Presentation on theme: "1.The universe began with a vast explosion that generated space and time, and created all the matter and energy in the universe. 2.After inflation ended."— Presentation transcript:
1.The universe began with a vast explosion that generated space and time, and created all the matter and energy in the universe. 2.After inflation ended in the first tiny fraction of a second, the universe continued to expand but not nearly so quickly. 3.For the next 300,000 to 500,000 years or so, the universe remained an enormous cloud of hot expanding gas. 4.As time moved forward, the pull of gravity exerted its influence on the early universe. 5.Within galaxies, as stars were being born, others died...often in enormous cataclysmic explosions. These explosions, called supernovae. 6.The sun formed within a cloud of gas in a spiral arm of the Milky Way galaxy. A vast disk of gas and debris that swirled around this new star coalesced into planets, moons, and asteroids.
Possible futures? Big Crunch Universe expansion slows to a stop, and starts contracting. Sufficient matter to stop and reverse expansion. Big Chill Universe continues to expand forever…… Insufficient matter to stop and reverse expansion Delicate Balance Expansion slows to a stop……and stops there…… Our Universe is expanding.
New studies of exploding stars in the farthest reaches of deep space indicate that the universe will expand forever. This is done by analyzing light from distant supernovae. Light from the supernova would have traveled half-way across the visible universe, and its wavelength would have been stretched by the expansion of the universe, a phenomenon known as red shifting. By comparing the faint light of distant supernovae to that of bright nearby supernovae, researchers could tell how far the light had traveled. Distances combined with red shifts of the supernovae give the rate of expansion of the universe over its history, allowing a determination of how much the expansion rate is slowing.
Predictions of the ultimate fate of the universe are also obtained by calculating the characteristic or maximum size of very distant radio galaxies. Fourteen radio galaxies with red shifts between zero and two were used for this study. All of the radio galaxies included in the study are classical double radio sources. Such classical double radio sources are cigar -shaped, with a black hole at the center and a radio "hot spot" at either end of the gaseous cigar.
Previous work by the Princeton group had established that all classical double radio galaxies at a given red shift, or distance from earth, are of similar maximum or characteristic size; this size depends on the inverse of the distance from earth. The apparent characteristic or maximum size of the full population of radio galaxies at the same red shift depends on the distance to the sources. Thus, equating the two measures of the characteristic or maximum size of the sources allows an estimate of the distance to the sources. The apparent size, or distance from hotspot to hotspot, of a high red shift radio galaxy is a clue to which of the competing models of the nature of the universe is most likely.
A relatively small size at great distance from earth would suggest a universe that will halt its current expansion and recollapse; a larger size suggests a universe that will continue to expand forever, but at an ever decreasing rate; an even larger size suggests the universe will continue to expand, and will expand at a faster and faster rate. The current work finds that at high red shift the galaxies are very large, with widely separated radio hotspots. Thus, the universe will continue to expand forever and will expand at a faster and faster rate as time goes by. The two methods used to determine expansion of universe are entirely different, yet yield essentially the same results. Therefore we can say that the universe is open and will continue to expand forever