Egos and intensity in the search for dark matter

Voices in the dark.

In the next few weeks, the world’s most sensitive dark matter detector will begin its operations under Italy’s Gran Sasso mountain. This seems a good time to point out that it is sharing the mountain with a detector that may already have found some. What a shame, then, that what might one day be viewed as a historic result has been mired in petty name-calling.

We’ve been looking for dark matter since 1933, when the astronomer Fritz Zwicky pointed out that clusters of galaxies move in ways that seemingly defy the laws of physics. The movement made sense only if the clusters were experiencing a gravitational pull from some invisible stuff nearby.

For various reasons, mostly to do with other astronomers not liking Zwicky very much, we’ve been searching for dark matter seriously only since the 1970s. During those four decades, there has been a series of pronouncements about its discovery being only a decade away. It might now be time to take those pronouncements a little more seriously: lately, the sensitivity of detectors has been improving tenfold every two years. We must surely be on the verge of finally nailing down the existence of dark matter. If we haven’t already, that is.

Dark matter doesn’t just hold gravity clusters together – it’s everywhere. It’s right here on earth, for instance: billions of dark matter particles fly through your body every second. You won’t feel them and they won’t harm you. They don’t interact much with the stuff of our everyday reality, which is what has made them so hard to detect.

While we don’t have any concrete detections of single particles, we do seem to have a discernible signal from passing through clouds of dark matter. It was first spotted by the DAMA dark matter detector, which is based, like the new DarkSide-50 detector, deep under the mountains at Gran Sasso. The rock covering them protects the instruments from distracting sources of noise.

In 2008, DAMA’s operators announced that they had identified a signal that rose and faded with the seasons. It might have been ignored, except that this is exactly what Katherine Freese predicted for a dark matter signal in 1986. She said that the intensity of dark matter detections should depend on the time of year, because as the earth whirls round the sun and the sun moves through the Milky Way, the amount of dark matter hitting the detectors will ebb and flow. It’s rather like the difference between walking into wind-driven rain, then turning and walking the other way. In June, dark matter hits Planet Earth full in the face; in December, it’s at our back.

So, it was pretty exciting that DAMA’s detector saw this predicted pattern. It was even more exciting when another detector, CoGeNT, based in a deep underground mine in Minnesota, also saw it. It’s a shame that a third detector, Xenon, didn’t.

Xenon is also in the Gran Sasso mine and there is no love lost between the leaders of these two research efforts. CoGeNT’s Juan Collar has called Xenon’s science “pure, weapons-grade balonium”. Not content with antagonising his peers, Collar has also accused the DAMA project of “cheapening the level of our discourse to truly imbecilic levels”.

Finding dark matter is proving to be astonishingly difficult and everyone knows there’s a Nobel prize at stake, so it’s not surprising that the claws are out.

Anyway, welcome to the fray, DarkSide-50; there is definitely room for more players in this competition. Whether there is room for more egos, however, is another matter.

Inside the DarkSide-50 experiment.

Michael Brooks holds a PhD in quantum physics. He writes a weekly science column for the New Statesman, and his most recent book is At the Edge of Uncertainty: 11 Discoveries Taking Science by Surprise.

This article first appeared in the 18 February 2013 issue of the New Statesman, Iraq: ten years on

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With everything from iPhones to clothing turning monochrome, is the West afraid of colour?

If modern design appears particularly achromatic, it only reflects the "chromophobia" which courses through the history of Western thought.

To many English observers, 1666 – the year that the poet John Dryden christened the annus mirabilis, or “year of miracles” – wasn’t especially miraculous. The country was gripped by plague and, after a hot, dry summer, the Great Fire cut a swath through London. But for Isaac Newton, then still a student, it did prove illuminating. It was in 1666 that he first used prisms to prove that white light was not a pure, indissoluble substance but was made up of different coloured rays. This was such a profound challenge to the prevailing world-view that even Newton was shaken. “I perswade my self,” he wrote, “that this Assertion above the rest appears Paradoxical, & is with most difficulty admitted.”

