Cosmology Cosmology 21 centimeter radiation is radiation produced during a hyperfine transition of neutral hydrogen from the triplet to the singlet state. The radiation naturally has 21 cm wavelength, or a frequency of 1.4 GHz. The line has a very long lifetime of about ten million years in a vacuum, although it can be considerably shortened due to collisions with other hydrogen atoms and interaction with the cosmic microwave background. It is of great interest in big bang cosmology because it is the only known way to probe the "dark ages" from recombination to reionization. Including the redshift, this line will be observed at frequencies from 200 MHz to about 9 MHz on Earth. It potentially has two applications. First, by mapping redshifted 21 centimeter radiation it can, in principle, provide a very precise picture of the matter power spectrum in the period after recombination. Second, it can provide a picture of how the universe was reionized, as neutral hydrogen which has been ionized by radiation from stars or quasars will appear as holes in the 21 centimeter background. ...more on Wikipedia about "21 centimeter radiation"
The Second Cambridge Catalogue of Radio Sources (2C) was published in 1955 by John R Shakeshaft and colleagues. It comprised a list of 1936 sources between declinations -38 and +83, giving their right ascension, declination, both in 1950.0 coordinates, and flux density. The observations were made with the Cambridge Interferometer, at 81.5 MHz. ...more on Wikipedia about "2C"
In cosmology, the Alpher-Bethe-Gamow paper (or αβγ paper) was created by Ralph Alpher, at the time a physics PhD student, and his advisor George Gamow. Their work, which would become the subject of Alpher's PhD thesis, argued that the big bang would be expected to create hydrogen, helium and heavier elements in the correct proportions to explain their abundance in the early universe. While the original theory neglected a number of processes important to the formation of heavy elements, subsequent developments showed that big bang nucleosynthesis is consistent with the observed constraints on all primordial elements. ...more on Wikipedia about "Alpher-Bethe-Gamow paper"
In the history of cosmology an ambiplasma is a hypothetical plasma containing a mixture of both matter and antimatter. This concept was developed as an alternative to the Big Bang theory. In this concept, the universe has always existed and has no "point" origin. Ambiplasma takes the form of proton-antiprotons (heavy ambiplasma) and electrons-positrons (light ambiplasma). Essentially the universe contains heavy symmetric ambiplasma with protective light ambiplasma, separated by the Leidenfrost effect. ...more on Wikipedia about "Ambiplasma"
In cosmology, the anthropic principle in its most basic form states the truism that any valid theory of the universe must be consistent with our existence as carbon-based human beings at this particular time and place in the universe. In other words, "If something must be true for us, as humans, to exist; then it is true simply because we exist." Attempts to apply this principle to develop scientific explanations in cosmology have led to some confusion and much controversy. ...more on Wikipedia about "Anthropic principle"
Baryogenesis is the generic designation for the hypothetical physical processes that generated an asymmetry between baryons and anti-baryons in the very early universe. ...more on Wikipedia about "Baryogenesis"
In physical cosmology, the Big Bang is the scientific theory that the Universe emerged from an enormously dense and hot state about 13.7 billion years ago. The Big Bang is a consequence of the observed Hubble's law velocities of distant galaxies that when taken together with the cosmological principle imply that space is expanding according to the Friedmann-Lemaître model of general relativity. Extrapolated into the past, these observations show that the Universe has expanded from a primeval state, in which all the matter and energy in the Universe was at an immense temperature and density. Physicists do not widely agree on what happened before this, although general relativity predicts a gravitational singularity. ...more on Wikipedia about "Big Bang"
In cosmology, Big Bang nucleosynthesis (or primordial nucleosynthesis) refers to the production of nuclei other than H-1, the normal, light hydrogen, during the early phases of the universe, shortly after the Big Bang. It is believed to be responsible for the formation of hydrogen (H-1 or H), its isotope deuterium (H-2 or D), the helium isotopes He-3 and He-4, and the lithium isotope Li-7. ...more on Wikipedia about "Big Bang nucleosynthesis"
(Big Bounce) According to some quantum loop gravity theorists, ...more on Wikipedia about "Big Bounce"
In cosmology, the Big Crunch is a hypothesized collapse of the universe upon itself after its expansion eventually stops —a counterpart to the Big Bang. ...more on Wikipedia about "Big Crunch"
