Deep in a mine on the edge of the North Yorkshire moors, a British-led team is trying to solve the biggest mystery in the univer

These two men aren't miners: they're astroparticle physicists whose lab is over half a mile beneath Yorkshire. They're looking for dark matter. They're not sure if it exists or if they'll find it. But they've got until March, and if they do, our world will never be the same again

The journey down, in a dark, cramped cage, air rushing past you, takes a full six-and-a-half minutes. At the deepest point, well over half a mile down below the North Yorkshire moors, the temperature can reach 40°C. If anything went wrong, you’d be trapped beneath layers of water-filled rock at nearly twice the depth of the infamous mine in Chile from which 33 miners had a narrow escape.

Of course, none of this worries the party of scientists travelling down into the Boulby potash mine in the cage this winter morning. If it did they’d be in the wrong field, for the job they do can only be carried out successfully at great depth, below the corrupting influence of the cosmic rays and radiation that bombard the Earth’s surface.

Though they’re dressed just like miners in orange overalls, safety boots with shin guards, hard hats, lamps and – attached to a big belt – the compulsory Self Rescuers (emergency breathing apparatus), they are in fact astroparticle physicists who have come here searching for something altogether more elusive than the mine’s main products, potash and rock salt. Something so elusive, indeed, that no one has yet proved it even exists.

At the bottom of the pit, the miners head one way – towards the pit face – while the scientists head another, down one of the long tunnels with which the mine is honeycombed, over 600 miles worth in all. So long as you don’t think about all the rock and water above you, it’s not especially claustrophobic.

The tunnels are tall and comfortably broad enough for two Land Rovers to drive past one another, and because they’re dug mainly through veins of rock salt they tend to close in at a much slower rate than they would in, say, a coal mine. The temperature is mild, the air breathable with a pleasant hint of salt on the lips.

The scientists climb into a diesel Land Rover made fire safe for underground use, drive 800 yards and park by a small side tunnel. This leads to a makeshift communications area whose plywood frame – currently awaiting reconstruction – is beginning to splinter under the pressure of the ground above.

After a pause here for coffee, they then carry on down a narrow corridor into a changing area, replace their boots and hats with clean ones, and slip on white, disposable zip-up overalls. Their underground laboratory must be kept pristine. That’s why, before they enter, they pass, one at a time, through what looks like a shower but is in fact a sealed vacuuming unit that sucks up every last speck of dust.

At last they are in the laboratory itself, an unremarkable looking, strip-lit room 300ft long with walls painted a grisly shade of fireproof mauve. Overhead are the runners for the two-ton crane that moves the heavy equipment; on one stretch of wall are banks of measuring equipment: computer monitors, dials, wires, meters.

In the middle are the two main pieces of experimental apparatus whose appearance gives little indication of their importance in helping to solve one of the last great mysteries of the universe.
One experiment consists of, mainly, a large box (70 cubic feet), swathed in unsightly transparent polypropylene sheeting, which gives it the appearance of a recent delivery as yet unwrapped.

The other experiment is also a cube, currently stripped to its constituent segments because it’s under repair by a visiting professor from California. It’s made with a series of frames on which are stretched, like on a kitchen egg-slicer, a series of wires so thin you daren’t look too closely lest your hard hat falls onto it and destroys thousands of pounds worth of kit.

The two devices are, respectively, a Dark Matter Detector (called ZEPLIN-III) and a Dark Matter Telescope (DRIFT-II) and both are in a race against time to find a substance so important that as much as 80 per cent of the universe may be made of it.

It’s so scientifically valuable that if only they can be the first to find it, their creators’ names will go down in history alongside Newton’s and Einstein’s; but, frustratingly, it’s so mysterious that none of the scientists involved on the project knows for certain whether dark matter even exists.

The search for dark matter is one of the aims of the £6 billion Large Hadron Collider project at CERN in Switzerland, and a major goal of other American and European projects. This very British attempt is costing less than £1 million a year to run.