Physics 513:   Introduction to Nonlinear Dynamics
Fall 2003

Professor Henry Greenside

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Sloan galaxy distribution
Fractals are sets of points that have a self-similar geometric or statistical structure upon magnification of any part of the set. An especially intriguing and modern fractal set of points (although perhaps not the most spectacular from an artistic point of view) is the positions of 200,000 galaxies up to two billion light years away from Earth (about 1/6 the diameter of the known universe!) as measured recently by the Sloan Digital Sky Survey. Each dot represents a separate galaxy and the color of the dot represents that galaxy's luminosity. An analysis of these data indicate that the baryonic matter that Earth is made of constitutes only 5 percent (!) of the mass of the universe. The rest of the mass consists 25 percent of "dark matter" and 70 percent of "dark energy". What these dark matter and energy consist of are two of the most interesting unsolved questions of current science. And how did the expansion of the universe and the gravitational coupling of matter to dark matter and energy produce this unusual clustered geometric structure?

Earlier figures shown on this page can be found here.

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