Milky Way's quiet life leaves it with no dark matter skeleton

THE Milky Way has had a sheltered life. A search for the signs of a violent galactic upbringing has come up empty, and the finding is helping astronomers understand our galaxy's history. It could also aid the search for dark matter.

Galaxies are shape-shifters. Far from being a single set of stars in an eternal spiral, the Milky Way has devoured countless smaller galaxies over its 13 billion year lifetime, and its shape has been in constant flux to accommodate the immigrants. It is riddled with alien stars, threshed from foreign galaxies as they joined ours.

If these galaxies were big hitters, the forces unleashed by a merger would push stars into the heart of our galaxy and create a flattened disc of accreted dark matter that lines up with the spiral disc of stars.

"If you have a disc galaxy and then you have a substantial merger, material is preferentially pulled towards the disc as [the merging galaxy] gets tidally torn to pieces," says Justin Read of the University of Surrey, UK, a co-author of the new study. "Because those shredded satellites will contain stars and dark matter, we can look for evidence that this has happened by picking through the stars in our backyard."

So Greg Ruchti of Lund University in Sweden and his colleagues searched through 4675 Milky Way stars from the Gaia-ESO Spectroscopic Survey looking for remnants of a large merger. They wanted stars with alien chemistry that were a little hotter than Milky Way natives, but rotating at the same speed.

But their galactic archaeological dig found no alien stars in the main disc – although they found plenty on more sedate orbits in the galaxy's suburbs. That suggests that the Milky Way has been steadily gobbling smaller galaxies, but nothing large enough to force new stars and dark matter directly into the disc (http://ift.tt/1cDdcp4).

If the Milky Way lacks a dark matter disc, this has implications for physicists hunting the elusive substance. Dark matter makes up 80 per cent of the universe's matter but only interacts with ordinary matter via gravity, so it is difficult to detect directly.

Earth-based experiments hope a dark matter particle will collide with an ordinary atom in an observable way. Dark matter particles from the galactic disc will give different signals to those from the halo of dark matter the Milky Way was born with –without a disc, the problem is more clear-cut.

Kevin Schawinski of the Swiss Federal Institute of Technology in Zurich says the findings are helpful for comparing the physics of the Milky Way with other galaxies. "The fascinating thing about the Milky Way is that we know it in gorgeous detail because we're in it, but it's also hard to put it in context for the same reason," he says. "We want to know how we got here and how the universe works. Our society and civilisation is the first one that has creation stories that might actually be true. The Milky Way is great, but how did it get that way?"

It would be good to know, since the Milky Way's quiet life is about to end. In 4 billion years, it will collide with its nearest major neighbour, Andromeda, which is roughly the same size and had a much more violent youth. When our stars and dark matter merge, our galaxies' histories will merge too.

Read: "The human universe: Exploring our place in space"

This article appeared in print under the headline "Low-key Milky Way lacks dark matter skeleton"

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That's no moon! Spacecraft mistaken for new natural satellite

Something looking awfully like a moon was detected in the sky today

For 13 hours today, Earth had a new moon – or so we thought. Now astronomers have realised that an apparent small asteroid orbiting our planet is actually the European Space Agency's Gaia space telescope.

The International Astronomical Union's Minor Planet Centre (MPC) in Cambridge, Massachusetts, keeps records of all the tiny space rocks in the sky and publishes new observations from around the world. This morning, MPC's Gareth Williams posted a description of 2015 HP116, seemingly an asteroid about a metre across that was spotted in a geocentric orbit by the Pan-STARRS telescope in Maui, Hawaii, last week.

Williams's analysis of the orbit suggested the object would remain bound to the Earth-moon system between October 2014 and March 2019, making it a temporary moon of our planet. That's not without precedent – simulations suggest hundreds of tiny moons could be orbiting Earth. One, called 2006 RH120, was spotted in orbit before drifting off a year later.

Near miss

There's just one problem. It turns out this object is actually Gaia, the European Space Agency telescope currently mapping a million stars in the Milky Way. Just 13 hours after announcing the discovery of the new moon 2015 HP116, the MPC issued a retraction. "These things do exist, this just isn't one of them unfortunately," says Williams.

The mysterious, temporary moon has turned out to be the Gaia space telescope (Image: ESA, image by C.Carreau)

Earth's orbital neighbourhood is littered with all kinds of space junk, from defunct satellites to leftover rocket boosters, so the MPC runs a number of checks to filter out sightings of artificial objects, but this time they failed. "For some reason, it didn't show up in the checks," says Williams. But after posting the notice on the MPC website, he reran the calculations, and out popped Gaia. The object was dimmer in Pan-STARRS's observations than Gaia normally is, which could account for the confusion.

If the story sounds familiar, it's because we've been here before. In 2007, the MPC issued a warning that an object called 2007 VN84 was heading for a near-miss with Earth. It actually turned out to be ESA's Rosetta spacecraft on a fly-by past Earth, building up enough speed for its historic rendezvous with comet 67P/Churyumov-Gerasimenko, which occurred last year.

