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April 2009 Archives

By Hamish Johnston

The BBC’s resident polymath Melvyn Bragg was talking physics again. This morning he was exploring the physics of nothing with Frank Close, Jocelyn Bell Burnell and Ruth Gregory. Bell Burnell, by the way, is president of the Institute of Physics.

The programme is called the Vacuum of Space and you can listen to it here.

The team began with a philosophical discussion of a vacuum — apparently it was heresy in the Middle Ages to suggest that nothing could exist — and moved swiftly on to Torricelli’s studies involving atmospheric pressure.

The three physicists then discussed aether, the Michelson-Morley experiment and concluded that “Einstein got rid of Reading Station”.

Then it was time to delve into the weird world of quantum mechanics and the virtual particles that appear to bubble out of nothing. The physicists were keen on using banking analogies to explain all this — I suppose we are all familiar with virtual money these days — but Melvyn banned any mention of banks.

I had to switch off early as I got to work, but the team seemed to be coming round to the conclusion that in the quantum world “the uncertainty principle abhors a vacuum” — a new twist on a very old concept.

LIGO in Hanford, Washington: Could two drops of helium beat it in the race to detect gravitational waves?

By Hamish Johnston

Experiments that search for gravitational waves tend to be very large. The LIGO detectors in the US, for example, have arms that are 4 km long.

This is because the gravitational interaction is much weaker than the electromagnetic forces that govern the detectors. As a result humongous masses and long distances are needed to produce the tiniest signal — indeed, gravitational waves have yet to be detected directly.

However, Raymond Chiao believes that gravitational waves can be detected in tiny drops of superfluid helium that are coated with a specific number of electrons.

The drops would be suspended in a strong magnetic field — a setup that conjures up the famous oil drop experiment that allowed Robert Millikan to measure the charge of the electron.

Chiao describes his experiment in a book entitled Visions of Discovery: New Light on Physics, Cosmology and Consciousness, to be published by Cambridge University Press in 2010. The book is edited by Chiao — who has a long and distinguished career in quantum optics — and includes contributions from Nobel laureates Anthony Leggett and William Phillips.

As far as I can tell, the trick in Chiao’s proposed experiment is to set the charge-to-mass ratio of the drops such that each electron corresponds to a ‘Planck mass’ quantity of helium. Objects lighter than the Planck mass tend to be governed by quantum mechanics rather than general relativity.

“Now the force of gravity is approximately 137 times stronger than the force of electricity”, he writes.

Furthermore, two such drops separated by a centimetre or so would act as a “quantum transducer” that could convert an incoming gravitational wave into an outgoing electromagnetic wave — which Chiao believes could be used to detect gravitational waves.

So what do other physicists think?

The chapter is prefaced with an editor’s note, which begins “The following chapter has been the subject of considerable controversy during the review process”.

It goes on to say that one reviewer thought Chiao’s proposal was “reasonable”, while the others “found this claim to be highly questionable”.

Apparently the problem is that “some statements in the paper may be inconsistent with the current theory of superfluids. However that theory may be wrong…” — I believe this refers to Chiao’s proposed mechanism that couples gravitational and electromagnetic waves on the surface of the drops.

One way or another, Chiao’s chapter makes for a fascinating read.

The perfect pizza toss revealed!

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How can chefs improve their technique?

By James Dacey

A trio of scientists at Monash University have studied footage of a professional chef to calculate the mechanics of the perfect pizza toss. This knowledge, they say, can now be used by engineers to improve the efficiency of micro-machines.

Kuang-Chen Liu and his team say this problem was a variation on the famous bouncing ball on vibrating platform problem. They report that for single dough-tosses, helical motion is best because it maximizes energy efficiency and the dough’s airborne rotational speed. For multiple tosses, they say a semi-elliptical motion is preferred because it is easier to maintain high-speed dough rotation.

Publishing their findings in Europhysics Letters, the researchers say this knowledge could now be used to optimize the design of standing wave ultrasonic motors (SWUM), applications of which include autofocus camera lenses.

