# Matéria escura

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A matéria escura, em astronomia, é qualquer matéria hipotética que não seja diretamente detectável, mas que os astrônomos inferem quando a massa real de qualquer objeto celeste observada não é suficiente para explicar um efeito gravitacional observado. É um dos dois conceitos (o outro é a energia escura) que os astrônomos evolucionistas evocam para explicar as observações que as cosmologias do universo-antigo, incluindo o big bang, não podem explicar. Recentemente, o criacionista John Hartnett sugeriu uma nova cosmologia, e uma nova física, que torna este conceito desnecessário.

## A primeira matéria escura

O primeiro registro da invocação de qualquer coisa semelhante a matéria escura foi a hipótese de um planeta chamado Vulcano em meados de 1850. Este planeta era suposto estar dentro da órbita de Mercúrio e ainda nunca foi diretamente observado a partir da Terra, por razões que nenhum astrônomo jamais explicou. Os astrônomos inferiram a existência deste planeta, porque Mercúrio apresenta uma precessão em sua órbita ao redor do Sol por 43 segundos de arco por século, mais rápido do que o esperado pela física newtoniana. Muitos trânsitos aparentemente observados de objetos não identificados através do sol eram considerados este planeta ainda não descoberto.

Então em 1915, Albert Einstein resolveu o problema. Ele mostrou que Mercúrio, no periélio, passa perto o suficiente do Sol para a Relatividade Geral para exigir uma correcção de segunda ordem. Ele publicou a correção e representou exatamente a precessão da órbita de Mercúrio, sem a necessidade de qualquer planeta, cinturão de asteróides, ou outro objeto ou objetos dentro dessa órbita.[1]

## O problema atual

O problema atual envolvendo um déficit de massa em observações astronômicas é conhecido desde a década de 1930, quando os astrônomos primeiro encontraram sérias diferenças entre as massas que inferiram pelo exame das velocidades orbitais e as massas que inferiram pela medição estelar, galática, e outras magnitudes visuais. A equação gravitacional clássica, derivada da teoria da gravidade de Sir Isaac Newton, dá a massa dinâmica total, em qualquer sistema que está dentro da órbita de qualquer corpo específico (por exemplo, uma estrela especial em sua galáxia):

$\frac {v^{{2}}R}{G}$

em que R é a distância do corpo a partir do baricentro, v é a velocidade orbital daquele corpo, e G é a constante gravitacional.

A massa luminosa de qualquer galáxia ou outro objeto é a massa que corresponde à luz medida a partir do objeto.

Jan Oort em primeiro lugar determinou que a massa total da nossa galáxia was insufficient by a factor of at least two to account for the galaxy's rotational speed.[2] The swiss astronomer Fritz Zwicky is also credited with the discovery of the discrepancy between dynamical and luminous mass, in 1933. Zwicky examined the Coma supercluster, and found that its dynamical mass exceeded the luminous mass by a factor of ten.[3][4][5]

Image of galactic cluster with ring of alleged dark matter around it
Since that time, astronomers have assumed that some form of matter, which gives off no measurable radiation, is nevertheless present in various galaxies and galactic clusters that clearly spin faster than their measured luminous masses would predict.[6] They acknowledge, however, that the notion of a new, non-luminous form of matter is difficult to accept. Yet many astronomers insist that they have observational evidence for which dark matter remains the only plausible explanation. One such communication comes from the Chandra X-ray Center, whose astronomers stated in 2006 that they had observed two galactic clusters for hundreds of hours, and that each one clearly showed a rotational speed consistent with far more mass than was visible.[7]

## Creationistic explanation

Creationism, of course, declares that any observed effect results from the creative action of God. In 2000, relying primarily on this theory, Don DeYoung, writing in the Creation Research Society Quarterly,[8] concluded that the hand of God was responsible for holding rapidly spinning galaxies and larger systems together, despite the observed mass deficits.

Most creation scientists, however, prefer to assume an economy of miracles. In that spirit, John Hartnett has produced a solution that requires no continuing miracle, but derives from a new understanding of the creation and expansion of the heavens.[1] Hartnett's system builds on the earlier work of Carmeli, who in 1996 proposed an extension of Einsteinian relativity to the cosmic scale (cosmological relativity). The Hartnett system, explained more fully in his work Starlight, Time and the New Physics, predicts that an expanding universe will produce rapidly spinning galaxies and larger systems as a consequence of the expansion and not due to gravity (or any other force) alone.

