Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Strasse 1, 85748 Garching bei München, Germany
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Precise astronomical observations of the cosmic expansion and the anisotropies of the cosmic microwave background have confirmed the simple cosmological “big bang” models. They have also produced evidence for a strange composition of the cosmic matter and energy density. The known baryons contribute only 5 percent to the cosmic substrate, while 25 percent are due to unknown dark matter particles, and 70 percent seem to come from a mysterious dark energy component which presently acts like a cosmological constant accelerating the cosmic expansion.
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