An artist's impression of SN 2006gyM, one of the brightest supernovas ever recorded. Photo: Weiss/NASA/CXC/Getty
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“Supernova in a bottle” will help create matter from light

The new process could provide a clean way of doing particle physics experiments.

In 1934, two physicists came up with a theory that described how to create matter from pure light. But they dismissed the idea of ever observing such a phenomenon in the laboratory because of the difficulties involved setting up such an experiment.

Now, Oliver Pike of Imperial College London and his colleagues have found a way to achieve this dream, 80 years after US physicists Gregory Breit and John Wheeler explained the theory. This group hopes to use high-energy lasers aimed at a specially designed gold vessel to convert photons into matter-antimatter particle pairs, recreating what happens in some exceptional stellar explosions.

Pike, who led the research published in the journal Nature Photonics, said, “The idea is that light goes in and matter comes out.” To be sure, the matter created won’t be every day-objects; instead the process will produce sub-atomic particles.

“To start with, the matter will consist of electrons and its antimatter equivalent positrons,” Pike said. “But with higher energy input in the lasers, we should be able to create heavier particles.”

Pike concedes this won’t be the first time light has been converted into matter. In 1997, US researchers at the Stanford Linear Accelerator Centre (SLAC) were able to do so, albeit in a different way.

The SLAC experiment used electrons to first create high-energy light particles, which then underwent multiple collisions to produce electrons and positrons, all within same chamber. This is called the multi-photon Breit-Wheeler process, named after the two physicists who came up with the theory in 1934.

“The key difference in the SLAC experiment and the one we propose is that our process will be more straightforward,” Pike said. In the new proposal, the laser beam will still be generated using free electrons, but it will be separated from the electrons.

Why create light using matter and then convert it back? Apart from showing that the Breit-Wheeler process can happen without the multiple photons the SLAC experiment needed, Pike thinks their process provides a clean way of doing particle physics experiments.

Current particle-physics experiments involve smashing sub-atomic particles at great speeds and sorting through the mess of new particles that are created in the explosion. This is how the Higgs boson was found in the Large Hadron Collider.

The new experimental design will be similar. Rather than involving a complicated mix of particles and photons, the laser beam will be sent into a small gold hohlraum (German for “empty room”). There, individual photons can interact with the radiation field that’s generated when the hohlraum is excited by a laser, creating the electron-positron pairs.

“While physicists have excellent methods to sift through such data, our process has the advantage that it will be easier to analyse,” Pike said. “Light will go in from one end of the hohlraum and particles created will come out from the other end.”

Pike and colleagues are now working to secure time on high-energy laser beams to carry out the experiment. The two likely candidates are Aldermaston, Berkshire in the UK or Rochester, New York in the US.

Andrei Seryi at the University of Oxford found the work interesting, but warned it is still too far away from being used in particle-physics experiments. “Theoretically, however, it would be great if we are able to create particles from only light.”

“With such high energy lasers, we may not need to build big particle colliders, such as the Large Hadron Collider, which is a 22km underground tunnel,” Seryi said.

Even if we do manage to create a photon collider, we would only be catching up with the natural world, where a specific type of supernova, called “pair instability,” involves the creation of proton-antiproton pairs. If Pike is able to achieve this phenomenon, he will essentially be creating a supernova in a bottle.

The ConversationThis article was originally published on The Conversation. Read the original article.

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