Friday 15 December 2017

How will the universe end?

Right now, all mass as we know it is composed of energy, because it is contained in the bonds in between the particles in atoms. Energy is also stored in other forms, including heat, electricity, the gravitational field, motion and in many other places. So where is it all going? There are three main theories for the end of the universe.

The first theory I am going to write about is the big rip. This is the theory where mass spreads too far apart, because of its momentum from the big bang, and all of the universe slowly rips apart.

Scientists have discovered that most of the galaxies around us are moving away from ours in all directions. What is more, they seem to be spreading apart faster than they are supposed to, considering the gravitational force in between them. It is very mysterious where the extra energy for this comes from, so it is called 'dark energy'. The mysteriousness from this makes us unsure of what will happen to the universe in the future, so we do not know if this theory is correct, However, the next one appears to be the most likely.

The second theory is the case where we consider a certain type of energy carrier: entropy. Entropy is a measurement of what we normally consider as heat. According to the second law of thermodynamics, entropy can be created, but not destroyed. Whenever we heat something up, we are adding to the ever-increasing amount of entropy in the universe, even when the light from the sun is absorbed by the ground, making entropy, or when we make entropy with our bodies. Energy is always carried away by the entropy whenever it is created, and that is where all of the energy from the earth goes; radiating into space being carried by entropy.

A theory for the end of the universe is that all mass will dissolve into energy carried by entropy, and the only thing left will be radiation. This theory is called heat death. The opposite of heat death is if the entropy spreads out too fast because of the expansion of the universe, and stars slowly die out as a result. This is the prevailing theory, and it is called the 'big freeze'. Despite the fact that entropy is always increasing and cannot be stopped, life and stars can only exist by using balances of entropy.

Fortunately, the next is more optimistic than these two, and it is still likely.

The last theory is that, since matter is spread out in the universe, it might fall under the gravitational attraction in between stars and galaxies after gravity overcomes the outward momentum given to the universe by the big bang. This could result in all of the the universe condensing to a single point, which could spark another big bang. This theory is called the 'big crunch', and it states that this might have happened to the universe several, if not infinite, times before.

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