Does dark matter exist?

After 80 years of agreement about the dark stuff, opinions may be changing.

The peasants are revolting. Last night the Flamsteed Astronomical Society met at the National Maritime Museum to hear a debate on the existence (or not) of dark matter. In a vote at the end, the audience decided it probably doesn’t exist.

The idea of dark matter has been around since 1933, when a Swiss astronomer called Fritz Zwicky found that centrifugal forces should have been tearing spinning galaxy clusters apart – but weren’t. The answer, he suggested, was that there was extra stuff in there, whose gravitational pull was holding everything together.
 
Astronomers now believe this stuff makes up around a quarter of the universe, if you take into account all the mass and energy in the cosmos. Ignore the pure energy, and dark matter accounts for 80 per cent of the universe’s mass. Which makes it a little embarrassing that we have never seen any.

Neither do we know what it looks like. We’ve been groping around for dark matter since about 1970. Various predictions have been made: in 1980, astronomer Vera Rubin said it would be found within 10 years. In 1990, astronomer royal Martin Rees said the dark matter mystery would be solved by the turn of the century. In 1999 Rees was aware he had been too hasty, and said we would know what dark matter is by 2004. Last January, CERN theoretical physicist and Gandalf lookalike John Ellis gave the physicists another decade.
 
But patience is starting to wear thin. At last night’s debate, Oxford physicist and co-presenter of The Sky at Night Chris Lintott made the case for dark matter; astronomy writer Stuart Clark argued that a modification to the laws of gravity, which are dictated by Einstein’s general relativity theory, held more promise for explaining the (apparently) missing mass. At the end of the evening, the audience sided with Clark and modifying gravity.
 
That’s not going to have dark matter astronomers quaking in their boots. But it is nonetheless indicative of a change of mood. Take what went on at the Cosmic Variance blog last week. Sean Carroll, the blog’s host, has always been bullishly pro dark matter. But it seems he has started to hedge a bit.
 
In a fascinating post, he published the trialogue he had been conducting with astronomer Stacey McGaugh, the original proponent of the modified gravity idea (it’s called MOND: modified Newtonian Dynamics) and German astrophysicist Rainer Plaga. Right at the top, Carroll concedes that “it may very well turn out that the behavior of gravity on large scales does not precisely match the prediction of ordinary general relativity”. In other words, he is saying, we might well have to modify gravity.
 
It’s worth pointing out a couple more reasons it’s OK to harbour doubts about the dark stuff. Last September, Durham astronomer Carlos Frenk admitted he was “losing sleep” over the results of his own computer simulations. His work had showed that the way simulated dwarf galaxies – mainly composed of dark matter – form in a halo around our own galaxy doesn’t tally with what we observe. His conclusion was that the standard theory of dark matter is almost certainly wrong, adding that searches for the stuff at the LHC in Geneva would therefore prove fruitless.
 
Then last month two groups of astronomers announced that dark matter wasn’t where it should be. The sun is meant to be surrounded by a halo of dark matter, and it isn’t.
 
If there really is no dark matter, that won’t be a mainstream view for decades to come. Once it’s got some momentum, it takes a lot of effort to change direction in science. But it does seem that, after 80 years, someone’s found the handbrake on the dark matter juggernaut.
 

Images of giant galaxy clusters, said to be mainly made up of dark matter. Photograph: Nasa/Getty Images

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.

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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