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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Forget “digital detoxes”. Spring clean your online life instead

Step one: remove the app on your phone which takes up the most time. 

In 2006, news broke that broke me. The British Heart Foundation unveiled a poster of a blonde girl guzzling a gallon of cooking oil. “What goes into crisps goes into you,” it read, as the charity declared that eating one packet of crisps a day equated to drinking five litres of oil a year.

I gave up crisps that Lent (an admirable act that was somewhat mitigated by devouring a six-pack of McCoy’s on Easter Sunday). Still, despite my continuing pack-a-day habit, the BHF’s statistic has never left me: 365 packets of salt and vinegar crisps are equal to five bottles of Filippo Berio. But other bad habits are harder to comprehend. Last week, I “liked” 36 things on Facebook, wrote ten tweets, and posted five Instagram pictures (two of which were selfies). What effect, if any, has this had on my mental and physical health? How much metaphorical cooking oil am I pouring into my body?

“You really don’t need to worry about the volume of your own social media interactions, based on the average digital user,” the founder of the digital detox specialists Time To Log Off, Tanya Goodin, told me. Goodin says that we “tap, click and swipe” our devices over 2,617 times a day and that the average person will post 25,000 selfies in their life.

Though these statistics seem shocking, what do they mean? What does swiping thousands of times a day do to our minds – or, for that matter, our thumbs? The experts are divided. In 2015, national newspapers spread stories suggesting that using an iPad would damage a toddler’s brain but the research didn’t mention the term “brain damage” once. In fact, as the Guardian pointed out in its debunking, studies produce mixed results: some say iPads help improve child literacy, others say they are distracting.

The studies about adults’ screentime are similarly hard to decipher. Heavy Facebook usage has been linked to depression but there isn’t any apparent cause and effect. Do depressed people use Facebook more, or does Facebook make us depressed? “Internet addiction disorder” (IAD) was a term originally coined as a hoax, but many now see it as a real and treatable problem. Yet it does not feature in the Diagnostic and Statistical Manual of Mental Disorders, and experts still struggle to set diagnostic criteria for it. How much internet is too much?

These academic ambiguities haven’t stopped the idea of the “digital detox” taking off. Detoxers refrain from using any electronics for a period of time in the hope that this will improve their mental health and real-world relationships. At the time of writing, if you search for “digital detox” on Instagram, you’ll find 25,945 people talking about their personal attempts. There are pictures of bike rides, sunsets and children playing, each posted – apparently without irony – to extol the virtues of getting off social media and turning off your phone.

Digital detoxing is also big business. Goodin runs workshops, retreats and camps where no electronics are allowed and the daily schedule consists of yoga, walking, swimming and drinking smoothies. The next one, in Italy, costs from £870 per head for a week. A multitude of such camps exist, as well as books, websites and guides on how to detox by yourself. To connect, man, you have to disconnect, you know?

All of this has made me a digital detoxing cynic. I don’t believe I need to switch off my phone to “live” better, because I believe my phone itself contains life. On Reddit, I can speak to strangers living hundreds of thousands of miles away about their lives. On Twitter, I can keep up to date – in real time – with news and events. If I want to learn yoga or make a smoothie, where will I go to find my local gym or the correct strawberry-to-spinach ratio? Technology can even inspire us to “get out more”. Last summer, the gaming app Pokémon Go spurred people to walk 2,000 more steps a day, and I’m willing to bet that brunch sales figures have skyrocketed since the invention of Instagram.

Digital detoxing relies on the vague idea that tech is somehow toxic. Even without scientific studies to back this up, most of us know from our own, anecdotal evidence how spending too much time on our phones can make us feel. We get down if our latest status doesn’t have enough likes, or our eyes hurt after the sixth “EXTREME PIMPLE POPPING” YouTube video in a row. So, at core, digital detoxing isn’t “wrong”: it is merely misguided. Instead of trying to cut out all technology for a week, we should be curbing our existing habits; rather than a digital detox, we should have a digital spring clean.

Delete – or hide – anyone on your Facebook friends list that you wouldn’t talk to in real life. Remove your work email from your phone (or ask your boss for a separate work phone if you absolutely need access). Delete the app that takes up most of your time – be it Facebook, Twitter or YouTube – so that you are forced to get to it manually, through your browser, and therefore become instantly more aware of how many times a day you open it up. Tanya Goodin also advises me to use my phone less at night. Essentially: go mild turkey. If this is too much and you believe you are addicted to your smartphone or laptop, then, of course, you should seek help (speak to your doctor or call the Samaritans on 116 123).

But most of us just need to get smarter about our internet use. Even if scientists proved that technology was damaging our brains, a week-long detox wouldn’t be the cure. Rather, we should focus on our bad personal habits and try to curb them. Do you get into too many arguments online? Do you ignore your partner because you’re staring at a screen? Do you post opinions you regret because you don’t think them through first? These behaviours are problematic – the internet itself isn’t. To control our lives, we shouldn’t switch off: we should get more switched on.

Amelia Tait is a technology and digital culture writer at the New Statesman.

This article first appeared in the 06 April 2017 issue of the New Statesman, Spring Double Issue

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