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Topic: Equation of State (Cosmology)

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	Equation of state Summary
		An equation of state is a quantitative relationship among the variables that determine the state of a given system, that is, whether it is solid, liquid, or vapor, its enthalpy or heat content, etc. The state of a system is its condition or situation, at a given instant, and is determined by its properties.
		Equations of state are useful in describing the properties of fluids, mixtures of fluids, solids, and even the interior of stars.
		The Elliott, Suresh, and Donohue (ESD) equation of state (EOS) was proposed in 1990.
	www.bookrags.com /Equation_of_state (2626 words)

	Equation of state (cosmology) - Wikipedia, the free encyclopedia (Site not responding. Last check: 2007-09-12)
		In cosmology, the equation of state of a perfect fluid is characterized by a dimensionless number w, equal to the ratio of its pressure p to its energy density Ï: w = p / Ï.
		The equation of state is used to describe the evolution of a perfect fluid in a homogeneous isotropic universe, the Friedmann-LemaÃ®tre-Robertson-Walker universe.
		In the simplest case, the equation of state of the cosmological constant is w = â’ 1.
	en.wikipedia.org /wiki/Equation_of_state_(cosmology) (535 words)

	Equation of state - Wikipedia, the free encyclopedia
		Equations of state are useful in describing the properties of fluids, mixtures of fluids, solids, and even the interior of stars.
		One of the simplest equations of state for this purpose is the ideal gas law, which is roughly accurate for gases at low pressures and high temperatures.
		The Redlich-Kwong equation is adequate for calculation of gas phase properties when the ratio of the pressure to the critical pressure is less than about one-half of the ratio of the temperature to the critical temperature.
	www.wikipedia.com /wiki/Equations_of_state (1590 words)

	Britannicaindia.com: Britannica Browse
		The state is a form of human association distinguished from...
		in cosmology, a view that the universe is always expanding but maintaining a constant average density, matter being continuously created to form new stars and...
		Austrian physicist who in 1879 formulated a law which states that the radiant energy of a flbody-a theoretical object that absorbs all radiation that falls...
	www.britannicaindia.com /britannica_browse/s/s63.html (1728 words)

	Dark energy - Wikipedia, the free encyclopedia
		In cosmology, dark energy is a hypothetical form of energy which permeates all of space and has strong negative pressure.
		The rate of expansion is parameterized by the cosmological equation of state.
		Measuring the equation of state of dark energy is one of the biggest efforts in observational cosmology today.
	en.wikipedia.org /wiki/Dark_energy (2565 words)

	Scalar Field and All That
		In cosmology we are already used to dealing with two examples of scalar fields - the cosmological constant and the inflaton field (or fields) that drive inflation.
		In the slow roll case, the kinetic energy is negligible and the equation of state is \rho = -p or w = -1.
		They solve the fine tuning problems, the equation of state today is determined by the matter density today, and observational consequences are easy to calculate, so ongoing precision measurements of the CMB anisotropy or matter power spectrum should probe the theory well.
	panisse.lbl.gov /~evlinder/umass/sca.html (1029 words)

	CERN Courier - On the trail of dark energy - IOP Publishing - article
		On the cosmology side, Robert Wagoner in 1986 examined how a general equation of state component would not only affect the expansion, but could be observationally probed with cosmological distance and age measurements.
		Both the modelling of and the investigation of the observational consequences of dark energy are now active industries within research in cosmology, covering a wide variety of the physics of the early and late universe.
		In general, the dark-energy equation of state will vary with time and so needs to be probed with observations over a range of epochs, or astronomical redshifts z (the fractional difference in the scale of the universe today relative to an earlier time).
	www.cerncourier.com /main/article/43/7/16 (1937 words)

	Cosmology with Very Large Gauge Models (1983)
		As discussed at length elsewhere, this equation of state may be modified by phase transitions associated with the restoration of spontaneously broken symmetries.
		equation of state can also be modified in complicated gauge models by the presence of effective couplings which become strong at high energies and which lead to strong interactions in the gas.
		Equation (2) shows that these effects occur if the number of fermions and Higgs scalar bosons becomes large compared to the number of gauge vector bosons.
	www.stephenwolfram.com /publications/articles/cosmology/83-cosmology/3/text.html (1221 words)

	Scalar Field and All That
		In cosmology we are already used to dealing with two examples of scalar fields - the cosmological constant and the inflaton field (or fields) that drive inflation.
		In the slow roll case, the kinetic energy is negligible and the equation of state is \rho = -p or w = -1.
		They solve the fine tuning problems, the equation of state today is determined by the matter density today, and observational consequences are easy to calculate, so ongoing precision measurements of the CMB anisotropy or matter power spectrum should probe the theory well.
	supernova.lbl.gov /~evlinder/umass/sca.html (1027 words)