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US farms hit by bird flu - but a vaccine might make things worse

Bird flu is rampaging across the Midwestern US this week. So far 8 million chickens and turkeys have been destroyed to stop the spread of H5N2, an offspring of Asia's H5N1 bird flu. Minnesota, the top US turkey producer, declared an agricultural emergency after announcing infected farms almost daily for two weeks. Iowa, the top egg producer, killed 3.8 million hens on one farm alone.

US agriculture officials hope the outbreaks will diminish as summer warmth and sunshine destroys flu viruses in the environment. But their bird flu problems may be only beginning. Wild ducks could infect the rest of the continent next autumn.

And while H5N2, unlike H5N1, seems to pose little threat to humans, the $45 billion US poultry industry is already suffering, as China, South Korea and Mexico ban US produce. Producers are calling for a poultry vaccine, and the US Department of Agriculture says it is developing one. But that might just make the problem worse by encouraging the spread of "silent" infections.

Running wild

The H5N2 virus story started last summer, when the H5N1 virus hybridised with others in wildfowl in Siberia to create a a new strain, H5N8. This reached the US, where it further hybridised to spawn the H5N2 that has now reached nine Midwestern US states and Ontario, Canada. US Department of Agriculture chief veterinary officer John Clifford said last week that most of the early farms infected got the virus from the environment, not other farms, suggesting it was introduced by wild birds. If wild birds are carrying it, says Jeffrey Hall of the US National Wildlife Health Center in Madison, Wisconsin, "these viruses could persist and spread in northern hemisphere waterfowl populations for an extended period".

Ducks are now headed to North America's arctic nesting grounds.If they spread H5N2 there, southbound migrants next autumn could carry it into eastern North America. Three eastern states are among the top ten egg producers in the US, while seven produce nearly two-thirds of US chicken.

Vaccination trap

At the moment, an infected farm must kill all of its birds to stop H5N2. Poultry producers want a vaccine instead. Researchers at the US Department of Agriculture are starting tests, and Clifford says he is talking to vaccine companies.

But "vaccination will always be the last option for avian influenza," says Henry Wan of Mississippi State University, who discovered H5N1 in 1996. Widespread poultry vaccination in China, Indonesia and Egypt has not got rid of that strain.

On the contrary, vaccinated poultry spread the virus without getting sick, making its spread invisible. Vaccination has moreover driven the evolution of H5N1 as these viruses adapt to the vaccinated birds. China is now trapped, say researchers: it wants to give up expensive poultry vaccination, but if it did, ubiquitous, silent infections with H5N1 would decimate the unvaccinated birds.

Even if the US avoided this trap, vaccination would hurt its poultry exports, worth $3 billion a year. Tests cannot distinguish vaccinated from infected birds, so importers reject meat and eggs from countries that vaccinate their poultry.

Ruben Donis of the US Centers for Disease Control and Prevention calls relying on vaccines to control bird flu "unrealistic". It might be possible to use an H5N2 vaccine on some high-risk farms with careful monitoring for silent infections, he says. But "so far, there is no reason to believe that H5 could not be controlled through culling", plus sanitary precautions aimed at keeping environmental viruses out of henhouses.

Depending on when – and if – summer weather starts killing off stray viruses, and more effective sanitary measures kick in, that could mean millions more dead chickens and turkeys, even before the ducks fly south again next autumn.

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Jolt of java helps spermbots in final race to the finish

CAFFEINE gives you a spike of energy before you crash back down – even if you're a robot made from bull sperm.

Spermbots, as they are called, were first developed in 2013 by Veronika Magdanz of the Leibniz Institute for Solid State and Materials Research in Dresden, Germany, and her colleagues. She wanted to create a microscopic robot that could be used to deliver drugs around the body, and realised that sperm cells come with a built-in propulsion system: their flagellum.

The team trapped the heads of bovine sperm cells inside microscopic metallic tubes, then used a magnetic field to control their direction of travel, like a compass needle aligning with Earth's magnetic field. Since then, they've been looking for ways to boost the bots' performance.

Caffeine makes sperm go faster in humans, so the team tried adding some to the spermbots' swimming pool. The sperm absorbed the caffeine and increased their speed by 30 per cent on average, but only for around 30 seconds. A minute later, the spermbots were flagging at around 70 per cent of their original speed (Advanced Functional Materials, doi.org/f266dh). "The speed boost is only useful for a final 'race to the finish line' of the spermbots, when they need to be accelerated for a short time before they finish their task," says Magdanz.

Magdanz is also investigating how spermbots could be used in reproductive technologies, such as the controlled delivery of a single sperm cell.

This article appeared in print under the headline "Jolt of java helps spermbots in final race to the finish"

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Old Scientist: How biologists tussled over the Loch Ness monster

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Old Scientist is our occasional column dedicated to gems from our 59 years of back issues

You just can't keep a good monster down, it seems. One of the most vitriolic exchanges in New Scientist's history has just broken the surface again, following a fresh look at the sacking in 1960 of a prominent scientist.