The belief that colours are inferior and therefore naturally subordinate, rather than fundamental, was not new in Newton’s day, nor did it end with his discovery of spectral colour. A pattern of chromophobia – an aversion to colours – courses through Western thought.

Writing in the fourth century BC, Aristotle argued: “The most attractive colours would never yield as much pleasure as a definite image without colour.” For Renaissance artists, this idea was defined by the division between disegno, drawing or design, and colore. Disegno was the foundation of any serious artistic endeavour. The preference for achromatic, “intellectual” form is also evident in architecture. Despite rock-solid evidence from the 19th century proving that Greek marble buildings and statues were once brightly painted, the classical ideal has remained anachronistically bleached. And while modernist and postmodern architects have made some use of colour, the primacy of form is unmistakable in the work of everyone from John Pawson to Zaha Hadid and Toyo Ito.

A broad cultural dislike of colour is curious because, speaking in evolutionary terms, our ability to see it has been crucial to our success. Colour vision in primates developed between 38 and 65 million years ago and makes us better able to find ripening red and yellow fruits amid green foliage. Neurons devoted to visual processing occupy much more of our neocortex real estate than those devoted to hearing or touch. Estimates vary but the Optical Society of America has suggested that it may be possible for humans to distinguish between up to ten million different shades.

And we have put this skill to good use. Bold colours have been used by many cultures to mark temporal and spiritual power. Tyrian purple, a rich, reddish dye said to resemble clotted blood, was made using an extract from two different kinds of Mediterranean shellfish and was beloved by emperors in the ancient world. A single pound of dyed cloth would cost a skilled craftsman three years’ wages and became steadily more expensive as the shellfish became rarer.

But even as such saturated colours were coveted, they also elicited disgust. The manufacture of many, including Tyrian purple, involved ingredients such as stale urine and dung. Dye and paintworks were relegated to the urban fringes. Increasingly, the wearing of bright colours was seen as vainglorious and ungodly. Protestants indicated their humility by whitewashing over jewel-coloured murals and smashing stained-glass windows in churches, and by restricting their sartorial palette predominantly to black. An echo prevails today in men’s suits: colours are largely confined to small accessories such as ties and white shirts are held up as the ne plus ultra of refined sophistication. (The late Apple co-founder Steve Jobs went one better, opting for a uniform of identical black turtlenecks.)

One reason for this distrust is that colours are difficult to conceptualise. Do they exist physically, or only in our brains? Does everyone see them the same way? Colours have been maligned as chaotic, fickle, irrational and female. The early Christian thinker St Augustine of Hippo accused them of “a seductive and dangerous sweetness”.

Our ambivalence to colour, however, has profited white. Like black, white has not been classed as a real colour since Newton. It has almost become an anti-colour. Take Apple, for example. Although Sir Jony Ive is usually credited with the company’s love for monochrome products (it was certainly Ive who brought this to its apogee), the trend predates his arrival. It can be traced back to the “Snow White” design language developed in the 1980s. Today, as consumer neophilia demands that technology be continually refreshed, Apple’s higher-end products are available in the smallest range of colours – usually just white, black and, for the Asian market, gold – while those lower down come in a slew of fruity brights.

White is not only big business for Apple. In 2014, a Californian man named Walter Liew was found guilty of 20 counts of economic espionage and sentenced to 15 years in jail for selling the secret to a very special shade of titanium-oxide white, used in everything from luxury cars to tennis courts, to Chinese firms for $28m.

Perhaps the final word on the matter should go to Le Corbusier. In 1925, the great modernist recommended that all interior walls should be whitewashed, to act as a moral and spiritual restorative. But he wasn’t just advocating white for white’s sake: although he continued to dabble with colour, he disapproved of it, too. “Let us leave to the clothes-dyers,” he wrote, “the sensory jubilations of the paint tube.”

“The Secret Lives of Colour” (John Murray) by Kassia St Clair will be published on 20 October

This article first appeared in the 26 May 2016 issue of the New Statesman, The Brexit odd squad