Hunting quantum gravity in the big bang's echoes

Uniting gravity with its quantum nemesis might take a detector the size of the universe. So say two physicists who think they have found a way to resolve one of the biggest conflicts in modern physics using high-resolution maps of the infant cosmos.

The universe is currently described using two distinct frameworks: gravity for larger objects such as planets and black holes, and quantum mechanics for the tiny world of bosons and quarks. Even though almost everyone expects these realms to be linked, no one has been able to build a bridge between the two. Previous work focused on trying to finding the graviton – the quantum unit of gravity – the sheer existence of which would join the two theories.

"It's actually very hard to construct a consistent theory in which gravity is not quantised but the rest of the world is," says Steven Carlip at the University of California, Davis.

Force particles

Three of the four fundamental forces are proven to be carried by their own particle, such as the photon that carries electromagnetism or the gluon that carries the strong force. So it makes sense that gravity should also have its own particle – the graviton. But gravity is the weakest force of the four forces, so we'd need something very massive to have the sensitivity required to detect a lone graviton. Some researchers have even suggested that it is impossible to ever find them, because a sufficiently sensitive detector would have to be so massive it would collapse into a black hole.

Now, Nobel laureate Franck Wilczek of the Massachusetts Institute of Technology and Lawrence Krauss of Arizona State University in Tempe suggest that our best shot may be to find ancient ripples in space-time called gravitational waves, which are predicted by general relativity.

Instead of hunting the graviton directly, they say, look to maps of the cosmic microwave background (CMB), the first light that travelled across the universe after the big bang. Such maps give strong evidence that the cosmos rapidly expanded during its first fractions of a second. That burst, called inflation, should have triggered gravitational waves that would have scattered the photons of the CMB in preferred directions, creating patterns of orientation in the light that are an imprint of the relic waves.

Quantum-mechanical activity

Wilczek and Krauss say that if we can find those imprints, we would have our long-sought evidence for quantum gravity. Using a mathematical tool called dimensional analysis, they found a positive link between the primordial gravitational waves and Planck's constant, which is used in quantum mechanics. That means quantum-mechanical activity would have been needed to create the gravitational waves during inflation, Wilczek says.

The idea is plausible, although it relies on a few unstated assumptions, says Carlip, who was not part of the team. For instance, physicists will need to be able to show that the polarisation of the CMB is down to the proposed primordial gravitational waves and not the result of some other process.

Wilczek reckons we will not have the sensitivity to detect the influence of primordial gravitational waves in the CMB for at least 10 to 15 years, despite new high-resolution maps from the Planck satellite.

However, if the waves really are quantum in nature, it will be worth the wait. "Most theoretical groups are convinced the gravitational field should be quantised," says Wilczek. "But while no one was surprised by the existence of the Higgs particle, based on theoretical predictions, it's quite another thing to see the damn particle."

Journal reference: arxiv.org/abs/1309.5343

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Infertile woman gives birth after boost to ovaries

A baby boy has been born following a new fertility treatment that awakens dormant eggs in women who have stopped menstruating.

The treatment could help women who have left child-bearing too late, or have been left infertile after treatment for cancer. But some have raised concerns that the technique has been rushed to the clinic before being properly tested.

Women are born with millions of immature eggs, or follicles, but only around 400 mature to the point where an egg is released into the fallopian tubes and could be fertilised. But some of these follicles remain, even after a woman has stopped menstruating.

Now researchers have found a way to wake these dormant follicles and produce eggs that are capable of being fertilised. The first test of this technique has resulted in a baby boy, born in December 2012 in Japan.

Chop and change

Immature follicles are usually kept in a dormant state by the PTEN gene, which suppresses a signalling pathway involved in cell growth. Aaron Hsueh at Stanford University Medical School in California and his colleagues had previously showed that immature mouse follicles could be stimulated to mature if pieces of ovary were incubated with a molecule that stimulates the signalling pathway that PTEN inhibits.

Hsueh's team also discovered that the physical act of cutting up the ovaries disrupts a second signalling pathway, called the Hippo pathway, which normally suppresses the growth of many of the body's other organs as well.

When the cut up and incubated tissue was implanted back into the mice, eggs were released and fertilised, resulting in the birth of live pups.

Now the team has used a similar process to give women with premature menopause a shot at being mothers, using their own eggs.

Follicle growth

Twenty-seven women who had been diagnosed with premature menopause volunteered to have their ovaries removed. Of these, only 13 had any residual follicles left. These women had their ovaries diced up and incubated with a PTEN inhibitor, before pieces were transplanted into their fallopian tubes. Ultrasound was used to monitor follicle growth.

In all, eight of the women produced mature follicles, and were given drugs to trigger the release of an egg. Five of them produced mature eggs which were harvested and fertilised by IVF. So far, three have had their embryos implanted, resulting in one birth and one on-going pregnancy. The third failed to implant.

