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What

is the Cosmic Microwave Background?

The Cosmic Microwave Background (CMB) and Cosmic Microwave Background (CMB) radiation is electromagnetic radiation of wavelength of the order of millimeters (MW) coming from all parts of the cosmos. This phenomenon will fit into the framework of the Big Bang Theory of Russian and American after George Gamow (1904 -1968) providing direct evidence of the validity of this theory. The explanation is: "some 380,000 years after the Big Bang the temperature of the original plasma composed of photons, electrons and protons decreased to 2,727 ° C due to the expansion of the universe. At this time the temperature was low enough for electrons and protons to unite to form neutral atoms of hydrogen, helium and traces of lithium (recombination) as the subject lost its ability to disperse and retain the photons. These photons formed a cosmic background radiation whose wavelength is stretched to the microwave because the universe's expansion into outer space by providing an average temperature of 2.73 K.

How is detected?

Americans In 1965 Arno Penzias (1933 - /) and Robert Wilson (1936 - /) of Bell Labs discovered by chance the FCM thinking it was a parasitic noise while proved a radioantena with were going to do radio astronomy studies. Thanks to this discovery won the Nobel prize in physics in 1978. In 1990 NASA launched the space of the satellite COBE (Cosmic Background Explorer) which won the first map of FCM and discovered a series of anisotropy (variations in temperature) of approximately one part per hundred thousand over the whole sky. On June 30, 2001 re-launched NASA satellite data to refine the FCM called WMAP (Wilkinson Microwave Anisotropy Probe) to the point Langraniano 2 or L2 (position where the gravity of the sun to the Earth- Moon equals the centripetal force of the system) to 1.5 million kilometers of land in the eclipsed sun in the opposite direction.


cosmic microwave background by COBE


The WMAP detected anisotropies of 20 millionths of a kelvin with regard to the average temperature of 2.73 K in areas up to 0.23 degrees of sky. To measure the FCM used two microwave reflector telescopes placed against each other. Each telescope consisted of a primary telescope of 1.6 x 1.4 meters and 1 meter a secondary radiation which concentrated power in 10 cones, 4 of which served to sample the frequency of 90 GHz or 3-wavelength millimeters and the other for frequencies of 22, 30, 40 and 60 GHz at the end of each cone radiation was divided into two orthogonal polarizations were amplified and phase changes until intertwined the two signals from two cones of half their food and temperature differences for some detectors. The WMAP completed a turn every 2 minutes and had a precession of 1 hour of comparing the temperature of a point with a thousand points of Heaven eliminating errors in measurement.


cosmic microwave background by the WMAP


In 2007 the European Space Agency (ESA) plans to launch the Planck satellite, including the point L2 measured temperature differences 5-millionths of a kelvin in areas less than one tenth of a degree.

How do you study?

probes obtained a map of the CMB anisotropies over the whole sky and he made a graph called Power Spectrum facing deviations from the mean temperature respect to the angular frequency of the sky (scale). In this diagram are obtained by a series of peaks representing the scales where temperature variation is greater, usually correspoderán to areas of space where matter density is higher zones of the structure of the cosmos on a large scale. The power spectrum can also be obtained from mapping studies of distant galaxies such as 2dF (2 Degree Field) or the SDSS (Sloan Digital Sky Survey) to face fluctuations in the density of matter on a cosmological scale.

What gives us?

studying the CMB power spectrum have taken many conclusions, which summarize step by step:

• direct test of the validity of the theory of inflation in the U.S. Alan Guth (1947 - /) and the Russian Andrei D. Linde (1948 - /): The origin of fluctuations in the CMB temperature can only be explained in light of inflationary theory according to which the 0.00000000000000000000000000000000000001 seconds after the Big Bang came a scalar field or elementary particle inflaton call that provided the energy needed to accelerate the expansion of the universe frantically so that the area grew faster than the observable universe is the space where the light is able to reach. As we know from quantum mechanics there is uncertainty in the position of particles called quantum fluctuations. The quantum fluctuations of the inflaton, greatly amplified by the accelerating expansion, led to differences in density of matter in the primordial plasma. The hot, dense plasma then behaves like a gas. The differences of density in the primordial gas spread in sound waves heating the gas in the densest areas and cooling in the most rarefied resulting in the characteristic distribution of the CMB temperature. The sound spectrum was formed by a fundamental frequency with a specific wavelength and a series of harmonic sound frequencies that are two, three, four, etc. times the fundamental frequency. Thus the fundamental wave gave rise to large cosmological structures and harmonic minor structures. Inflation acoustic waves generated all at once, so the universe is structured in such harmony, but the wave amplitude of the harmonics becomes negligible after the third harmonic (from the tenth of a degree sky). This is because the wavelength of these harmonics was less than the distance between two particles of the primordial gas. The regions created by the fundamental wave having a size of one degree in the sky which indicates that structures formed nearly a billion light-years.
• geometry of the universe: With the knowledge of the size fundamental wave (nearly a billion light-years) and the distance that the FCM has come to Earth (45,000 million light-years, though the photons have only taken 13,700 million years to go), we have a cosmic triangle whose angles measure exactly 180 °. This means that the universe is Euclidean geometry, ie, is flat. The flatness or curvature of the universe depends on the energy denidad there in the universe. The energy density for the universe is flat and calculated theoretically called critical density, whose value is 0.00000000000000000000000000001 g / cc.
• energy density each type of material and evidence of the existence of dark energy Inflation Theory predicts that sound waves had the same amplitude on all scales but there is a decrease in the amplitude of harmonics resulting in some differences subtle temperature at smaller scales. This is because the sound waves were upset by the force of gravity. In recombination fundamental wave froze when gravity compressing the densest regions, but the first harmonic was frozen when gravity compressed regions in diluted so that the temperature variations were lower (lower wave amplitude). According to this difference in amplitudes we can calculate the gravitational intensity and the intensity of sound pressure that generated the current structures. Gravitational intensity as calculated above and is the value of the energy density of photons and baryons. The results were that the density was 5% of the critical density. Measuring the ratio of amplitudes of the first three peaks was calculated that the densities of cold dark matter must be 25% of the critical density. There comes a escalandaloso result, since 70% of the critical density does not appear anywhere. In this 70% percent is called dark energy responsible for the current rate acceleration of the universe.
• squeeze in the theory of the formation of the first stars: Before WMAP was thought that the first stars had formed about 1,000 million years after the Big Bang reionised again the primordial gas to plasma. This will only polarize the plasma 5% of the FCM at large scales. Thanks to satellite has been found that the CMB is polarized by 17% at large scales. This implies that the date of reionization and the first star formation was at 300 million years after the Big Bang.