The key concept of the Carmeli-Hartnett cosmological relativity system is the description of the cosmos, not as space-time, but as space-mass-velocity. The velocity in view here is the radial velocity of objects in an expanding universe, which is always a function of the distance from the center of the expansion, as:

$\bigg (}{\frac {1}{\tau }}{\bigg )$

where Falhou ao verificar gramática (Falha na conversão para PNG; verifique se o latex, dvips, gs e convert foram correctamente instalados): \tau

is a constant (evaluated at 4.28 * 1017 s) that is the reciprocal of the Hubble factor H0 in weak gravity.[9]

More to the point, Carmeli and Hartnett showed that space itself expands in any galaxy or larger-sized object. Hartnett then showed that this expansion predicts a significantly increased rotational speed for any particle in that object.[10] Specifically,

$4}=GM{\frac {2}{3}}a_{0}{\Bigg \{}{\bigg (}{\frac {R}{2a}}{\bigg )}^{{9/2}}8\Pi ^{{3/2}}{\Bigg \}$

where R = radial position, a0 is a critical acceleration value, G is the gravitational constant, M is the total luminous mass of the galaxy (or group or cluster or supercluster) involved, and Falhou ao verificar gramática (Falha na conversão para PNG; verifique se o latex, dvips, gs e convert foram correctamente instalados): \Pi

depends on the Bessel functions of the ratio R/2a.

The above equation is very similar to the Tully-Fisher relation between luminosity and maximum rotational speed,[11][12]

$4$

where L = luminosity, or

Falhou ao verificar gramática (Falha na conversão para PNG; verifique se o latex, dvips, gs e convert foram correctamente instalados): A=k+4\times \ln v

where A = absolute magnitude. The Tully-Fisher relation was empirical, but Hartnett has given it a theoretical basis. Furthermore, the M given in Hartnett's equation is the regular luminous mass and not a Newtonian dynamical mass. Hence, no correction for any dark-matter proportion is necessary.

Hartnett tested his equation against the observed values of circular velocity of tracer gases in object NGC 3198 as a function of radial distance from the center. He found that this equation fit the observations almost exactly, while a traditional Newtonian equation for radial velocity,

$2}={\frac {GM}{R}$

predicted circular velocities much lower than observed. Hence Hartnett's conclusion that luminous masses are correct, but the physical model that predicts radial velocity is incorrect. Thus, as Einstein obviated the planet Vulcan, Hartnett now claims to obviate dark matter.

## Evolutionistic concept

### Estimated proportion

The Wilkinson Microwave Anisotropy Probe (WMAP) team at NASA has used measurements of cosmic microwave background radiation[13] to determine that the universe is geometrically flat. According to standard cosmology, the universe should then be at a critical mass density of 9.9 * 10-27kg/m³. The actual mass density of the universe is more than twenty times less than that.[14]

Current theory suggests that the familiar baryonic matter (composed of atoms) constitutes only 4.6% of the total mass-energy in the universe. Dark matter constitutes 23% of the total, while dark energy comprises the remaining 72%.[14]

### Proposed explanations for dark matter

Evolutionistic astronomers have generally focused on the following explanations for the discrepancy between dynamical and luminous mass:

1. Brown dwarf stars and similarly massive but relatively non-luminous objects. Astronomers have in fact invented a new name for a class of objects that include brown dwarf stars and other massive objects: Massive Compact Halo Objects, or MACHOs.[3][5][14][15]
2. Supermassive black holes. Astronomers are now attempting to detect these objects by their relativistic effects on light, in which they act as lenses.[14]
3. New, previously unknown forms of matter. Many cosmologists have formed hypotheses that suggest entirely new particles of matter. They call these Weakly Interactive Massive Particle, or WIMPs.[14][3][5] Other cosmologists have suggested other types of particles, named axions.[1][16] The recently sought Higgs boson is another candidate for a dark-matter elementary particle.
4. A new theory of gravity. In 1983, Mordecai Milgrom first suggested that Newtonian dynamics was insufficient to explain the gravitational interactions of massive objects like galaxies and galactic clusters. He therefore suggested a Modified Newtonian Dynamic, or MOND, in which gravitational attraction varied inversely to the first power of the orbital radius, not its square as Newton originally assumed.[1][2]