Ultimately, Hsueh says the technique could be used to help women who have stopped menstruating, and may not be responding to conventional treatment. "This data shows that there are small follicles still sitting there after women have stopped menstruating. This is a way that you can get them to work."

However, Evelyn Telfer, a fertility researcher at the University of Edinburgh, UK, says much more work is needed to ensure the technique is safe before it is routinely used in the clinic. "It's an interesting first step, but we need to do many controlled studies – without implanting the embryos – to show that at each stage of the procedure these eggs are normal," she says. "People say it's a baby at all costs, but if the baby is compromised in any way then that's a problem."

It's also not clear whether the women would have produced mature follicles, and ultimately eggs, if their ovaries had been diced up and re-implanted without exposing them to a PTEN inhibitor.

Journal reference: PNAS, DOI: 10.1073/pnas.1312830110

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SpaceX gets a rival - and tests novel reusable rocket

The nascent commercial space-flight industry showed off something old and something new on Sunday.

One company, Orbital Sciences of Dulles, Virginia, docked with, and delivered cargo to, the International Space Station (ISS) – only the second commercial entity to do so, but a capability that government agencies have long had.

Meanwhile SpaceX of Hawthorne, California, tested novel reusable rocket technology at the same time as launching a clutch of satellites.

For Orbital, the docking of its Cygnus cargo drone at 07.00 Eastern Standard Time on 29 September was a relief. The drone took off on 18 September but its docking with the ISS was delayed a week owing to a GPS data format mix-up that required a software patch.

The successful docking should inject some healthy competition into the market to deliver cargo to the ISS – previously SpaceX was the only commercial entity offering this service. It should also improve reliability, which may allow the full scientific and human potential of the space station to be realised.

Uncontrollable roll

If you count government agencies, Cygnus is the fifth type of unmanned vehicle to carry supplies to the ISS, following Russia's Progress, Europe's ATV, Japan's HTV and SpaceX's Dragon freight capsules.

For a truly new twist on space flight from the commercial sector, turn to the second launch of the same day. Just a few hours after an ISS robot arm plucked Cygnus from the void, SpaceX launched the latest version of its Falcon 9 rocket from the Vandenberg Air Force Base in California.

Earlier versions of Falcon 9 have launched SpaceX's Dragon capsule to the ISS. This one propelled a Canadian polar science satellite called Cassiope and a clutch of CubeSats to low Earth orbit – but it also attempted the first ever test of a potentially reusable rocket.

After the satellite-carrying second stage had freed itself, the first stage, which would normally simply burn up and be lost forever, fired three of its nine engines. That braked its supersonic climb, allowing it to re-enter and free fall under control towards the Pacific Ocean.

It was then due to reduce its vertical velocity further as it neared the ocean, to demonstrate the viability of a soft landing from orbit for the stage – SpaceX has previously carried out tests of its earthbound Grasshopper rocket to test the same thing.

But instead, it developed an uncontrollable aerodynamic roll, which caused fuel to slosh around the edges of the tank, depriving the landing burn of fuel. So the stage broke up on impact with the water.

Positive failure

"Rocket booster relit twice (supersonic retro and landing), but spun up due to aero torque, so fuel centrifuged and we flamed out," tweeted SpaceX's founder Elon Musk.

Although this particular reusability test failed, Musk had previously warned that it would do so – and the fact that the test is happening at all is encouraging space-flight observers.

"There will always be a failure rate in testing," says Greg Sadlier, a space analyst with consultancy London Economics. "Reusability is a laudable aim and SpaceX should not be discouraged in its attempts to get it right."

SpaceX's Dragon capsule is already the only one of the robotic delivery craft that is reusable: while Dragon deorbits and parachutes into the ocean for retrieval by boat, the Progress, ATV, HTV and Cygnus are all wasted, frying on a fiery re-entry into Earth's atmosphere.

Making rockets reusable will vastly cut the waste further – and stop the volume of space debris from continuing to rise, says space-flight researcher Hugh Lewis at the University of Southampton, UK. "There are a lot of upper rocket stages that remain in orbit after launch and we are now having to deal with the debris problem they cause. So this is a good initiative."

Sadlier sees the wasteful approach to capsules and rockets as unsustainable. "Developing reusable spacecraft is key to opening up wider access to space," he says. "Reusability would be a game-changer, as it has the potential to revolutionise the economics of space flight."

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No need for gods any more

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Climate report: How the science has moved on

The science of climate change has moved on a great deal in the six years since the last IPCC report. We break down the most important new findings

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Brake away: Rethinking how we land on Mars

THE cramped room smells of hot breath. About 50 people are clustered in front of a floor-to-ceiling window, straining for a better view of the desert outside. The silence is only broken when one of them muffles a cough with the crook of his arm, a gesture that exposes the dark stain at his armpit.

