A map generated by ESA's Swarm array, detailing changes in the Earth's magnetic field - red is strengthening, blue is weakening. Image: ESA/DTU Space
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Get ready for the Earth's magnetic field to flip over

New satellite data has indicated that the Earth's magnetic field is weakening, ahead of a rare - but regular - event.

It's still somewhat surprising to think that plate tectonics has only been an accepted and established for roughly 50 years. That is, our understanding of the structure of atoms was more sophisticated, earlier, than our understanding of the planet we live on. Though, that's maybe unfair; as much as scientists could infer the existence of plate tectonics from, for example, the similarities between the coastlines of Africa and South America, gathering evidence to prove that the Earth has a crust floating on a molten mantle was somewhat difficult. (And it meant that the person credited as the modern theory's originator, Alfred Wegener, was considered a crank for years before the establishment changed its mind.)

After the Second World War, scientists were given the chance to use submarine-detecting devices for peaceful research missions, mapping the ocean floor. In the early 1960s a series of papers were published on the magnetic properties of the undersea world, with some surprising findings - it appeared that some places appeared to have ocean floor with a magnetic field that was the reverse of the Earth's. This chimed with the experience of fisherman living off volcanic islands, who have known for centuries that some patches of ocean can cause the north point of a compass to suddenly switch and point south; and it was consistent with magnetic rocks on land that also seemed to have the "wrong" magnetic polarisation.

Yet what became clear when those patches of irregularity were mapped, across the whole of the Atlantic and Pacific, was that they weren't randomly allocated patches - rather, it became clear that the ocean floor was laid out in long, symmetrical stripes of magnetism, emanating from faults like the Mid-Atlantic Ridge. It was clear that magma was coming up from inside the planet, magnetised with a certain polarity, and then cooling and forming new rock as two tectonic plates moved apart from each other; and that every time the Earth's magnetic field flipped, it reversed the polarisation of the magma that was becoming new sea floor. It was a key discovery in confirming the theory of plate tectonics.

It might be a surprise to hear that the Earth's magnetic field flips over, but it does - every few hundred thousand years, the field weakens, then suddenly (which is relative in this context, on the order of a few hundred years) what was north-facing becomes south-facing, and what was south-facing becomes north-facing. We monitor the Earth's magnetic field with satellites these days, and the European Space Agency's Swarm array has noticed it weakening more significantly than expected:

Measurements made over the past six months confirm the general trend of the field’s weakening, with the most dramatic declines over the Western Hemisphere.

But in other areas, such as the southern Indian Ocean, the magnetic field has strengthened since January.

The latest measurements also confirm the movement of magnetic North towards Siberia.

Rune Floberghagen, the mission manager for Swarm, told Live Science that this new data could mean that a flip is due within the next few hundred years, contrary to earlier estimates of around 2,000 years from now.

We don't yet know whether this is signifying a "proper" flip like the Brunhes–Matuyama reversal of nearly 800,000 years ago, or a more temporary one like the one that occured roughly 40,000 years ago during the last ice age, but which only lasted for slightly more than 400 years. This is in part because we still aren't totally sure why these reverses even happen at all. The poles wobble anyway, and it could be that the molten core of the Earth is a bit like a spinning top, occasionally changing its pattern of movement and falling over; or it could be because of large chunks of mantle nearer the surface "fall" into the centre periodically, causing turbulence that throws things off.

Regardless, the changing of the magnetic field is not a cause for alarm, even if the magnetic field is largely responsible for protecting us all from the worst effects of cosmic radiation. This is because the magnetic field does not entirely disappear - it just weakens. There are some who theorise that these events have been linked with mass extinction events, but the evidence is tenuous at best.

Ian Steadman is a staff science and technology writer at the New Statesman. He is on Twitter as @iansteadman.

ILONA WELLMANN/MILLENNIUM IMAGES, UK
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How the internet has democratised pornography

With people now free to circumvent the big studios, different bodies, tastes and even pubic hair styles are being represented online.

Our opinions and tastes are influenced by the media we consume: that much is obvious. But although it’s easy to have that conversation if the medium we are discussing is “safe for work”, pornography carries so much stigma that we only engage with it on simple terms. Porn is either “good” or “bad”: a magical tool for ­empowerment or a destructive influence on society. Many “pro-porn” campaigners shy away from nuanced critique, fearing it could lead to censorship. “Anti-porn” campaigners, convinced that porn is harmful by definition, need look no further than the mainstream tube sites – essentially, aggregators of clips from elsewhere – to gather examples that will back them up.

