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31

Astronomy / Neutron starbursts can forge gold

« on: August 05, 2014, 06:31:39 PM »

New evidence has been uncovered of a rare cosmic event that is proposed as a source of heavy elements such as gold.

Observations from the Hubble Space Telescope appear to show a distant collision between two neutron stars - the remnants of massive supernovae.

Astronomers suggest that such collisions are responsible for ultra-short bursts of gamma rays occasionally seen across the Universe.

The work is described in a paper on the pre-print server Arxiv.org.

Although rare, neutron star collisions would generate the enormous fluxes of neutrons needed to make elements heavier than iron, like platinum, lead and gold, by rapid neutron capture.

Prof Edo Berger and colleagues from Harvard University analysed Hubble observations of a short burst of gamma rays, lasting only one fifth of a second, seen from a galaxy 3.9 billion light years away.

The infrared afterglow of this burst of gamma-ray light appears to show the characteristics expected during radioactive decay of atomic nuclei generated in a neutron star collision.

This sort of event emits light with an intensity that lies between normal star light and that of a supernova, and the term "kilonova" has been coined to describe it.

They appear to be around 1,000 times rarer than supernova explosions, and occur when the remnants of two supernovae collide.

If confirmed, the result represents the first observation of a neutron star collision, and provides an explanation for the rapid "R-process" of atom-building that must generate the heavy elements on the periodic table, such as gold and platinum.

Neutron stars are incredibly dense and massive. As well as bursts of light, when they collide they are also expected to send gravity "shock waves" through the Universe.

Experiments in America and Europe are now focussed on measuring such waves, and combined with the type of events seen by Hubble in the last month this will provide a further confirmation of neutron star collision.

Astronomers are now testing the conclusions of the Harvard group with further detailed analysis of the Hubble data.

32

Astronomy / Triple star system 'can reveal secrets of gravity'

« on: August 05, 2014, 06:31:21 PM »

Astronomers have discovered a unique triple star system which could reveal the true nature of gravity.

They found a pulsar with two white dwarfs all packed in a space smaller than Earth's orbit of the Sun.

The trio's unusually close orbits allow precise measurements of gravity and could resolve difficulties with Einstein's theories.

The results appear in Nature journal and will be presented at the 223rd American Astronomical Society meeting.

"This triple system gives us a natural cosmic laboratory far better than anything found before for learning exactly how such three-body systems work and potentially for detecting problems with general relativity that physicists expect to see under extreme conditions," said Scott Ransom of the US National Radio Astronomy Observatory (NRAO) in Charlottesville, VA.

"This is a fascinating system in many ways, including what must have been a completely crazy formation history, and we have much work to do to fully understand it."

Pulsars emit lighthouse-like beams of radio waves that rapidly sweep through space as the stars spin on their axes.

They are formed after a supernova collapses a burnt-out star to a dense, highly magnetised ball of neutrons.

Using the Green Bank Telescope, the astronomers discovered a pulsar 4,200 light-years from Earth, spinning nearly 366 times per second.

Such rapidly-spinning bodies are called millisecond pulsars - and are used by astronomers as precision tools for studying gravitational effects and other phenomena.

Subsequent observations showed the pulsar is in a close orbit with a white dwarf star, and that pair is in orbit with another, more-distant white dwarf.

Green Bank radio telescope, West Virginia
Green Bank is 100m wide - the world's largest fully steerable radio telescope
Three-body systems are keenly studied because they allow competing theories of gravity to be tested.

But until now the only known triple system containing a millisecond pulsar was one with a planet as the outer companion, causing only weak gravitational interactions.

"This is the first millisecond pulsar found in such a system, and we immediately recognised that it provides us a tremendous opportunity to study the effects and nature of gravity," Prof Ransom said.

"The gravitational perturbations imposed on each member of this system by the others are incredibly pure and strong."

By precisely timing the arrival of the pulses, the scientists were able to calculate the geometry of the system and the masses of the stars.

The pulsar's inner white-dwarf companion has an orbital period of less than two days, while the outer dwarf has a period of almost a year.

The system gives the scientists the best opportunity yet to look for violations of the equivalence principle described by Einstein - which states that the effect of gravity on a body does not depend on the nature or internal structure of that body.

This was famously illustrated by Galileo's dropping of two balls of different weights from the Leaning Tower of Pisa, and Apollo 15 Commander Dave Scott's dropping of a hammer and a falcon feather while standing on the Moon in 1971.

Rather than drifting to the ground, the feather plummeted, falling as fast as the hammer. Without air resistance to slow the feather, both objects hit the lunar dust at the same time.

"While Einstein's theory of general relativity has so far been confirmed by every experiment, it is not compatible with quantum theory," said Prof Ransom.

"Because of that, physicists expect that it will break down under extreme conditions."

High-precision timing of the pulsar's "lighthouse" flashes will let astronomers hunt for deviations in the equivalence principle at a sensitivity several orders of magnitude greater than ever before, said astronomer Prof Ingrid Stairs of the University of British Columbia.

"Finding a deviation would indicate a breakdown of general relativity and point us toward a new, correct theory of gravity," she said.

The 223rd AAS meeting runs from 5-9 January in Washington DC.

33

Astronomy / Dark matter hints in widest-yet view of dark mystery

« on: August 05, 2014, 06:30:58 PM »

Researchers have released the biggest images yet detailing dark matter, the mysterious substance that makes up 85% of the Universe's mass.

Each image, a billion light-years across, shows evidence of dark matter clumps scattered through the cosmos.

The team from the Canada-France Hawaii Telescope inferred the dark matter's existence by the way it bends light.

The images were presented at the 219th meeting of the American Astronomical Society in Austin, US.

The four images were taken at four different seasons of the year, each capturing a swath of the sky about as large as a palm held at arm's length.

They are a big step forward in understanding both dark matter itself, and the means by which dark matter influences the way normal matter clumps into the galaxies we see in the night skies.

Together, they represent the images of more than 10 million galaxies, whose light gives the only hints of the large-scale structure of dark matter.

Continue reading the main story
Dark energy and dark matter mysteries

Dark matter distribution simulation
Gravity acting across vast distances does not seem to explain what astronomers see
Galaxies, for example, should fly apart; some other mass must be there holding them together
Astrophysicists have thus postulated "dark matter" - invisible to us but clearly acting on galactic scales
At the greatest distances, the Universe's expansion is accelerating
Thus we have also "dark energy" which acts to drive the expansion, in opposition to gravity
The current theory holds that 73% of the Universe is dark energy, 23% is dark matter, and just 4% the kind of matter we know well
BBC Universe: Dark matter
BBC Universe: Dark energy
"Light coming toward us from a distant galaxy is bent by the gravity of a lump of matter in the middle," explained Catherine Heymans of the University of Edinburgh.

"Einstein's theory of general relativity tells us that mass bends space and time, so when light comes toward us through the Universe, if it passes some dark matter, its light gets bent and the image we see gets bent and distorted," Dr Heymans told the meeting.

