Factbox: The search for dark matter and anti-matter
GENEVA (Reuters) - A particle detector designed to search space for "dark matter" and anti-matter has been developed by scientists at the CERN project in Geneva and is due to be attached to the International Space Station next February.
Following are some scientific terms relating to its planned investigations over the next 20 years:
* ANTI-MATTER - Scientists say the "Big Bang" that brought the universe into being 13.7 billion years ago must have created equal amounts of matter and its opposite, anti-matter. One of the great mysteries of physics is what happened to the anti-matter, since hardly any has been found in the observed universe. Matter and anti-matter annihilate each other on contact, releasing energy.
* ANTI-UNIVERSE - Some researchers, and science fiction writers, have postulated that the anti-matter created a separate but parallel anti-universe, existing on the edge of the known universe and a mirror image of it and everything in it, including life.
* MATTER - The stuff of the universe that can be seen either with the naked eye or through microscopes or telescopes because it emits or reflects light. Scientists say it makes up less than 5 per cent of the content of the universe.
* DARK MATTER - Cosmic matter that cannot be seen because it gives out no light. Based on otherwise unexplained curvature in the path of stars and galaxies as they move through space, astrophysicists calculate that it must make up about 23 per cent of the known universe.
* DARK ENERGY - Like dark matter, cosmologists have little idea what it is. They estimate that it accounts for 72 per cent of the universe. Most believe it is a form of material that has an inverse gravity, repelling matter that comes close to it. This, scientists theorize, is driving the expansion of the universe, pushing stars, planets and galaxies farther and farther apart.
* COSMIC RAYS - There are two types: neutral cosmic light rays from space, which have been studied and measured since the 1960s, and ultra-high energy or charged cosmic rays, which cannot be studied on earth because they are absorbed as soon as they enter the atmosphere. Scientists believe they are emitted by supernovae, explosions of massive stars deep in space.
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