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A high-stakes test is about to begin at China Lake Naval Air Weapons Station in the Mojave desert in California. It will gauge the performance of a vital new technology for landing on Mars, and the results will shape the future of the planet's exploration.

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No need for gods any more

• Book information


• Big Gods: How religion transformed cooperation and conflict by Ara Norenzayan


• Published by: Princeton University Press


• Price: £19.95, $29.95

True believers think atheists cannot be expected to behave morally (Image: Abbas/Magnum)

As societies mature, many outgrow the need for a spiritual superbeing, argues Big Gods: How religion transformed cooperation and conflict

IN THE beginning, there were many gods. Societies entertained supernatural beings of bewildering variety. They resided in the heavens, the underworld and the forces of Earth, in things living and nonliving. They were appeased by worship, ritual or sacrifice, communicated with by oracle or divination. They harboured extreme passions, wielded extraordinary powers, and bestowed gift or punishment at will.

How, out of this pantheon, did a handful of monotheistic and polytheistic faiths come to dominate? Ara Norenzayan's perspective is a kind of theological take on survival of the fittest. In Big Gods, he argues that Islam, Christianity and other world religions prospered because they had a competitive edge over their rivals. They alone offered all-knowing, interventionist deities who judged immoral behaviour, an arrangement that encouraged cooperation among large groups of anonymous strangers – because "watched people are nice people". In short, they allowed groups to scale up: they paved the way for modern civilisation.

It is a neat, grand theory, one that Norenzayan seems well qualified to deliver. A social psychologist at the University of British Columbia, Canada, he had a hand in the experimentation and fieldwork he documents to illustrate the roots and nature of human prosociality.

He is conscious of previous attempts to explain religion in a Darwinian framework or as a by-product of human cognition and draws on them liberally. Furthermore, he grew up amid the violence and religious strife of 1980s Lebanon, curious about why a "once vibrant, cosmopolitan society turned against itself, and imploded" over differences in ideas and outlook.

It is a convincing thesis, and whether or not you buy it, some of its implications are compelling. For example, Norenzayan asks why in religious societies atheists are so profoundly distrusted – as many surveys have shown – rather than simply disliked or ignored. The reason, he suggests, is they are considered freeriders. To the faithful, those who don't believe in divine monitoring cannot be expected to act morally.

But he also finds that prejudice against atheists diminishes in nations with strong state institutions. Police, judiciary, and the rule of law can be as effective as a supernatural power at ensuring cooperation and accountability. This explains Norenzayan's most acute observation, addressed only in the last chapter: some of the most cohesive and peaceful societies are also the least religious. In Denmark, he notes, people don't steal bicycles even – especially – when the bicycles are free to use.

Such countries, largely in Scandinavia, have passed a threshold. No longer requiring their big gods to sustain large-scale cooperative behaviour, they have effectively outgrown them. They have "climbed the ladder of religion, and then kicked it away".

None of this explains why the US, one of the most economically developed countries in the world, is still among the most religious, where more than 90 per cent of people believe in God and close to half in a literal interpretation of Genesis. The US, an outlier in this, is a reminder that religion is about more than cooperation, that belief thrives perhaps because it eases deep existential anxieties where reason and logic cannot help.

The ideas in Big Gods resonate well beyond academic debates on the origins of religion. Think of the recent fracas over Twitter and other social media that allow users to speak anonymously, a privilege that has encouraged some to abuse whoever irks them.

This is what happens when people evade both big gods and secular eyes. If watched people are nice people, the unwatched can be the nastiest of all.

This article appeared in print under the headline "Goodbye gods!"

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Climate report: How the science has moved on

"Human influence on the climate system is clear."

With these words, Thomas Stocker of the University of Bern in Germany summed up the new assessment of climate science by the Intergovernmental Panel on Climate Change (IPCC). Stocker was one of the report's co-chairs.

The new report, published last Friday, reaffirms the findings of the previous assessment in 2007: humans are to blame for warming now and in the future.

But there is always more to learn, and the report's individual chapters contain a lot of new science. New Scientist breaks down the most important new findings.

Ice and sea

The past six years have been a golden age for ice studies. "Polar regions have been changing very rapidly, providing data for our projections on sea ice, snow cover, ice sheets and sea level rise," says David Vaughan of the British Antarctic Survey in Cambridge, UK, the lead author of the cryosphere chapter.

New understanding of how big ice sheets on Greenland and Antarctica might break up has forced the IPCC to almost double its estimates of likely sea level rise by the end of the century – to as much as 1 metre.