"Dark matter is leaving its signature on the images of very distant galaxies."

The survey is some 100 times larger than the previous largest map of the web of dark matter, gathered by the Hubble telescope's Cosmic Evolution Survey, or Cosmos.

In the new image, the full-scale distribution of vast clumps of dark matter can be seen around galaxy clusters, connected by wispy filaments of dark matter and trailing off to enormous voids where no matter exists.

Thankfully for theoretical astrophysicists, these images line up neatly with theory.

"Our theories of dark matter say that it should form a giant intricate cosmic web and that's exactly what we see in this data, a cosmic web that's housing the galaxies that we can see," Dr Heymans told BBC News.

Astronomy of scale
Dark matter at these huge, cosmological scales is only one part of the story, however, and Sukanya Chakrabarti of Florida Atlantic University presented work showing how the "dark matter halo" that surrounds individual galaxies can be characterised.

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It's very widely believed that our final understanding of the 'dark universe' is going to have to invoke some new physics, something that will forever change our view”

Catherine Heymans
University of Edinburgh
Building on work first presented at last year's meeting, Dr Chakrabarti showed how the ripples in the gas trailing behind spiral galaxies are giving an ever-better view of how dark matter is distributed around galaxies, and how it may influence how they form.

Rachel Mandelbaum of Princeton University said that the findings were significant, tackling the mystery on two fronts.

"Both of these results represent two important ways of studying dark matter but in very different regimes," she told the meeting.

"They're important in themselves, but they're also important as a proof-of-concept for the future, allowing us to see how powerful these methods will be with other data sets to do additional work."

And a great deal of work is still needed. Dr Heymans conceded that we still need to find out the nature of the dark matter particle, as well as discover more about the even more mysterious dark energy, which serves to drive the Universe's expansion even as dark matter works to draw things together.

"I'll be very honest with you, we don't know what the dark matter particle is, we don't know what this dark energy is coming from," she said.

"It's very widely believed that our final understanding of the 'dark universe' is going to have to invoke some new physics, something that will forever change our view of the Universe.

"What the team is presenting today are the first steps to reaching this goal."

34

Astronomy / How close are we to finding dark matter?

« on: August 05, 2014, 06:30:37 PM »

Dark matter makes up about a quarter of the cosmos, but we still don't know what it is. As part of a two-part series called Light & Dark on BBC Four, physicist Jim Al-Khalili pondered how close we are to understanding the mysterious "dark stuff".

Given all the progress we've made in modern physics over the past century, you may be forgiven for thinking that physicists are approaching a complete understanding of what makes up everything in our Universe.

For example, all the publicity surrounding the discovery of the Higgs boson last year seemed to be suggesting that this was one of the final pieces of the jigsaw - that all the fundamental building blocks of reality were now known.

So it might come as something of a shock to many people to hear that we still don't know what 95% of the Universe is made of.

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The stars in galaxies revolve around like undissolved coffee granules on the surface of you mug of coffee just after you've stopped stirring it”

It's all rather embarrassing. Everything we see: our planet and everything on it, the moon, the other planets and their moons, the Sun, all the stars in the sky that make up our Milky Way galaxy, all the other billions of galaxies beyond with their stars and clouds of interstellar gas, as well as all the dead stars and black holes that we can no longer see; it all amounts to less than 5% of the Universe.

And we don't even know if space goes on for ever, what shape the Universe is, what caused the Big Bang that created it, even whether it is just one of many embedded multiverses.

About a quarter of all the stuff in our Universe is thought to be made up of dark matter. We know this because galaxies appear to weigh a lot more than the sum of all the normal matter they contain that we know about.

Many astronomical observations, including the patterns made by galaxies in the night sky, the motions of stars within a galaxy and the images of distant galaxies distorted by the intervening matter, all point to the unmistakable gravitational effect of some sort of elusive invisible - and therefore.. erm... dark matter.

Continue reading the main story
Dark energy and dark matter mysteries

Dark matter distribution simulation
Gravity acting across vast distances does not seem to explain what astronomers see
Galaxies, for example, should fly apart; some other mass must be there holding them together
Astrophysicists have thus postulated "dark matter" - invisible to us but clearly acting on galactic scales
At the greatest distances, the Universe's expansion is accelerating
Thus we have also "dark energy" which acts to drive the expansion, in opposition to gravity
The current theory holds that 68% of the Universe is dark energy, 27% is dark matter, and just 5% the kind of matter we know well
BBC Universe: Dark matter
BBC Universe: Dark energy
For example, the stars in galaxies revolve around like undissolved coffee granules on the surface of your mug of coffee just after you've stopped stirring it. The faster the stars are moving, then the harder they must be pulled towards the centre to keep them from flying away.

If the only matter in the galaxy was the stuff you could see then the outer stars should be revolving much more slowly than they actually are. In fact they are moving round so fast that without some extra gravitational force to hold on to them, they'd be flying off into the depths of space.

The only way to explain the way these stars are observed to behave is if there is additional gravitational attraction due to some kind of invisible form of matter, which surrounds the stars. And to have the effect it does, it would have to contain many times more mass than all the visible forms of matter put together.

The problem with dark matter is that, whatever it is made of, it seems to interact very weakly with normal matter. This makes it very hard to catch - like trying to catch a shadow. In fact, it streams right through the Earth as easily as sunlight passes through a glass window.

There are three different ways we can try to find out what dark matter is made of. We can look out into space and see the results of collisions of dark matter particles by trying to detect the normal matter particles created in the debris of these collisions; or we can try to catch dark matter particles directly as they stream through the Earth; or we make them ourselves in particle accelerators like the Large Hadron Collider at Cern.

It is the second of these methods though that is the most promising as far as current experiments go.

Dark matter map   Nasa/Esa/Massey
Dark matter can be mapped by studying its gravitational effects on the matter we can see
Most scientists believe that dark matter takes the form of particles called Weakly Interacting Massive Particles, or WIMPs, and that millions of these are streaming through us every second without a trace. In the last decade, there have been a number of announcements by different research groups around the world claiming to have seen hints of these elusive particles. One group has even claimed to have detected a dark matter signal definitively.

Several of these experiments are taking place at the Gran Sasso National Laboratory in central Italy, the world's largest underground laboratory, which lies beneath almost a kilometre-and-a-half of solid rock and can only be reached through a tunnel cut deep into the Italian Apennines.

The reason for this is because our planet is also constantly being bombarded by cosmic rays, which collide with the upper atmosphere creating a cascade of particles that shower down onto the surface of the Earth.

The rock above the laboratory effectively forms a 1,400m-thick roof that absorbs most of these particles, shielding and protecting the equipment below. But crucially for the researchers, dark matter itself passes straight through the rock, and, the hope is, into their detectors.

However, much recent excitement in the dark matter community has been surrounding the latest results from another underground laboratory. The LUX (Large Underground Xenon) detector is situated down a deep gold mine in South Dakota.

