The whole universe is expanding in all directions; however, everything was closer together 13.8 billion years ago and at one point all the galaxies converged to a single point (Howell, E. 2017). It is said that the universe has expanded to get as large as it is now, and that it will continue to expand. When the universe started as one point, it was just hot, light and energy combined with miniature particles. Nothing like what we see now as everything has stretched and more room has been taken up, and due to this it has become cooler. When the particles joined together, they formed atoms. Those atoms then grouped together, and overtime atoms had merged together to form galaxies and stars. While stars were being born and dying, asteroids, comets, planets and black holes were formed (Stoller-Conrad, J. 2019).
Redshift is when atoms are heated to high temperatures and they admit light at specific wave lengths. For visible light this means they move towards the red end of the spectrum. This is called redshift. The redshift applies to all wave lengths whether it is visible or not. No matter what direction you look most galaxies in every direction was moving away, however, later on redshift was compared with how far away the galaxies were (Howell, E. 2018). This information told scientists’ that the further away a galaxy was, the more redshifted it was, meaning the faster it was moving (Enotes, 2019). The Doppler Effect was another way that scientists determined that the universe is expanding. The Doppler Effect was named after Christian Doppler, who learned that sound waves would have a greater frequency if the object was moving towards the observer and lower frequency if the source was moving away from the observer (Hatheway, B. 2010).
Cosmic Background Microwave, (CMB), is radiation that spreads throughout the universe and can be discovered in each direction. Microwave radiation is indistinguishable to the naked eye as you can only see it with instruments. CMB had been present just after the Universe had begun. This was the thought to be left over radiation from the “Big Bang.” (Tate, K. 2013). It is said that when the universe was born it experienced a fast inflation and expansion, even though the universe is still expanding today. Scientists use the CMB to help us understand how the universe was formed early. Before the universe had expanded the universe was a very hot place, however, as it expands the gas surrounded cools down. CMB is the ‘Big Bang’ left over heat dating back over 400,000 years.
An opposing theory to the Big Bang Theory is the Steady State Theory. The Steady-State Theory is a belief that the universe will always be expanding while retaining a steady average density, the matter is continually produced to form new stars and galaxies at the same rate whereby old ones are unobservable. A world of a steady state has no beginning or end in time; and the vision of the grand scale from any point within it. For example, the average galaxy size and structure is the same. Galaxies of all ages are mixed up. Around 1920 the theory was first put forward by Sir James Jeans and was revised by Hermann Bondi and Thomas Gold in 1948. It was developed further by Sir Fred Hoyle so that he would deal with the problems that had arisen with the alternative Big Bang Theory. Observations since the 1950s have provided evidence that disproves the steady-state picture and confirms the Big Bang model (The Editors of Encyclopaedia Britannica, 2019). The idea of the Steady State Theory is supported by the redshift evidence, but not by the Cosmic Background Microwave Radiation, unlike, the Big Bang which is supported by both. When the Cosmic Background Microwave Radiation was discovered, the Steady State theory lost support and was no longer considered likely (BBC Bitesize, 2019).
The Steady-State theory doesn’t support the Big Bang Theory as there was no beginning or end to the universe. Steady state says the universe simply existed. In order to keep the universe’s density from decreasing it requires that the matter be frequently created. The Steady State Theory is supported by the redshift evidence, but not by the Cosmic Background Microwave Radiation, unlike, the Big Bang that is supported by both.
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