But the authors controversially dismissed the work of scientists who think it could be 2 metres or more. "Those predictions are based on extrapolation, but we have better information than that now, based on knowledge of ice processes," says Tony Payne of the University of Bristol, UK, lead author on sea level change.

Vaughan agrees. "We are now more confident that ice sheet collapse isn't going to happen in the next few decades." But the Antarctic ice sheets could have an Achilles heel, such as Pine Island glacier. "If anything scary happens it will be in Antarctica," says Payne.

Up in the air

Another key issue is the effect of clouds. "IPCC hasn't done a good job on clouds before," says clouds lead author Piers Forster of the University of Leeds, UK. "They were a big unknown in modelling warming."

In 2007, it was uncertain even whether clouds cooled or warmed the planet overall. "But we now believe that they are a positive feedback on temperature," he says. "Their warming effect will intensify with global warming."

Forster's chapter also reports on another important uncertainty: the cooling effect of smoke and other aerosols, which some argued almost negated the warming effect of greenhouse gases in the short term.

It now seems aerosols are counteracting less global warming than previously thought. This is good news for attempts to clean up smog. If the aerosols had been keeping a lid on warming, cleaning up smog could have produced a dangerous surge in warming. This now seems less likely to happen, so we can save lives by getting rid of air pollution without worrying too much about this potential downside.

Short-term blips

An important emerging issue, according to Stocker, is whether the unexpected hiatus in atmospheric warming over the past 15 years is a blip or evidence of a longer term trend.

The oceans could provide the explanation, says Stephen Rintoul of Australia's CSIRO research organisation, the oceans lead author. Temperature sensors in the oceans suggested that the surface layers joined the hiatus after 2003. "But the deeper ocean shows no slowing in warming, and sea levels continue to rise – which we believe is still mostly down to thermal expansion," says Rintoul. If heat is being redistributed in the oceans, the cooler surface could be cooling the air above.

This report also has more than previous ones on the effects of "near term" warming up to 2050, says Rowan Sutton of the University of Reading, UK.

It now seems this warming will probably be distinguishable from natural variability much faster in tropical regions than in mid-latitudes. That is a crucial threshold. "Once natural systems exceed the bounds of natural variability, there is greater potential for rapid and unpredictable change," says Sutton.

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Will push for global digital privacy treaty succeed?

Former National Security Agency contractor Edward Snowden's leaks of surveillance secrets have already prompted concerted efforts to reform spy laws in the US. But now a burgeoning international attempt to rein in the mass surveillance is taking shape.

Led by the German government, a loose coalition of privacy chiefs from countries across the world is pushing to update an influential international human rights treaty that enshrines the right to privacy.

German officials first wrote to their counterparts in other European Union countries with the proposal after Snowden's revelations about the sweeping scope of spy programmes operated by the NSA. They were seeking support for an attempt to protect citizens' right to privacy in the Internet Age – and the effort is now beginning to gather momentum.

The intention is to draw up an additional protocol to the International Covenant on Civil and Political Rights, a 1966 multilateral treaty that is part of the Universal Declaration of Human Rights and is endorsed by more than 160 countries, including the US. Article 17 of the ICCPR already states that citizens should not be "subjected to arbitrary or unlawful interference with [their] privacy, family, home or correspondence" and contains a vague so-called "general comment" that says the collection of information from computers must be "regulated by law".

But the German government wants to broaden and update article 17, adding an additional protocol for the "digital sphere" that specifically covers the conduct of spy agencies. It may as well be named the "Snowden protocol," as it is being put forward as a direct result of the backlash sparked by the NSA whistle-blower's disclosures.

International support

Data protection chiefs in Austria, Hungary, Switzerland and Lichtenstein were quick to back the plan, which the German government says was initially proposed in a letter it sent to other EU member states in July. Last week, however, the proposal received a major boost at the International Conference of Data Protection and Privacy Commissioners in Warsaw, Poland. The annual conference was attended by a diverse selection of privacy and data protection officials from across the world, with representatives attending from countries including Japan, New Zealand, France, Slovenia, Uruguay, Belgium, Ireland, Finland, Spain, Australia, Germany, Burkina Faso, Canada, the US and the UK.

During a closed session at the conference open only to the privacy chiefs, a resolution was put forward for a vote on the proposal to update article 17. They voted overwhelmingly in favour of the idea, recognising a need to "create globally applicable standards for data protection and the protection of privacy in accordance with the rule of law".

Notably, only one country did not approve of the resolution: the US. A representative from the Federal Trade Commission abstained. I sent an email to the FTC asking why it refused to endorse the proposal, but had not received a response at the time of publication.

At this point, the proposed article 17 protocol is still a long way off. It will eventually need to be put forward at the United Nations and voted on by member states, and that could take time. But the growing appetite to amend the international treaty in light of the Snowden revelations is highly symbolic if nothing else, reflecting widespread concerns about the power of mass surveillance technology in the digital age to trample over basic universal privacy rights.

