Explane Dark matter to me please?

Question

I know that some scientists think the beyond our solar system there is dark matter but i want to know more about it?

Answer 1

You can learn more here:
http://en.wikipedia.org/wiki/Dark_matter

Answer 2

With physics and mathematics, it is possible to calculate the effect of gravity if you know the mass of the objects and various other factors. These laws work well for predicting the behavior of objects on Earth. However, astrophysicians noticed at some point, while observing spacial systems, that what was observed in space did not correspond to what was predicted by the mathematical laws.

Several theories were made in attempt to explain this. A first theory was that our laws of gravity are wrong. Another theory, which is often considered as the most likely today, is dark matter. Someone realized that if you used more mass in the calculations than what we believe is the mass, the theoretical calculations matched the observations. This theory therefore suggests that there must be more matter in the universe than we thought. It was called dark matter because we know nothing about it and have no real way of detecting it.

It is thought that it does not emit or reflect enough electromagnetic radiation (such as light, x-rays and so on) to be detected directly, making it very difficult to detect. It is thought that it is not made of the same thing as the matter we see everyday on Earth.

Recently, a group of scientists claimed they had found a way to observe dark matter. Since dark matter is supposedly very different from normal matter, it is expected to act differently. They observed two galaxies placed in such a position that normal matter would be stuck behind while dark matter would not, and by measuring gravity they were able to detect what they say is two clouds of two different kinds of matter. Whether this proves the existence of dark matter is still under discussion, however.

Answer 3

Short version:
Nonluminous matter not directly detectable by astronomers, hypothesized to exist because the mass of the visible matter in the universe cannot account for observed gravitational effects. Long believed to exist in large quantities, it enters into many theories of the origin of the universe and its present large-scale structure and into models of gravitation and other fundamental forces between particles. Numerous candidates for dark matter have been proposed over the years, but none has yet been confirmed.

Long Version:

dark matter, material that is believed to make up (along with dark energy) more than 90% of the mass of the universe but is not readily visible because it neither emits nor reflects electromagnetic radiation, such as light or radio signals. Its existence would explain gravitational anomalies seen in the motion and distribution of galaxies. Dark matter can be detected only indirectly, e.g., through the bending of light rays from distant stars by its gravity.

Dark matter may consist of dust, planets, intergalactic gas formed of ordinary matter, or of MACHOs [Massive Astrophysical Compact Halo Objects], nonluminous bodies such as burned-out stars, black holes, and brown dwarfs; these are the so-called hot dark matter and would be dispersed uniformly throughout the universe. The discovery in 2001 of a large concentration of white dwarf stars in the halo surrounding the Milky Way indicates that these burned-out stars could represent as much as a third of the dark matter in the universe.

Other theories hold that it is made of elementary particles that played a key role in the formation of the universe, possibly the low-mass neutrino or theoretical particles called axions and WIMPs [Weakly Interacting Massive Particles]; these are the so-called cold dark matter and would be found in clumps throughout the universe. In 1996 a Japanese team at the Univ. of Tokyo led by Yasushi Ikebe reported on dark-matter clumping in the galactic cluster Fornax. Clumps were found in two distinct regions: around a massive galaxy in the center of the cluster and, in larger amounts, around the entire cluster. This suggests that the slower, cold dark matter might form the smaller clumps associated with the galaxy while the faster, hot dark matter might form the larger clumps associated with the galactic cluster.

Computer simulations of the formation of the universe favored the cold dark matter but tended to predict the formation of too many dwarf galaxies when compared to the observed universe. This led to the postulation of warm dark matter, which resolved the simulation problems. Unlike cold dark matter, which has mass but virtually no velocity or temperature, or hot dark matter, which has mass and is highly energetic, warm dark matter has mass and a low temperature corresponding to an extremely low velocity.

Answer 4

Gravity controls the movement of objects, like stars, galaxies, etc.,. Gravity results from the presence of mass. Astronomers have observed and precisely measured the movement of spiral galaxies. The observed motions can not be explained by any mass that they can detect, like other nearby galaxies, stars, gas and dust within the galaxy, etc.,. The conclusion is that there must be some other mysterious and unknown type of mass present that causes the observed motions. That unknown and so far undetected mass is called 'dark matter.'

Answer 5

Hi. lithiumdeuteride (from the makers of Star Trek) has the answer that I would have given if I was quick enough. A good answer.