The Death of Universe.

 

The Universe.

The Death of Universe/ The End of Universe.

The universe was born one day by the Big Bang and like any other object in this universe, the universe will also die one day. But, the statement that 'universe will die one day' gives rise to many questions like:

1. When the universe will die?
2. How it will die? or What will be the reason for its end?
3. Will the universe be dead forever? 
4. Will any other universe may take birth after it's death?

Well, these questions are still not completely answered by anyone but there are few theories about 'how the universe will die?' Among many theories for the end of the universe, there are three popular ones. These three theories are:-

1. The Big RIP
2. Heat Death/ Freeze Death
3. Big Crunch & Big Bounce

These theories are formed on the fact that our universe is continuously expanding and the rate of its expansion is also accelerating. Let's understand the expansion of our universe by an example:- suppose you throw a ball upwards, so after reaching some height, one point will come when the velocity of ball will become zero and due to the gravitational acceleration the ball will come back. But, when it comes to the expansion of our universe, it is like throwing a ball upwards and starring the ball going far and far. Strange right? So, the ball requires a force to continuously move upwards, and in the case of our universe this energy is a strange unknown force which we call 'dark energy'. This unknown energy is responsible for the continuous expansion of our universe. So, now we have understood the fact of expansion of our universe and now we will understand the three theories one by one.

1.Big RIP

 since its birth Universe has been expanding for unknown reasons. New space is created everywhere equally, the space between galaxies expand so they move apart. Space inside galaxies also expanding but here gravity is strong enough to keep them together. In the big rip scenario the expansion accelerates up to a point where space expands so fast that gravity cannot compensate for this effect anymore, the result is Big RIP. At first, only large structures like Galaxies are torn apart since space between the single object expands very fast. Next Big bodies like black holes, stars, and planets die their gravity isn't strong enough to keep them together so they dissolve into their components. In the end, space would expand faster than the speed of light, atoms would now be affected and they would just disband. Once space is expanding faster than light no particle in the universe cannot interact with any other particle anymore. The universe would dissolve into countless lonely particles that won't be able to touch anything else in a strange timeless universe.

2.Heat Death/ Big Freeze/ Big Crunch

Now let us take an example to understand this: Suppose there are two objects which are tied with a rubber band and each object is being pulled away from each other by another rubber bands tied to each object separately, somewhat like this:

So, the example which we have taken right now seems quite easy and normal but, what if these two objects are nothing but two galaxies. Yes, somewhat like this only happens with two galaxies or other celestial objects. They are bound together by the force of gravity and at the same time, they are being pulled apart by the force of expansion of our galaxy due to dark energy. In the big freeze scenario, the universe will extend to such a point where the gravitational force becomes won't have much impact on the celestial bodies, due to which clusters of galaxies will separate. The objects within the galaxies- suns, planets, and solar systems would move away from each other until galaxies will dissolve into lonely objects, floating separately in the vast space. The light emitted by stars won't reach the planets and the gas emitting from them would become too thin to form stars. And due to lack of heat and the light, the universe would become darker and darker & ultimately it will freeze. Oh! man this is too scary but, don't worry this will happen after trillions of years.

3.Big Crunch/ Big Bounce

This is the most uplifting scenario. In this scenario, the universe stops expanding due to the end of dark energy. And the gravitational force will become the dominating force of the universe. As the universe stops expanding the gravitational force will start attracting all the galaxies and stars. Galaxies will start rushing towards each other and resulting in collisions of galaxies and stars. And as they clumped together the gravitational force would become stronger and stronger. Since a smaller universe also means a hotter universe, the temperature will rise everywhere all at once. Minutes before the big crunch the cores of atoms will be ripped apart, and many black holes will be created. Finally, all the black holes will form a single giant black hole that will contain the entire mass of the universe & at the last moment the black hole will destroy everything including itself. The Big Bounce theory states that this has happened to the universe a lot of times and the big universe goes through an infinite cycle of expansion and contraction. So, we have got the answer to our question that the universe won't be dead forever.