Denys Tucker had claimed in our pages to have seen a mysterious creature in Scotland's second-largest lake, Loch Ness. And yesterday, doubtless to the delight of the tourism entrepreneurs who thrive on the story of "Nessie",Google released an image from its Street View survey showing strange lumps on the surface of the loch. It was also the anniversary of the first publication of the "surgeon's photograph" purporting to show Nessie's neck and head, which appeared in the Daily Mail on 21 April 1934. Only in 1975 was it unmasked as a hoax.

Back in 1960, when Tucker's claim of a sighting was made in New Scientist, the possible existence of a huge creature in Loch Ness, hotly tipped to be a plesiosaur, was being taken much more seriously by scientists than it is today. Now, with benefit of hindsight and multiple surveys of the whole loch, we know that the "monster" is unlikely to exist. Many of the key "photographs" and evidence from 50 years ago have been revealed either as hoaxes or as having more mundane explanations.

Heated science

In 1960, though, some scientists were engaged in serious and heated debate about Nessie. One of them was Denys Tucker, who had been made chief scientist at London's Natural History Museum the year before. Nessie was, he argued, an elasmosaurus, an exceptionally long-necked genus of the plesiosaurs common 80 million years ago, and considered long extinct.

Tucker didn't last long in his post: he was sacked on 31 July 1960. How much was this down to his pursuit of Nessie?

A request by The Independent newspaper under the UK's Freedom of Information provisions has produced documents kept secret for 50 years. In one, his paymasters asked him to consider whether Nessie was a "suitable topic" for the museum's leading scientist – demonstrating that senior bureaucrats viewed a fixation on Nessie as unhealthy.

In the end Tucker was sacked for "long, continued, vexatious, insubordinate and generally offensive conduct towards the museum's director and other senior staff". That decision effectively ended his career. He actively challenged it for more than seven years, and kept wading in on Nessie. The initial trigger was a feature in New Scientist by prominent biologist Maurice Burton, dismissing almost all the evidence and theories put forward for Nessie's existence since the spate of "sightings" in the 1930s (22 September 1960, p 773).

Otters, probably

Burton systematically demolished almost all the evidence for Nessie, concluding that "the plesiosaur theory begins to look a bit tattered". He claimed that a large object moving in Loch Ness, captured on film earlier that year, was probably a motor boat. Other "sightings" of "young plesiosaurs" were probably adult otters. His favoured explanation was that the monster amounted to nothing more than large clumps of rotting vegetable matter, buoyed to the surface by methane.

Burton also expressed surprise that in claimed sightings and accounts, the "creature" seldom, if ever, broke the surface for breath. Regarding one supposedly extended sighting, he observed that "I have yet to see any air-breathing aquatic animal remain at the surface for 40 minutes without taking advantage of this position to renew its supply of oxygen through the lungs".

This prompted a bristling letter from Tucker (27 October 1960, p 1144), in which he made his ill-fated claim to have seen the monster himself. "I, a professional marine zoologist of respectable experience, did see a large hump travelling across flat calm water between Inchnacardoch and Glendoe on 22 March 1959, and do quite unashamedly assert that it belonged to an unnamed animal," he wrote.

After delivering a searing critique of Burton's feature, Tucker concluded: "I am quite satisfied that we have in Loch Ness one of the most exciting and important problems in British zoology today&ellip; I can see no explanation in the light of the evidence other than an unknown animal. And at present, for the life of me, I cannot imagine any other animal than an Elasmosaur which could possibly fill the bill."

Getting the hump

Burton, in a response published beneath Tucker's letter, stuck to his guns and dismissed the claimed sighting in 1959. "His personal observation of a large hump is no more valuable than several thousand similar eye-witness depositions, and the fact he can 'unashamedly assert that it belonged to an unknown animal' is interesting, but does not constitute scientific proof," he wrote.

In his next riposte Tucker appeared to be apoplectic with rage (17 November 1960, p 1346). "At the risk of being accused of immodesty, I would suggest that when an experienced zoologist states that he has seen an unusual animal and sticks his professional neck out to testify, the circumstance is not to be cavalierly dismissed as 'no more valuable than several thousand similar eye-witness depositions'."

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Nice legs: Native American bee poses for his close-up

(Image: Clay Bolt/www.claybolt.com, http://ift.tt/1HPXB1x)

HE MAY look soft and furry – but don't be fooled. "Out of all the species of bees that I've photographed during this project, this little guy was the only one that actually looked up at me and bared its mandibles," says photographer Clay Bolt.

Bolt has set himself the task of documenting every native North American bee. The project was borne out of the realisation that one species – Apis mellifera – was grabbing the limelight in US coverage of colony collapse disorder, and it wasn't even a native bee. There are nearly 4000 more, from the rusty-patched bumble bee to this one, called the (Megachile melanophaea).

Female leafcutter bees chew small circles from the edge of leaves, and use these to form tubular cells. Into each tube, she deposits a ball of pollen and an egg. The larva will feed on the pollen when it hatches.

