Physics Shocker: First Glimpse of Mysterious Dark Matter?

Published December 18, 2009

| London Times

Tantalizing hints of dark matter — the mysterious substance thought to make up a quarter of the universe — have been picked up for the first time, in an American laboratory buried half a mile underground.

Scientists working on the Cryogenic Dark Matter Search, in the disused Soudan iron ore mine in Minnesota, announced last night that they had detected two events with the signature of the weakly-interacting massive particles thought to make up dark matter.

If the signals are confirmed by further observations that will begin next year, they would rank as one of the most important recent advances in physics and understanding of the cosmos.

The nature of dark matter has challenged scientists for more than 70 years. It has been known since the 1930s that the visible matter we can see in stars, galaxies and clouds of cosmic dust accounts for less than 5 per cent of the total mass of the Universe.

Some 25 per cent of the mass is thought to be dark matter, and another 70 per cent to be still more mysterious dark energy. They are known principally from their gravitational effects on galaxies and other normal matter.

The CDMS researchers stressed, however, that they were not claiming to have discovered dark matter: There is a good chance that the events were caused by something else. The probability that the signals were caused by ordinary radioactive decay or cosmic rays is about one in four, they said. A one in 1,000 chance of a random event would be needed to confirm that dark matter has finally been seen.

"In the new data set there are indeed two events seen with characteristics consistent with those expected from WIMPs," the CDMS team said in a statement. "However, there is also a chance that both events could be due to background particles."

"Scientists have a strict set of criteria for determining whether a new discovery has been made, in essence that the ratio of signal to background events must be large enough that there is no reasonable doubt," the CDMS team continued.

For more on this amazing discovery, read the full story at the Times Online.

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