Just like the CMB, the pattern of fluctuations in the data is intimately related to the constituents of the Universe: it is the same density fluctuations in the early Universe that formed the hot and ...Just like the CMB, the pattern of fluctuations in the data is intimately related to the constituents of the Universe: it is the same density fluctuations in the early Universe that formed the hot and cool spots in the CMB and the high- and low-density regions that are seen as galaxy clusters, filaments, and voids today.