NATS 1750 Lecture Notes - Lecture 2: Edwin Hubble, Intelligent Lighting, Protostar
7 Jan 2018
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The doppler effect: waves compress or relax with relative motion. Compressed: shorter wavelength; higher frequency relaxed: longer wavelength; lower frequency. A stopped train sounds different than a moving train. As the train approaches, a person hears a higher pitch. As the train passes, the pitch drops (higher to lower). As the train recedes, a person hears a lower pitch: the doppler effect influences light waves too. Red light has a longer wavelength (lower frequency). Blue light has a shorter wavelength (higher frequency): moving light waves reveal the doppler effect. Light moving away from an observer expands (red). The expanding universe theory the whole universe is expanding. Analogous to bread dough galaxies farther from earth are moving away faster than galaxies close to earth: the big bang. All matter and energy compressed to a single point. Hydrogen and helium were the first elements to form: birth of the first stars. After continued expansion, atoms and molecules accumulated into patchy clouds.
