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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Why have men become so lonely – and how does it affect their health?

New findings show the consequences of having a lonely heart.

Go out and get some friends. No, seriously. Hop on the Tube and act faux-interested in the crap-looking book your fellow commuter is reading, even if it's on their Kindle. Chances are it's better than the one in your bag, and they're probably a decent human being and just as lonely, like you and me.

A new slate of facts and figures are showing just how widespread loneliness, is while simultaneously being amazingly terrible for your health.

Research led by Steven Cole from the medicine department at University of California, Los Angeles is showing the cellular mechanisms behind the long known pitfalls of loneliness. Perceived social isolation (PSI) – the scientific term for loneliness –increases the exposure to chronic diseases and even mortality for individuals across the world.

The authors examined the effects of loneliness on leukocytes, also known as white blood cells, which are produced from stem cells in the bone marrow and are critical to the immune system and defending the body against bacteria and viruses. The results showed loneliness increases signalling in the sympathetic nervous system, which is responsible for controlling our fight-or-flight responses, and also affects the production of white blood cells.

Recently, the Movember Foundation, which focuses on men's health and wellbeing, carried out a survey with the help of YouGov investigating friendship and loneliness amongst men. The results are alarming, with only 11 per cent of single men across the spectrum in their early 20s to late-middle age saying they had a friend to turn to in a time of crisis, the number rising to 15 per cent for married men.

Friendship has shown not only to be important to a person's overall wellbeing, but can even add to a person's earnings. A previous study involving 10,000 US citizens over 35 years showed people earned 2 per cent more for each friend they had.

The Movember Foundation survey comes soon after the Office for National Statistics (ONS) showed that men in Britain make up 58 per cent of the 2.47m people living alone between the ages of 45 and 64. The reasons behind this figure include marrying later in life and failed marriages, which usually result in children living with the mother. Women still make up the majority of the 7.7m single-occupant households across all ages in the country, at approximately 54 per cent.

Chronic loneliness seems to have slowly become a persistent problem for the country despite our hyper-connected world. It's an issue that has made even Jeremy Hunt say sensible things, such as "the busy, atomised lives we increasingly lead mean that too often we have become so distant from blood relatives" about this hidden crisis. He's previously called for British families to adopt the approach of many Asian families of having grandparents live under the same roof as children and grandchildren, and view care homes as a last, not first, option.

The number of single-person households has continued to increase over the years. While studies such as this add to the list of reasons why being alone is terrible for you, researchers are stumped as to how we can tackle this major social issue. Here's my suggestion: turn off whatever screen you're reading this from and strike up a conversation with someone who looks approachable. They could end up becoming your new best friend.