Expanding Universe'

Why was the Hubble constant assumed to be decreasing and slowing down (decelerating) the expansion rate of the Universe, while at the same time Dark Energy is presumably accelerating the expansion? And to thicken the plot. recent news from NASA indicates that the Hubble constant is now increasing. Can you clarify this enigma? Also., if the Hubble constant eventually decreases, why is there a lower limit to its value?
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