And the flamboyant gold leg manes? "Some males in this group have very furry front legs, which are used to cover the eyes of females during mating," says Bolt. He speculates that this is to stop the females being distracted by other males during copulation.

This article appeared in print under the headline "Sweet chile of mine"

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19th-century champagne haul shows seabed is perfect wine cooler

"Animal notes" and "wet hair" were the terms used to describe 170-year-old champagne hauled up from the bottom of the Baltic Sea in 2010. We now have chemical confirmation that the wine had aged well, but the mystery over how it got there is even murkier.

When the 163 bottles were recovered from 50 metres beneath the waves, seals on the corks showed that the wine had come from champagne houses Veuve Clicquot, Ponsardin, Heidsieck and Juglar (renamed Jacquesson & Fils in 1829). They were estimated to be between 170 and 180 years old.

Three of the Veuve Clicquot bottles were tasted by oenologists – on first opening they described the champagne as "sometimes cheesy", with "animal notes" and elements of "wet hair".

Swirling the champagne around in a glass to oxygenate it softened the flavours, which were then deemed to be grilled, spicy, smoky and leathery with fruity and floral notes.

Philippe Jeandet of the University of Reims Champagne-Ardenne, France, and his colleagues later got their hands on 2-millilitre samples from each bottle, which they ran through a detailed chemical analysis. This showed that the wine had been aged in wooden barrels, probably for six to eight months. That's consistent with documents left behind by Madame Clicquot, and different from the vineyard's modern practice of making its champagne in steel containers.

Mysterious destination

Traces of copper and iron came either from iron nails in the wooden barrels or iron instruments used during the winemaking, but did not spoil the wine.

The location of the bottles suggested they were on their way from Germany to Russia when they sank, sometime during the early 1800s. Russians at the time liked their bubbly very sweet – Madame Clicquot's notes mention that it was common practice in Russia to have a small bowl of sugar on the table to spoon into their wine. To cater to this market Clicquot made special extra-sweet batches for them.

So, if the Baltic bottles had been intended for Russia, they should have contained extra sugar. Jeandet and his colleagues found that while they were sweeter than modern bottles, they were nowhere near sweet enough for that market. They think they must have been destined for German tables, but admit that makes it difficult to explain why their ship was sailing through the northern Baltic.

"Overall, our analysis confirms that this champagne has kept the intrinsic characteristics of what a champagne is," says Jeandet. "This is fantastic, to observe that after 200 years of ageing at bottom of the sea."

Expensive taste

The conditions that the bottles were preserved in – complete darkness and a constant temperature between 2 ºC and 4 ºC – were ideal for wine ageing, he adds.

"Considering that these champagnes had been aged underwater for 170 years, they were amazingly well preserved," says Patrick McGovern, who studies the history of food and alcohol production at the University of Pennsylvania in Philadelphia. "[They are] testimony to human innovation in producing fermented beverages, which were central to human cultures around the world."

To commemorate the find, last year Veuve Clicquot sank 300 bottles and 50 magnums of champagne near where the 170-year-old bottles were found, inside a specially designed cage.

Jeandet says the experiment is mostly a marketing ploy. "I'm sure it will not change the taste of the wine but people will be proud to put it on their table and say, 'ho! You know this bottle has spent six years under the sea'. I know there are a lot of people ready to pay a lot of money for these bottles."

The 170-year-old champagne bottles are some of the oldest ever to have been tasted. In 2009, Perrier-Jouet opened an 1825 vintage from its cellars: at the time of tasting it was 184 years old and still tasted fine, with notes of truffles and caramel.

Journal reference: PNAS, DOI: 10.1073/pnas.1500783112

Correction, 21 April 2015: When this article was first published on 20 April 2015, the title prematurely aged the Champagne by a century. This has now been corrected.

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Vampire feeds on decaying matter and spawns eggs in batches

It's a tough life deep in the ocean, so you can't really blame the vampire squid for taking a break. All other species of soft-bodied cephalopod so far studied produce their offspring in one glorious bout of reproduction, usually just before they die. But not the vampire squid. This sinister-looking creature feeds on zooplankton and decaying organic material in its struggle to survive up to 3000 metres deep.

Henk-Jan Hoving at the Helmholtz Centre for Ocean Research in Kiel, Germany, and his team dissected 43 female vampire squid captured in tow nets off the coast of southern California. They found 20 adults that had released some eggs, but still had immature egg cells available for future spawning. One squid had released at least 3800 eggs, judging by her empty follicles, but still had around 6500 left.

Based on the number of eggs the team observed ripening together in batches, they estimated that the squid release about 100 eggs at a time – suggesting this female had already undergone at least 38 bouts of spawning, and could have gone on for another 65.

This could be an adaptation to their life in the deep ocean. "By reproducing in multiple cycles, it may allow vampire squid to make use of its low-calorie food source," says Hoving.

