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Scientists Gather in Europe's Deepest Mine to Fathom Life, Universe

Posted on: Wednesday, 6 February 2008, 06:00 CST

BILLIONS of them pass through our bodies on a regular basis. But tiny and invisible, they leave no mark or trace of their passing and do us no harm.

In fact, were it not for the "wimp" particle, life as we know it would not exist.

At least, that's the theory which will be put to the test when researchers including scientists from Edinburgh University switch on one of the world's most sensitive detection devices at the bottom of Europe's deepest mine, in Yorkshire, in the next few days.

At present, the wimp (weakly interacting massive particle) exists only in the minds of physicists but an international race is on, with strong competition from teams in the United States, Italy and Japan, to detect its presence.

If found, it should take scientists to the verge of establishing an all-encompassing "theory of everything" which explains how the universe formed and how small particles interact.

Isaac Newton's theory of gravity and subsequent modifications by Albert Einstein work well when applied to objects on the Earth. But in the early 1930s, an astronomer called Fritz Zwicky realised they did not explain the nature of galaxies - elaborate spiral arms of stars should simply spin out into the universe because the gravitational forces appear too weak to hold them together.

The leading solution to emerge was the idea of "dark matter", a vast amount of invisible material that would generate the required amount of gravity.

Over the decades, the make-up of dark matter and another mysterious, theoretical force, dubbed "dark energy", has remained elusive.

However, wimps have emerged as one of the leading candidates and, for the first time, scientists believe they have created a device - a machine called Zeplin III - capable of detecting one.

One member of the team, Dr Alex Murphy, a physicist at Edinburgh University, said doing so would help resolve one of the strangest mysteries of the universe.

"Maybe I am biased, but dark matter and dark energy are perhaps the two greatest unknowns in science at the moment," he said.

"It's tremendously important what on Earth is going on - or rather what is going on in the heavens. Without dark matter, the galaxies would never have formed, and with no galaxies there would be no humans."

Zeplin III, which cost up to GBP 4 million and is undergoing final testing, was placed 1,100m down the Boulby potash and rock- salt mine, where confusing background radiation can be avoided.

The problem is that wimps are almost impossible to detect because they have such a small effect on the ordinary stuff of which humans, stars and planets are made.

"With normal matter, like the chair you are sitting on, the particles making up the chair have an electromagnetic interaction," Dr Murphy said. "If the particles in that chair didn't have this interaction, you'd fall through."

Wimps may ultimately explain the presence of dark matter, a problem on the scale of galaxies, but the whole idea of their existence came from the study of matter on the very smallest scale.

Particle physicists had developed a good model for how particles acted, but were at a loss to explain why. A theory called super- symmetry suggested that for each of the two-dozen or so known particles, there was an unknown particle.

According to the theory, all but one of these shadowy particles would have a relatively short lifespan, and they would decay over time to become long-lived weakly interacting massive particles, hence wimps. Dr Murphy said. "If we can discover this one thing, it will resolve things on the small scale and the large scale."

Source: Scotsman, The

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