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Cosmology: The History and Nature of Our UniverseDiscussing cosmic properties; the universe is lumpy at the scale of galaxies and galaxy clusters; at larger scales, it is smooth and similar in all directions; this property of homogeneity and isotropy is called the cosmological principle.![True History Channel]()

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Now PlayingCosmology: The History and Nature of Our UniverseDiscussing cosmic properties; the universe is lumpy at the scale of galaxies and galaxy clusters; at larger scales, it is smooth and similar in all directions; this property of homogeneity and isotropy is called the cosmological principle.0
Cosmology: The History and Nature of Our UniverseThe most familiar constituents of the universe are atomic matter and light; neutrinos make up another component; 96 percent of the universe is dark energy and dark matter; the relative amounts of these constituents changes as the universe expands.