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Study Guide #4

# Study Guide #4 - Study Questions GEOL 125 Earth History...

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Study Questions Guide #4 (F07) GEOL 125: Earth History Dr. Hammond What observations do models for the origin of the Universe seek to explain? What basic assumptions are made in developing such models? What observations does the Big Bang theory explain that are not predicted by the Steady State Model? Models for the origin of the Universe seek to explain the following: Draw the Hubble Plot for galaxy clusters (velocity vs. distance). How is each parameter determined? What is the significance of this plot? Graph: ch.8-pg.1 Distance (x-axis) vs. Velocity (y-axis) Put galaxies outside our local cluster on this graph Velocity is measured by the Doppler shift (all red shifted b/c moving away from us) Distance is measured by (if mass known, can determine what luminosity has to be, look at brightness and then that would tell us how far away they are; otherwise we can assume all stars have similar brightness’ and use that to determine the distance.) Distance= (velocity)*(length of time in travel); Velocity=(Distance)*( 1time ); time=time all things were together at one point in space. Used to develop the Big Bang concept Parameter determined : axis Significance of this plot:  Galaxy superclusters are receding, and the greater the velocity, the  greater the distance. This relationship can be interpreted as evidence that at some time in  the past all galaxies were at a common point. How can the slope of the Hubble Plot be used to estimate the age of the Universe? What assumptions must be made for this calculation? What would curvature on this plot indicate? Is there evidence for curvature, and in what direction? Slope of the Hubble Plot = velocity/ distance = (units of time to the negative 1)

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We assume that all galaxies were coincident at one point in time and no acceleration (due  to gravitational effects) has occurred at this time. 1/H = distance/ velocity = Hubble Time =  Age of Universe. If the Universe has experienced significant deceleration, the slope for distant objects should  be larger than for nearby objects, and the curvature should be concave upward. The  observations indicate only a small amount of curvature.  The curvature is concave down. The significance of the reversed curvature is not fully  appreciated, but it appears that the expansion of the Universe is accelerating, for unknown  reasons. This would mean that the Universe is open (it will expand forever), and that it’s  age is slightly greater than predicted Hubble Time. It may also mean that Einstein’s  cosmological constant may exist. Draw a graph illustrating the cosmic microwave background radiation (intensity vs.
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Study Guide #4 - Study Questions GEOL 125 Earth History...

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