# What is the ultimate fate of universe?

The fate of universe is a topic in cosmology. The theoretical restrictions of these allows the possibilities of evolution and ultimate fate of universe. Keeping the mythological beliefs behind, many scientists worked on it and came up with few conclusions. In 1920s-1950s Edwin Humble observed few things and said galaxies appeared6 to be moving away from each other, by taking reference of the well accepted big-bang theory. (very small universe and very dense) about 13.8 billion years ago.

The ultimate fate can be decided by few factors.

1. Average motion of galaxy

2. Structure of universe

3. Amount of dark matter and dark energy

After Hubble did his observation, he came up to a conclusion that (1913) the universe is expanding.

From then the query of it origin and date started.

The famous Einstein's theory of general relativity (1915) was formulated. He could find many possible solutions to the equations of general relativity. Each of the solutions marked towards the positive results of fate of universe. Einstein believed the universe to be static, he found that the equations could be easily solved by allowing the universe to expand now but contract at further future. He added the constants and named them cosmological constant. But there the energy density was kept constant, unaffected by the expansion or contraction of the Universe. The role the energy density was to offset the effects of gravity to keep the universe static. But thereafter the Hubble's conclusion of expanding universe, Einstein said that the cosmological constant was the greatest blunder of his life.

The most important parameter that will be deciding the fate of universe is omega. The density parameter - May be defined as the ratio of average matter density of universe to that of critical value of density. The omega factor decides the geometry and structure of universe.

There are three conditions possible.

1. Omega>1- this will lead us to the open Universe. There are no parallel line, all line will gradually meet. Eventually the gravity stops the expansion and then the contraction starts untill all matter collapse to a point "Big crunch"

2. If omega<1 it will lead us to closed universe. The closed universe expand forever. Gravitational force here is almost negligibly slowing the expansion. The dark energy is continuously accelerating the expansion. When the dark energy overcomes the effects of gravity, electromagnetism and nuclear force the ultimate fate leads to the universal heat death. "The Big freeze" (temperature approached to zero).

3. If omega=1 it will lead us to the flat universe. The flat universe expands forever but continually at decelerating rate. The expansion rate is slowed down by the dark energy. The ultimate fate of the at universe is same as the open Universe.

Concluding the article, we observed that the fate of universe depends upon number of factors but among them the most important factor to decide the fate is the density parameter. The fate of our universe is not a easy task to decide. It will depend on the structure of universe we are undergoing.

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