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Cosmic background radiation is electromagnetic radiation from the Big Bang. The origin of this radiation depends on the region of the spectrum that is observed. One component is the cosmic microwave background. This component is redshifted photons that have freely streamed from an epoch when the Universe became transparent for the first time to radiation. Its discovery and detailed observations of its properties are considered one of the major confirmations of the Big Bang. The discovery (by chance in 1965) of the cosmic background radiation suggests that the early universe was dominated by a radiation field, a field of extremely high temperature and pressure.
The Sunyaev–Zel'dovich effect shows the phenomena of radiant cosmic background radiation interacting with "electron" clouds distorting the spectrum of the radiation.
There is also background radiation in the infrared, x-rays, etc., with different causes, and they can sometimes be resolved into an individual source. See cosmic infrared background and X-ray background. See also cosmic neutrino background and extragalactic background light.
1896: Charles Édouard Guillaume estimates the "radiation of the stars" to be 5.6 K.
1926: Sir Arthur Eddington estimates the non-thermal radiation of starlight in the galaxy has an effective temperature of 3.2 K.
1930s: Erich Regener calculates that the non-thermal spectrum of cosmic rays in the galaxy has an effective temperature of 2.8 K.
1931: The term microwave first appears in print: "When trials with wavelengths as low as 18 cm were made known, there was undisguised surprise that the problem of the micro-wave had been solved so soon." Telegraph & Telephone Journal XVII. 179/1"
1938: Nobel Prize winner (1920) Walther Nernst re-estimates the cosmic ray temperature as 0.75 K.
1946: The term "microwave" is first used in print in an astronomical context in an article "Microwave Radiation from the Sun and Moon" by Robert Dicke and Robert Beringer.
1946: Robert Dicke predicts a microwave background radiation temperature of 20 K (ref: Helge Kragh)
1946: Robert Dicke predicts a microwave background radiation temperature of "less that 20 K"[ clarification needed ] but later revised to 45 K (ref: Stephen G. Brush).
1946: George Gamow estimates a temperature of 50 K.
1948: Ralph Alpher and Robert Herman re-estimate Gamow's estimate at 5 K.
1949: Ralph Alpher and Robert Herman re-re-estimate Gamow's estimate at 28 K.
1960s: Robert Dicke re-estimates a MBR (microwave background radiation) temperature of 40 K (ref: Helge Kragh).
1965: Arno Penzias and Robert Woodrow Wilson measure the temperature to be approximately 3 K. Robert Dicke, P. J. E. Peebles, P. G. Roll and D. T. Wilkinson interpret this radiation as a signature of the Big Bang.
The Big Bang theory is a cosmological model of the observable universe from the earliest known periods through its subsequent large-scale evolution. The model describes how the universe expanded from an initial state of extremely high density and high temperature, and offers a comprehensive explanation for a broad range of observed phenomena, including the abundance of light elements, the cosmic microwave background (CMB) radiation, and large-scale structure.
The cosmic microwave background, in Big Bang cosmology, is electromagnetic radiation as a remnant from an early stage of the universe, also known as "relic radiation". The CMB is faint cosmic background radiation filling all space. It is an important source of data on the early universe because it is the oldest electromagnetic radiation in the universe, dating to the epoch of recombination. With a traditional optical telescope, the space between stars and galaxies is completely dark. However, a sufficiently sensitive radio telescope shows a faint background noise, or glow, almost isotropic, that 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, and earned the discoverers the 1978 Nobel Prize in Physics.
Cosmic noise and galactic radio noise is random noise that originates outside the Earth's atmosphere. It can be detected and heard in radio receivers. Cosmic noise characteristics are similar to those of thermal noise. Cosmic noise is experienced at frequencies above about 15 MHz when highly directional antennas are pointed toward the sun or to certain other regions of the sky such as the center of the Milky Way Galaxy. Celestial objects like quasars, super dense objects that lie far from Earth, emit electromagnetic waves in its full spectrum including radio waves. We can also hear the fall of a meteorite in a radio receiver; the falling object burns from friction with the Earth's atmosphere, ionizing surrounding gases and producing radio waves. Cosmic microwave background radiation (CMBR) from outer space, discovered by Arno Penzias and Robert Wilson, who later won the Nobel Prize for this discovery, is also a form of cosmic noise. CMBR is thought to be a relic of the Big Bang, and pervades the space almost homogeneously over the entire celestial sphere. The bandwidth of the CMBR is wide, though the peak is in the microwave range.