Atlas detector at Cern
The Large Hadron Collider will be used to probe the dark matter mystery when it re-starts in 2015
Its first three-month run took place earlier this year and while it did not detect any dark matter particles, it has shown itself to be the most powerful and sensitive detector of its kind so far.

It has already ruled out a number of candidate signals seen in other experiments - and knowing what dark matter isn't is almost as important as knowing what it is. Next year it is to begin its work in earnest.

Scheduled to start in 2014, this will be a continuous 300-day run that, it is hoped, will finally directly detect dark matter particles. And if it doesn't, well physicists are already designing a new bigger and more sensitive detector: the LZ experiment, which they believe should definitively detect WIMPs - if they're out there.

Of course, if physicists continue to come up empty-handed in their search, then it just may be that we've got it wrong about dark matter altogether. If it turns out not to be made up of WIMPs we will have to go back to our blackboards in the search for an alternative theory and explanation for what we are seeing through our telescopes.

And what happens when we solve the dark matter mystery? Well, there's still the two thirds of the Universe that is even more mysterious - the stuff called dark energy. And we have hardly even begun to figure out how to go looking for that.

35

Astronomy / Cosmic crash unmasks dark matter

« on: August 05, 2014, 06:29:08 PM »

Striking evidence has been found for the enigmatic "stuff" called dark matter which makes up 23% of the Universe, yet is invisible to our eyes.
The results come from astronomical observations of a titanic collision between two clusters of galaxies 5.7 billion light-years away.
Astronomers detected the dark matter because it separated from the normal matter during the cosmic smash-up.
The research team are to publish their findings in the Astrophysical Journal.
They used the Hubble and Chandra space telescopes to study the object MACSJ0025.4-1222 - formed after an incredibly energetic collision between two large galaxy clusters.
Each of these large clusters contains about a quadrillion times the mass of our Sun.
   
 It puts to rest all the worries that the Bullet Cluster was an anomalous case. We have gone out and found another one 
Richard Massey, Royal Observatory Edinburgh
A technique known as gravitational lensing was used to map the dark matter with Hubble.
If an observer looks at a distant galaxy and some dark matter lies in between, the light from that galaxy gets distorted.
It looks as if it is being seen through lots of little lenses. And each of these lenses represents a piece of dark matter.
Astronomers used the Chandra X-ray telescope to map ordinary matter in the merging clusters, mostly in the form of hot gas, which glows brightly in X-rays.
As the two clusters that formed MACSJ0025 merged at speeds of millions of kilometres per hour, hot gas in the two clusters collided and slowed down.
However, the dark matter kept on going, passing right through the smash-up.
Speeding bullet
This phenomenon has been seen before, in a structure called the Bullet Cluster - which also formed after the collision of two large galaxy clusters. The Bullet Cluster lies closer to Earth, at a distance of 3.4 billion light-years.
"It puts to rest all the worries that the Bullet Cluster was an anomalous case. We have gone out and found another one," co-author Richard Massey, from the Royal Observatory Edinburgh, told BBC News.
The study sheds light on the properties of dark matter.
The fact that dark matter does not slow down in the collision supports a view that dark matter particles interact with each other only very weakly or not at all (when one excludes their gravitational interaction).
"Dark matter makes up five times more matter in the Universe than ordinary matter," said co-author Marusa Bradac, from the University of California at Santa Barbara (UCSB).
"This study confirms that we are dealing with a very different kind of matter, unlike the matter that we are made of. And we're able to study it in a very powerful collision of two clusters of galaxies."
Larger sample
The latest astronomical observations suggest that dark matter makes up some 23% of the Universe. Ordinary matter - such as the galaxies, gas, stars and planets - makes up just 4%.
The remaining 73% is made up of another mysterious quantity; dark energy, which is responsible for speeding up the expansion of the cosmos.
CMS at Cern (M. Brice/Cern)
The Large Hadron Collider may shed further light on dark matter
According to one model, dark matter may be comprised of exotic sub-atomic "stuff" known as Weakly Interacting Massive Particles (WIMPS).
Others hold that the dark substance consists of everyday matter, rather than some elusive sub-atomic particle. However, this ordinary matter, referred to as Massive Astrophysical Compact Halo Objects (MACHOS), happens to radiate little or no light.
A powerful physics experiment, the Large Hadron Collider, situated on the French-Swiss border, could shed further light on this question after it begins operating later this year.
Dr Massey said his team had found other candidates for colliding clusters.
"Ideally, we don't want just one or two, we want lots of these things to really study them statistically," he explained.
"Then we either use the whole lot, or pick out one 'golden bullet' which will provide the best constraints on what dark matter is."
The Hubble Space Telescope failed just after the team had taken their image of MACSJ0025, so they have not yet been able to study these other candidates.
Dr Massey said the astronomers hope to do this after the next Hubble servicing mission with the space shuttle, which is due to launch in October 2008.

36

Astronomy / Supernova 'dust factory' pictured

« on: August 05, 2014, 06:28:41 PM »

Striking images of a young supernova brimming with fresh dust have been captured by a telescope in the Chilean desert.

It is the first time astronomers have witnessed the genesis of the grains which formed galaxies in the early universe.

The pictures were captured by the Alma (Atacama Large Millimeter/submillimeter Array) telescope.

They were revealed at the 223rd meeting of the American Astronomical Society.

They will be published in the Astrophysical Journal Letters.

Fading giants
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Space is quite a messy place”

Remy Indebetouw
Astronomer
The universe is full of tiny solid particles – from the dark bands we see in the Milky Way to the beautiful clouds in iconic pictures from the Hubble telescope.

Dust collapses into planets and aids the formation of stars. But despite its ubiquity, there was no firm evidence of where it actually emerged from in the first place.

In today's universe, it largely forms around dying stars as they burn out. But these fading giants were not around at the dawn of the universe.

“It's the same problem as we have in my house – there's a lot of dust and we don't know where it comes from. Space is quite a messy place," quipped Remy Indebetouw, an astronomer with the National Radio Astronomy Observatory.

“So we took one of the most technologically advanced telescopes ever – Alma – and tried to find out how dust formed in the early universe.”

"Supernovas have long been thought to be the creators – the bright factories that burst out building blocks for galaxies. But catching one in the act is far from easy.

"And even when we do spot a supernova cloaked in a dusty plume, there's the old chicken-egg problem: how do we know that the cloud wasn't there first?”

'Not a nuisance'
To settle the argument, a team of astronomers from the UK and US used Alma to observe the glowing remains of 1987A, the closest recently observed supernova, 168,000 light-years from Earth.

They predicted that, as the gas cooled after the explosion, solid molecules would form in the centre from atoms of oxygen, carbon, and silicon bonded together.

Earlier observations of 1987A with the infrared telescope Herschel had only detected a small amount of hot dust.

But thanks to the power of the Alma radio telescope array, which stretches out over the Atacama desert, it took only 20 minutes to capture the evidence on camera.

“We found a remarkably large dust mass concentrated in the central part of the ejecta [cloud of particles],” said Dr Indebetouw.

