Nonstandard cosmology

The standard Modèle of cosmology is the name given to the cosmological Modèle which was essential little by little like offering the only realistic description of the major part of the history of the universe, of the Big Bang until our days. A whole of more or less elaborate models however were born during the last decades. These models, qualified cosmologies nonstandard propose or claim to offer a vision radically different from the history and the structure to large scales of the Univers.

The concept of nonstandard cosmology should not be confused with that of exact solutions of the equations of the General relativity (the equations of Einstein) describing a universe as a whole, but of which description proves to be physically unrealistic. the Universe of Gödel, discovered at the end of the Years 1940 by Kurt Gödel, or the Espace of Taub-NUT, a little later discovered is solution exact of general relativity, but not claiming to describe the universe. These solutions are of real interest however, because they highlight certain aspects of the general theory of relativity which do not show through in more realistic contexts.

Motivation and context

One distinguishes in practice two types of nonstandard cosmologies:

• Those which go back to one time when the current cosmological model was not well supported by observations, and which offered at the time a plausible alternative to the scenario finally selected. These models have of this fact been the subject of a certain academic activity, with a certain number of articles published in scientific magazines with Reading panel. The relevance of these models was actually discussed, but those were abandoned little by little, proving in major dissension with certain observations. The Theory of the stationary state, proposed at the end of the Years 1940 by Fred Hoyle, Thomas Gold and Hermann Leaped, as well as the Universe of Einstein, proposed in 1917 by Albert Einstein, are examples of cosmology from now on not standard having given place to a certain quantity of work published in scientific magazines at reading panel.
• Those, posterior, which were proposed whereas they did not offer an interesting alternative to the standard model. The majority of these models hardly were the subject of work other than those their authors. They are thus ideas which were always extremely marginal within the academic medium. Some of them however were the subject of a certain press coverage and their name is known near the general public. In the French-speaking mode, the Théorie of the twin universes of the researcher to the retirement Jean-Pierre Petit (inspired by the homonymous theory but not having either had a strong scientific impact of Andrei Sakharov), or the gravitational instanton of null size, Igor and Grichka Bogdanoff is examples of models not having given place to a scientific activity other that their respective authors, but nevertheless popularized by their authors by works intended for the general public (“One lost half of the universe” and “Before Big Bang”, respectively). In this category can also line up various attempts at allegedly scientific speech held by certain monks. The Intelligent design, regarded as concerning the Pseudo-science by the American Academy of Science , and criticized by the the Vatican, is included in this category.

In a case as in the other, one attends two types of justification distinct for this type of models:

• on the one hand the fact that there exists (or would exist) a tension between the standard model of cosmology and the observations which would return the first incompatible one with these last. These tensions are called upon to justify the need for seeking other cosmological scenarios;
• in addition a sales leaflet of more abstract nature, related to the fact that the standard model of cosmology offers an aspect more descriptive than explanatory of the universe. This criterion, often more subjective, can be put in parallel with the assumption of the épicycle S of Ptolémée, which made it possible to predict with a high degree of accuracy the movement of the Planet S, while resting on a convainquant whole of concepts relatively little from a physical point of view.

Theories having given place to a certain academic activity

Universe of Einstein

See also: Universe of Einstein

The very first cosmological model resulting from the equations of general relativity was proposed by Albert Einstein in 1917. It was called thereafter Univers of Einstein. The universe of Einstein rested on two assumptions, namely that the universe was static, and that it was homogeneous. These two assumptions carried out Einstein to propose a solution with the equations of general relativity describing a universe known as “spherical”, i.e. having a space Courbure positive, and having a structure by certain side similar to that of a Sphère ordianire, but having a dimension moreover. This assumption carried out Einstein to propose (even with to deduce within the framework from its starting assumptions) the existence of the matter shape having a repulsive action at long distance, essential to compensate for the gravitational attraction of the ordinary matter. This matter shape was called by cosmological Einstein Constante.

The universe of Einstein was abandoned at the end of the Années 1920 following the description by Edwin Hubble of the Expansion of the universe. It seems that Einstein always was badly at ease with the idea that the Espace-temps can be dynamic, and the assumption of the expansion of the universe was accepted by him only with one certain reserve.

Theory of the tired light

See also: tired Light

The theory of the tired Lumière is an attempt suggested by Albert Einstein to reconcile his assumption of static universe with the observation of the expansion of the universe. The latter being deduced from the observation of a Shift towards the red proportional to the distance for the galaxies, this idea was also recommended by Fritz Zwicky in 1929 like possible alternative explanation. Einstein had put forth the assumption that the light can, for a reason not specified to lose proportionally energy at the distance covered, from where the name of “tired light”. So for an individual photon the tired light is indistinguable assumption of the expansion of the universe, it makes different predictions in certain contexts. In particular, a distribution of photons presenting a spectrum black Corps guard, even if it is not with the thermal balance a spectrum of black body because of expansion of the universe, with a Température which decrease during time. In the case of the tired light, a spectrum of black body is deformed during time. The cosmological diffuse Fond represents the whole of the photons resulting from the dense phase and heat which the paramount Univers knew. It do not interact with the current matter, because of too weak density of this one. The cosmological diffuse bottom had a spectrum of black body in the past, owing to the fact that it was, whereas the universe was very dense and very heat, in interaction with the matter. Since these interactions ceased, approximately 380  000 years after Big Bang (time known as of the recombination). It is observed today that the cosmological diffuse bottom still has a spectrum of black body (it is even the black body most perfect known). This observational fact, bench at the beginning of the Years 1990 by the satellite COBE (and which was worth the Nobel Prize of physics 2006 with the person in charge of instrument FIRAS having made it possible to establish result, John C. Mather) invalid the assumption of the tired light.

