Dark skies: a view of the milky way during a meteor shower, Myanmar. Photo: Getty
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Dark energy vs dark matter: a battle of two cosmic monsters

Michael Brooks’s Science Column.

It might be the most prestigious journal in physics, but the Physical Review Letters is no good at teasers. Early in November it published a paper entitled: Indications of a Late-Time Interaction in the Dark Sector. Hardly a great headline for what should have been, in the style of Alien v Predator, “Dark Matter v Dark Energy” – a story of two cosmic monsters locked in eternal conflict.

We believe these monsters exist, but we haven’t seen either of them and we know very little about them. We have suspected the existence of dark matter since 1933, when a Swiss astronomer noticed something odd about the way galaxy clusters spin. They looked like they were being held together by the gravitational pull of invisible matter, which he duly named dark matter. We have been trying to see the stuff ever since, to no avail.

Dark energy is a more recent idea. It, too, comes from astronomical observations, this time of supernovae. A 1998 analysis of the light from these stellar explosions suggested that not only is the universe expanding, but this expansion is getting faster all the time. That can only happen with the help of energy from some unknown source – hence dark energy.

Together, dark energy and dark matter make up 96 per cent of the universe. Now, it turns out, dark energy may be consuming the dark matter.

The discovery came from more observations: this time, of the rate at which cosmic structures form. Dark matter seeds galaxy formation, but galaxies aren’t forming as fast as we would expect. This would make sense if dark matter were disappearing from the universe, but various straightforward explanations for why that might occur have failed to correspond with the observed facts. Now a team of British and Italian researchers has created a computer model that does match the observations. Critical to its success is the idea that dark matter is slowly being converted to dark energy.

According to the simulation, the ingestion of dark matter would be a relatively recent phenomenon, beginning roughly eight billion years ago. If it is really happening, it is important to understand, because our attempts to chart the history of the universe depend on dark matter’s role in forming cosmic structures.

Working from observations of the cosmic microwave background radiation, which came into being roughly 300,000 years after the Big Bang, researchers have shown that the radiation’s distribution through the universe would have seeded long filaments of dark matter. The gravitational pull of these filaments attracted the first atoms of normal matter, gradually creating stars and galaxies in long strings. This is the kind of structure we see now.

Yet if dark energy is slowly taking over from dark matter our previous calculations of cosmic history will have to be corrected. And intriguingly (spoiler alert), it will change our predictions. If dark energy is consuming dark matter, the universe will become dominated by dark energy more quickly than previously thought. That will precipitate an inglorious finale in which dark energy’s repulsive power pushes everything interesting away from us.

Eventually, all the other galaxies will be so far away, and receding so fast, that their light will never reach what remains of our Milky Way. Nearby stars will burn out. Our sun is expected to end its life as a huge single crystal of carbon: a dark diamond in the sky, with no surrounding starlight to make it sparkle.

Afterwards, all the atoms will drift apart and then the fundamental particles of matter will slowly decay to nothing. It’s not a Hollywood ending, but don’t complain that you weren’t warned. 

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.

This article first appeared in the 27 November 2014 issue of the New Statesman, The rise of the insurgents

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A quote-by-quote analysis of how little Jeremy Hunt understands technology

Can social media giants really implement the health secretary’s sexting suggestions? 

In today’s “Did we do something wrong? No, it was social media” news, Health Secretary Jeremy Hunt has argued that technology companies need to do more to prevent sexting and cyber-bullying.

Hunt, whose job it is to help reduce the teenage suicide rate, argued that the onus for reducing the teenage suicide rate should fall on social media companies such as Facebook and Twitter.

Giving evidence to the Commons Health Committee on suicide prevention, Hunt said: “I think social media companies need to step up to the plate and show us how they can be the solution to the issue of mental ill health amongst teenagers, and not the cause of the problem.”

Pause for screaming and/or tearing out of hair.