Dutch data protection chief Jacob Kohnstamm, who also chairs the European Parliament's working group on data protection issues, told me that he believes there is a need for the UN to tackle the transparency and proportionality concerns raised by the surveillance programmes. "One of the problems that we are facing is that there is no supra-national regulation," Kohnstamm said.

What difference does it make?

Of course, even if an update to article 17 of the ICCPR is eventually accepted by countries at the UN, there is no guarantee that it will have a substantive impact. The ICCPR is enforced by the UN's Human Rights Committee, but its recommendations are not legally binding, making the committee mostly just a moral authority. As the various dragnet spying programmes exposed by Snowden have shown, the US, the UK and the three other partners in the so-called "Five Eyes" network – New Zealand, Australia and Canada – have for years ignored what international treaties and human rights law says about the right to privacy. However, the coalition led by Germany is at least trying to recognise that it is a problem to have intelligence agencies aggressively eavesdropping on millions of communications daily – and that is a significant development in itself.

In the meantime, more serious options are still on the table that could have a tangible impact on the spying in the shorter term. Several politicians in the European Parliament are pushing to suspend or radically reform data-sharing agreements with the US, and angry leaders in countries like Brazil and Mexico, which were reportedly targeted for surveillance, may force the Obama administration to make assurances that it will cease or at least limit its politically charged eavesdropping in these countries. On Obama's home turf, too, the debate about snooping is still raging, with freshly proposed reforms seeking to rein in the scope of NSA surveillance.

Snowden said that his biggest fear about leaking the secret files was that . But it seems clear at this point that he can rest easy, because change is already in motion.

This article originally appeared in Slate . Ryan Gallagher reports from the intersection of surveillance, national security, and privacy for Slate's Future Tense blog. He is also a Future Tense fellow at the New America Foundation.

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Rockstar planet hunter: Genius award will free my brain

Astrophysicist and newly named MacArthur genius Sara Seager talks about her hunt for exotic new worlds, and draws links between parenting and science

You have been studying exoplanets – planets outside the solar system that orbit Sun-like stars – almost since they were first discovered. How did you get into it?

I was wrapping up a project on cosmology and looking for a new project when exoplanets were discovered. My adviser, Dimitar Sasselov, thought they were interesting, so I started working on hot Jupiter atmospheres in 1996. I was one of the first people to work on exoplanet atmospheres, and was able to lay the foundations for that subfield.

Why focus on atmospheres?

It was a natural extension of my cosmology work, which explored how radiation was absorbed and re-emitted by atoms in the early universe. Studying photons at different wavelengths is how we know anything about space. So it's a natural question to ask about exoplanets – although a hard one.

Did you know it would get so big?

Not at all. I was just doing what seemed interesting at the time. I call it the random walk strategic path.

What have been the highlights in the field since you began exoplanet research?

Since I started, detection techniques have flourished – and they've succeeded wildly. Now we're in the discovery phase, finding exotic worlds. We're being surprised over and over again. We'd get jaded, thinking we'd seen it all, and then we'd see something new: circumbinary planets, which orbit two stars instead of one, for example, or compact multi-planet systems. There are so many examples.

What's your favourite planet?

It is always the next, most interesting one to be discovered. That's my favourite thing about exoplanets, there's always something else about to happen.

What's next in the hunt for exoplanets?

I personally have a pretty single-minded focus: finding exoplanets where we can use telescopes to analyse their atmospheres and see if they're inhabited. There are some proposed telescopes that would help with that, like The Transiting Exoplanet Survey Satellite (TESS) or the Starshade mission concept. But the more immediate future is direct imaging from the ground. They're not going to find Earth-like planets, but they may find a whole population of planets we didn't know were out there.

You're also known for building tiny satellite telescopes called CubeSats. How did you get into that?

I got started doing CubeSats when the Terrestrial Planet Finder mission, which was supposed to directly image Earth-like planets, lost funding in 2005. I was like, well, what can I personally do to keep things moving forward?

The question is, if there is a transiting "Earth" around a nearby star, how would we find it? The Kepler space telescope was being made ready to go. When I learned about CubeSats, I thought we could make a small telescope and find an Earth.

Admittedly I didn't really know what I was doing then. But the thing I love about MIT is that nobody says "no". No matter how hard it is, if you believe in it, someone else will. So we engaged a team of undergraduate students to build ExoplanetSat, a prototype nanosatellite that could monitor a Sun-like star for two years. The project became really complicated and expensive, like a microcosm of any other space mission. We still haven't launched it yet. So we started doing more simple ones – that's how I got into CubeSats.

You're known among colleagues for a 'let's do it ourselves' approach. What drives it?

