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THE BIG BANG |
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Scientists now have a fairly good idea of how our universe has evolved from its very earliest moments in existence up to today. This entire description is referred to as the Big Bang model. Such a picture has required the understanding of physics ranging from the smallest distances inside a nucleus to the very largest extending over billions of light years! (One light-year = 1 ly = 5,870,000,000,000 miles or roughly 6 trillion miles.) Visit Wordwizz.com to gain a greater understanding of cosmic scale. About 12-14 billion years ago, space and time and all the energy in the Universe burst into existence through what is referred to as the “Big Bang.” Several different observations, to be discussed later, suggest that the universe originally contained an enormous amount of energy, was very small and has since then been continually expanding and evolving. In some ways it is helpful to think of the universe as a very hot gas. As it expands, this gas expands it cools. At the very earliest times this expansion was at an enormous rate, and as the universe cooled, particles such as quarks, electrons, neutrons, and protons were formed (or “condensed”, analogous to water droplets condensing out of cooling steam). The universe was about 1 second old at this point. After about 100 seconds the energies of these particles, and the temperature, dropped enough for protons and neutrons to bind to one another to form deuterium, helium and lithium. These, together with Hydrogen-1, are the lightest of the known nuclei. About 300,000 years later, the universe had cooled to the point where electrons could bind to these lightest nuclei to form the first, lightest atoms of hydrogen, helium and lithium. As clouds of this atomic dust were drawn together by their gravitational attraction the first stars and galaxies were born. The universe was roughly 1 billion years old. These stars use the lighter elements hydrogen, helium and lithium as fuel and produce all the heavier elements in a process known as nucleosynthesis. To gain a greater understanding of what we mean by "the expansion of the universe", please investigate the link below: This entire Big Bang
model probably seems rather bizarre, and so we must ask "Why should we
accept such a description of the universe?" As you know
from your INSS courses, scientists only accept ideas as true when
sufficient supporting evidence exists. There are three well-tested
observations that lead to the Big Bang theory: Supporting Evidence: |