"This reproductive strategy gives advantages to the vampire squid to save energy in the very poor feeding conditions of the deep sea environment," says Bahadir Önsoy of Mugla Sitki Kocman University in Turkey. "In deep sea habitats, the temperature is low, so the metabolism of an animal that lives there is expected to be slow."

Daniel Stephen of Utah Valley University in Orem agrees the strategy is probably an adaptation to the squid's environment, but he isn't surprised. Repeated bouts of spawning are known in their shelled relatives, the nautiluses.

Journal reference: Current Biology, DOI: 10.1016/j.cub.2015.02.018

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Space geckos seen playing on their trip into orbit

Video: Space geckos play in zero gravity

Sometimes a little less gravity is all it takes to cut loose. For a group of Russian space-faring geckos, the extra lift of zero-g appears to have been all the encouragement they needed to engage in a bit of unprecedented tomfoolery.

The 15 geckonauts took off in April 2013 on board the uncrewed Bion-M1 satellite, along with some mice, gerbils, snails and fish. One gecko wriggled free of its coloured identification collar before take-off, and the collar spent the 30 days of orbital flight floating around its enclosure. On-board cameras captured the geckos – whose sticky feet meant they didn't float – nudging the collar around with their noses (see video).

It's a highly unusual display of play in a reptile, says herpetologist Gordon Burghardt at the University of Tennessee in Knoxville, who wasn't involved in the study. "It's the first demonstration of object play in geckos – something that is rare in any lizard," he says.

Burghardt had previously argued that reptiles rarely play because most have to fend for themselves from birth, and – being cold-blooded – they have little surplus energy for activities that don't immediately affect their survival. As a counter-example, crocodiles, which do have caring parents, have been seen engaging in play.

Burghardt had also predicted that environments where reptiles need to burn less energy might give them enough juice to fool around. Specifically, he had thought of turtles floating in warm water. But you can hardly blame him for not thinking of geckos hanging out in zero gravity.

Journal reference: Journal of Ethology, DOI: 10.1007/s10164-015-0426-8

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Does music strike a chord with everyone?

Stephen McAdams played movie tunes to Mbenzélé pygmies in the Congo rainforest to find out whether music is a universal language

Why do you want to know whether music has the same effect on everyone?

Every culture has music, so if we want to understand humans, we need to understand why music is there and why it is used in different ways. Deciphering what aspects of it are dependent on our basic biology and what aspects are dependent on culture will help us find answers to these questions.

You played movie tunes to Mbenzélé pygmies in the Congo rainforest. Why them?

Their exposure to Western music was nil: they are hunter-gatherers who live in the forest. They rarely go into big cities and they don't have radios.

You also played the tunes to a group of Canadians. So is music a universal language?

In some ways, yes. Emotional arousal was the same in both groups – a reflection of whether the music was exciting or restful. That was assessed subjectively by the listeners, and objectively by measuring heart rate, breathing and so on. This common response is probably driven by certain acoustic properties, such as tempo.

Why would some elements of music do this?

Arousal is probably linked in evolutionary terms to preparation to deal with a threat or new situation. When music accelerates or suddenly gets shrieky, for example, it seems to cue this alert response – the heart rate rises and so on.

What aspects of the music did not prompt a universal response?

We looked at whether the music evoked happy/joyful or sad/scary feelings, and got a positive/negative rating. We used music from three films: the melancholy theme from Schindler's List, the scary shower scene from Psycho and the upbeat Cantina scene tune from Star Wars. The Canadians reacted as you might expect. For the pygmies, we got no clear physiological results and subjectively, they found all the music negative.

Why might the Mbenzélé not like the Western music?

All the pygmies' own music is highly arousing and positive. They feel negative emotions disrupt the harmony of the forest and they depend on the forest and so they want it to be happy.

What is the Mbenzélé's own music like?

Mostly vocal, with some clapping and beating on log drums, but of a sophistication that is comparable to Western symphonic music, with extraordinary polyphonies and polyrhythms.

Did they have a favourite movie tune?

Music for them is functional – they don't sit around and consume it. Music accompanies various kinds of activities. I don't think the idea of having a favourite would make sense to them.

Did the field work in Congo go smoothly?

For the pygmies, if you can't dance to it, it's not music. It took some persuading to get them to sit still for the research.

This article appeared in print under the headline "Jungle boogie"

Profile

Stephen McAdams is professor of music research at Schulich School of Music at McGill University in Montreal, Canada, and also Canada Research Chair in Music Perception and Cognition. His research is published in Frontiers in Psychology

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Proto quantum computer inspired by Victorians gets a speed boost

Quantum computers should theoretically outpace ordinary ones, but attempts to build a speedy quantum machine have so far come up short. Now an approach based on a Victorian counting device seems to be getting close.

This proto-quantum computer can only solve one problem. But that problem, called boson sampling, seems to be very difficult for an ordinary computer to solve, so physicists hope that such a device will conclusively demonstrate the promise of computing based on exotic physics. "The goal is to show quantum supremacy with the simplest approach," says Fabio Sciarrino of Sapienza University in Rome, Italy, who helped develop the new machine.

