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Danielle Fairweather Brian S. Glenn Chelsea Butcher For thousands of years, many scientists struggle with the idea of the vastness of our universe. Is our universe infinite? Or does it have an edge somewhere far out in space? Universe believed to consist of earth, moon, sun, and planets Outer limit of the universe was the sphere of fixed stars Believed the moon was closest to the earth since it was more visible to the eye and the movement was noticeable No means to estimate distance Moon 27 days Mercury 88 days Venus 225 days Mars 2 years Jupiter 12 years Saturn 29 years Galileo: Argued universe was huge and the distance to the stars was immense Stars are only points of light and the appearance of a disk in an illusion Kepler’s “Third Law” Relative distance within solar system known Size of universe unknown until one distance were known accurately The ancient Greeks were the first to decide that the universe had to be one of two things: Finite or Infinite. Then in the early 1800s, German astronomer Heinrich Olbers argued that the universe must be finite. He believed that if the universe were infinite and had stars in every direction, then the viewer of the sky would always eventually spot a star. Therefore, the entire surface of the sky should, therefore, be as bright as a star. But because there are dark areas in the sky, the universe must be finite. But, when Isaac Newton discovered his law of gravity, he understood gravity to be a force that is always attractive. Therefore, every object in our universe must attract every other object and if the universe were finite, the entire universe would collapse on itself due to this attraction. When Einstein developed his theory of gravity in the General Theory of Relativity, his equations said that the universe should be either expanding or collapsing, yet he assumed that the universe was static. He called it the cosmological constant his "greatest blunder.” However, in 1929 Edwin Hubble measured the redshifts of a number of distant galaxies and their apparent brightness. When he plotted redshift against relative distance, he found that the redshift of distant galaxies increased as a linear function of their distance. The only explanation for this observation is that the universe was expanding. Einstein’s “greatest blunder” proved to be correct. Scientists decided that one theory for the expansion of our universe is that all matter of the universe began at one point and expanded, and is still expanding. This is called the Big Bang. The discovery of the big bang theory is the beginning of the universe as we understand it today. Though the exact size of the universe is still unknown, the ideas behind universe expansion still remain today as the prominent way of thinking. The universe is still an unknown place, though throughout the years we have made many leaps toward understanding it. If the universe was said to have boundaries, it would conflict with ideologies of having a creator and creation. Proof of a finite universe would be claiming there is no god. After the discovery that the universe is expanding, it laid to rest the ideas that troubled past astronomers This led us to our predominant theories and ways of thinking involving the universe today The fate of the universe can be determined by measuring how fast the universe expands relative to how much matter the universe contains There are three possible types of expanding universes (ours is unknown): Open-the universe will expand forever Flat-expands forever but expansion rate will slow to zero after an infinite amount of time Closed-eventually stops expanding and collapses on itself (possibly leading to another big bang) Open Flat Closed Is the universe expanding into a newer, larger space? There is nothing that we have or can measure at this current time that would show us anything about the larger space The fate of the universe determines the fate of humankind Viewer discretion advised http://www.youtube.com/watch?v=kCpjgl2baLs