Cosmic microwave background
The cosmic microwave background (CMB or CMBR) is microwave radiation that fills all space in the observable universe. It is a remnant that provides an important source of data on the primordial 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, or other object. This glow is strongest in the microwave region of the radio spectrum. The accidental discovery of the CMB in 1965 by American radio astronomers Arno Penzias and Robert Wilson was the culmination of work initiated in the 1940s.CMB is landmark evidence of the Big Bang theory for the origin of the universe. In the Big Bang cosmological models, during the earliest periods, the universe was filled with an opaque fog of dense, hot plasma of sub-atomic particles. 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 Thomson scattering, and so the universe became transparent. Known as the recombination epoch, this decoupling event released photons to travel freely through space – sometimes referred to as ''relic radiation''. However, the photons have grown less energetic due to the cosmological redshift associated with the expansion of the universe. The ''surface of last scattering'' refers to a shell at the right distance in space so photons are now received that were originally emitted at the time of decoupling.
The CMB is not completely smooth and uniform, showing a faint anisotropy that can be mapped by sensitive detectors. Ground and space-based experiments such as COBE and WMAP have been used to measure these temperature inhomogeneities. The anisotropy structure is determined by various interactions of matter and photons up to the point of decoupling, which results in a characteristic lumpy pattern 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. Extracting fine details from the CMB data can be challenging, since the emission has undergone modification by foreground features such as galaxy clusters. Provided by Wikipedia
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Verantwoordelijke uitgever: Gust Wallaert
Date 1964
“...Centrale der Metaalbewerkers van België (CMB)...”
periodiek
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Affiche uitgegeven in 1990 door de Centrale der Metaalbewerkers van België (CMB) voor informatie over het brugpensioen. Afbeelding: tekening van ...
By CMB
Date 1990
Date 1990
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Affiche uitgegeven in (1987) door de Centrale der Metaalbewerkers van België (CMB) voor de sociale verkiezingen. Afbeelding: tekening van een ...
By CMB, De Batselier, Georges
Date 1987
Date 1987
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By Centrale der Metaalbewerkers van België (CMB)
Date 1899-1989
Date 1899-1989
Archiefcollectie
Bibliotheekcollectie
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Archiefcollectie
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Affiche uitgegeven in 1982 door de Centrale der Metaalbewerkers van België (CMB) voor een perscommuniqué. Afbeelding: tekening van een kraan ...
By CMB, Decoster, Fons
Date 1982
Date 1982
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Affiche uitgegeven in 2000 door de Centrale der Metaalindustrie van België (CMB) voor de sociale verkiezingen. Afbeelding: militanten bij een ...
By CMB, Jorissen, Herwig
Date 2000-2000
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Affiche uitgegeven in 1979 door de Centrale der Metaalindustrie van België (CMB) voor de sociale verkiezingen. Tekst: vandaag… om morgen ...
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Date 1979-1979
Date 1979-1979
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Affiche uitgegeven in 1979 door de Centrale der Metaalindustrie van België (CMB) voor de sociale verkiezingen. Tekst: 3 CMB Centrale ...
By CMB, Vandeperre, Roger
Date 1979-1979
Date 1979-1979
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Het archief geeft een goed beeld van de vrij omvattende taken van een syndicale werking in een middelgroot bedrijf. De ...
By CMB-delegatie ACEC-Gent
Date 1954-1991
Date 1954-1991
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