Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Alan McDougall on 12/08/2008 13:40:57
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How does dark matter and dark energy effect the fate of the universe?
Wikk article.
Some theorists think that dark energy and cosmic acceleration are a failure of general relativity on very large scales, larger than superclusters. It is a tremendous extrapolation to think that our law of gravity, which works so well in the solar system, should work without correction on the scale of the universe. Most attempts at modifying general relativity, however, have turned out to be either equivalent to theories of quintessence, or inconsistent with observations. It is of interest to note that if the equation for gravity were to approach r instead of r2 at large, intergalactic distances, then the acceleration of the expansion of the universe becomes a mathematical artifact,[clarify] negating the need for the existence of Dark EnergyNature of dark energy
The exact nature of this dark energy is a matter of speculation. It is known to be very homogeneous, not very dense and is not known to interact through any of the fundamental forces other than gravity. Since it is not very dense—roughly 10−29 grams per cubic centimeter—it is hard to imagine experiments to detect it in the laboratory.
Dark energy can only have such a profound impact on the universe, making up 70% of all energy, because it uniformly fills otherwise empty space. The two leading models are quintessence and the cosmological constant. Both models include the common characteristic that dark energy must have negative pressure.
In physics and cosmology, dark matter is matter that does not interact with the electromagnetic force, but whose presence can be inferred from gravitational effects on visible matter.
According to present observations of structures larger than galaxies, as well as Big Bang cosmology, dark matter accounts for the vast majority of mass in the observable universe. The observed phenomena which imply the presence of dark matter include the rotational speeds of galaxies, orbital velocities of galaxies in clusters, gravitational lensing of background objects by galaxy clusters such as the Bullet cluster, and the temperature distribution of hot gas in galaxies and clusters of galaxies.
Dark matter also plays a central role in structure formation and galaxy evolution, and has measurable effects on the anisotropy of the cosmic microwave background. All these lines of evidence suggest that galaxies, clusters of galaxies, and the universe as a whole contain far more matter than that which interacts with electromagnetic radiation: the remainder is called the "dark matter component."
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OK
I Will bounce off this thread by stating that dark matter has a colossal effect on the fate of the universe. Due to the repulsive energy of dark energy the universe expansion is accelerating at a speed greater than that of light and will eventually cause the universe t expand exponentially resulting in a bleak dark cold death in the very far future
Of course there is no concensus on this and the jury is still out debating