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Module 3 Practice Examination
Answer for essay question 21
A complete answer includes all of these points.
A minimal answer has the key points but not all the details:
Historical Background
Two discoveries in the 1920's and 1930's led to the formation of the Big Bang Theory. In the 1920's, astronomers V.M. Slipher and Edwin Hubble independently discovered that the stars they could see had shifted to the red end of the spectrum. Hubble interpreted the red shifts as distortions in the stars' spectrum as a result of their movement away from the earth. This is similar to the Doppler effect. The discovery that the universe seems to be expanding lead to the development of the Big Bang Theory. If things are getting farther apart now, then they must have been closer together in the past.
The second discovery was that stars are composed primarily of hydrogen and helium.
The Big Bang Theory
If things were closer together in the past, then they would also have had increased energy and would have been hotter in the past. The Big Bang Theory presumes all the matter particles of the universe were at no distance from each other, and temperature, density and curvature of the universe were infinite (no outer limits or center).
At 10-43 seconds after the Big Bang, the void created by the Big Bang is filled with radiation and matter. Matter and antimatter exchange identities. The primordial cosmos expands and begins to cool. Neutrinos, photons, electrons, positrons, neutrons, and protons move about through space. After three minutes of cooling, nucleosynthesis begins; those neutrons and protons that were bound together at the point of cooling form helium.
The universe continues to expand for four hundred thousand years, and cools to 4,000oK. Free electrons and protons now can join together to form hydrogen. Hydrogen interacts with the cosmic debris and rays of light are formed. Low temperature radiation bathes the universe. Hydrogen and helium condense and stars are formed. In the centers of stars, other elements are formed through the fusion of hydrogen atoms. Planets form by the condensation and cooling of minerals and atoms which are produced by fusion in stars.
"Big Bang" is actually an inaccurate representation of the theory. According to the theory, space is infinite and has no center. All the particles were, at one point, so close together that there was no distance between them. Then they expanded so that they were still at equal distances from each other, but were farther apart. They continue to slowly expand.
Predictions of the Big Bang Theory
The Big Bang Theory predicted that at 400,000 years after the Big Bang, low temperature (around 5oK) cosmic radiation flooded the universe. Twenty years after the theory was introduced, two physicists, while trying to eliminate all background interference noise from their radio antenna, discovered a low level interference that could not be eliminated. Theoreticians interpreted the background hum to be the cosmic background radiation released into the universe billions of years ago. The cosmic background radiation was determined to be 2.7oK and completely uniform in all directions to one—one hundredth of a degree.
Red shift expansion and the presence of helium and hydrogen in the universe are claimed to be predictions of the Big Bang Theory. But they were discovered before the Big Bang was developed. The Big Bang Theory was formulated to explain the expansion of the universe, it is not a prediction of the Big Bang Theory.
Problems with the Big Bang Theory
The Big Bang Theory is an attempt to explain the origin of all things without God. The problem is that the ultimate question of origins remains unanswered. How did a random, primeval, undirected event create complexity? From where did the first protons, electrons, neutrons and other particles come?
The Big Bang Theory made a prediction about cosmic background radiation, and completely uniform background radiation was found. Uniform radiation, was not a part of the Big Bang prediction though. In the sequence of events, radiation came after 400,000 years of cooling and expansion, so it ought not to have been uniform. To counter the problem of uniform radiation, a theoretical model of inflation was developed.
A second problem developed due to the radiation. After the uniform radiation was found, astronomers began to find vast organizations of galaxies. In the late 1980's, Harvard astronomers Margaret Geller and John Huchra found the "Great Wall"—an enormous concentration of galaxies that spans at least 500 million light years. There are also many voids that are virtually free of any galaxies at all. Concentrations of many galaxies and vast areas that are free of galaxies do not comply with the uniform background radiation.
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