	Curriculum Vitae R. Ruffini
		The coe~cients of the metric $\delta \alpha \beta$ are determined by the Einstein equations with a source term given by the mean value $\langle \phi \vert\tau_\mu\nu\vert \phi \langle$ of the energy--momentum tensor operator constructed from the scalar or the spinor field.
		Within the framework of a Gamow cosmology with massive neutrinos a scenario is proposed in which both galactic halos and globular clusters are formed due to the existence of a critical injection mass.
		The equations of states are considered for the various decoupling epochs and they are different from classical Bose gas, particularly, in the case of bosons which decoupled at their relativistic regime.
	www.icra.it /People/Ruffini/Ruffini_publication.htm (12481 words)

	Personal Page for Scott Watson
		Lacking the exact equations of string theory, they showed from a simple counting argument that three dimensions was the maximum number that could expand under this process.
		This argument was further investigated in the context of Dilaton cosmology.
		Then the analysis will be continued by obtaining an equation of state and introduce an effective action for the theory.
	www.het.brown.edu /people/watson/pages/statementofresearch.htm (519 words)

	The Equation of State in Astrophysics - Cambridge University Press
		Equations of state in stellar structure and evolution H. Van Horn; 2.
		Equation of state of stellar plasmas F. Rogers; 3.
		Equation of state of dense hydrogen and the plasma phase transition F. Perrot and C. Dharma-wardana; 13.
	www.cambridge.org /catalogue/catalogue.asp?isbn=9780521472609 (744 words)

	Big Bang Theory - Origin of Universe - 0rig.in (Site not responding. Last check: 2007-09-12)
		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.
		Huge advances in Big Bang cosmology were made in the late 1990s and the early 21st century as a result of major advances in telescope technology in combination with large amounts of satellite data such as that from COBE, the Hubble Space Telescope and WMAP.
		Dark energy in its simplest formation takes the form of a cosmological constant term in Einstein's field equations of general relativity, but its composition is unknown and, more generally, the details of its equation of state and relationship with the standard model of particle physics continue to be investigated both observationally and theoretically.
	www.0rig.in /cosmology/big_bang_theory.htm (4780 words)

	CosmoCoffee :: View topic - [astro-ph/0411673] Illuminating Dark Energy with Cosmic Shear
		One of the principal goals of modern cosmology is to constrain the properties of dark energy.
		At present, numerous surveys are aiming to determine the equation of state, which is assumed constant due to our poor understanding of its behaviour (and since higher order parameterisations lead to unwieldy errors).
		However it is painfully apparent from the myriad of dark energy theories that assuming a time-independant equation of state may be quite inappropriate.
	www.cosmocoffee.info /discuss/astro-ph/0411673 (475 words)

	A Big Bang Cosmological Argument For God's Nonexistence
		Einstein's equation says, in simplified terms, that the geometry (curvature) of spacetime is determined by the distribution of mass and energy in spacetime.
		This equation suggests that if the matter in the universe is sufficiently dense, then the curvature of spacetime will become so great that it eventually curves to a point, as at the tip of a cone.
		(2) The earliest state of the universe is inanimate
	www.infidels.org /library/modern/quentin_smith/bigbang.html (8589 words)

	MIT Astrophysics: Cosmology
		The standard model is specified by the size, spatial geometry (open, closed, or flat), and composition of the universe as well as the nature and statistical properties of the small-amplitude initial fluctuations that seeded the formation of galaxies and large scale structure in the universe.
		Astrophysical cosmology focuses on measuring the parameters of the standard model and studying the formation, evolution, and properties of cosmic structures.
		Using both radio (Jacqueline Hewitt) and optical (Paul Schechter) techniques, MIT astronomers are measuring time delays in the multiple images of gravitationally lensed quasars to refine the measurement of the cosmic expansion history and thereby to deduce the equation of state on large scales in the universe.
	web.mit.edu /physics/research/areasofresearch/astrophysics/cosmology.html (705 words)

	Why Steven Hawking's Cosmology Precludes a Creator
		S is the state of the universe that may be called the "big bang"; it precedes the inflationary epoch and gives rise to inflation.
		The probability of the existence of the 3-space S is not conditional upon the existence of any concrete object (body or mind) or concrete event (state of a body or mind) or even upon the existence of any quantum vacuum, empty space or time; the probability follows only from the mathematical properties of possible universes.
		Quantum cosmology is false since it includes among its conditions e + b, and omits G. It is not the mere omission of G that renders quantum cosmology a false theory; it is the inclusion of probabilistically irrelevant conditions e and b as the conditions for h.
	www.philoonline.org /library/smith_1_1.htm (7779 words)

	CfCP: Research (Site not responding. Last check: 2007-09-12)
		The supernovae results have been strongly bolstered by the recent cosmic microwave background measurements of the curvature of the universe, as well as numerous studies of large scale structure and measurements of galaxy clusters, which clearly indicate that only ~1/3 of the energy density of the universe is contributed by matter.
		The implications for both fundamental physics and cosmology are so profound that the theoretical and experimental underpinnings of this result must be fully investigated and, most importantly, verified by independent experimental techniques.
		To determine the equation of state a larger area must be surveyed and the cluster gas properties must be better understood.
	cfcpdev.uchicago.edu /research/structures (902 words)