Supernova 1987A
The data from Alma was combined with observations by Nasa's Hubble and Chandra telescopes to create this supernova image
“And all of that matter – the red area you see at the centre of the picture – was there in the core of the star before it exploded.That's the exciting thing.

“People think of dust as a nuisance - something that gets in your way. But it turns out it's pretty important.”

While supernovae signal the destruction of stars, they are also the source of new material and energy, says Dr Jacco van Loon of Keele University, a co-author on the study.

“Our lives would be very different without the chemical elements that were synthesised in supernovae throughout history,” he said.

“Grains are incredibly difficult to make in the vast emptiness of space. And if supernovae indeed make lots of them, this has very important and positive consequences for the eventual formation of the Sun and the Earth.”

Alma Observatory graphic

37

Astronomy / Deepest galaxy cluster ever pictured by Hubble

« on: August 05, 2014, 06:27:55 PM »

The "deepest ever" image of a group of galaxies - "Pandora's Cluster" - has been captured by the Hubble Space Telescope.

The blue arcs in the picture are distant galaxies as they appeared 12 billion years ago - not long after the Big Bang.

The hidden objects are revealed through the "magnifying lens" of the cluster Abell 2744.

The image was unveiled at the 223rd meeting of the American Astronomical Society (AAS) in Washington DC.

It is the first in a set of super-deep views of the Universe taken by Hubble's Frontier Fields observing programme, and published on the Arxiv preprint server.

Funhouse mirror
In the foreground are the colourful spirals and elliptical galaxies of Abell 2744, a massive cluster in the constellation Sculptor.

It is nicknamed Pandora for its strange and violent formation history, which unleashed many new phenomena to astronomers.

Galaxy GN-z10-1
One of the earliest galaxies ever seen - as it appeared 13.2 billion years ago
Abell's immense gravity acts as a lens to warp, brighten and magnify more distant objects lurking in the background.

The long exposure by Hubble reveals almost 3,000 of these background galaxies, interwoven with hundreds in the foreground.

The faintest is 10-20 times fainter than any galaxy ever seen before.

They appear brighter thanks to the lensing phenomenon, but are also smeared, stretched and duplicated - like faces in a funhouse mirror.

The remarkable photograph will be combined with images from Nasa's Spitzer telescope and Chandra X-ray Observatory to give new insights into the origin of galaxies and their accompanying black holes.

It was one of three spectacular new findings by Hubble unveiled at the AAS conference.

Four brilliant young galaxies have been pictured as they were 13.2 billion years ago - just 500 million years after the Big Bang.

The brightest was forming stars 50 times faster than our Milky Way does today, but is only one twentieth the size.

Abell 1689
These previously unseen galaxies gave birth to most stars in the cosmos today
Although Hubble has previously identified galaxies at this early epoch, astronomers were surprised to find objects 10 to 20 times more luminous than anything seen before.

"These just stuck out like a sore thumb because they are far brighter than we anticipated," said Garth Illingworth of the University of California at Santa Cruz.

"There are strange things happening... we're suddenly seeing luminous, massive galaxies quickly build up at such an early time. This was quite unexpected."

For the first time, the astronomers were able to estimate the masses of these early galaxies, by using Spitzer to measure their total luminosity.

"They were much larger than we expected to find. Only 1% of our Milky Way. But that is a big galaxy for that early era," said Dr Illingworth.

The discovery of such rich activity at the extreme limits of Hubble's range bodes well for Nasa's James Webb Space Telescope (JWST), currently in development.

3D printed galaxy
3D printing brings Hubble's spectacular images to life for the visually impaired
JWST would allow astronomers to look even farther back in time to see some of the first galaxies ever made in the Universe.

"We're reaching back through 96% of the life of the Universe to these galaxies - that's an astonishing undertaking. And with James Webb, we can learn even more," said Dr Illingworth.

Another new striking image released from Hubble features the "unseen" galaxies thought to be responsible for the "baby boom" that created most stars we see today.

Deep exposures in ultraviolet light, made with Hubble's Wide Field Camera 3, revealed a sample of 58 small, faint galaxies that existed more than 10 billion years ago.

Normally too dim for Hubble to see, these galaxies were revealed through gravitational lensing focused on the massive cluster Abell 1689 in the constellation Ursa Major.

"There's always been a concern that we've only found the brightest of the distant galaxies - the tip of the iceberg," said Brian Siana of the University of California at Riverside.

"We believe most stars forming in the early Universe occur in galaxies we normally can't see at all. Now we have found those 'unseen' galaxies, and we're really confident we're seeing the rest of the iceberg."

A new project to bring these stunning images to life for the blind and visually impaired was unveiled at the AAS meeting: 3D printed galaxies - with different textures for dust clouds, nebulae and other celestial features.

"The visually impaired can now explore and appreciate the beauty of Hubble images through touch," said Carol Christian, of the Space Telescope Science Institute.

"Our ultimate goal - anyone who would like to hold a piece of the Universe in their hands can get the data from Hubble and print them in their school, library, or their home."

38

Astronomy / Cosmic 'web' seen for first time

« on: August 05, 2014, 06:27:29 PM »

The hidden tendrils of dark matter that underlie the visible Universe may have been traced out for the first time.

Cosmology theory predicts that galaxies are embedded in a cosmic web of "stuff", most of which is dark matter.

Astronomers obtained the first direct images of a part of this network, by exploiting the fact that a luminous object called a quasar can act as a natural "cosmic flashlight".

Details of the work appear in the journal Nature.

The quasar illuminates a nearby gas cloud measuring two million light-years across.

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In this case we were lucky that the flashlight is pointing toward the nebula and making the gas glow”

Sebastiano Cantalupo
University of California, Santa Cruz
And the glowing gas appears to trace out filaments of underlying dark matter.

The quasar, which lies 10 billion light-years away, shines light in just the right direction to reveal the cold gas cloud.

For some years, cosmologists have been running computer simulations of the structure of the universe to build the "standard model of cosmology".

They use the cosmic microwave background, corresponding to observations of the very earliest Universe that can be seen, and recorded by instruments such as the Planck space observatory, as a starting point.

Their calculations suggest that as the Universe grows and forms, matter becomes clustered in filaments and nodes under the force of gravity, like a giant cosmic web.

The new results from the 10-metre Keck telescope in Hawaii, are reported by scientists from the University of California, Santa Cruz and the Max Planck Institute for Astronomy in Heidelberg.

They are the first direct observations of cold gas decorating such cosmic web filaments.

UM 287 quasar and gas
The observed portion of the cosmic web (cyan) is about 2 million light-years across
The cosmic web suggested by the standard model is mainly made up of mysterious "dark matter". Invisible in itself, dark matter still exerts gravitational forces on visible light and ordinary matter nearby.

Massive clumps of dark matter bend light that passes close by through a process called gravitational lensing, and this had allowed previous measurements of its distribution.

But it is difficult to use this method to see very distant dark matter, and cold ordinary matter remains tricky to detect as well.

