by Ira Mark Egdall<\/p>\n
This is the way the world ends The first hints that the universe is expanding<\/strong> came in 1917 when Albert Einstein applied his general theory of relativity to the universe as a whole. (In those days, the known universe consisted of just our Milky Way galaxy.) To Einstein\u2019s surprise, his field equations showed a universe which was either expanding or contracting. Since there was no evidence for such a thing, Einstein added his famous cosmological constant to model an eternally static<\/em> universe \u2013 one that has always been and will always be the same size. <\/p>\n Then in 1927, Belgian priest and physicist Georges Lema\u00eetre — based on his solutions to Einstein\u2019s original field equations, published redshift data, and Edwin Hubble\u2019s distance determinations — proposed the universe is actually expanding. Faced with this compelling evidence, Einstein dropped the cosmological constant from his equations. <\/p>\n Dark Energy<\/strong><\/p>\n Some seventy years later two independent teams led by Saul Perlmutter and Brian Schmidt discovered the expansion of the universe is speeding up<\/em>. (See Hubble, Keck, and the Nobel Prize below.) The mysterious cause of this acceleration has been dubbed “dark energy\u201d.<\/p>\n Einstein had called his cosmological constant \u201cthe greatest mistake of my life.\u201d But now a much larger magnitude cosmological constant appeared necessary to model this accelerating expansion. It seems Einstein is such a genius that even when he makes a mistake, he turns out to be right after all – sort of.<\/p>\n The Future of the Universe<\/strong> Assuming dark energy continues to exist in the same amount in the future (a big assumption since we have no idea what it is), cosmological models for a flat universe including a cosmological constant predict the expansion of the universe will continue to accelerate. As a result, some 100 billion years from now all but the closest galaxies will be receding from us faster than the speed of light, making them impossible to see. <\/p>\n In a trillion years, generation after generation of stars will have finally used up all the hydrogen and helium gases in the universe. With no more nuclear fuel, stars will no longer form, galaxies will go dim, and matter will consist of dead stars, cold planets, and spent meteorites. <\/p>\n In a billion billion years, random collisions of stellar objects will eventually drive many stars to lower galactic orbits. As they circle the black holes at their galactic center, they will give off even stronger gravitational waves. Over time this loss in energy will drive stars closer and closer to the black holes, eventually to be absorbed. Galaxies will then consist of enormous black holes surrounded by dead stars. <\/p>\n But be not dismayed — there is still some hope for our universe. <\/p>\n The End (or the Beginning?)<\/strong> <\/p>\n In an estimated 10^97 to 10^106 years (that\u2019s some billion billion billion billion billion billion billion billion billion billion billion years), black holes will finally evaporate due to Hawking radiation. And per Hawking\u2019s theory, during the final moments of evaporation, these black holes will become white holes, \u201cpumping new matter into the universe in an unpredictable fashion.\u201d So at least theoretically, our universe will continue to exist in some strange new way. <\/p>\n However, predictions for the future of our universe are a very much a work in progress. There are still major questions to be resolved — like what dark energy actually is. Current physics research, including yet to be substantiated theories such as string theory, has the potential to shed new light on both how the big bang came to be as well as the ultimate fate of our universe. But until our understanding of dark energy improves and\/or a new theory replaces general relativity and quantum mechanics, the future of the universe remains speculative at best.<\/p>\n Stay tuned.<\/p>\n References for this article: I welcome all comments — pro and con.<\/p>\n My website: marksmodernphysics.com by Ira Mark Egdall This is the way the world ends This is the way the world ends This is the way the world ends Not with a bang but a whimper. – T. S. Eliot, \u201cThe Hollow Men\u201d, 1925 The first hints that the universe is expanding came in 1917 when Albert Einstein applied … Continue reading “Dark Energy and the Future of the Universe”<\/span><\/a><\/p>\n","protected":false},"author":11,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-104","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"http:\/\/blogs.scienceforums.net\/ime\/wp-json\/wp\/v2\/posts\/104","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/blogs.scienceforums.net\/ime\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/blogs.scienceforums.net\/ime\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/blogs.scienceforums.net\/ime\/wp-json\/wp\/v2\/users\/11"}],"replies":[{"embeddable":true,"href":"http:\/\/blogs.scienceforums.net\/ime\/wp-json\/wp\/v2\/comments?post=104"}],"version-history":[{"count":0,"href":"http:\/\/blogs.scienceforums.net\/ime\/wp-json\/wp\/v2\/posts\/104\/revisions"}],"wp:attachment":[{"href":"http:\/\/blogs.scienceforums.net\/ime\/wp-json\/wp\/v2\/media?parent=104"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/blogs.scienceforums.net\/ime\/wp-json\/wp\/v2\/categories?post=104"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/blogs.scienceforums.net\/ime\/wp-json\/wp\/v2\/tags?post=104"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
\nThis is the way the world ends
\nThis is the way the world ends
\n Not with a bang but a whimper.<\/em>
\n– T. S. Eliot, \u201cThe Hollow Men\u201d, 1925<\/p>\n
\n(see Freedman, Kaufmann, Universe<\/em>)<\/p>\n
\n1) Michael Way, Harry Nussbaumer, Letters, Phys. Today<\/em>, Aug. 2011, p. 8.
\n2) B. Greene, The Fabric of the Cosmos<\/em>, p. 301.
\n3) R. A. Freedman, W. J. Kaufmann III, Universe<\/em>, 6th Edition, p. 661 (including \u201cpumping\u201d quote).<\/p>\n
\nFollow me on twitter @IMEgdall<\/p>\n","protected":false},"excerpt":{"rendered":"