What Is The Shape Of Universe?

What is the shape of the Universe? What would the universe look like if you somehow step outside the universe? Scientists and astronomers have struggled with this, taking measurements to determine the geometry of the cosmos and predict the future of universe. So, what have they discovered so far?

What are the factors that affect the shape of Universe?

The General Relativity explains that mass and energy bends the curvature of the universe. As a result, the density of the universe - the ratio of the total mass of the universe to its volume - determines the shape of the universe. And the shape of the universe further helps us to determine its future.

Scientists have calculated critical density of the Universe - the density of the universe if it is flat. Critical density is proportional to the square of the Hubble constant - which helps in the calculation of the expansion rate of the universe.  

With the help of General Relativity, scientists can determine the curvature of the the universe by using the density parameter - denoted by Omega (Ω). Density parameter is the ratio of the average density of the universe to the critical density.

  

This leads to three possibilities -  

• If  Ω = 1, the universe is flat.
• If  Ω > 1, then universe has a positive curvature and the universe has a closed shape. E.g. sphere.
• If  Ω < 1, then the universe has a negative curvature and has a open structure. E.g. Saddle.

If the universe contains exactly the same mass to eventually stop expanding, its density will be equal to the critical density. This means that the universe will gradually stop expanding over a infinite time, which states that the universe is flat and infinite.

If the density of the universe is more than the critical density then it contains enough mass to eventually stop expansion. Once the universe stop expanding, it will start to contract as the attractive force of gravity takes control. The galaxies will then stop moving away from each other and start to move towards each other. This will cause the opposite of the Big Bang, often called the Big Crunch.
This means the universe has a closed shape like a sphere, finite, though without boundries. This is called the closed universe.

NASA

However, on the contrary, if the density of the universe is less than the critical density, then there is not enough mass in the universe to stop expansion and the universe will continue to expand forever. The shape of the universe will then be open like the surface of a saddle. This is called a open universe.

So exactly is the shape of the universe?

Universe is very big. 

It was Edwin Hubble in the 20th century who first proclaimed that the universe is expanding while studying distant galaxies. He announced that the universe is expanding in all the directions. Since then scientist have refined their calculations to study the rate of expansion of the universe.

There are various instruments that measures the background radiation in an effort to determine the shape of universe. In 2013, scientists announced that the universe is known to be flat with 0.4% margin of error.

Conclusion : 

Let us admit it, the Universe is mysterious. Everytime we see it, we find something new and undiscovered. We cannot surely say the shape of the universe. Even that 0.4% error can change the complete shape and curvature of the universe. Whatever be the shape of universe, we must make sure that it will not remain unexplored.