Don’t worry though; Hunt wasn’t simply trying to pass the buck, despite the committee suggesting he direct more resources to suicide prevention, as he offered extremely well-thought out technological solutions that are in no way inferior to providing better sex education for children. Here’s a quote-by-quote analysis of just how technologically savvy Hunt is.

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“I just ask myself the simple question as to why it is that you can’t prevent the texting of sexually explicit images by people under the age of 18…”

Here’s Hunt asking himself a question that he should be asking the actual experts, which is in no way a waste of anybody’s time at all.

“… If that’s a lock that parents choose to put on a mobile phone contract…”

A lock! But of course. But what should we lock, Jeremy? Should teenager’s phones come with a ban on all social media apps, and for good measure, a block on the use of the camera app itself? It’s hard to see how this would lead to the use of dubious applications that have significantly less security than giants such as Facebook and Snapchat. Well done.

“Because there is technology that can identify sexually explicit pictures and prevent it being transmitted.”

Erm, is there? Image recognition technology does exist, but it’s incredibly complex and expensive, and companies often rely on other information (such as URLs, tags, and hashes) to filter out and identify explicit images. In addition, social media sites like Facebook rely on their users to click the button that identifies an image as an abuse of their guidelines, and then have a human team that look through reported images. The technology is simply unable to identify individual and unique images that teenagers take of their own bodies, and the idea of a human team tackling the job is preposterous. 

But suppose the technology did exist that could flawlessly scan a picture for fleshy bits and bobs? As a tool to prevent sexting, this still is extremely flawed. What if two teens were trying to message one another Titian’s Venus for art or history class? In September, Facebook itself was forced to U-turn after removing the historical “napalm girl” photo from the site.

As for the second part of Jezza’s suggestion, if you can’t identify it, you can’t block it. Facebook Messenger already blocks you from sending pornographic links, but this again relies on analysis of the URLs rather than the content within them. Other messaging services, such as Whatsapp, offer end-to-end encryption (EE2E), meaning – most likely to Hunt’s chagrin – the messages sent on them are not stored nor easily accessed by the government.

“I ask myself why we can’t identify cyberbullying when it happens on social media platforms by word pattern recognition, and then prevent it happening.”

Jeremy, Jeremy, Jeremy, Jeremy, can’t you spot your problem yet? You’ve got to stop asking yourself!

There is simply no algorithm yet intelligent enough to identify bullying language. Why? Because we call our best mate “dickhead” and our worst enemy “pal”. Human language and meaning is infinitely complex, and scanning for certain words would almost definitely lead to false positives. As Labour MP Thangam Debbonaire famously learned this year, even humans can’t always identify whether language is offensive, so what chance does an algorithm stand?

(Side note: It is also amusing to imagine that Hunt could even begin to keep up with teenage slang in this scenario.)

Many also argue that because social media sites can remove copyrighted files efficiently, they should get better at removing abusive language. This is a flawed argument because it is easy to search for a specific file (copyright holders will often send social media giants hashed files which they can then search for on their databases) whereas (for the reasons outlined above) it is exceptionally difficult for algorithms to accurately identify the true meaning of language.

“I think there are a lot of things where social media companies could put options in their software that could reduce the risks associated with social media, and I do think that is something which they should actively pursue in a way that hasn’t happened to date.”

Leaving aside the fact that social media companies constantly come up with solutions for these problems, Hunt has left us with the burning question of whether any of this is even desirable at all.

Why should he prevent under-18s from sexting when the age of consent in the UK is 16? Where has this sudden moral panic about pornography come from? Are the government laying the ground for mass censorship? If two consenting teenagers want to send each other these aubergine emoji a couple of times a week, why should we stop them? Is it not up to parents, rather than the government, to survey and supervise their children’s online activities? Would education, with all of this in mind, not be the better option? Won't somebody please think of the children? 

“There is a lot of evidence that the technology industry, if they put their mind to it, can do really smart things.

Alas, if only we could say the same for you Mr Hunt.

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