Astrophysicists looking for evidence of dark matter

Astrophysicists are looking everywhere - inside the Large Hadron Collider, in deep mines and far out into space - for evidence of dark  matter, which makes up about 25 percent of the energy density of the universe. Despite the recent tantalising observation of excess  high-energy positrons - thought to be due to dark matter, researchers say we're not quite there yet.

Positron is an elementary particle having the same mass and magnitude of charge as an electron but exhibiting a positive  charge. Worldwide, the hunt for dark matter is in full swing. In the 17-mile-long tunnel of the Large Hadron Collider near Geneva,  Switzerland, scientists are smashing together subatomic particles at nearly light speed in a quest for insight into the nature of the  universe. In dark mine shafts, researchers are registering faint hints of subatomic particles that they surmise could be dark matter.  There are satellite, balloon-borne and ground-based endeavours to find high-energy gamma rays, neutrinos and antimatter that  could be signatures of dark-matter particles.

Models predict that when dark-matter particles collide, they'll annihilate some of the time into electrons and positrons.Scientists  working on a satellite experiment called PAMELA recently identified a large excess of positrons, causing a flurry of excitement about having detected dark matter. These studies sharpens predictions of what scientists can expect to detect from the annihilation of dark-matter particles in our galaxy.

While it shows that currently popular models cannot account for the excess positrons observed, it leaves open the possibility that discovery of dark-matter evidence could be right around the corner, perhaps within reach of current and planned experiments. Success in these multipronged efforts would bring astronomers closer to identifying the invisible material that constitutes a quarter of the world and determines the architecture of the visible universe and physicists would have the first evidence supporting the theory that all forces of nature can be unified under one mathematical expression.

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