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Dark SideFrom MicaThe Power of the Dark Side - How Dark Matter and Dark Energy Dominate the Fate of our Universe 95% of our Universe is made of material that not only can't we see, but that nearly doesn't interact with light at all. Only 5% of the Universe is made up of protons, neutrons, and electrons— the stuff that we normally recognize as matter. About 30% of the Universe is made up of Dark Matter, a tenuous substance that hold together galaxies and clusters of galaxies. We don't know exactly what it is, we have not (as of April 4, 2008, anyway!) identified particles of Dark Matter in the laboroatory... but we know that it exists, for we have seen the effects of it on the motions of stars inside galaxies and on the motions of galaxies, and on the light passing through clusters of galaxies. Even more exotic is Dark Energy; for, while Dark Matter holds galaxies together with its gravity, Dark Energy has a negative gravitational effect! Dark Energy makes up about 70% of our Universe, and is spread quite evenly throughout the Universe. It doesn't have any appreciable effects where matter clumps together (such as on a planet, or even within a galaxy), but it is dominating the expansion of our Universe as a whole, causing that expansion to get ever faster and faster with time. MediaClick here for a PDF file with the slides shown during the talk |