The glowing hydrogen illuminated by the distant quasar in these new observations traces out an underlying filament of dark matter that it is attracted to it by gravity, according to the researchers' analysis.

"This is a new way to detect filaments. It seems that they have a very bright quasar in a rare geometry," Prof Alexandre Refregier of the ETH Zurich, who was not involved in the work, told BBC News.

"If indeed gravity is doing the work in an expanding Universe, we expect to see a cosmic web and it is important to detect this cosmic web structure."

In the dark
He added: "What is expected is that the dark matter dominates the mass and forms these structures, and then the ordinary matter, the gas, the stars and everything else trace the filaments and structures that are defined by the dynamics of the dark matter."

"Filaments have been detected indirectly before using gravitational lensing, which allows us to see the distribution of the dark matter.

"Part of the ordinary matter has formed stars, which we can see, but another component is the gas. If the gas is very hot it emits X-rays and can be seen using X-ray telescopes. Other techniques to detect cooler gas now include the method described here."

Continue reading the main story
Dark energy and dark matter mysteries

Lux dark matter detector
Gravity acting across vast distances does not seem to explain what astronomers see
Galaxies, for example, should fly apart; some other mass must be there holding them together
Astrophysicists have thus postulated "dark matter" - invisible to us but clearly acting on galactic scales
At the greatest distances, the Universe's expansion is accelerating
Thus we have also "dark energy" which acts to drive the expansion, in opposition to gravity
The current theory holds that 68% of the Universe is dark energy, 27% is dark matter, and just 5% the kind of matter we know well
How close are we to finding dark matter?
Sebastiano Cantalupo, lead author of the article, and others have used the same method previously to look for glowing gas around quasars, and had seen dark galaxies.

"The dark galaxies are much denser and smaller parts of the cosmic web. In this new image, we also see dark galaxies, in addition to the much more diffuse and extended nebula," Dr Cantalupo, from UCSC, explained.

"Some of this gas will fall into galaxies, but most of it will remain diffuse and never form stars.

"The light from the quasar is like a flashlight beam, and in this case we were lucky that the flashlight is pointing toward the nebula and making the gas glow. We think this is part of a filament that may be even more extended than this, but we only see the part of the filament that is illuminated by the beamed emission from the quasar."

While the observations support the cosmological simulations' general picture of a cosmic web of filamentary structures, the researchers' results suggest around 10 times more gas in the nebula than predicted from typical computer simulations.

They postulate that this may simply be due to limitations in the spatial resolution of the current models, or, more interestingly perhaps, may be because the current grid-based models are missing some aspect of the underlying physics of how galaxies form, evolve, and interact with quasars.

"We now have very precise measurements of the amount of ordinary matter and dark matter in the Universe," said Prof Refregier.

"We can only observe a fraction of the ordinary matter, so the question is what form the remainder takes. These results may imply that a lot of it is in the form detected here."

39

Astronomy / Astronomers weigh up Milky Way

« on: August 05, 2014, 06:26:38 PM »

The Milky Way is lighter than astronomers previously thought, researchers have concluded.

A team of scientists led by the University of Edinburgh found it has about half the mass of a neighbouring galaxy, known as Andromeda.

Their estimates come from working out the mass of invisible matter found in the outer regions of both galaxies.

They concluded that dark matter accounted for Andromeda's extra weight.

Dark matter is a little-understood invisible substance which makes up most of the outer regions of galaxies.

The researchers have estimated that Andromeda contains twice as much dark matter as the Milky Way, causing it to be twice as heavy.

The Milky Way and Andromeda have similar structures and are the two largest in a region of galaxies which astronomers call the Local Group.

The researchers say their work should help them learn more about how the outer regions of galaxies are structured.

Andromeda Galaxy
The researchers concluded that Andromeda contains twice as much dark matter as the Milky Way
According to the research group, previous studies were only able to measure the mass enclosed within both galaxies' inner regions.

Dr Jorge Penarrubia, of the University of Edinburgh's School of Physics and Astronomy, who led the study, said: "We always suspected that Andromeda is more massive than the Milky Way, but weighting both galaxies simultaneously proved to be extremely challenging.

"Our study combined recent measurements of the relative motion between our galaxy and Andromeda with the largest catalogue of nearby galaxies ever compiled to make this possible."

The study, published in the journal Monthly Notices of the Royal Astronomical Society, was carried out in collaboration with the University of British Columbia, Carnegie Mellon University and NRC Herzberg Institute of Astrophysics.

The work was supported by the UK's Science and Technology Facilities Council.

40

Natural Science / How facial features drive our first impressions

« on: August 05, 2014, 06:26:04 PM »

Whether it's a curled lip or a keen cheekbone, we all make quick social judgements based on strangers' faces.

Now scientists have modelled the specific physical attributes that underpin our first impressions.

Small changes in the dimensions of a face can make it appear more trustworthy, dominant or attractive.

The results, published in the journal PNAS, could help film animators or anyone looking to create an instant impression on a social network.

Dr Tom Hartley, a neuroscientist at the University of York and the study's senior author, said the work added mathematical detail to a well-known phenomenon.

"If people are forming these first impressions, just based on looking at somebody's face, what is it about the image of the face that's giving that impression - can we measure it exactly?"

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Three key dimensions of a first impression

Approachability: how likely is this person to help (or hinder) me?
Dominance: how capable is this person of carrying out those intentions?
Attractiveness: is this person young and good looking - a potential romantic partner?
Positive first impressions are especially important in a world dominated by social media, from LinkedIn to Tinder.

Dr Hartley sees the commercial potential in applying his numerical model to the photos people use to present themselves online. "It's obviously potentially very useful," he told the BBC.

To make the calculations, each of 1,000 face photos from the internet was shown to at least six different people, who gave it a score for 16 different social traits, like trustworthiness or intelligence.

Overall, these scores boil down to three main characteristics: whether a face is (a) approachable, (b) dominant, and (c) attractive.

Jump media playerMedia player helpOut of media player. Press enter to return or tab to continue.
Cartoon faces based on the new mathematical model, sliding along 3 scales: approachability, dominance and attractiveness
By measuring the physical attributes of all 1,000 faces and putting them together with those scores, Dr Hartley and his team built a mathematical model of how the dimensions of a face produce those three impressions.

The next step was to get the computer to extrapolate. Using their new model, the team produced cartoon versions of the most (and least) approachable, dominant and attractive faces - as well as all the possibilities in between.

Example faces
Six faces and their computerised approximations, including study author Dr Tom Hartley (second from left)
John Humphrys
The same treatment given to the Today programme's John Humphrys
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“
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You could use these kind of numbers to decide when is a good time to take a photograph, or to choose the photograph that's really optimal in putting forward the best possible impression”

Dr Tom Hartley
University of York
Finally, and most importantly, these cartoon results could be tested. When the researchers quizzed more participants about their impressions of the artificial, cartoon faces, the ratings matched. People said that the computer's cartoon prediction of an approachable face was, indeed, approachable - and so on.

