Have you ever wondered where all the stars, sun, and planets come from? The Big Bang Theory; what is it? According to scientists across the world, the universe was born from an explosion which they named The Big Bang. Up till the 20th century, scientists believed that the universe was infinite and ageless. In 1920, through the use of a mighty telescope, Edwin Hubble, one of the greatest astronomers of the 20th century, made two shocking discoveries. One; the Milky Way was not the only galaxy in our universe. Two; all the different galaxies are constantly moving away from each other. This meant that the universe was expanding and getting bigger all the time.
Hubble’s Law: the farther away objects are from Earth, the faster they are moving away from us
A few years later, Georges Lemaître, a Belgian cosmologist, said “If the universe is always getting bigger, then long ago, it was smaller. And long, LONG ago, it was much smaller. This means that billions of years ago, everything in the universe was contained in a tiny ball that exploded!” (American Museum of Natural History)
The Big Bang: a moment 13.8 billion years ago when the universe began as a tiny dense fireball that exploded
Timeline of the Universe
Around 13.8 billion years ago, the universe started as a single point which exploded with an unimaginable amount of energy. This created matter and moved it outwards to make billions of galaxies in our universe. Astrophysicists named this explosion The Big Bang. The explosion flung energy in all directions at the speed of light with extremely hot temperatures (temperatures hotter than the sun’s core). (Exploratorium)
At this time, the universe was made up of hot, tiny particles mixed with light and energy. The universe expanded and stretched quickly, causing the universe to cool down. This cooling allowed for matter to form. After a few seconds of The Big Bang, protons and neutrons started to form and within a few minutes, the first nucleus was created. This was mostly hydrogen and helium. Hundreds and thousands of years later, electrons started to stick to the nuclei to form complete atoms.
About a billion years later, gravity caused these atoms to come together and form huge gas clouds, which were able to form stars and galaxies. Over billions of years, stars can create heavier elements such as carbon and oxygen in their cores using the help of lighter elements such as hydrogen and helium. When they explode, they release these elements into space. Then, this matter condenses and stars, planets, and satellites are created.
Formation of our galaxy, the Milky Way
Proof of The Big Bang Theory
The Hubble Space Telescope
Today, scientists and astronomers all across the world, utilize different tools and techniques to discover as much information as they can find to understand the different planets, the sun, the other galaxies. Although we have a general idea about the beginning of the universe, there are still thousands of unanswered questions about outer space.
One of the research tools is the Hubble Space Telescope, named after Edwin Hubble. This telescope was launched in April 1990 and it became the largest and most versatile space telescope. It can send pictures of very distant galaxies and stars, pictures that are not only beautiful to look at, but pictures that can help astronomers and cosmologists conduct studies.
The idea for the Hubble Space Telescope came about after the discoveries of a multitude of problems with regular telescopes. As industrialization grew, the lights of cities posed a problem as the telescope could not pick up the faint images of the galaxies and stars. Along with the city lights, the clouds and atmosphere also made it difficult to view outer space from the surface of the Earth. To overcome these problems, it was suggested that aerospace engineers across the world work together to create a telescope to be launched. After almost 20 years of work, the Hubble Space Telescope was ready for launch. (“The Hubble Space Telescope for Children: Astronomy and Space for Kids - FreeSchool”)
Using The Hubble Space Space Telescope and Hubble’s Law, scientists were able to calculate the universe's age. This shows how long ago the universe was created, which in turn provides evidence and an estimation of the age of The Big Bang (University of Western Australia).
Cosmic Microwave Background Radiation (CMBR)
Based on The Big Bang Theory, the initial universe (minutes after The Big Bang), was hot and dense and it eventually cooled down over time. Cosmologists were able to calculate the temperature of the universe today and searched for evidence from that.
In 1960, it was discovered that radio signals can be reflected off orbiting satellites. At first, it was believed that the radiation observed was from nearby cities, however, gradually, it was discovered that the radiations were coming from beyond the Milky Way. These radiations were named the “cosmic microwave background radiation.” Further research discovered the radiation was leftover heat radiation from the Big Bang.
Today, CMBR is very cold due to the constant expansion of the universe, however, it fills the entirety of the universe and can be detected during the night and day.
Final Notes
The cosmos is one of the greatest mysteries known to mankind. As time goes on, we understand many possibilities and secrets the universe holds. The Big Bang is one of these secrets. It is still not determined what caused The Big Bang, however, we know what happened afterwards. There are many hypotheses about the future of the universe, but we can not be sure which ones are correct and which ones are false.
In conclusion, The Big Bang Theory is the start of the universe; the start of everything known to mankind. It is a very interesting topic and this is a small introduction to it. Read upcoming blogs for more scientific secrets and ideas!
Written By: Krisha L
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