I think it's just a personality thing. I don't really trust using other people's models. You can't get inside their heads. We like to do things ourselves and understand them, then you can act rapidly when there's a new problem. You know exactly what your model can do.

You were just awarded a MacArthur Genius Grant of $650,000. How will you use the prize money?

I'm going to be using it on the home front. I'm a single, widowed mother. I need to free my brain so I can think creatively. To think creatively is a huge privilege. My husband was very supportive. It's overwhelming, running a household by yourself, and also having time with your kids and to do your job right. My kids are 8 and 10 now, so this is perfect timing. This will get me through the next decade.

Is it hard to integrate your roles as a single parent and a rock star astronomer?

It's all sort of related. I try to be a creative mom, to think about problems logically, to solve problems the way I would solve them at work: what is the real problem I have to solve, not just what does it look like? And I try to have fun with the kids.

PROFILE

Sara Seager is an astrophysicist at the Massachusetts Institute of Technology. She is a recipient of a 2013 MacArthur 'genius grant'.

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First physical evidence of why you're an owl or a lark

They say the early bird catches the worm, but night owls may be missing far more than just a tasty snack. Researchers have discovered the first physical evidence of structural brain differences that distinguish early risers from people who like to stay up late. The differences might help to explain why night owls seem to be at greater risk of depression.

Around 10 per cent of people qualify as morning people or larks, and a further 20 per cent are night owls – with the rest of us falling somewhere in between. Your lark or night owl status is called your chronotype.

Previous studies have suggested that night owls experience worse sleep, more tiredness during the day and consume greater amounts of tobacco and alcohol. This has prompted some to suggest that they are suffering from a form of chronic jet lag.

To investigate further, Jessica Rosenberg at RWTH Aachen University in Germany and colleagues used diffusion tensor imaging to scan the brains of 16 larks, 23 night owls and 20 intermediate chronotypes. They found a reduction in the integrity of night owls' white matter – brain tissue largely comprised of fatty insulating material that speeds up the transmission of nerve signals – in areas associated with depression.

"We think this could be caused by the fact that late chronotypes suffer from this permanent jet lag," says Rosenberg, although she cautions that further studies are needed to confirm cause and effect.

Skewed body clocks

Although the team controlled for tobacco and alcohol use, it's possible that gene variants that skew people's body clocks towards nocturnal living could affect the structure of the brain. It's also not clear whether the structural changes have any implications for people's health.

"It's interesting that there are individual differences, but we need to understand what is causing them and find ways of creating environments in which those differences can be attenuated," says Dirk-Jan Djik, director of the Surrey Sleep Research Centre in Guildford, UK, who was not involved in the study.

Rosenberg suggests that people's work schedules should change to fit in with their natural sleep patterns, but Djik says there may be an easier way. For example, research published last month suggests that night owls who cut their exposure to artificial light and boosted their exposure to sunlight found their body clocks shifted towards earlier waking and sleeping (Current Biology, DOI: 10.1016/j.cub.2013.06.039).

Journal reference: Neuroimage, DOI: 10.1016/j.neuroimage.2013.07.086

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It's never too late for a midlife crisis

Ditch the Porche-driving cliché for a better understanding of life crises – be they midlife, quarter-life or late-life, says psychologist Oliver Robinson

You surveyed more than 1000 adults in the UK about their experience of life crisis. Why?

The concept of a midlife crisis is a well known one perpetuated by books and films. And recently the idea of a quarter-life crisis, between 20 and 30, has also gained a fair amount of media coverage. But there's a surprising lack of robust research on these events, and almost none on later life crisis.

Everyone has periods of difficulty. Isn't a life crisis an unnecessary cultural construct?

It is culturally constructed, but not unnecessary. A crisis is a period in a person's life that lasts at least a year during which there is an unusual level of emotional instability, negativity and, crucially, major changes. This is important because right now, when you diagnose mental health problems, where you are in life doesn't really come into it. We are saying that it should.

So which is the trickiest decade?

They are all pretty tricky. At any decade in your life, our results suggest that there is a 40 to 50 per cent chance of having a life crisis. There's a slight increase with age and in general women tend to experience more than men – but that could be because they may be more open to admitting that they have had a hard time.

What characterises each decade?

In your 20s, crises tend to be about whether you are making the correct decisions for the rest of your life, namely in your job and relationship. In your 30s, work-related issues and break-ups feature prominently. In your 40s, for women bereavement is often an issue, most likely for a parent. For men, it is still to do with their job but it has moved to "Holy crap, I've got a lot to do".

In your 50s, you get features of both early and later life crises – bereavement and ill health. This may be why late midlife is so potent. And that continues in your 60s, with retirement-related issues and heightened awareness of mortality.

Is there a silver lining to a crisis?