So has all this work revealed humanity's ultimate trustworthy jawline, or the most assertive shape for eyebrows? Dr Hartley is cautious.

"Lots of the features of the face tend to vary together," he explained. "So it's very difficult for us to pin down with certainty that a given feature of the face is contributing to a certain social impression."

There are some obvious trends however - including the tendency for masculine faces to be perceived as dominant, or for a broadly smiling face to seem more approachable and trustworthy.

This points to a potentially worrying implication: brief facial expressions can make a big difference to how we are received by strangers.

"It might be problematic if we're forming these kind of judgements based on these rather fleeting impressions," Dr Hartley said, "particularly in today's world where we only might see one picture of a face, on social media, and have to form our impression based on that."

Cartoon faces
A mathematical model produced cartoon faces based on how people rated various facial dimensions
On the other hand, the findings could help people put their best face forward.

"It might be very useful for organisations who are interested in people's faces," said Dr Hartley.

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“
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[Being] approachable is tied to smiling expressions and unapproachable to frowning or angry expressions, while dominance is tied to masculine features”

Dr Anthony Little
University of Stirling
That might include interests as diverse as photographers, Facebook and Pixar.

"You would be able to use these kind of numbers to decide when is a good time to take a photograph, or maybe to choose the photograph that's really optimal in putting forward the best possible impression - and you might want to put forward different kinds of social impressions in different situations."

Animators, on the other hand, "have to give life, and give some social meaning, to the faces of their characters just by changing small things," Dr Hartley said.

"What we're doing is trying to put that on a scientific footing. It's been fascinating to find out more about it."

Dr Anthony Little, a reader in psychology at the University of Stirling, said the findings point to something "simple and important" about the way physical attributes guide our social responses.

Silly face
Impressions included attractiveness and trustworthiness - potential mate or used car salesman?
"The results highlight that the way we see other people may be in relatively simple terms, as approachable/unapproachable and dominant/submissive," said Dr Little, whose own research on faces and psychology includes using a website to crowd-source ratings.

"Each of these two factors looks to be tied to specific face features. So, approachable is tied to smiling expressions and unapproachable to frowning or angry expressions, while dominance is tied to masculine features.

"The third factor, youthful-attractiveness, appears less distinct."

This is because of interplay between attractiveness and the other two factors, Dr Little explained.

41

Natural Science / Quantum computing device hints at powerful future

« on: August 05, 2014, 06:24:59 PM »

One of the most complex efforts toward a quantum computer has been shown off at the American Physical Society meeting in Dallas in the US.

It uses the strange "quantum states" of matter to perform calculations in a way that, if scaled up, could vastly outperform conventional computers.

The 6mm-by-6mm chip holds nine quantum devices, among them four "quantum bits" that do the calculations.

The team said further scaling up to 10 qubits should be possible this year.

Rather than the ones and zeroes of digital computing, quantum computers deal in what are known as superpositions - states of matter that can be thought of as both one and zero at once.

In a sense, quantum computing's one trick is to perform calculations on all superposition states at once. With one quantum bit, or qubit, the difference is not great, but the effect scales rapidly as the number of qubits rises.

The figure often touted as the number of qubits that would bring quantum computing into a competitive regime is about 100, so each jump in the race is a significant one.

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“
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We're right at the bleeding edge of actually having a quantum processor”

Erik Lucero
University of California, Santa Barbara
"It's pretty exciting we're now at a point that we can start talking about what the architecture is we're going to use if we make a quantum processor," Erik Lucero of the University of California, Santa Barbara told the conference.

The team's key innovation was to find a way to completely disconnect - or "decouple" - interactions between the elements of their quantum circuit.

The delicate quantum states the team creates in their qubits - in this case paired superconductors known as Josephson junctions - must be manipulated, moved, and stored without destroying them.

"It's a problem I've been thinking about for three or four years now, how to turn off the interactions," UCSB's John Martinis, who led the research," told BBC News.

"Now we've solved it, and that's great - but there's many other things we have to do."

Qubits and pieces
The solution came in the form of what the team has termed the RezQu architecture. It is basically a blueprint for a quantum computer, and several presentations at the conference focused on how to make use of it.

"For me this is kind of nice, I know how I'm going to put them together," said Professor Martinis.

"I now know how to design it globally and I can go back and try to optimise all the parts."

RezQu seems to have an edge in one crucial arena - scalability - that makes it a good candidate for the far more complex circuits that would constitute a quantum computer proper.

"There are competing architectures, like ion traps - trapping ions with lasers, but the complexity there is that you have to have a huge room full of PhDs just to run your lasers," Mr Lucero told BBC News.

Quantum bit and resonator on a chip (E Lucero)
The team has been steadily increasing the complexity of their quantum devices
"There's already promise to show how this architecture could scale, and we've created custom electronics based on cellphone technology which has driven the cost down a lot.

"We're right at the bleeding edge of actually having a quantum processor," he said. "It's been years that a whole community has blossomed just looking at the idea of, once we have a quantum computer, what are we going to do with it?"

Britton Plourde, a quantum computing researcher from the University of Syracuse, said that the field has progressed markedly in recent years.

The metric of interest to quantum computing is how long the delicate quantum states can be preserved, and Dr Plourde noted that time had increased a thousand fold since the field's inception.

"The world of superconducting quantum bits didn't even exist 10 years ago, and now they can control [these states] to almost arbitrary precision," he told BBC News.

"We're still a long way from a large-scale quantum computer but it's really in my eyes rapid progress."

42

Natural Science / Quantum computing device hints at powerful future

« on: August 05, 2014, 06:24:48 PM »

One of the most complex efforts toward a quantum computer has been shown off at the American Physical Society meeting in Dallas in the US.

It uses the strange "quantum states" of matter to perform calculations in a way that, if scaled up, could vastly outperform conventional computers.

The 6mm-by-6mm chip holds nine quantum devices, among them four "quantum bits" that do the calculations.

The team said further scaling up to 10 qubits should be possible this year.

Rather than the ones and zeroes of digital computing, quantum computers deal in what are known as superpositions - states of matter that can be thought of as both one and zero at once.

In a sense, quantum computing's one trick is to perform calculations on all superposition states at once. With one quantum bit, or qubit, the difference is not great, but the effect scales rapidly as the number of qubits rises.

The figure often touted as the number of qubits that would bring quantum computing into a competitive regime is about 100, so each jump in the race is a significant one.

Continue reading the main story
“
Start Quote

We're right at the bleeding edge of actually having a quantum processor”

Erik Lucero
University of California, Santa Barbara
"It's pretty exciting we're now at a point that we can start talking about what the architecture is we're going to use if we make a quantum processor," Erik Lucero of the University of California, Santa Barbara told the conference.

The team's key innovation was to find a way to completely disconnect - or "decouple" - interactions between the elements of their quantum circuit.

The delicate quantum states the team creates in their qubits - in this case paired superconductors known as Josephson junctions - must be manipulated, moved, and stored without destroying them.

