DSST Astronomy notes 1

B this was then interpreted to mean that the more

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b) This was then interpreted to mean that the more distant a galaxy, the higher its speed of recession--in other words, the faster it's moving away from us. c) This finding is known as the law of red shifts; it is often simply referred to as Hubble's Law. 158) Big Bang Theory - The currently most widely accepted theory for how the universe was formed a) According to the Big Bang theory, the universe started around 12 to 14 billion years ago. b) There are other theories which have been espoused by big name scientists, c) Currently the Big Bang theory is the most commonly accepted and well-known explanation for how the universe came to be. 159) Singularity - In the Big Bang theory, everything originated from a single tiny, infinitely dense and hot and massive point a) Inside of this singularity was contained all of the matter and energy of the universe, which means nothing (not even space) existed outside of it. This singularity then expanded into the universe as we know it today. (a.i.1) Note that at the core of each black hole is also thought to exist a singularity. b) A singularity simply refers to a point of infinite density and infinitesimal (immeasurably small) volume. c) It is imagined that in a singularity, space and time would become infinitely distorted. 160) There are three main ideas which are seen as supporting evidence by proponents of the Big Bang theory. (a.i.1) The first is that according to Hubble's Law, the universe is Expanding (a.i.1.a) As you recall, Hubble discovered that the light coming from almost all galaxies is redshifted (only about 100 galaxies have been recorded which are blueshifted), which he interpreted to mean that they are moving farther away and that the universe is expanding. This would suggest that at one time the universe was compacted. (a.i.2) The second big idea seen to support the Big Bang theory was the discovery of Cosmic Microwave Background (CMB) radiation. (a.i.2.a) In 1948, three scientists Gamow, Alpher, and Herman predicted that based on the idea that the universe started out hot and dense, and proceeded to expand and cool, that there should be some kind of relic radiation left over spread out throughout the universe. (a.i.2.b) In 1965, two radio astronomers, Penzias and Wilson, discovered what is cited today as one of the most compelling pieces of evidence of the Big Bang--microwave radiation with a temperature of about 2.7K that uniformly pervades the entire observable universe. (a.i.2.c) This radiation, known as CMB radiation, is interpreted to be the left over heat from the Big Bang. (a.i.3) The third idea used to support the Big Bang theory is the idea of Big Bang Nucleosynthesis, which suggests that the universe should mainly consist of light elements such as helium. (a.i.3.a) The idea of Big Bang Nucleosynthesis is that within the first few minutes of the Big Bang, temperatures and densities were high enough that protons and neutrons floated as free particles--not bound up in atoms. (a.i.3.b)
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b This was then interpreted to mean that the more distant a...

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