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what can we know more from cmb
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“We’re realizing that the CMB does not only tell us about the initial conditions of the universe. It also tells us about the galaxies themselves,” said Emmanuel Schaan, also a cosmologist at SLAC.
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https://www.quantamagazine.org/shadows-in-the-big-bang-afterglow-reveal-invisible-cosmic-structures-20230313
more than three decades back but as if it was just yesterday to me
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The Chern-Simons term would rotate the plane of polarization of radiation from distant galaxies, an effect which is not observed.
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https://journals.aps.org/prd/abstract/10.1103/PhysRevD.41.1231