"It's a problem I've been thinking about for three or four years now, how to turn off the interactions," UCSB's John Martinis, who led the research," told BBC News.

"Now we've solved it, and that's great - but there's many other things we have to do."

Qubits and pieces
The solution came in the form of what the team has termed the RezQu architecture. It is basically a blueprint for a quantum computer, and several presentations at the conference focused on how to make use of it.

"For me this is kind of nice, I know how I'm going to put them together," said Professor Martinis.

"I now know how to design it globally and I can go back and try to optimise all the parts."

RezQu seems to have an edge in one crucial arena - scalability - that makes it a good candidate for the far more complex circuits that would constitute a quantum computer proper.

"There are competing architectures, like ion traps - trapping ions with lasers, but the complexity there is that you have to have a huge room full of PhDs just to run your lasers," Mr Lucero told BBC News.

Quantum bit and resonator on a chip (E Lucero)
The team has been steadily increasing the complexity of their quantum devices
"There's already promise to show how this architecture could scale, and we've created custom electronics based on cellphone technology which has driven the cost down a lot.

"We're right at the bleeding edge of actually having a quantum processor," he said. "It's been years that a whole community has blossomed just looking at the idea of, once we have a quantum computer, what are we going to do with it?"

Britton Plourde, a quantum computing researcher from the University of Syracuse, said that the field has progressed markedly in recent years.

The metric of interest to quantum computing is how long the delicate quantum states can be preserved, and Dr Plourde noted that time had increased a thousand fold since the field's inception.

"The world of superconducting quantum bits didn't even exist 10 years ago, and now they can control [these states] to almost arbitrary precision," he told BBC News.

"We're still a long way from a large-scale quantum computer but it's really in my eyes rapid progress."

43

Natural Science / Quantum computing could head to 'the cloud', study says

« on: August 05, 2014, 06:23:28 PM »

A novel high-speed, high-security computing technology will be compatible with the "cloud computing" approach popular on the web, a study suggests.

Quantum computing will use the inherent uncertainties in quantum physics to carry out fast, complex computations.

A report in Science shows the trick can extend to "cloud" services such as Google Docs without loss of security.

This "blind quantum computing" can be carried out without a cloud computer ever knowing what the data is.

Quantum computing has been heralded as the most powerful potential successor to traditional, electronics-based computing.

One of the peculiarities of the branch of physics called quantum mechanics is that objects can be in more than one state at once, with the states of different objects tied together in ways that even Albert Einstein famously referred to as "spooky".

Instead of the 0 and 1 "bits" of digital computing, quantum computing aims to make use of these mixed and entangled states to perform calculations at comparatively breathtaking speeds.

Other quantum trickery comes in cryptography, the art of encrypting data. Data is encoded in delicately prepared states - most often those of single particles of light called photons - and the data cannot be "read" without destroying them.

Quantum cryptography uses this feature to send the "keys" to decrypting messages with high security.

However, the quantum computing approach is still in its formative stages, able to carry out only simple calculations - and quantum cryptography is, for the most part, limited to the laboratory setting.

The world in which both are accessible to consumers has seemed distant.

Cue bits
The new work, by University of Vienna quantum computing pioneer Anton Zeilinger and a team of international scientists, combines the two.

They show that future technology need only come up with a means of making quantum bits, or qubits, at home; the heavy lifting of quantum computing can then be done in the cloud completely securely.

Quantum cryptography setup in laboratory
Quantum computing and cryptography equipment is still for the most part restricted to laboratories
A user would send single qubits - each perfectly secure - to a remote computer, along with a recipe for the measurements to be made.

The process is completely clear to the user - for example, finding all the numbers that multiply together to reach the number 2,012 - but because the number 2,012 is encrypted, the instructions appear to be a series of random steps on an unknown number.

The remote computer blindly "entangles" the unknown bits, carries out the steps, and sends the qubits back down the line, solving the problem without ever decoding what is going on.

The team built a system demonstrating that the approach works, using a number of computational steps that might make up future computing scenarios.

Much remains to be developed for a cloud/quantum computing future - first of all, a means to create qubits at home, which could be done with existing technology if there were a consumer demand.

Long-distance quantum cryptography has already been demonstrated in a real-world application: the technology was put to use in elections in Switzerland in 2007 using a custom network of fibres.

More recently, researchers at University College Cork demonstrated that similar quantum information can be sent down the same fibres that bring broadband to many homes around the world.

What is still lacking, and preoccupying quantum physicists around the world, is the workhorse quantum computer itself.

The computer's complexity is steadily rising; results earlier this month suggest the juggling of some 84 qubits simultaneously.

As with the earliest days of more familiar computer technology, however, significant simplification, miniaturisation and a plunge in costs will be necessary before quantum computing becomes a resource in the cloud.

44

Natural Science / Quantum computing: Is it possible, and should you care?

« on: August 05, 2014, 06:22:52 PM »

What is a quantum computer and when can I have one? It makes use of all that "spooky" quantum stuff and vastly increases computing power, right? And they'll be under every desk when scientists finally tame the spooky stuff, right? And computing will undergo a revolution no less profound than the one that brought us the microchip, right?

Well, sort of.

That is broadly what has been said about quantum computers up to now, but it's probably best to pause here and be clear about what is, at this stage, most likely to come.

First things first, though: just what do they do? Many media outlets have dived into the academic literature sporadically to shed some light on the effort.

BBC News has reported that quantum computers "exploit the counterintuitive fact that photons or trapped atoms can exist in multiple states or 'superpositions' at the same time", and "quantum computing's one trick is to perform calculations on all superposition states at once" - plus, other quantum weirdness means the whole business "can then be done 'in the cloud' completely securely".

This week has seen two more advances in the field. In one, a team reporting in Nature describes the first fully quantum network, in which "qubits" - quantum bits, the information currency of quantum computers - were faithfully shuttled between two laboratories.

In another, a team writing in Science says they have "entangled" two qubits - representing the simplest core of a quantum computer - within a semiconductor, materials that standard computer makers are already familiar with manufacturing.

(It has been truly busy recently; the largest ensemble of working qubits was reported on Arxiv in January, and the biggest quantum computer number-crunching feat was published in Physical Review Letters in late March.)

Bet it works
It is all a bit bewildering, so to sum up the state of the field: very small-scale, laboratory-bound quantum computers that can solve simple problems exist; most researchers say the idea of massively scaled-up versions looks perfectly plausible on paper; but making them is an engineering challenge that practically defies quantifying.

Scott Aaronson, an expert in the theory of computation at the Massachusetts Institute of Technology, is one believer in the scaled-up quantum computer. He recently offered a $100,000 prize for a convincing proof that such a device could not be made.

Continue reading the main story
Essence of the quantum advantage

"Qubit" probability distributions
Scott Aaronson, MIT

You frequently hear that quantum computers "try all the possibilities in parallel" - that's a very drastic oversimplification.