	The Steady-State Theory (Site not responding. Last check: 2007-09-12)
		Originally the big bang theoy suggested that all the heavy elements were produced at the start of the universe, but now it is accepted that only the helium and a little lithium was produced then and both theories now accept the role of supernovae in the creation of heavy elements.
		One important and little known attribute of the steady state theory is its importance to an aspect of electromagnetic and quantum theory.
		Steady state is not without problems though, there are several areas in which it is in difficulty.
	www.schoolsobservatory.org.uk /study/sci/cosmo/internal/steady.htm (769 words)

	Citebase - Brane cosmology with a van der Waals equation of state (Site not responding. Last check: 2007-09-12)
		Brane cosmology with a van der Waals equation of state
		The evolution of a Universe confined onto a 3-brane embedded in a five-dimensional space-time is investigated where the cosmological fluid on the brane is modeled by the van der Waals equation of state.
		We extend the equation of state of GCG (Generalized Chaplygin Gas) to $w<-1$ regime and show, from the point of view of dynamics, that the parameters of GCG should be in the range of $0<\alpha<1$.
	citebase.eprints.org /cgi-bin/citations?id=oai:arXiv.org:gr-qc/0401060 (752 words)

	Towards an Occult Interpretation af Steiner's Cosmology
		Wachsmuth and Poppelbaum combined the Anthroposophical cosmology with the Geological time-scale and equated the different evolutionary stages of life that characterised each geological era with the consciousness of "Man" (the anthroposophical "root races") in each of Steiner's eras.
		This equivalence is not unreasoinable because the anthroposophical cosmology sees the kingdoms of nature as emanating from the human entity in past eras.
		As I have mentioned, Steiner's elaborate cyclic cosmology, like that of the Theosophists, is a form of emanationism: the materialisation of gross planes or worlds out of subtle ones; the difference being that the Theosophists and Anthroposphists lent a historical slant to their cosmology.
	www.kheper.net /topics/Anthroposophy/Steiner_and_Wilber.htm (1565 words)

	My Research
		These, in turn, are sensitive to the main cosmological paremeters, including the equation of state of dark energy.
		Therefore, strong constraints on the power spectrum normalization, matter content, and the equation of state of the Universe can potentially be obtained from large cluster surveys extending to high (z>1) redshifs.
		Evolution of cluster abundance is one of the most sensitive cosmological probes which can constrain the power spectrum normalization, matter content, and the equation of state of the dark energy.
	astro.uchicago.edu /~daisuke/Research/research_statement.html (1973 words)

	Equation of state (cosmology) - Enpsychlopedia (Site not responding. Last check: 2007-09-12)
		In cosmology, the equation of state of a perfect fluid is characterized by a dimensionless number w, equal to the ratio of its pressure p to its energy density ρ: $w=p/\rho .$
		If a is the scale factor and t is the proper time, then they are related to the equation of state by $\rho\propto a^{-3(1+w)} and, if the fluid is the dominant form of matter in the universe, a\propto t^{-\frac{2}{3(1+w)}} .$
		In the simplest case, the equation of state of the cosmological constant is $w=-1 .$
	psychcentral.com /wiki/Equation_of_State_(Cosmology) (555 words)

	Ned Wright's Cosmology Tutorial
		Cosmology is the study of the origin, current state, and future of our Universe.
		In addition to the cosmology tutorial, there is also a relativity tutorial and extensive discussions on the age, density and size of the Universe.
		The course notes (124 pages, 393 equations, 48 figures) for the upper division undergraduate Stellar Systems and Cosmology course, Astronomy 140, that I last taught in spring 2006 are available on the Web.
	www.astro.ucla.edu /~wright/cosmolog.htm (2959 words)

	The Equation of State in Astrophysics - Cambridge University Press (Site not responding. Last check: 2007-09-12)
		Equations of state in stellar structure and evolution H. Van Horn; 2.
		Equation of state of stellar plasmas F. Rogers; 3.
		Equation of state of dense hydrogen and the plasma phase transition F. Perrot and C. Dharma-wardana; 13.
	uk.cambridge.org /catalogue/catalogue.asp?isbn=0521472601 (739 words)

	Gemini Observatory
		Dark energy is a new, unaccounted-for form of energy that opposes the self-attraction of matter (due to gravity) and accelerates the expansion of the universe.
		The equation of state defines the time dependence of the dark energy density.
		The goal of the SNLS is to obtain 700 well-observed Type Ia supernovae in the redshift range between 0.2 and 0.9 to increase the statistical significance for values of w.
	www.gemini.edu /index.php?option=content&task=view&id=162 (885 words)

	CosmoCoffee :: View topic - [astro-ph/0409574] Constraining Dark Energy with X-ray Galaxy Clusters, Supernovae and the ...
		We examine a series of dark energy models with up to three free parameters: the current dark energy equation of state w_0, the early time equation of state w_et and the scale factor at transition, a_t.
		From a combined analysis of all three data sets, assuming a constant equation of state and that the Universe is flat, we measure w_0=-1.05+0.10-0.12.
		For non-flat models with a constant equation of state, we measure w_0=-1.09+0.12-0.15 and obtain a tight constraint on the current dark energy density, Omega_de=0.70+-0.03.
	cosmocoffee.info /viewtopic.php?t=36 (918 words)

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