Boson samplers are based on a device created by the 19th-century polymath Francis Galton to study statistical distributions. It consists of a wooden board studded with offset rows of pegs. Balls are dropped one by one from the top of the board and ping their way down, bouncing left or right at each peg, before collecting in bins at the bottom. Since balls are more likely to end up in a central bin than one at the edges, you end up with a bell curve distribution across the width of the board. In the pre-computer age, it was one of the best ways to compute this distribution, which often crops up in statistics.

The quantum version swaps balls for photons, which travel along a network of intersecting channels in an optical chip. When two photons collide, their ensuing paths are determined by the laws of quantum mechanics, producing a unique distribution. With enough photons, calculating this distribution becomes very difficult on an ordinary computer, so doing it with real photons in a quantum device is the only practical option.

In 2012, four research groups, including Sciarrino's, demonstrated the first working boson samplers with three photons. But scaling to larger numbers was challenging as it is difficult to produce single photons on demand. The leading method, which involves shooting a laser at a crystal, spits out photons at random times, so you can't get enough in the boson sampler at once.

Scattershot approach

That's why Sciarrino has turned to a slightly different version of the problem, called scattershot boson sampling. This involves using a larger number of photon sources, so that their randomly generated photons have a higher chance of colliding. His team used six sources and were able to produce three photons at once. That means the new boson sampler is no more computationally powerful than the 2012 examples, but operates on average 4.5 times as fast.

"We only have shown a proof-of-principle improvement," says Sciarrino. Now his team is working to improve its sources even further, with the aim of challenging an ordinary computer – each additional photon roughly doubles the difficulty of the calculation. "If you want to start seeing a large improvement, you need something like 20 or 30 sources."

Scott Aaronson of the Massachusetts Institute of Technology, who helped come up with the idea of boson sampling, thinks the device is an important milestone, but not yet a breakthrough. "Hopefully they will have better scaling going forward," he says. "Twenty or 30 photons would be spectacular."

A boson sampler isn't inherently useful, although last year a group of researchers at Harvard University published a theoretical paper suggesting one might be able to calculate the vibrational properties of certain molecules. In any case, the skills and technology needed to get one working with more photons should help enable more general-purpose quantum computers in the future, says Aaronson.

Even if it can't factor large numbers or perform other quantum tricks, a device that unambiguously demonstrates quantum supremacy would be a major scientific breakthrough. Perhaps the first record-beating boson sampler will one day sit in a museum alongside Charles Babbage's difference engine, the mechanical precursor to modern computers. "I like that image," Aaronson says. "I'd go visit it in a museum."

Journal reference: Science Advances, DOI: 10.1126/sciadv.1400255

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Is super-diverse Amazon microbiome something to strive for?

The Yanomami people in the Venezuelan rainforest have the most diverse population of gut microbes ever seen, far more varied than Western guts. Does it matter?

Hunter-gathering in the rainforests and mountains of northern Brazil and southern Venezuela, the Yanomami eat a high-fibre diet based largely on cassava. For thousands of years, some groups have lived without contact with the rest of the world and are thought to be some of the few remaining communities never to have been exposed to antibiotics, which can wipe out the microbes in your gut.

So in some ways, the discovery, announced this week, that they carry the most diverse gut microbiomes ever documented is unsurprising. However, there is increasing evidence that our health is linked to the well-being of the microbes that call our gut home. So is the unspoilt, diverse ecosystem of the Yanomami something we should strive for?

Vaccination trip

Every year, the Venezuelan ministry of health visits newly identified communities to provide them with health services such as vaccinations, in part to protect them from diseases they could catch from gold miners that visit these regions. The decision to visit the particular Yanomami village that has now been studied was taken after it was spotted from the air in 2008.

Accompanied by interpreters who could explain the experiment in the Yanomami language, in 2009, scientists joined the medics and took mouth and forearm swabs and faecal samples from the villagers. The people they encountered had T-shirts and machetes and knew the Spanish word for "medicine", but said they had never encountered non-Yanomami people before.

Sequencing the genes in the faecal samples revealed that the Yanomami carried nearly double the diversity of microbial species in their intestines compared with people living in the US. They also had about 30 to 40 per cent more diversity than a less isolated group of Venezuelan hunter-gatherers that has largely maintained its traditional lifestyle but has occasionally used antibiotics and eaten processed foods.

The Western way

"Our results suggest that Westernisation leads to the reduction of diversity, to different microbiota compositions," Maria Dominguez-Bello of the New York University School of Medicine, who led the research, told a teleconference on Wednesday.

Her colleague Jose Clemente of the Icahn School of Medicine at Mount Sinai in New York, said the results suggest that even minimal exposure to modern lifestyle practices such as using antibacterial soaps and cleansers, taking antibiotics and having Caesarean sections, which mean babies don't pass through their mother's birth canal and pick up her microbes, can result in a dramatic loss of microbial biodiversity.

