<\/p>\n
<\/iframe><\/p>\n<p>(<b>CMB<\/b>, <b>CMBR<\/b>), or <b><i>relic radiation<\/i><\/b>, is <a href=\"https:\/\/en.wikipedia.org\/wiki\/Microwave_radiation\" title=\"Microwave radiation\"><i>microwave<\/i> radiation<\/a> that fills all space in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Observable_universe\" title=\"Observable universe\">observable universe<\/a>. With a standard <a href=\"https:\/\/en.wikipedia.org\/wiki\/Optical_telescope\" title=\"Optical telescope\">optical telescope<\/a>, the background space between stars and galaxies is almost completely dark. However, a sufficiently sensitive <a href=\"https:\/\/en.wikipedia.org\/wiki\/Radio_telescope\" title=\"Radio telescope\">radio telescope<\/a> detects a faint background glow that is almost <a href=\"https:\/\/en.wikipedia.org\/wiki\/Isotropic\" title=\"Isotropic\">uniform<\/a> and is not associated with any star, galaxy, or other <a href=\"https:\/\/en.wikipedia.org\/wiki\/Astronomical_object\" title=\"Astronomical object\">object<\/a>. This glow is strongest in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Microwave\" title=\"Microwave\"><i>microwave<\/i><\/a> region of the electromagnetic spectrum. Its energy density exceeds that of all the photons emitted by all the stars in the history of the universe. The accidental <a href=\"https:\/\/en.wikipedia.org\/wiki\/Discovery_of_cosmic_microwave_background_radiation\" title=\"Discovery of cosmic microwave background radiation\">discovery of the CMB<\/a> in 1964 by American radio astronomers <a href=\"https:\/\/en.wikipedia.org\/wiki\/Arno_Allan_Penzias\" title=\"Arno Allan Penzias\">Arno Allan Penzias<\/a> and <a href=\"https:\/\/en.wikipedia.org\/wiki\/Robert_Woodrow_Wilson\" title=\"Robert Woodrow Wilson\">Robert Woodrow Wilson<\/a> was the culmination of work initiated in the 1940s.<\/p>\n<p>The CMB is the key experimental evidence of the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Big_Bang\" title=\"Big Bang\">Big Bang<\/a> <a href=\"https:\/\/en.wikipedia.org\/wiki\/Scientific_theory\" title=\"Scientific theory\">theory<\/a> for the origin of the universe. In the Big Bang <a href=\"https:\/\/en.wikipedia.org\/wiki\/Cosmological_model\" title=\"Cosmological model\">cosmological models<\/a>, during the earliest periods, the universe was filled with an <a href=\"https:\/\/en.wikipedia.org\/wiki\/Opacity_(optics)\" title=\"Opacity (optics)\">opaque<\/a> fog of dense, hot <a href=\"https:\/\/en.wikipedia.org\/wiki\/Plasma_(physics)\" title=\"Plasma (physics)\">plasma<\/a> of <a href=\"https:\/\/en.wikipedia.org\/wiki\/Sub-atomic_particle\" title=\"Sub-atomic particle\">sub-atomic particles<\/a>. As the universe expanded, this plasma cooled to the point where protons and electrons combined to form neutral atoms of mostly hydrogen. Unlike the plasma, these atoms could not scatter thermal radiation by <a href=\"https:\/\/en.wikipedia.org\/wiki\/Thomson_scattering\" title=\"Thomson scattering\">Thomson scattering<\/a>, and so the universe became transparent. Known as the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Recombination_(cosmology)\" title=\"Recombination (cosmology)\">recombination epoch<\/a>, this <a href=\"https:\/\/en.wikipedia.org\/wiki\/Decoupling_(cosmology)\" title=\"Decoupling (cosmology)\">decoupling event<\/a> released <a href=\"https:\/\/en.wikipedia.org\/wiki\/Photons\" title=\"Photons\">photons<\/a> to travel freely through space. However, the photons have grown less <a href=\"https:\/\/en.wikipedia.org\/wiki\/Photon_energy\" title=\"Photon energy\">energetic<\/a> due to the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Cosmological_redshift\" title=\"Cosmological redshift\">cosmological redshift<\/a> associated with the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Expansion_of_the_universe\" title=\"Expansion of the universe\">expansion of the universe<\/a>. The <i>surface of last scattering<\/i> refers to a shell at the right distance in space so photons are now received that were originally emitted at the time of decoupling.<\/p>\n<p>The CMB is very smooth and uniform, but maps by sensitive detectors detect small but important temperature variations. Ground and space-based experiments such as COBE, WMAP and <i>Planck<\/i> have been used to measure these temperature inhomogeneities. The anisotropy structure is influenced by various interactions of matter and photons up to the point of decoupling, which results in a characteristic pattern of tiny ripples that varies with angular scale. The distribution of the anisotropy across the sky has frequency components that can be represented by a power spectrum displaying a sequence of peaks and valleys. The peak values of this spectrum hold important information about the physical properties of the early universe: the first peak determines the overall curvature of the universe, while the second and third peak detail the density of normal matter and so-called dark matter, respectively.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>(CMB, CMBR), or relic radiation, is microwave radiation that fills all space in the observable universe. With a standard optical telescope, the background space between stars and galaxies is almost completely dark. However, a sufficiently sensitive radio telescope detects a faint background glow that is almost uniform and is not associated with any star, galaxy, [\u2026]<\/p>\n","protected":false},"author":709,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[33,1965,48],"tags":[],"class_list":["post-233141","post","type-post","status-publish","format-standard","hentry","category-cosmology","category-mapping","category-particle-physics"],"_links":{"self":[{"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/posts\/233141","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/users\/709"}],"replies":[{"embeddable":true,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/comments?post=233141"}],"version-history":[{"count":0,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/posts\/233141\/revisions"}],"wp:attachment":[{"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/media?parent=233141"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/categories?post=233141"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/tags?post=233141"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}