There can be. Half the people said that their lives had become better as a result of changes they made; some said the benefits and downsides balanced each other out; a smaller proportion said they never really recovered.

Do your findings kill off the character of the middle-aged man full of existential angst?

Not quite. The research suggests there may be something to it. While men in their 40s are no more likely to have a crisis, those who do are more likely than other groups to see it as a negative without any subsequent benefits.

What practical use do these results have?

They help frame life difficulties in a way that shows they are part of normal life. Not having a crisis at any point in your life was extremely unusual – only 4 per cent of respondents aged 50 and over said they had never had one. There is this subtle but fairly insidious tendency, especially among young adults, to think that adulthood will be a fairly easy ride, like living in a glossy magazine. So when the hard times hit they are not prepared for it. We hope this helps change that.

This article appeared in print under the headline "What is a midlife crisis?"

Profile

Oliver Robinson is a psychologist at the University of Greenwich, UK. He studies how major life transitions influence personality and well-being and is author of Development through Adulthood (Palgrave Macmillan)

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Black-hole eruption nearby is a warning for us all

Cosmic threats, like the flare-up 2 million years ago of the Milky Way's black hole, are a reminder that humanity’s survival is up to us

TWO million years ago, something not quite human looked up at the sky and saw a glowing light, about the size of the moon, that hadn't been there before. That light was a huge eruption at the black hole at the centre of our galaxy, according to new research by astronomers.

We can only make educated guesses at what our predecessors would have made of this strange sight, which took place long before recorded history. We're not even sure which species of hominin might have been looking (see "Early humans saw black hole light in the night sky"). But what should we Homo sapiens make of it?

We might take it as further evidence of the precariousness of our existence: how the universe teems with threats, some still unsuspected, that might wipe us out in an instant. Had our planet orbited a star closer to the Milky Way's black hole, it would have been bathed in radiation – probably killing off our ancestors.

Cosmic radiation, which might also come from a supernova, is one of the few scenarios that could wipe out life on Earth, although bacteria might survive even that (see "DNA-grabbing bacteria hint at early phase of evolution"). Perhaps that's far-fetched; but then again, we don't know how many worlds out there may have been sterilised by abrupt cosmic events.

But what significance do such threats hold for our quotidian existence? After all, we can't do much about erupting black holes. But think on: if Earth were emptied of life, it would be emptied of much more besides. In fact, the planet would eventually be transformed beyond recognition, becoming a hellish grey rock (see "Lifeless Earth: What if everything died out tomorrow?").

That scenario really is far-fetched – even the gloomiest eco-worrier need not lose sleep over it. But it does highlight how closely intertwined our planet's geology and biology are. And it is that intertwining that we humans are picking at with our continuing assaults on the environment.

Despite the toll we're taking on the Earth's other inhabitants, the threat here is not ultimately to the planet, or even its biosphere. It's to us. Subtract humans, and after not too long the planet would carry on much as before (New Scientist, 14 October 2006, p 36).

These threats, unlike the cosmic perils, are tractable. We can try to sort out the mess we've made. Or settle other planets to help ensure our species' survival. In the face of a pitiless universe and indifferent planet, human survival is of concern only to humans. Unlike our ancestors, we can do more than just look on in bafflement.

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Light-bending black hole mimic is first you can watch

Video: Artificial black hole mimics curved spacetime

A plastic black hole traps light just like the real deal, and is the first such structure, natural or artificial, that you can actually watch in action. Unlike the real thing, it isn't dangerous – but it is helping to demystify one of nature's weirdest objects and might even have applications for energy-harvesting devices like solar cells.

Black holes are most famous for swallowing light, or anything else in their path. But this fate only awaits objects that get sucked past a point called the event horizon.

Less well known is a black hole's photon sphere, a region of warped space-time outside the horizon that merely traps light in curved paths. Astronomers have never observed a photon sphere – even outside genuine black holes - because, by definition, trapped light can't escape and reach your eyes so you can see it.

So to visualise this process, Hui Liu at Nanjing University in China and colleagues built an artificial black hole.

In nature, black holes swallow and trap light via their immense gravity, something that would be difficult, not to mention incredibly dangerous, to recreate in the lab. Instead, Liu's team used a sheet of plastic – and mimicked the effect of gravity by varying its refractive index, the property that determines how much a substance bends light.

Making light curve

The refractive index is different for different materials. That is why a straw poking out of a glass of water appears crooked: water bends light more than air, so has a higher refractive index. A material with a constantly varying refractive index would take this to the extreme, with lots of little bends creating a smooth curve – rather like a black hole's photon sphere.

Liu's team added quantum dots, tiny pieces of semiconducting material that fluoresce when illuminated, to molten acrylic glass, then poured the mixture onto a rotating quartz sheet, slowly spreading it out.

