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.

Show Hide image

Forget fake news on Facebook – the real filter bubble is you

If people want to receive all their news from a single feed that reinforces their beliefs, there is little that can be done.

It’s Google that vaunts the absurdly optimistic motto “Don’t be evil”, but there are others of Silicon Valley’s techno-nabobs who have equally high-flown moral agendas. Step forward, Mark Zuckerberg of Facebook, who responded this week to the brouhaha surrounding his social media platform’s influence on the US presidential election thus: “We are all blessed to have the ability to make the world better, and we have the responsibility to do it. Let’s go work even harder.”

To which the only possible response – if you’re me – is: “No we aren’t, no we don’t, and I’m going back to my flowery bed to cultivate my garden of inanition.” I mean, where does this guy get off? It’s estimated that a single message from Facebook caused about 340,000 extra voters to pitch up at the polls for the 2010 US congressional elections – while the tech giant actually performed an “experiment”: showing either positive or negative news stories to hundreds of thousands of their members, and so rendering them happier or sadder.

In the past, Facebook employees curating the site’s “trending news” section were apparently told to squash stories that right-wingers might “like”, but in the run-up to the US election the brakes came off and all sorts of fraudulent clickbait was fed to the denizens of the virtual underworld, much – but not all of it – generated by spurious alt-right “news sites”.

Why? Because Facebook doesn’t view itself as a conventional news provider and has no rubric for fact-checking its news content: it can take up to 13 hours for stories about Hillary Clinton eating babies barbecued for her by Barack Obama to be taken down – and in that time Christ knows how many people will have not only given them credence, but also liked or shared them, so passing on the contagion. The result has been something digital analysts describe as a “filter bubble”, a sort of virtual helmet that drops down over your head and ensures that you receive only the sort of news you’re already fit to be imprinted with. Back in the days when everyone read the print edition of the New York Times this sort of manipulation was, it is argued, quite impossible; after all, the US media historically made a fetish of fact-checking, an editorial process that is pretty much unknown in our own press. Why, I’ve published short stories in American magazines and newspapers and had fact-checkers call me up to confirm the veracity of my flights of fancy. No, really.

In psychology, the process by which any given individual colludes in the creation of a personalised “filter bubble” is known as confirmation bias: we’re more inclined to believe the sort of things that validate what we want to believe – and by extension, surely, these are likely to be the sorts of beliefs we want to share with others. It seems to me that the big social media sites, while perhaps blowing up more and bigger filter bubbles, can scarcely be blamed for the confirmation bias. Nor – as yet – have they wreaked the sort of destruction on the world that has burst from the filter bubble known as “Western civilisation” – one that was blown into being by the New York Times, the BBC and all sorts of highly respected media outlets over many decades.

Societies that are both dominant and in the ascendant always imagine their belief systems and the values they enshrine are the best ones. You have only to switch on the radio and hear our politicians blithering on about how they’re going to get both bloodthirsty sides in the Syrian Civil War to behave like pacifist vegetarians in order to see the confirmation bias hard at work.

The Western belief – which has its roots in imperialism, but has bodied forth in the form of liberal humanism – that all is for the best in the world best described by the New York Times’s fact-checkers, is also a sort of filter bubble, haloing almost all of us in its shiny and translucent truth.

Religion? Obviously a good-news feed that many billions of the credulous rely on entirely. Science? Possibly the biggest filter bubble there is in the universe, and one that – if you believe Stephen Hawking – has been inflating since shortly before the Big Bang. After all, any scientific theory is just that: a series of observable (and potentially repeatable) regularities, a bubble of consistency we wander around in, perfectly at ease despite its obvious vulnerability to those little pricks, the unforeseen and the contingent. Let’s face it, what lies behind most people’s beliefs is not facts, but prejudices, and all this carping about algorithms is really the howling of a liberal elite whose own filter bubble has indeed been popped.

A television producer I know once joked that she was considering pitching a reality show to the networks to be called Daily Mail Hate Island. The conceit was that a group of ordinary Britons would be marooned on a desert island where the only news they’d have of the outside world would come in the form of the Daily Mail; viewers would find themselves riveted by watching these benighted folk descend into the barbarism of bigotry as they absorbed ever more factitious twaddle. But as I pointed out to this media innovator, we’re already marooned on Daily Mail Hate Island: it’s called Britain.

If people want to receive all their news from a single feed that constantly and consistently reinforces their beliefs, what are you going to do about it? The current argument is that Facebook’s algorithms reinforce political polarisation, but does anyone really believe better editing on the site will return our troubled present to some prelap­sarian past, let alone carry us forward into a brave new factual future? No, we’re all condemned to collude in the inflation of our own filter bubbles unless we actively seek to challenge every piece of received information, theory, or opinion. And what an exhausting business that would be . . . without the internet.

Will Self is an author and journalist. His books include Umbrella, Shark, The Book of Dave and The Butt. He writes the Madness of Crowds and Real Meals columns for the New Statesman.

This article first appeared in the 24 November 2016 issue of the New Statesman, Blair: out of exile