“The only difference is that a chef tosses dough about once a second, a few tens of centimetres into the air. A SWUM tosses the rotor a few million times a second into the air,” said James Friend, one of dough-physics experts at Monash.

A strong contender for this year’s Ig Nobel prizes?

By Michael Banks

The Twitter bandwagon keeps on rolling.

Earlier this month Physics World joined the likes of Barack Obama, 10 Downing Street and the US rapper Snoop Dogg on Twitter — a website where people can post an answer to the question “what are you doing?” in under 140 words.

While some people actually do write — or “tweet” — what they are doing in every detail, most use it to post interesting links to stories that appear on the web. For example, Physics World tweets links to stories and blog entries that appear on our website.

Now, Robert Simpson, a PhD student from Cardiff University in the UK, has created a website that ranks papers appearing on the arXiv preprint server according to their popularity on Twitter.

His website searches Twitter for tweets that mention an arXiv url or posts that are tagged “#arxiv” and include the paper’s unique identifier.

The website retrieves and lists all the tweets and produces a table of the most popular papers, authors and arXiv categories ranked by how many tweets they have received.

The website has only been active since 16 April, but already there have been 75 tweets quoting arXiv papers.

This week’s top three papers include an introduction to machine learning, a 3D study of the photosphere of HD99563 and power-law distributions in empirical data.

The paper ranked fourth in the table, however, as far as I could tell was an April fool’s joke, which proclaimed that pi has changed since 1900 BC. So maybe think twice before taking such a ranking seriously.

Ancient light as seen by Gemini (false colour)

By Hamish Johnston

One problem with reporting breakthroughs in astronomy is that someone is always claiming to have discovered the oldest/largest/brightest/dimmest/smallest object yet. And by the time you have written your story — someone else will claim to have done better.

That’s why my eyes rolled a bit when I read the press release “Farthest known object: New gamma-ray burst smashes cosmic distance record”, which arrived last night from the AAS.

However, upon closer inspection, this one really does look interesting.

As its name suggests, GRB 090423 was discovered last Thursday and astronomers believe that the burst occurred more than 13 billion years ago — about 630 million years after the Big Bang.

That’s about 100 million years older than the previous record, which was held by a ancient galaxy.

Gamma rays from GRB 090423 were first spotted by NASA’s Swift satellite, which quickly turned its X-ray and ultraviolet instruments on the object. No visible light was seen, but Swift did manage to capture the burst’s fading X-ray afterglow.

Meanwhile here on Earth, astronomers were turning their telescopes to that patch in the sky. The Gemini North and UK Infrared telescopes in Hawaii managed to capture infrared light from the burst (above).

By analysing how much the wavelength of the light light has been red-shifted, astronomers worked out that the light has travelled over 13 billion light years before reaching Earth.

The chart below shows the age of GRB 090423 compared to other known objects.

You can read all about the search for gamma ray bursts in this article in Physics World.

Beyond redshift eight

Glimpsing the energy future

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Solar power in the US: Dark red = highest potential. Pale yellow = lowest potential

By James Dacey

At the end of last week, Hamish drew attention to David MacKay - a UK physicist who is on something of a crusade to take the “hot air” out of the sustainable energy. Mackay’s approach is to explain the potential of each renewable technology option in everyday numerical concepts.

This week, in the US, a collaboration between Google Earth and the Natural Resources Defense Council (NRDC) is attempting to bring the same simplicity to the visual representation of renewable energy options.

They have launched an online interactive map of the US showing the best (and worst) regions to generate energy from the sun, wind, biomass from wood and crop waste, and biogas from animal waste at livestock and poultry farms.

“This new tool is designed to help regular people from farmers to politicians, financiers to reporters understand that renewables are here now and posed to become major players in our energy mix,” said Nathanael Greene, NRDC’s Director of Renewable Energy Policy.

Whether or not this map does have a big impact on professional stakeholders remains to be seen. Personally, I think the more important thing about the maps is their visual impact… as somebody commented on the associated blog:

“It makes a clean-energy future seem imminent, and eminently do-able”

From just glancing at the maps one thing that becomes quickly apparent is the reliance that the East may come to have on the sparsely-populated regions of the West where important sources like solar, wind and geothermal power have far more potential.

