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Tests using
 the Origin of Structure
•Original “clumpiness” is a “blown up” version of the small fluctuations in density present early in the big bang and seen in the background radiation.
–We can compare the structure implied to that expected from the “Grand Unification Theories”
•Rate at which clumpiness grows depends on density of universe
–Amount of clumpiness seems consistent with “flat universe” density
–That means you need dark matter to make clumpiness grow fast enough
From our text:  Horizons, by Seeds