It can be difficult to disentangle which medical and lifestyle practices have the biggest impact on the microbiome says Jens Walter of the University of Alberta in Canada, who worked on both the Yanomami study and another one published this week that showed that the microbiomes of rural Papua New Guineans are also more diverse than those of US residents.

However, antibiotic use is high in Papua New Guinea, suggesting that it is other factors that are responsible for the relatively high microbiome diversity observed there.

Does it matter?

So does a more diverse microbiome make for a healthier person? Possibly. Healthier people do seem to host a more diverse array of microbes but it's hard to know whether one causes the other. There is some evidence that losing certain microbial species is linked to some cancers, plus giving mice antibiotics can make them gain weight, so perhaps a good mix of microbes in your gut can keep you from piling on the pounds.

"It is an interesting hypothesis that the rise of Western diseases might be caused by the depletion of the gut microbiota," says Walter. But it's difficult to draw any conclusions about the benefits of microbial diversity by comparing ourselves directly with the Yanomami or Papua New Guineans because overall health and life expectancy is greater in modern societies.

Walter doesn't recommend striving drastically to make the paltry Western gut look more Yanomamian. Poor sanitation is probably one factor contributing to the Papua New Guinean's high microbial diversity, but they have high levels of infectious diarrhoea as a result – not a situation that Western urbanised nations would want to return to.

And a quick-fix method, like receiving a faecal transplant from a Yanomami person, would not be safe, says Walter. But restricting antibiotics and Caesareans to medically necessary cases can't hurt, neither can eating more fibre, he suggests.

While visiting the village, the medics administered some antibiotics. Depending on the specific antibiotics given , one of the last remaining examples of a pre-antibiotic microbiome has probably already been sullied, says Björn Olsen of Uppsala University in Sweden. "It's becoming harder and harder to find people like these Amerindians in our extremely urbanised world," he says.

Journal references: Science Advances, DOI: 10.1126/sciadv.1500183 (Yanomami people); Cell Reports, DOI: 10.1016/j.celrep.2015.03.049 (Papua New Guineans)

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North pole of spinning dwarf planet Ceres glows in the sunlight

(Image: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA)

It's the sun-lit north pole of a dwarf planet, in more detail than we've ever seen before. These images of Ceres, the largest object in the asteroid belt between Mars and Jupiter, were snapped by NASA's Dawn spacecraft last Friday.

The spacecraft captured the photos from a distance of 33,000 kilometres as it passed over the dwarf planet's pole after more than a month on its dark side. It should soon gather views of other features, including a mysterious set of bright spots on the surface that could contain watery volcanoes.

Meanwhile, NASA's New Horizons probe is speeding its way towards Pluto and has sent back the first blurry colour photos of the dwarf planet and its largest moon, Charon. We'll get our best-ever view of Pluto when the spacecraft flies past it on 14 July.

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Feedback: Striving to name polyfailure

Feedback is our weekly column of bizarre stories, implausible advertising claims, confusing instructions and more

WHAT should we call the phenomenon exemplified by Feedback's perception that "anyone who suspects the probability of a set of independent failures occurring together to be vanishingly small should urgently make plans to cope with them all happening at once" (7 March)? So far, 21 readers have been keen to help.

Six of you suggested Murphy's law, also known as Sod's law: "Anything that can go wrong, will go wrong." Bill Sloman noted the "necessary corollary that whichever name you use for it won't be the one used by the person you are talking to". Bob Malcolm was reminded of a journalist asking a UK Met Office spokesperson, in the aftermath of some weather phenomenon, "Why can't you predict these freak events?"

Bob also likes the "Law of the Inevitability of Freak Events", ...

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Parasitic populations solve algorithm problems in half the time

PARASITES are nature's thieves, but we can harness this behaviour for our own gain.

We use algorithms to work out complicated problems like the best truck route or crew schedule, because finding a good solution means fiddling with the values of many parameters simultaneously.

One way they can do this is by using groups of virtual creatures that wander through "parameter space", looking for valleys that represent the lowest values. Mathematicians have taken inspiration from actual animals, from grey wolves to ants. One limitation, though, is that the animals sometimes fail to notice a deeper valley nearby. Adding parasites can stop this from happening, say Shi Cheng of the University of Nottingham Ningbo, in China, and his colleagues.

In their model, a swarm of animals searched for the lowest valleys, but was then joined by a second, parasitic population. This group searched for valleys, but also abducted the most successful animals and made them work for the parasite team.

The result of this struggle for life was a more varied collection of creatures that enabled the parasitic algorithm to solve a problem in half the time (Applied Soft Computing, doi.org/3j6).

This article appeared in print under the headline "Parasites make for efficient algorithms"

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Eye of the beholder: How colour vision made us human

(Image: Jimmy Turrel)

IT TOOK a rather unremarkable garment for people to begin to question their view of reality. On 26 February this year, a photo of a dress went viral – not for its stylishness, but because of its chameleonic colours. Some saw it as blue and black, while others thought it white and gold. Still others, to their enduring unease, saw first one combination, then the other.