We talk about a 30% chance of rain tomorrow - we'd never say there's a negative 30% chance. But quantum mechanics is based on "amplitudes", which can also be negative. If you want to find the probability that something will happen, you have to add up all the amplitudes.

With a quantum computation you're trying to choreograph things such that for a given wrong answer there are all these different paths that could lead to it, some with positive amplitude and others with negative amplitude - they cancel each other out.

For a given right answer, the paths leading to that should all be positive or all negative, and amplitudes reinforce. When you measure it, the right answer should be measured with high probability.

But he has no illusions that it is just around the corner.

"I get kind of annoyed by all the (popular media) articles reporting every little experimental advance," he told BBC News.

"The journalists have to sell everything, so they present each thing like we're really on the verge of a quantum computer - but it's just another step in what is a large and very difficult research effort.

"It was more than 100 years between Charles Babbage and the invention of the transistor, so I feel like if we can beat that, then we're doing well - but that's a hundred years for people to say 'works great on paper, but where is it?'"

More than that, though, even the most optimistic researchers believe that quantum computers will not be a wholesale replacement for computers as we now know them.

The only applications that everyone can agree that quantum computers will do markedly better are code-breaking and creating useful simulations of systems in nature in which quantum mechanics plays a part.

Martin Plenio, director of the Institute for Theoretical Physics at the University of Ulm, Germany, said that "it might never happen that it will be a device that sits here under my desk".

"A quantum computer can do all the things that a classical computer can do, and some of those things it can do much better, faster, like factoring large numbers," he told BBC News.

"But for many questions it's not going to be superior at all. There is simply no point to use a quantum computer to do your word processing."

Quantum add-ons
Others are more sanguine about the utility of what will come out of the current research efforts.

Alan Woodward, a professor of computing at the University of Surrey, cites a couple of recent advances that, to his mind, signify a significant push toward a computer that might sit under his or Prof Plenio's desk.

Quantum entanglement experiment
Quantum experiments are still complex and bulky lab-based beasts
Most quantum computers to date have been designed to tackle a single problem, unlike the general-purpose computers we use now. But Prof Woodward says that a report in Nature Photonics in December represents the first "programmable" quantum computer.

And, he said it is significant that an industry giant like IBM is getting into the game; at a meeting of the American Physical Society in March, IBM researchers reported significant advances in just how long they could preserve the quantum information in their qubits.

"Are you going to have a purely quantum computer in five years? No - what you'll have is elements of these things coming out, you always do with technology," he told BBC News.

"In the same way you have a graphics processor card along with a main processor board in a modern computer, you'll see things added on; people will find a means of using quantum computing and the quantum techniques, and that's how I think it'll move forward.

"And those I can definitely see in the five-year period."

Prof Woodward is in the minority in thinking that the consumer market will benefit widely from quantum computers; the problem of course is making predictions about a technology that has, since its inception, always seemed possible but even now is not incontrovertibly achievable.

Dr Aaronson concedes that perhaps the long term may bear out a greater desire and use for it.

"It's hard for me to envision why you'd want a quantum computer for checking your email or for playing Angry Birds. But to be fair, people in the 1950s said 'I don't see why anyone would want a computer in their home', so maybe this is just limited imagination.

"Maybe quantum video games will be all the rage 100 years from now."

45

Natural Science / Quantum memory 'world record' smashed

« on: August 05, 2014, 06:22:25 PM »

A fragile quantum memory state has been held stable at room temperature for a "world record" 39 minutes - overcoming a key barrier to ultrafast computers.

"Qubits" of information encoded in a silicon system persisted for almost 100 times longer than ever before.

Quantum systems are notoriously fickle to measure and manipulate, but if harnessed could transform computing.

The new benchmark was set by an international team led by Mike Thewalt of Simon Fraser University, Canada.

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"39 minutes may not seem very long. But these lifetimes are many times longer than previous experiments”

Stephanie Simmons
Oxford University
"This opens the possibility of truly long-term storage of quantum information at room temperature," said Prof Thewalt, whose achievement is detailed in the journal Science.

In conventional computers, "bits" of data are stored as a string of 1s and 0s.

But in a quantum system, "qubits" are stored in a so-called "superposition state" in which they can be both 1s and 0 at the same time - enabling them to perform multiple calculations simultaneously.

The trouble with qubits is their instability - typical devices "forget" their memories in less than a second.

There is no Guinness Book of quantum records. But unofficially, the previous best for a solid state system was 25 seconds at room temperature, or three minutes under cryogenic conditions.

In this new experiment, scientists encoded information into the nuclei of phosphorus atoms held in a sliver of purified silicon.

Magnetic field pulses were used to tilt the spin of the nuclei and create superposition states - the qubits of memory.

The team prepared the sample at -269C, close to absolute zero - the lowest temperature possible.

Artist's impression of a phosphorus atom qubit in silicon, showing a ticking clock
When they raised the system to room temperature (just above 25C) the superposition states survived for 39 minutes.

What's more, they found they could manipulate the qubits as the temperature of the system rose and fell back towards absolute zero.

At cryogenic temperatures, their quantum memory system remained coherent for three hours.

"Having such robust, as well as long-lived, qubits could prove very helpful for anyone trying to build a quantum computer," said co-author Stephanie Simmons of Oxford University's department of materials.

Continue reading the main story
Future directions in computing

Spintronics
Quantum
Photonics
DNA computing
Chemical computing
"39 minutes may not seem very long. But these lifetimes are many times longer than previous experiments.

"We've managed to identify a system that seems to have basically no noise."

However she cautions there are still many hurdles to overcome before large-scale quantum computations can be performed.

For one thing, their memory device was built with a highly purified form of silicon - free from the magnetic isotopes which interfere with the spin of nuclei.

For another, the spins of the 10 billion or so phosphorus ions used in this experiment were all placed in the same quantum state.

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"What's most important is this is silicon. The global investment in this material means it has a lot of potential for engineering”

Dr Thaddeus Ladd
HRL Laboratories
Whereas to run calculations, physicists will need to place different qubits in different states - and control how they couple and interact.

"To have them controllably talking to one another - that would address the last big remaining challenge," said Dr Simmons.

Independent experts in the quantum field said the new record was an "exciting breakthrough" that had long been predicted.

"This result represents an important step towards realising quantum devices," said David Awschalom, professor in Spintronics and Quantum Information, at the University of Chicago.

"However, a number of intriguing challenges still remain. For instance - will it be possible to precisely control the local electron-nuclear interaction to enable initialisation, storage, and readout of the nuclear spin states?"

The previous "world record" for a solid state quantum system at room temperature - 25 seconds - was held by Dr Thaddeus Ladd, formerly of Stanford University's Quantum Information Science unit, now working for HRL Laboratories.

"It's remarkable that these coherence states could be held for so long in a measurable system - as measurement normally introduces noise," he told BBC News.

"It's also a nice surprise that nothing goes wrong warming up and cooling the sample again - from an experimental point of view that's pretty remarkable.

"What is perhaps most important is that this is silicon. The global investment in this particular material means that it has a lot of potential for engineering."