The Big Freeze is a scenario in which the universe simply becomes too cold to sustain life due to continued expansion. ...more on Wikipedia about "Big Freeze"
The Big Rip is a cosmological hypothesis about the ultimate fate of the Universe. ...more on Wikipedia about "Big Rip"
The big-particle hypothesis suggests that the dark matter in the universe is made up of big particles that are light years across. ...more on Wikipedia about "Big-particle hypothesis"
Brane cosmology is a protoscience motivated by, but not rigorously derived from, superstring theory and M-theory. The idea is to solve problems in cosmology using speculative particle physics theories and in turn use cosmological observations to motivate ideas in string theory. ...more on Wikipedia about "Brane cosmology"
The bubble universe model is a variant of the inflationary model of the big bang. This model, proposed by physicist Andrei Linde, postulates that our universe is one of many that grew from a multiverse consisting of vacuum that had not yet decayed to its ground state. ...more on Wikipedia about "Bubble universe theory"
A closed universe is a universe in which there is enough internal mass to warp the boundary of the universe until becomes totally curved - nothing can exit through the universe's boundary, it has effectively sealed itself. ...more on Wikipedia about "Closed universe"
The comoving distance or conformal distance of two objects in the universe is the distance divided by a time-varying scale factor representing the expansion of the universe. As a result the comoving distances on average are not increasing with time. The scale factor is usually taken to be one at present, so currently the comoving distance is equal to the ordinary distance. ...more on Wikipedia about "Comoving distance"
The Copernican principle is the philosophical statement that no "special" observers should be proposed. The term originated in the paradigm shift from the Ptolemaic model of the heavens, which placed Earth at the center of the Solar system because it appears that everything revolved around Earth. Nicolaus Copernicus demonstrated that the motion of the heavens can be explained without the Earth being in the geometric center of the system, so the assumption that we are observing from a special position can be dispensed with. ...more on Wikipedia about "Copernican principle"
The cosmic distance ladder refers to the methods by which astronomers determine the distances to celestial objects. Each rung of the ladder provides information that can be used to determine the distances at the next higher rung. ...more on Wikipedia about "Cosmic distance ladder"
In physical cosmology, the cosmic egg is a cosmological concept developed in the 1930s and explored by theoreticians during the following two decades. The idea comes from a perceived need to reconcile Edwin Hubble's observation of an expanding universe (which is also predicted by Einstein's equations of general relativity) with the notion that the universe must be eternally old. ...more on Wikipedia about "Cosmic egg"
Cosmic inflation is the idea, first proposed by Alan Guth in 1981, that the nascent universe passed through a phase of exponential expansion (the inflationary epoch) that was driven by a negative pressure vacuum energy density. This expansion is similar to a de Sitter universe with positive cosmological constant. As a direct consequence of this expansion, all of the observable universe originated in a small causally-connected region. Quantum fluctuations in this microscopic region, magnified to cosmic size, then became the seeds for the growth of structure in the universe (see galaxy formation and evolution). The particle responsible for inflation is generally called the inflaton. ...more on Wikipedia about "Cosmic inflation"
In cosmology, the cosmic microwave background radiation (most often abbreviated CMB but occasionally CMBR, CBR or MBR) is a form of electromagnetic radiation discovered in 1965. It has a thermal black-body spectrum which peaks in the microwave range. Most cosmologists consider the cosmic microwave background radiation to be the best evidence for the hot big bang model of the universe. ...more on Wikipedia about "Cosmic microwave background radiation"
The Cosmic Neutrino Background (CNB) is the background particle radiation composed of neutrinos ...more on Wikipedia about "Cosmic neutrino background"
Cosmic variance is the idea that we are only able to observe one universe, so it is difficult to make statistical statements about cosmology on the scale of the entire universe. ...more on Wikipedia about "Cosmic variance"
In cosmochemistry, the Cosmochemical Periodic Table of the Elements in the Solar System is a periodic table that lists all known chemical elements. In addition, it supplements the standard periodic table with extra information for each element, including its condensation temperature, ...more on Wikipedia about "Cosmochemical Periodic Table of the Elements in the Solar System" There's a bit of www.shortopedia.com in all of us.
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