They placed a microscopic polystyrene sphere at the centre, which served as an anchor, with the material thickest nearest the sphere and thinning as it got further away. "This makes the effective refractive index vary in the same way the curvature of space varies around black holes," says Liu. In fact, the same Einstein field equations used to model black holes can describe the behaviour of light in the acrylic.

Shining a laser through the material allows you to watch the artificial black hole in action – and to visualise other familiar gravitational effects.

Beams that are relatively far away from the microsphere are slightly bent towards it before continuing on their way. When gravity causes the same effect in space, it is known as gravitational lensing. This occurs whenever a light beam passes a massive object such as a star or galaxy, altering the beam's path as it travels along curved space-time- and can be used to get a better view of distant objects, such as exoplanets.

In the case of the artificial black hole, though, the pull increases as the laser moves closer to the polystyrene sphere, and eventually there is a point where it curves the light completely around. Previously artificial black holes have been created that mimic the event horizon of a black hole, in an attempt to detect a mysterious process called Hawking radiation – but this is the first artificial object to recreate the photon sphere.

Visible sphere

What's more, unlike a real black hole, the photon sphere can be imaged, thanks to the quantum dots. While the actual light that is trapped remains invisible, as in a real black hole, the quantum dots absorb some of it and emit red light at a different angle, allowing it to escape the black hole's grasp. This provides an exact trace of the true photon sphere's path and can be imaged by a camera.

"Our work reports a quite simple and ingenious method to mimic light trapping around a black hole," says Liu.

Ulf Leonhardt of the Weizmann Institute in Rehovot, Israel, who has previously created an artificial event horizon, says Liu's structure provides another way to study black holes. "It illustrates that there is no big mystery in the lensing effects in general relativity, you can do the same thing with ordinary materials."

Liu says the model could be used to study the effects of general relativity around a real black hole, but the ability to trap light could also have more practical applications. "It could be quite useful for solar cells, photon detectors, microlasers and many other energy harvesting devices."

Journal reference: Nature Photonics DOI: 10.1038/nphoton.2013.247

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Hacking firm hints at cybercrime's professional elite

A new report has outed a shadowy organisation called Hidden Lynx – a 100-strong group of expert hackers who are available for hire

LAST June, one of the world's most advanced hacker groups hit a problem. The US defence contractor whose systems it wanted to access only allowed a small set of trusted IP addresses to connect to their network. In an unusual move – hackers typically go for the low-hanging fruit – the group hacked the company that provided the IP whitelisting service, enabling it to forge access certificates.

This group, which calls itself Hidden Lynx, was given a vague face last week when antivirus software-maker Symantec released a report profiling it. Believed to be based in China, the group is known only through traces of malicious software bearing its mark found in the compromised computers of some of the world's largest companies.

Symantec estimates the group has 100 employees and says it has been operating for four years, specialising in attacks on financial and government institutions in the US. Chances are, the hackers will never be caught.

Steve Santorelli, a director of non-profit organisation Team Cymru – which monitors the internet's criminal underbelly – says Hidden Lynx is typical of what has become a gigantic cybercrime industry, with professional hacker groups raking in millions of dollars around the world.

Hidden Lynx and others are for hire, and while their expertise comes at a price, Santorelli says it's fairly easy to find them: "That's not because they overtly advertise, but because there is so much stuff on [online message board] Pastebin. Whether they'd give you the time of day is another question."

The group is a boutique hacker organisation, says Symantec analyst Gavin O'Gorman. It uses sophisticated signed malware that the antivirus firm has only seen on rare, linked occasions.

"Some of the technology they are using is breathtaking," says Santorelli. "They are bleeding edge computer scientists making serious amounts of money."

China makes a particularly good base for hacking groups, says criminologist Craig Webber of the University of Southampton in the UK, because Western law enforcement has practically zero influence there. "If you tell the Chinese authorities they have problems, they often turn around and say 'Is it affecting our citizens? If not then sorry, it's nothing to do with us'. "

Professional hacker groups are not restricted to illegal activities. O'Gorman points to Hacking Team, an Italian outfit which builds the commercial surveillance tool Da Vinci. "There are a couple of companies that will offer not quite a hacking service, but will offer trojans and exploits which they claim they will only sell to law enforcement," he says.

The rise of large professional hacking groups like Hidden Lynx combined with the development of such borderline products means the average person has greater access to carrying out sophisticated computer attacks than ever before, says O'Gorman. What's more, many of the sophisticated tools used by hackers have now leaked into underground marketplaces, where anyone can buy them, says Santorelli.

Professional hacking has reached a point where hacker high jinks are now looked down upon, he says. "There's a saying in these communities: no one makes any money if you break the internet."

This article appeared in print under the headline "Hackers for hire"

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