Cosmic Microwave Background Radiation

Extracted Attributes

• Type

  Relic radiation, Microwave radiation, Uniform black body thermal energy

• Origin

  Released during the recombination epoch when the universe became transparent

• Spectrum

  Microwave region of the electromagnetic spectrum

• Temperature

  2.72548 ± 0.00057 K

• Significance

  Cornerstone evidence for the Big Bang theory, afterglow of the early universe

• Energy Density

  Exceeds that of all photons emitted by all stars in the history of the universe

• Characteristics

  Almost uniform faint glow with minute temperature variations (anisotropies)

• Universe Age at Emission

  Approximately 380,000 years after the Big Bang

Timeline

• The recombination epoch occurs, where protons and electrons combine to form neutral atoms, making the universe transparent and allowing photons to travel freely, which are observed today as the CMB. (Source: Wikipedia, web search)

  Early Universe (~380,000 years after Big Bang)

• The Cosmic Microwave Background Radiation is accidentally discovered by American radio astronomers Arno Allan Penzias and Robert Woodrow Wilson. (Source: Wikipedia, web search, ESA)

  1965-00-00

• Arno Allan Penzias and Robert Woodrow Wilson are awarded the Nobel Prize in Physics for their discovery of the Cosmic Microwave Background. (Source: web search)

  1978-00-00

Cosmic microwave background

The cosmic microwave background (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, or other object. This glow is strongest in the microwave region of the electromagnetic spectrum. Its total energy density exceeds that of all the photons emitted by all the stars in the history of the universe. The accidental discovery of the CMB in 1965 by American radio astronomers Arno Allan Penzias and Robert Woodrow Wilson was the culmination of work initiated in the 1940s. The 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. 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 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 Planck 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. Extracting fine details from the CMB data can be challenging, since the emission has undergone modification by foreground features such as galaxy clusters.

Web Search Results

• Cosmic Microwave Background Radiation

  The cosmic microwave background (CMB) radiation is a crucial piece of evidence that supports the big bang model for the origin of the universe. First observed accidentally by the radio engineers Arno Penzias and Robert Wilson in 1965, the CMB is a diffuse, uniform background of microwave radiation that comes from all directions in the sky. Astronomers have sought progressively more detailed observations of the CMB, using satellites and balloons to get above the bulk of the Earth's atmosphere. [...] The discovery of the cosmic microwave background radiation is a striking confirmation of the big bang model. The temperature matches that expected for redshifted radiation emitted by a hot gas soon after the universe began, when it was a thousand times smaller and a thousand times hotter than it is now. We can see directly back to 380,000 years after the big bang, when the universe was just 0.003 percent of its current age. The uniformity is a direct verification of the cosmological principle, [...] an indication that at least the early universe was homogeneous and isotropic. Most important of all, the cosmic microwave background radiation is evidence that the universe has evolved; it's a fossil that tells of a hot, dense, and featureless universe out of which galaxies, stars, planets, and people were forged.

• Cosmic microwave background

  The cosmic microwave background (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, or other object. This glow is strongest in the microwave region of the electromagnetic spectrum. Its [...] The cosmic microwave background radiation is an emission of uniform black bodythermal energy coming from all directions. Intensity of the CMB is expressed in kelvin (K), the SI unit of temperature. The CMB has a thermal black body spectrum at a temperature of 2.725 48±0.000 57 K.( Variations in intensity are expressed as variations in temperature. The blackbody temperature uniquely characterizes the intensity of the radiation at all wavelengths; a measured brightness temperature at any [...] The cosmic microwave background radiation and the cosmological redshift-distance relation are together regarded as the best available evidence for the Big Bang event. Measurements of the CMB have made the inflationary Big Bang model the Standard Cosmological Model.( The discovery of the CMB in the mid-1960s curtailed interest in alternatives such as the steady state theory.(

• Case Study: The Cosmic Microwave Background Radiation

  The cosmic microwave background radiation is the faint remnant glow of the big bang. This false color image, covering about 2.5 percent of the sky, shows fluctuations in the ionized gas that later condensed to make superclusters of galaxies. Photo courtesy of the BOOMERANG Project. [...] In 1964, Arno A. Penzias and Robert W. Wilson at the Bell Telephone Laboratories in New Jersey began investigating the microwave radio emissions from the Milky Way and other natural sources. They had a very sensitive detector connected to a large horn-shaped antenna, previously used for satellite communication. When the two scientists tuned their equipment to the microwave portion of the spectrum, they discovered an annoying background static that wouldn’t go away. No matter where they pointed [...] Case Study: The Cosmic Microwave Background Radiation Part of the Cosmic Horizons Curriculum Collection Become a Member » Get Tickets » # Case Study: The Cosmic Microwave Background Radiation Part of the Cosmic Horizons Curriculum Collection. In 1929, Edwin Hubble showed that the light from distant galaxies is shifted to longer wavelengths in proportion to their distances from the Milky Way.

• What is the cosmic microwave background?

  The cosmic microwave background (CMB) is leftover radiation from the Big Bang or the time when the universe began. As the theory goes, when the universe was born it underwent rapid inflation, expansion and cooling. (The universe is still expanding today, and the expansion rate appears different depending on where you look). The CMB represents the heat leftover from the Big Bang. [...] The cosmic microwave background (CMB) radiation tells us the age and composition of the universe and raises new questions that must be answered. See how the Cosmic Microwave Background works and can be detected here. The cosmic microwave background (CMB) radiation tells us the age and composition of the universe and raises new questions that must be answered. See how the Cosmic Microwave Background works and can be detected here. [...] Breaking space news, the latest updates on rocket launches, skywatching events and more! Robert Wilson discovered the cosmic microwave background (CMB) radiation in 1964 along with Arno Penzias, putting the Big Bang theory on solid footing. Wilson and Penzias won the 1978 Nobel Prize in physics for the find. (They shared the award with Soviet scientist Pyotr Kapitsa.)

• ESA - Cosmic Microwave Background (CMB) radiation

  ESA menu toggle ESA search toggle ESA title ESA logo Planck’s view of the cosmic microwave background # Cosmic Microwave Background (CMB) radiation The Cosmic Microwave Background (CMB) is the cooled remnant of the first light that could ever travel freely throughout the Universe. This 'fossil' radiation, the furthest that any telescope can see, was released soon after the Big Bang. [...] The CMB radiation was discovered by chance in 1965. Penzias and Wilson, two radio astronomers in the United States, registered a signal in their radio telescope that could not be attributed to any precise source in the sky. It apparently came from everywhere with the same intensity, day or night, summer or winter. They concluded that the signal had to come from outside our Galaxy. It came almost from the origin of the Universe.