The theory of the stationary state

See also: Theory of the stationary state, Theory of the quasi-stationary state

The theory of the stationary state is a model suggested at the end of the Années 1940 by Fred Hoyle, Thomas Gold and Hermann Bondi, supposing that the universe is eternal and immutable. The origin of this idea was double: on the one hand to extend the concept of the cosmological Principle in time, on the other hand, to reconcile tensions which existed at the time between the age of the universe deduces from the value of the Constante from Hubble and the age from oldest stars. The theory of the stationary state stipulated that the universe was expanding, but that the dilution caused by this one was compensated by a phenomenon of creation of matter via a field called Champ C. Thus, the universe would be on this assumption eternal and stationary.

This model was put in difficulty by the discovery of the cosmological diffuse Fond in the current of the Années 1960, the cosmological diffuse bottom being explainable only by the fact that the universe knew a dense and hot phase in the past. Holding of the stationary state tried to call upon a possible thermalization of the stellar radiation by tiny aglets of Fer, without to prove rigorously that an iron abundance could be produced by the stellar evolution. Another more general problem with this model lies in its incapacity to explain the Métallicité observed universe. The stellar evolution predicts indeed that the helium abundance produces by the stellar evolution is about 3 to 4 times larger than that of the whole of the heavier elements. Observationnellement, one observes that approximately 25% of the mass of the baryon Matière of the universe are in the form of helium, and only 2% pennies the shape of heavier elements, sign which it must exist helium produced before the first generations of stars. Lastly, the stationary state does not predict evolution of the populations of Galaxie S according to their distance, contrary to the recent observations, which clearly highlight an evolution of the mass, metallicity, rate of interaction and morphology of these objects.

Incompetent to give an account of very many observations, this model was given up by his author themselves with the profit of the Théorie of the quasi-stationary state. This theory remains based on the idea that the universe creates during the time of the matter, but is distinguished from the theory of the stationary state by the fact that the universe is not in a stationary state (i.e. its average Densité is not constant any more during time, the dilution caused by the Expansion of the universe being counterbalanced more exactly by the phenomenon of creation of matter), but has a cyclic history, based on an alternation of phases of expansion and contraction. These ideas are denounced by the great majority of the Cosmologue S as being fallacious and erroneous. In particular, one should observe that remote objects not present a shift towards the red, but a Décalage towards blue, sign which they are sufficiently far to be seen at one time when the universe was in a phase of contraction.

The universe plasma

See also: Universe plasma

The Univers plasma is a cosmological model suggested by the Nobel Prize of physics Hannes Alfven, whose main feature is to affirm that the phenomena of electromagnetic nature play a part of equal importance that of the Gravitation in the structuring of the universe with large scales. In particular, the observation of various filament structures in the universe was presented by Alfven like the proof of the existence of electrical currents to very large scales. The universe plasma was not the subject of work of quantitative nature. It does not make either predictions, even qualitative, on the Expansion of the universe (or in any case the linear croisasnce of the shift towards the red of the galaxies with the distance), the cosmological diffuse Fond, or the paramount Nucléosynthèse.

Because of the legitimate prestige of its inventor, the universe plasma has a small number to support, primarily resulting from the physics of the plasma. Some scientific articles were published in the review IEEE Transactions one Plasma Science, which does not publish work in other fields of the Astrophysique. In the Anglo-Saxon world, the concept of the universe plasma was diffused near the general public by a book written by the independent researcher Eric Lerner, entitled The Big Bang never happened (“Big Bang forever take place”). This researcher does not have not cepandant production notably quoted by the remainder of the scientific community, and its work is not the comment object published. At most the Cosmologue Edward L. “Ned” Wright, amongst other things member of the missions COBE and WMAP devotes him it a heading on its professional page describing the errors of reasoning which it found in the above mentioned book. These criticisms were the answer object on behalf of Lerner, without to answer all the objections raised by Wright.

Models having had a certain echo near the general public

Creationnism

See also: Créationnisme, Intelligent design

The creationnism in the broad sense is the thesis according to which the Earth the Univers, was created by a supreme being, i.e. a God. Usually, the expression is used to qualify the thesis according to which the universe was created literally such as described the Bible; a modernized version, with scientific appearance, does not claim that the universe was set up such as it is today in six days, but affirms that its evolution was guided. The two theses are regarded as nonnonrefutable scientists because within the meaning of Karl Popper.

Scientific statute

Nonstandard cosmologies do not present the criteria considered as essentiles to a realistic cosmological model (therefore they can be regarded as “not standard”, to see cosmological Modèle - Viability and criteria of relevance of a cosmological model). In particular, none of these models is sufficiently studied by its promoters to be confronted in a way detailed with the precise observational data like the Anisotropie S of the cosmological diffuse Fond measured with an extreme precision by the Artificial satellite WMAP, or the space repair of the Galaxie S, revealed by great statements like the 2dF or SDSS. In general, these models suffer in any event from a certain number of defects which return this type of useless detailed analysis. A commonplace example is the universe of Einstein, which, not predicting the expansion of the universe, is necessarily incompatible with the cosmological observations most elementary, and thus does not require to be confronted with recent precise observations. Holding of these nonstandard cosmologies call upon for their part an incomprehension of their work by the Scientific community to explain the little of interest caused by their work.

Random links:

David Adler | Karl Albrecht | Nizas (Herault) | KorriGo | Zazamarolahy | Eddy Ferhi | Enno_Patalas

© 2007-2008 speedlook.com; article text available under the terms of GFDL, from fr.wikipedia.org