Tim Thompson[2] has recently suggested yet another possibility to which most astronomers pay scant attention. He suggests that the major attractive force that allows galaxies and systems of higher mass to rotate with such excessive speed is not gravity at all, but electrostatic forces. He reminds his readers that electrostatic forces are stronger than gravity, and also that the strength of a magnetic field varies inversely as the first power, not the square, of the distance from the center. This is very close to Milgrom's MOND, with the advantage of having an underlying theory to explain it,[2] which Milgrom's system does not have.[1]

Don DeYoung challenged the notion of dark matter as a fanciful concept with little justification.[8] He pointed out that none of the conventional explanations popular at the time were satisfactory:

1. Non-luminous stars, the usual candidates for MACHOs, would have to be far more common than they actually are, by several orders of magnitude, for them to account for the mass deficit.
2. Black holes are a theoretical construct that have not thus far been verified.
3. Efforts to detect WIMPs and axions have thus far produced no definitive findings.

DeYoung also challenged the notion that galaxies or galactic clusters were necessarily stable. He did not comment directly on Milgrom's modified dynamic, but he did suggest that gravity was poorly understood.

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## Referências

1. Hartnett, John. Starlight, Time and the New Physics. Creation Book Publishers, 2007. ISBN 9780949906687.
2. Thompson, Tim. "Missing 'Dark' Matter." The Electric Cosmos, n.d. Accessed July 28, 2008.
3. Silk, Joe. "Dark Matter." Department of Astronomy, University of California-Berkeley, ca. 1995. Accessed July 28, 2008.
4. Soter S and deGrasse-Tyson N, eds. "[Fritz Zwicky's Extraordinary Vision]." Excerpt from Cosmic Horizons: Astronomy at the Cutting Edge, New Press, 2000. ISBN 978-1565846029 Accessed July 28, 2008.
5. Miller CM. "Cosmic Hide and Seek: the Search for the Missing Mass." 1995. Accessed July 28, 2008.
6. Authors unknown. "Dark Matter Mystery." Field Guide to X-ray Astronomy, Chandra X-ray Center, Harvard University, Cambridge, MA, August 29, 2006. Accessed July 28, 2008.
7. Hupp E, Roy S., and Watzke M. "NASA Finds Direct Proof of Dark Matter." NASA, press release 06-297, August 21, 2006. Accessed July 28, 2008.
8. DeYoung DB. "Dark Matter." Creation Research Society Quarterly, 36(4), March 2000. Accessed July 28, 2008.
9. Evolutionistic astronomers might assume that this value gives the age of the universe; it does in fact give a value very close to the visible radius of the universe, measured in light-years. It probably does represent a value that an observer at the limits of the visible universe might measure for its age—because the Carmeli-Hartnett system also predicts tremendous time dilation at the center of the expansion.
10. Hartnett JG, "Spiral galaxy rotation curves determined from Carmelian general relativity," Int. J. Theor. Phys. 45 (2006) 2118-2136. arXiv:astro-ph/0511756 doi:10.1007/s10773-006-9178-0
11. Tully RB and Fisher JR, "A New Method of Determining Distance to Galaxies", Astron. Astrophys. 54, 661-673 (1977)
12. "The Tully-Fisher Relation," The Astroprof's Page, April 4, 2007
13. Hinshaw GF, and Griswold, B. "WMAP Mission Results." NASA, April 17, 2008. Accessed July 26, 2008.
14. Hinshaw GF, and Griswold B. "WMAP - Content of the universe." NASA, April 17, 2008. Accessed July 28, 2008.
15. White, Martin. "Dark Matter." Department of Astronomy, University of California at Berkeley, Berkeley, California, ca. 1995. Accessed July 28, 2008.
16. The name Axion is a registered trademark of the Colgate-Palmolive Company (USA) and was the name of a once-popular brand of laundry detergent used to pre-soak heavily-soiled garments before washing them with a conventional detergent. The astrophysicists who coined this name suggested that axions performed some kind of cosmic cleansing.