Theories of the Origins of the Universe
There are two main theories for the beginning of the universe that are used today. These are the Big Bang theory and the Steady State theory. Both theories have been changed and updated over the years as scientists find out more information.
Both the Big Bang and Steady State theories suggest that the universe is expanding. It has been observed that distant galaxies are moving away from us. This supports the suggestion that the universe is expanding.
The Steady State theory was developed in the late 1940’s by Hermann Bondi, Thomas Gold and Fred Hoyle. This theory states that the universe always existed and that it has no beginning and no end. It also states that new matter is continually being created to fill space. This theory began to fade in 1960’s after the discovery of quasars. Quasars are thought to be luminous galactic cores, powered by super massive black holes. Quasars are so far away that their light takes several billion light years to reach the Earth. Therefor quasars are objects of the past and indicate that the universe was very different. Another discovery caused us to drift even further from the Steady State theory. This was the discovery of cosmic background radiation by Arno Panzias and Robert Wilson. Cosmic background radiation is thought to be leftover radiation from the ‘Big Bang’. The Steady State theory explained that cosmic background radiation was in fact the light from ancient stars which has been absorbed and emitted by galactic particles. Astronomers found that cosmic background radiation was very smooth meaning it couldn’t have come from different sources. Since the discovery of cosmic background radiation the steady state theory is no longer accepted by most cosmologists.
Both the Big Bang and Steady State theories suggest that the universe is expanding. It has been observed that distant galaxies are moving away from us. This supports the suggestion that the universe is expanding.
The Steady State theory was developed in the late 1940’s by Hermann Bondi, Thomas Gold and Fred Hoyle. This theory states that the universe always existed and that it has no beginning and no end. It also states that new matter is continually being created to fill space. This theory began to fade in 1960’s after the discovery of quasars. Quasars are thought to be luminous galactic cores, powered by super massive black holes. Quasars are so far away that their light takes several billion light years to reach the Earth. Therefor quasars are objects of the past and indicate that the universe was very different. Another discovery caused us to drift even further from the Steady State theory. This was the discovery of cosmic background radiation by Arno Panzias and Robert Wilson. Cosmic background radiation is thought to be leftover radiation from the ‘Big Bang’. The Steady State theory explained that cosmic background radiation was in fact the light from ancient stars which has been absorbed and emitted by galactic particles. Astronomers found that cosmic background radiation was very smooth meaning it couldn’t have come from different sources. Since the discovery of cosmic background radiation the steady state theory is no longer accepted by most cosmologists.
The Big Bang Theory suggests that at some point the universe had zero size. Nearly four billion years ago, the universe was the size of a pin head also called a singularity. Then this singularity burst outwards in an expansion, rather than an explosion, and this was the Big Bang. Georges Lemaitre was the man that theorised that the universe expanded from a single initial point that he referred to as the ‘primeval atom’. The universe started to cool immediately after the expansion. 1 x 10-35 seconds after the Big Bang an inflation occurred, that is, the universe suddenly grew in size very quickly. An estimated one second after the Big Bang the universe was approximately 10 billion degrees Celsius and was like a soup of tiny particles. These were matter and antimatter. Matter and antimatter annihilate each other. One in a billion residuals particles of matter remained due to and imbalance in the amount of matter and antimatter created. The earliest atoms started to form when our universe was around 380,000 years old and had cooled enough for particles of matter to fuse together. Gravity began to effect the matter and the particles fused together to form huge clusters of matter. 50-100 million years pass and stars and planets begin to form.
Astronomers and cosmologists did not believe the Steady State theory as it is difficult to understand how matter can be created from nothing. Einstein realized that energy and matter are actually different forms of the same thing. He came up with the formula E=mc2 or energy= mass x speed of light squared. Using this formula you can multiply the mass of an object by the speed of light and calculate the amount of energy. A small amount of matter can be converted to energy. Therefor a large amount of energy could be converted to mass. A short time after the big bang all that existed was a large amount of energy. Some of this energy could have been converted into matter.
There are many theories of what the fate of the universe will be. Two theories are the ‘Big Crunch’ and the ‘Big Rip’.
The Big Crunch theory is that gravity would pull all matter together. Instead of seeing galaxies moving away from us we will see the galaxies moving towards us. The shrinking of the universe would cause the temperature of the universe to rise. Collisions between clusters of galaxies would happen increasingly. The Big Crunch would not necessary be the Big Bang in reverse, as the collapsing material would be clumped and there would be many black holes. When the universe was in its early stages it was smooth and ‘unclumped’. If the Big Crunch were to happen the universe would be called a closed universe. But, since there is only a small amount of matter in the universe and gravity not being strong enough, theories suggest that the Big Crunch will never happen.
In the Big Rip the expansion of the universe would continue. First clusters of galaxies would be torn apart leaving isolated galaxies in the centre of the observable universe. Sixty million years before the end, individual galaxies would be ripped apart, sending what’s left of stars flying in all directions. Now, matter is more isolated and the universe is emptier. Now the expansion of the universe gets faster. The matter that makes up stars will eventually be ripped apart and any planets still surviving will be destroyed. All that would be left is a sea of atoms. If the expansion continues to accelerate the atoms would be pulled apart leaving only radiation. The universe would be left as a sea of radiation and particles.
Bibliography For This Page
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Red apple education 2012, ‘Skwirk, Iteractive Schooling’, viewed 6 August 2012,
http://www.skwirk.com.au/p-c_s-4_u-138_t-402_c-1413/steady-state-theory/nsw/steady-state-theory/the-big-bang-and-our-universe/the-formation
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Willis, B 1999, ‘E=mc2 Explained’, viewed 6 August 2012, http://www.worsleyschool.net/science/files/emc2/emc2.html
May, B Moore, P Lintott, C 2006, ‘Bang, The Complete History of the Universe’, Carlton Books Ltd, Bristol.
Faraday Schools 2011, ‘The Big Bang Theory’, viewed 6 August 2011, http://www.faradayschools.com/how-science-works/science-year-10-11/the-big-bang-theory/
Pirani, F Roche, C 1994, ‘Introducing The Universe’, Penguin Group, London.
Red apple education 2012, ‘Skwirk, Iteractive Schooling’, viewed 6 August 2012,
http://www.skwirk.com.au/p-c_s-4_u-138_t-402_c-1413/steady-state-theory/nsw/steady-state-theory/the-big-bang-and-our-universe/the-formation
Schmidtke, K 2012, The Big Bang, teacher notes, Mercy College, Mackay, 6 August.
Willis, B 1999, ‘E=mc2 Explained’, viewed 6 August 2012, http://www.worsleyschool.net/science/files/emc2/emc2.html