The Universe
Two questions concerning our evolving Universe were at the center stage during the last century:
1. Will the universe expand forever or will it start contracting at some stage due to its own Gravity?
2. What is the geometry of the universe?
According to the General Theory of Relativity, these two questions related to why is the newest expanding in the first place? Frankly, we do not know. All one can say is that Einstein's general theory of relativity, which provides a Framework describe the universe, admits this possibility full stop and what will be the eventual fate of the universe? This is a question that concerns the geometry of the universe, and general relativity has a precise answer for this full stop according to general relativity, the curvature of space can be zero a positive or negative full stop which of these three possibilities describe how the universe depends on how much matter there is in the universe. If the density is greater than a certain "critical density" (whose value is roughly the mass of 5 protons per cubic meter),
then the gravity of the universe will eventually pull back the matter, and the universe will be finite full stop the curvature of space would be positive.
if, on the other hand, the density is less than the critical value then the curvature of space would be negative full stop if the density of the universe is precisely equal to the critical density then the curvature of space would be zero.
to be cont.
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