Dark matter

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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 behaviour 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 theorical 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. ^[1] 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.

• Dark Matter Observed, [1]