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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Amazon's unlikely role in the Calais relief efforts

Campaigners are using Amazon's wishlist feature - more commonly used for weddings and birthdays - to rally supplies for the thousands camped at Calais. 

Today and yesterday, relief efforts have sprung up across the web and IRL following the publication of shocking photos of a drowned refugee child. People are collecting second hand clothes and food, telling David Cameron to offer refuge, and generally funneling support and supplies to the thousands in Calais and across Europe who have been forced from their homes by conflict in Syria and elsewhere. 

One campaign, however, stuck out in its use of technology to crowdsource supplies for the Calais camp. An Amazon wishlist page - more familiar as a way to circulate birthday lists or extravagant wedding registries - has been set up as part of the  #KentforCalais and #HelpCalais campaigns, and is collecting donations of clothes, food, toiletries, tents and sleeping supplies. 

Judging by the Twitter feed of writer and presenter Dawn O'Porter, one of the list's organisers, shoppers have come thick and fast. Earlier today, another user tweeted that there were only six items left on the list - because items had sold out, or the requested number had already been purchased - and O'Porter tweeted shortly after that another list had been made. Items ordered through the list will be delivered to organisers and than transported to Calais in a truck on 17 September. 

This, of course, is only one campaign among many, but the repurposing of an Amazon feature designed to satiate first world materialism as a method of crisis relief seems to symbolise the spirit of the efforts as a whole. Elsewhere, Change.org petitions, clothes drives organised via Facebook, and Twitter momentum (which, in this case, seems to stretch beyond the standard media echo chamber) have allowed internet users to pool their anger, funds and second-hand clothes in the space of 24 hours. It's worth noting that Amazon will profit from any purchases made through the wishlist, but that doesn't totally undermine its usefulness as a way to quickly and easily donate supplies. 

Last year, I spoke to US writer and urbanist Adam Greenfield, who was involved New York's Occupy Sandy movement (which offered relief after after hurricane Sandy hit New York in 2011) and he emphasised the centrality of technology to the relief effort in New York:

Occupy Sandy relied completely on a Googledocs spreadsheet and an Amazon wishlist.  There was a social desire that catalysed uses of technology through it and around it. And if that technology didn't exist it might not have worked the way it did. 

So it's worth remembering, even as Amazon suffers what may be the worst PR disaster in its history and Silicon Valley's working culture is revealed to be even worse than we thought, that technology, in the right hands, can help us make the world a better place. 

You can buy items on the Amazon wishlist here or see our list of other ways to help here

Barbara Speed is a technology and digital culture writer at the New Statesman and a staff writer at CityMetric.