Big Bang Series Part 1 - The Big Bang: An Overview

The Big Bang is one of the biggest and most talked about theories in the history of astronomy and physics. If you don’t know what it is already, the Big Bang refers to the massive explosion of energy billions of years ago which gave birth to our entire universe. Imagine a tiny dot on a sheet of paper – this was where all the energy in the universe was contained 13.7 billion years ago. Now imagine this dot suddenly exploding, shooting out all its energy. As this energy flowed out over billions of years, it created all of the things we see and know of in our universe today.  The Big Bang is a theory, meaning there is a lot of evidence to prove it and most scientists agree on it. However, there are certain parts about this theory that we have little understanding of, and this is why the Big Bang is such a big topic in science that so many people are interested in. Here, I will give you a brief overview of the stages of the Big Bang and why it is such an object of fascination.  

 The Big Bang can be divided up into two eras, the Radiation Era and the Matter Era. During the Radiation Era particles were extremely energized, but after, during the Matter Era, they became less energetic and started to combine into stars, elements, and planets. 

 The Radiation Era 

Believe it or not, all the things that happened in this era occurred within the first couple of minutes of the Big Bang!  

The first second: in very beginning of the first second of the Big Bang, the four forces of our universe we know of today: gravity (which causes things to fall), electromagnetic force (which holds electrons in place), strong nuclear force (which holds atoms’ nuclei in place), and weak nuclear force (which are responsible for radiation) were combined into one unified fundamental force. Over the course of the next second, they all split from each other at different times. As they did this, all the elementary particles were formed. Elementary particles are the particles that make up things like protons and neutrons. Some of these particles are: quarks, electrons, and photons.  During this time of particle creation, the universe was expanding and was extremely hot - so hot that the existing particles couldn’t bind to form new ones. Scientists are still very puzzled over this first second of the Big Bang because the laws of physics don’t exactly work – they tend to break down. 

 After the first second, for the next few minutes: after this initial second, the universe still expanded, but cooled enough so that new particles, like protons and neutrons, formed and then combined into the nuclei of simple elements like hydrogen and helium.  Nuclei are just atoms without electrons.  

 The Matter Era 

Scientists understand more about this era because the laws of physics work better.  

Clouds, stars, and planets: after the first couple of minutes and for the next billion years, the universe continued to expand and cool. This allowed electrons to bind to the nuclei of hydrogen and helium, creating more stability in the universe.  For hundreds of millions of years, these hydrogen and helium atoms clustered into clouds and then eventually formed stars when these clouds combined and got really dense. When stars form, their heat allows for particles to fuse in new ways, creating novel elements. All the materials you can touch – even your own body - are composed of atoms that were made in the hearts of stars!  Sometimes, when a star dies, it can explode, shooting all the elements it created outwards. This allowed for planets, moons, and asteroids to be made. Solar systems and galaxies formed as more and more stars are born.  

Then, about 4.5 billion years after the Big Bang, our solar system began to form, beginning life as we know it.  

Picture Source: NASA