When we talk about the influence of porn, the emphasis is usually on a particular type of video – hardcore sex scenes featuring mostly slim, pubic-hairless women and faceless men: porn made for men about women. This kind of porn is credited with everything from the pornification of pop music to changing what we actually do in bed. Last year the UK government released a policy note that suggested porn was responsible for a rise in the number of young people trying anal sex. Although the original researcher, Cicely Marston, pointed out that there was no clear link between the two, the note prompted a broad debate about the impact of porn. But in doing so, we have already lost – by accepting a definition of “porn” shaped less by our desires than by the dominant players in the industry.

On the day you read this, one single site, PornHub, will get somewhere between four and five million visits from within the UK. Millions more will visit YouPorn, Tube8, Redtube or similar sites. It’s clear that they’re influential. Perhaps less clear is that they are not unbiased aggregators: they don’t just reflect our tastes, they shape what we think and how we live. We can see this even in simple editorial decisions such as categorisation: PornHub offers 14 categories by default, including anal, threesome and milf (“mum I’d like to f***”), and then “For Women” as a separate category. So standard is it for mainstream sites to assume their audience is straight and male that “point of view” porn has become synonymous with “top-down view of a man getting a blow job”. Tropes that have entered everyday life – such as shaved pubic hair – abound here.

Alongside categories and tags, tube sites also decide what you see at the top of their results and on the home page. Hence the videos you see at the top tend towards escalation to get clicks: biggest gang bang ever. Dirtiest slut. Horniest milf. To find porn that doesn’t fit this mould you must go out of your way to search for it. Few people do, of course, so the clickbait gets promoted more frequently, and this in turn shapes what we click on next time. Is it any wonder we’ve ended up with such a narrow definition of porn? In reality, the front page of PornHub reflects our desires about as accurately as the Daily Mail “sidebar of shame” reflects Kim Kardashian.

Perhaps what we need is more competition? All the sites I have mentioned are owned by the same company – MindGeek. Besides porn tube sites, MindGeek has a stake in other adult websites and production companies: Brazzers, Digital Playground, Twistys, PornMD and many more. Even tube sites not owned by MindGeek, such as Xhamster, usually follow the same model: lots of free content, plus algorithms that chase page views aggressively, so tending towards hardcore clickbait.

Because porn is increasingly defined by these sites, steps taken to tackle its spread often end up doing the opposite of what was intended. For instance, the British government’s Digital Economy Bill aims to reduce the influence of porn on young people by forcing porn sites to age-verify users, but will in fact hand more power to large companies. The big players have the resources to implement age verification easily, and even to use legislation as a way to expand further into the market. MindGeek is already developing age-verification software that can be licensed to other websites; so it’s likely that, when the bill’s rules come in, small porn producers will either go out of business or be compelled to license software from the big players.

There are glimmers of hope for the ethical porn consumer. Tube sites may dominate search results, but the internet has also helped revolutionise porn production. Aspiring producers and performers no longer need a contract with a studio – all that’s required is a camera and a platform to distribute their work. That platform might be their own website, a dedicated cam site, or even something as simple as Snapchat.

This democratisation of porn has had positive effects. There’s more diversity of body shape, sexual taste and even pubic hair style on a cam site than on the home page of PornHub. Pleasure takes a more central role, too: one of the most popular “games” on the webcam site Chaturbate is for performers to hook up sex toys to the website, with users paying to try to give them an orgasm. Crucially, without a studio, performers can set their own boundaries.

Kelly Pierce, a performer who now works mostly on cam, told me that one of the main benefits of working independently is a sense of security. “As long as you put time in you know you are going to make money doing it,” she said. “You don’t spend your time searching for shoots, but actually working towards monetary gain.” She also has more freedom in her work: “You have nobody to answer to but yourself, and obviously your fans. Sometimes politics comes into play when you work for others than yourself.”

Cam sites are also big business, and the next logical step in the trickle-down of power is for performers to have their own distribution platforms. Unfortunately, no matter how well-meaning your indie porn project, the “Adult” label makes it most likely you’ll fail. Mainstream payment providers won’t work with adult businesses, and specialist providers take a huge cut of revenue. Major ad networks avoid porn, so the only advertising option is to sign up to an “adult” network, which is probably owned by a large porn company and will fill your site with bouncing-boob gifs and hot milfs “in your area”: exactly the kind of thing you’re trying to fight against. Those who are trying to take on the might of Big Porn need not just to change what we watch, but challenge what we think porn is, too.

The internet has given the porn industry a huge boost – cheaper production and distribution, the potential for more variety, and an influence that it would be ridiculous to ignore. But in our failure properly to analyse the industry, we are accepting a definition of porn that has been handed to us by the dominant players in the market.

Girl on the Net writes one of the UK’s most popular sex blogs: girlonthenet.com

This article first appeared in the 16 February 2017 issue of the New Statesman, The New Times