In physical cosmology, Big Bang nucleosynthesis is the production of nuclei other than those of the lightest isotope of hydrogen during the early phases of the Universe. Primordial nucleosynthesis is believed by most cosmologists to have taken place in the interval from roughly 10 seconds to 20 minutes after the Big Bang, and is calculated to be responsible for the formation of most of the universe's helium as the isotope helium-4 (4He), along with small amounts of the hydrogen isotope deuterium, the helium isotope helium-3 (3He), and a very small amount of the lithium isotope lithium-7 (7Li). In addition to these stable nuclei, two unstable or radioactive isotopes were also produced: the heavy hydrogen isotope tritium ; and the beryllium isotope beryllium-7 (7Be); but these unstable isotopes later decayed into 3He and 7Li, as above.
This timeline of cosmological theories and discoveries is a chronological record of the development of humanity's understanding of the cosmos over the last two-plus millennia. Modern cosmological ideas follow the development of the scientific discipline of physical cosmology.
George Gamow, born Georgiy Antonovich Gamov, was a Soviet-American theoretical physicist and cosmologist. He was an early advocate and developer of Lemaître's Big Bang theory. He discovered a theoretical explanation of alpha decay by quantum tunneling, invented the liquid drop model and the first mathematical model of the atomic nucleus, and worked on radioactive decay, star formation, stellar nucleosynthesis and Big Bang nucleosynthesis, and molecular genetics.
The Cosmic Background Explorer, also referred to as Explorer 66, was a satellite dedicated to cosmology, which operated from 1989 to 1993. Its goals were to investigate the cosmic microwave background radiation (CMB) of the universe and provide measurements that would help shape our understanding of the cosmos.
Arno Allan Penzias is an American physicist, radio astronomer and Nobel laureate in physics. Along with Robert Woodrow Wilson, he discoverered the cosmic microwave background radiation, which helped establish the Big Bang theory of cosmology.
Ylem is a term that was used by George Gamow, his student Ralph Alpher, and their associates in the late 1940s for a hypothetical original substance or condensed state of matter, which became subatomic particles and elements as we understand them today. The term ylem was actually resuscitated by Ralph Alpher.
The discovery of cosmic microwave background radiation constitutes a major development in modern physical cosmology. The cosmic background radiation (CMB) was measured by Andrew McKellar in 1941 at an effective temperature of 2.3 K using CN stellar absorption lines observed by W. S. Adams. Theoretical work around 1950 showed the need for a CMB for consistency with the simplest relativistic universe models. In 1964, US physicist Arno Penzias and radio-astronomer Robert Woodrow Wilson rediscovered the CMB, estimating its temperature as 3.5 K, as they experimented with the Holmdel Horn Antenna. The new measurements were accepted as important evidence for a hot early Universe and as evidence against the rival steady state theory. In 1978, Penzias and Wilson were awarded the Nobel Prize for Physics for their joint measurement.
Observational cosmology is the study of the structure, the evolution and the origin of the universe through observation, using instruments such as telescopes and cosmic ray detectors.
Robert Henry Dicke was an American astronomer and physicist who made important contributions to the fields of astrophysics, atomic physics, cosmology and gravity. He was the Albert Einstein Professor in Science at Princeton University.
In physical cosmology, the age of the universe is the time elapsed since the Big Bang. The current measurement of the age of the universe is around 13.8 billion years – 13.787±0.020 billion years within the Lambda-CDM concordance model. The uncertainty has been narrowed down to 20 million years, based on a number of studies which all gave extremely similar figures for the age. These include studies of the microwave background radiation by the Planck spacecraft, the Wilkinson Microwave Anisotropy Probe and other space probes. Measurements of the cosmic background radiation give the cooling time of the universe since the Big Bang, and measurements of the expansion rate of the universe can be used to calculate its approximate age by extrapolating backwards in time.
Ralph Asher Alpher was an American cosmologist, who carried out pioneering work in the early 1950s on the Big Bang model, including Big Bang nucleosynthesis and predictions of the cosmic microwave background radiation.
Robert Herman was a United States scientist, best known for his work with Ralph Alpher in 1948-50, on estimating the temperature of cosmic microwave background radiation from the Big Bang explosion.
The history of the Big Bang theory began with the Big Bang's development from observations and theoretical considerations. Much of the theoretical work in cosmology now involves extensions and refinements to the basic Big Bang model. The theory itself was originally formalised by Belgian Catholic priest, mathematician, astronomer, and professor of physics Georges Lemaître.
Big Bang: The most important scientific discovery of all time and why you need to know about it is a book written by Simon Singh and published in 2004 by Fourth Estate.
Andrei Georgievich Doroshkevich is a Russian theoretical astrophysicist and cosmologist, head of the laboratory on the physics of the early universe at the Lebedev Physical Institute.
Cosmic infrared background is infrared radiation caused by stellar dust.