The Universe and the Big Bang Theory

We are often told that we have to study the past in order to understand the future. For example, the causes of past battles, wars, and rebellions need to be understood in order to prevent the same events from happening a century later. However, what about events on a much grander scale?

This image  shows one scientist's interpretation of how the universe began

The universe is literally everything. All people, planets, space, matter, and energy can be summed up with that one word. But how did it begin? Approximately 13.8 billion years ago in a period called the planck epoch, the universe was born. This number was determined by scientists who studied the earliest objects within the universe, and found out the rate at which they were expanding. There are many theories saying the universe expanded from a miniscule to immense size in a time period shorter than one second. 

The early universe is believed to have been filled with energy, which eventually changed into particles that turned into elements such as hydrogen and helium. Later on, these atoms went on to create stars and galaxies, where other elements were created. 

The Big Bang model conveys the idea that the universe has two major forces pulling it in different directions. The force of gravity pulling the universe in is challenged by the momentum of the forces causing it to expand. As of this moment, we are expanding and accelerating as a universe, so it can be concluded that the outward forces are stronger. The explanation as to why the universe is accelerating has no definite answer, but there are theories. One dubious explanation is that there is in fact no dark energy, and gravity does not work in the way that we believe. The other reason could be that even in space, particles of energy disappear and reappear, effectively creating energy. 

This image compares the expanding universe with a expanding loaf of bread, with the raisins representing the galaxies as they are pushed further apart by the force of heat

There are three possible outcomes for the universe in a few billion years. The expansion of the universe will either be infinite, turn into a contraction, or expand eternally, but extremely slowly. The outcome of the universe cannot yet be determined using current technology but will, in time, be known.