Download Last Years test.- Contemporary Physics | PHYS 2074 and more Assignments Physics in PDF only on Docsity! Highlights of Contemporary Physics: Cosmology ā Worksheet Questions J. H. Simonetti ...... These questions are meant to provide you with some practice before the exam. They will give you an idea of the style and level of the exam questions. They should also help you see what sort of proļciency I expect for the exam. The exam will be closed book (closed notes). You may bring a calculator. You will be given some essential equations and numbers on the front page of the exam. For example: H0 = 50 km/s/Mpc = 1/(20Ć 109 y). 1. Sketch a graph showing how the scale fac- tor of the universe changes with time if we live in a universe with an open geometry, and the cosmological constant is zero. 2. You discover a distant galaxy whose spec- trum indicates it has a redshift of 1.5. What was the scale factor of the uni- verse when the light you have received was emitted by the galaxy? (a) 4.00 (b) 0.40 (c) 2.50 (d) 0.50 (e) 0.25 How did you ļgure this out? 3. Under the simple assumptions of Olbersās paradox, the night sky is expected to be inļnitely bright. What are those assump- tions? 4. What is the ācosmological principleā? 5. Assume we live in a ļat geometry uni- verse, ! = 0, and H0 = 50 km/s/Mpc. What is the age of the universe? 6. The future fate of the universe depends upon (a) how quasars have changed over time. (b) the cosmological constant. (c) the cosmic microwave background. (d) the mass density of the universe. (e) the energy density of the universe and the cosmological constant. (f) the Hubble constant and the mass density of the universe. 7. Describe the geometry of space if we live in an open geometry universe. Draw a picture to help. 8. Describe a problem with the Newtonian model of cosmology. 9. Explain how the redshifts of distant galaxies come about in an expanding uni- verse. 10. Brieļy explain the evidence suggesting the expansion of the universe is acceler- ating. 1