The discussions that rippled across the web as a result illustrated a fundamental truth: colour is one of the most vivid and personal experiences we have. But while colour feels extremely real and present, we are still learning exactly how events in our evolutionary past combined to create our particular form of colour vision – and beyond the odd optical illusion, just how important it has been in making us who we are. "Humans wouldn't be here if we ...

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Dogs tap into human bonding system to get close to our hearts

Video: Eye-to-eye bonding

Ever felt hopelessly bonded to your pooch when it stares at you lovingly? It turns out that man's best friend may have hijacked a uniquely human bonding mechanism, ensuring that we love and care for it.

Knock-on chemical and behavioural effects occur when humans bond: eye contact leads to release of the "love hormone" oxytocin, which elicits caring behaviour, and this in turn causes the release of more oxytocin. This loop has been shown to be important for human bonding, for example between mothers and their children.

Oxytocin bonding occurs in other mammals, too, but humans were thought to be unique in using eye contact as part of this cycle. "Facing others is a threatening behaviour in other animals," says Miho Nagasawa at Azabu University in Japan.

But when she and her colleagues got a bunch of dog owners to gaze into their pets' eyes, they found that oxytocin levels rose not just in the humans – but in the pooches too.

In contrast, when Nagasawa's team tested hand-reared wolves, they found no such effect, and wolves spent little time gazing into their owners' eyes.

They then sprayed either oxytocin or a placebo into 27 dogs' noses, in a randomised experiment. Female dogs that received the hormone spent more time staring longingly at their owners, and oxytocin levels also rose in those people.

This means that the tendency to gaze into eyes must have evolved during the domestication of dogs, says Nagasawa. She adds that it's the first demonstrated case of convergent evolution in cognitive traits between a human and another species.

The only hitch was that although both male and female dogs – and their owners – received an oxytocin boost from eye contact, male dogs didn't spend more time looking at their owners' eyes when they were sprayed with the hormone.

Nagasawa suggests that this could be because among males oxytocin is known to increase hostility towards members of other groups, so the sprays might have made the male dogs more vigilant about strangers in the room during the experiment.

Close connection

Pat Shipman at Penn State University in University Park has argued that the co-evolution of dogs and humans – possibly starting as long as 36,000 years ago – gave humans the edge over Neanderthals.

"I had predicted that both domestic dogs and humans would show adaptations to enhanced non-verbal communication, but I had not thought of the oxytocin link," she says. "As the first species to be domesticated, dogs have a very ancient and very profound link to humans that affected both of us."

But not everyone is convinced this shows that dogs evolved to hijack our bonding mechanism through staring into our eyes.

Jessica Oliva at Monash University in Melbourne, Australia, agrees that oxytocin was key to the evolution of dogs from wolves, allowing them to bond with humans. But she thinks that the eye-gazing behaviour could be learned rather than having evolved over time. "It could be a conditioning thing," she suggests.

Clive Wynne of Arizona State University in Tempe agrees. He says that wolves he works with do make eye contact if they've been brought up in close contact with people. "I'm questioning the attempt to interpret these results as an evolutionary process," says Wynne.

Nagasawa agrees that wolves and other animals can learn to make eye contact, but says it comes easier to dogs. And to her, that suggests the behaviour has evolved.

She says this might just be the tip of the iceberg, too. Next, she wants to study whether dogs feel empathy with humans. "Most dog owners say when they feel sad, their dogs feel sad too. And when the owners feel happy, maybe the dogs feel happy too. So maybe the dogs are very sensitive to the owners' feelings," she says.

Journal reference: Science, DOI: 10.1126/science.1261022

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Plane creates vibrant landscape painting by firing laser pulses

(Image: Norbert Pfeifer/TU Wien)

What would Turner think of a landscape painting created by a plane? This artistic-looking map was captured in 3D by laser pulses fired from an aircraft as it flew over the conservation area of Ágotapuszta in Hungary. Each type of vegetation within the mosaic of salt meadows, grasslands and marshes is represented in a different colour.

The aerial system was developed by Norbert Pfeifer from the Vienna University of Technology in Austria and his colleagues to monitor Europe's nature reserves, which cover a fifth of the continent's surface. To retain their status, regular checks have to be carried out at least once every six years, which is far easier to do from the air than on land.

A plane scans a strip of land between 300 and 800 metres wide by directing half a million infrared laser pulses at the ground every second. By measuring the return travel time of each pulse, computer algorithms can work out the total distance of the round trip and build up the shape of a landscape.

Protruding features, such as trees, are revealed by pulses that have travelled a shorter distance. Even minute details like weeds and vehicle tracks come to life.

(Image: Norbert Pfeifer/TU Wien)

A ground-level view, shown above, can also be recreated by looking at a specific cross-section of the 3D map. From this detail, ecologists should be able to determine the leafiness and height of the trees as well as the species.

Journal reference: Canadian Journal of Remote Sensing, DOI: 10.5589/m13-013

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