EPSC 201 lecture1.pdf

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McGill University
Earth & Planetary Sciences
EPSC 201
Anthony Williams- Jones

EPSC 201 Lecture 1 The universe started off with the Big Bang Theory. It is perceived as a singularity. The universe was infinitely small and hot and evolved by expanding fairly rapidly. There was a super hot point. The whole of the universe was compressed into this small volume. We evolved through a period of quick evolution (the first few fractions of a second). This period of rapid expansion was less than a second long. Matter was soon visible (though it was really hot). That matter was really a soup. There was also anti-matter. We would not be here if matter had no won the battle between matter vs anti-matter. How do we know the universe is expanding? Are stars and galaxies are moving away from us during expansion or are they at a steady state position? As the universe expanded, the particles should be moving further apart. The Doppler Effect: This question can be addressed by understanding the Doppler effect. The train’s pitch increases as it moves toward you and decreases as it moves away. The distribution of pattern of sound shows that the sound waves are further apart away from the sound source and the sound waves are closer together next to the sound source. The distance between the waves also demonstrates the amplitude is greater closest to the sound source. In the electromagnetic spectrum, only waves of a particular length are visible to the naked eye. Red waves are longest (lower frequency) and blue waves are shortest (higher frequency – more waves per a given distance). Stars appear to us as white however some stars are blue in color, others are red. Aria has a visible red star as well as a nebula (a cloud of gas in which stars are born). There is a tendency of light to move towards the blue end of the spectrum. If the celestial object is moving towards you it will tend to move towards to the blue end (we call this being blue shifted). If the object is moving away from you, it becomes red shifted. The color is relative to where you are. The pattern of black lines has the same distribution on each color spectrum. Matter will absorb energy. In this case, hydrogen is taking out energy from the electromagnetic spectrum at particular wavelengths. This effectively is the spectrum of hydrogen. The black lines demonstrate the wavelengths at which hydrogen absorbs energy in the color spectrum. The second spectrum shows blue shifted and the last spectrum shows red shifted. To the right is the fingerprint of hydrogen. In a lab, you examine the pattern of lines and how the distribution differs. If you perform an experiment on a known sample and the results come back as such: Blue shifted: galaxy is moving towards you Red shifted: galaxy is moving away from you The patterns of lines would change depending on the sample (due to the unique structures of the chemical compounds). Different types of matter will have different types of fingerprints. A Belgian priest was the first person to come up with th
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