17 April 2008

Science update: dark matter

The DAMA (DArk MAtter) team, led by Rita Bernabei of the University of Rome claims again that they have detected dark matter. See the New York Times article. The DAMA group basically has a big vat (500 pounds) of sodium iodide nearly a mile underneath the Gran Sasso mountain in Italy. They claim to record flashes of light when a WIMP smashes into it because of the Earth's passage through a 'wind' of dark matter particles as it goes around the sun. The flashes of light come about because the sodium iodide is a scintillating material. This method utilizes the idea that the change in the Earth's orientation as it orbits the Sun varies, on a seasonal basis, with its interaction with the cloud of WIMPs that is believed to fill the Solar System. The DAMA team's results are exciting, but so far, no other group has been able to verify them.

A bit of background info. Dark matter is a form of matter that does not emit or reflect enough electromagnetic radiation to be observed directly. We have a lot of indirect evidence, especially gravitational effects on visible matter, for dark matter, but we don't know what it is. A WIMP is a 'weakly-interacting-massive-particle' and is one leading candidate for dark matter. Note that WIMPS only interact through the weak nuclear force and gravity.

Suffice to say, I'd love to read a story featuring dark matter! :)

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