ASTR123 Homework Notes for Final 1 Aristotle assumed the Universe was infinite in extent and age What are the logical physical observational problems with the Universe being of infinite age Aristotle assumed the Universe was infinite in extent and age this was believed for many decades Aristotle was surely wrong as the Universe is finite in age and can be supported with certain studies Aristotle assumed that the Universe was infinite in extent and age due to his false research Aristotle assumed the Universe was infinite in extent and age because the dust interrupted his view to see distant stars The distribution of stars is not uniform in the Universe and there are only a finite number We know the Universe is expanding so distant stars are red shifted into darkness while the Universe is young which means distant light has not even reached Earth yet Since we know of this expansion in order for this expansion to be possible there had to be a time where the Universe did not exist 2 Describe some of the necessary assumptions needed for Erasthosenes method to work Although this method produced a reasonably accurate measure of the size of the Earth what do you think the major sources of error might be Erasthosenes ability to produce a reasonably accurate measure of the size of the Earth is astounding The necessary assumptions needed for Erasthosenes method to work are abounding Erasthosenes needed to understand basic geometry and have a well knowing about time and shadows With this he had to assume that the earth was spherical and he had to believe that the sun gives off vertical rays Even though Erasthosenes developed a reasonably accurate measurement of the size of the Earth there is a possibility of some errors that changed his result I believe that the lack of geographical knowledge of the places in which he measured could have a major affect 3 Even thought the Ptolemaic model is completely incorrect it remained as the established model for about 1800 years Briefly discuss why you think this model was so widely accepted that no one questioned it for centuries I believe that the completely incorrect Ptolemaic model was widely accepted for 1800 years because of the Truth model that was explained in Chapter 1 our pre disposition for acquiring the Truth as fast as possible and then tenaciously hanging on to that Truth in the face of conflicting data If a scientist proclaims something to be true that is what society is going to believe because they have the knowledge on that It is not likely that an individual would question a knowledgeable source if it sounds accurate because most individual s whom do not have an immense knowledge on a topic will not question someone of higher power 4 Explain how Galileo s observation of the phases of Venus implied in fact almost proves that the Sun must be at the center of the Solar System Galileo s observation on the phases of Venus brought upon a new understand of the Sun The Sun was now known to be the center of the Universe Venus was found to always lay on a line directly between the earth and sun which will show a crescent phase Galileo observed Venus going through a complete set of phases just like the moon and increasing and decreasing in size in just the right way as would be expected to happen were it in orbit around the sun 5 Explain the difference in cultural conditions in the time of Nicholas of Cusa compared to Bruno which lead to the latter being burned at the stake even though he mostly just re iterated what Cusa had said The difference in cultural conditions in the time of Nicholas of Cusa compared to Bruno lead to the latter being burned even if he mostly just re iterated what Nicholas of Cusa had said was mainly because of each individuals main beliefs and ideas The Catholic Church ultimately defeated Bruno by the differences he entailed 6 What assumption does Hubble have to make in order to turn this into a velocity distance relation from which it can be seen that more distant galaxies are moving at higher radial velocities than more nearby galaxies Hubble must assume that the diameter of a galaxy can provide evidence on how far away it is The galaxies redshifts that are more visible are closer in light years then the galaxies that are harder to see It can be seen that for the most part more distant galaxies are moving at higher radial velocities and that is because as the universe expands the galaxies get farther from each other and the apparent velocity will appear to be larger for the more distant galaxies 7 Summarize the Shapley Curtis debate and its implications on the overall size of our Galaxy and the size of the Universe What kinds of evidence did Shapely use to promote his basic premise that our Galaxy was in fact the entire Universe This debate is also known as The Great Debate that took place in 1920 Both Shapley and Curtis had very strong opinions on this debate that they refused to back down they conversed over the Scale of the Universe Their strong personalities brought upon new realizations as each one of them had accurate accusations even if they also had false accusations as well Curtis argued that the Universe has many different galaxies while Shapley argued that the spiral nebulae were just gas clouds and that the Universe was just one large galaxy Shapley used the Sun and placed it very far from the center of the universe as Curtis placed the Sun near the center of the Universe Both of these men had some correct views and both men were wrong in other ways 8 Google on Andrew Mckellar Microwave Background McKellar actually detected the MWB in 1941 but did not realize it Speculate why you think he was unable to put his data together to claim initial discovery and the eventual Nobel Prize for this discovery The discovery of the Microwave Background was a major development in physical cosmology as it was evidence for an expanding universe Andrew Mckellar unknowingly detected the Microwave Background in 1941 but there were some valuable pieces missing There was a very bad war going on in Europe during the time of his discovery and shortly after the United States went into war as well These countries being involved in war made it difficult for anyone to discuss McKellar s discovery Time went by as these countries were just developing after war and McKellar s papers were forgotten about in observary files These files were left alone and nobody paid any attention to them Another issue was that Mckeller published into an