By João Medeiros

One of the highlights of the “Science Beyond Fiction” conference in Prague was Lazlo Barabasi’s talk - “From Human Travel Patterns to Mobile Viruses”

Barabasi, author of the excellent book “Linked” , is one of the world experts on the topic of social networks.

In his talk, Barabasi presented novel insights about the science of human mobility patterns. The applications of such a study are incredibly wide-ranging, from understanding of how ideas and diseases spread, to the planning of traffic and urban spaces.

As one might guess, there is a huge element of randomness in the way we move.
Einstein, of course, was the first to theorize about random walk theory in the context of Brownian motion - the drunkard sailor paradigm (which constituted the first evidence for atoms).

The paradigm for how people move was first established by a series of studies by G.M.Vishwanathan on the mobility patterns of tagged birds and monkeys. What Vishwanathan found out was that animals do not follow the drunkard sailor pattern (ie, a Gaussian pattern) but instead follow a pattern compounded of lots of small steps with some big jumps, the so called Levy flight pattern, which is described as a power law distribution.

The first challenge in studying human mobility is how to get the data. Equipping millions of people with GPS track systems is prohibitively expensive (and probably ethically wrong).

But mobility data can be extracted from a variety of datasets which indirectly inform us of how we move.

For humans, this was first studied by Brockmann, who studied the motion of dollar bills (an explanation of their method can be found in their website What Brockmann found was that humans also obey the Levy flight pattern.
Barabasi also studied the mobility problem, using a mobile phone database composed of 7 million users, tracked between 2004 and 2009. His findings support the dollar bill findings.

Barabasi and collaborators (among whom is Cesar Hidalgo, who wrote a feature for PW last December) further discovered that the shape of human trajectories can be grouped into distinct categories according to typical ranges of motion, say one group for people who tend to move within a radius of 3 km, other for people who have radius of motion in the order of 100 km, etc.

What he found, was that within each category, the scaled patterns of motion are indistinguishable. This property - universality - means that all categories of human travelers can be described by one unified model.

This is important to understand many phenomena that derive from human mobility patterns. One such application is the understanding of mobile phone viruses.
Paradoxically, the first insight into the study of mobile phone viruses is to understand why mobile phone viruses are really not that relevant at the moment.

Experts estimate that there are approximately 600 varieties of mobile phone viruses. However, they exist only in smartphones, which, at the moment only detain 5% of the mobile phone marketshare.

These viruses spread in two ways. One, via Bluetooth, spreads in a manner similar to influenza, ie, related to physical proximity. The second mode of transmission is via MMS. These viruses spread in a manner akin to computer viruses and therefore have a capacity to spread non-locally.

In other words, the spread of Bluetooth virus depends on human mobility patterns, whilst MMS viruses depend on individual social networks. Understanding their modes of propagation leads us to understand their patterns of spreading. Simulations show that Bluetooth viruses may take days to reach everyone within a given region. MMS viruses, on the other hand, take only a matter of hours before reaching a maximum level of contagion. This saturation point is highly dependent on the level of market share of the smartphones.

MMS viruses are not dangerous below the level of 10% marketshare. Above that, however, we get a phase transition point and the virus can spread quickly everywhere within a matter of hours.

At the moment we are under that threshold, but when we reach that critical point, mobile phone viruses will become a serious threat to communications, especially since standard counter measures, such as anti-virus, are very difficult to install in smartphones due to the inherent memory capacity limitations on those phones.

Beyond the specific topic of mobile phone viruses, the work of Barabasi shows how mobile phones are quickly becoming a social experiment on itself, a gold mine of data in the study of social networks and human mobility patterns.


By Hamish Johnston

Are you feeling environmentally smug because you don’t leave your mobile-phone charger plugged in all the time?

Well I’m afraid that the physicist David MacKay wants to knock the wind out of your micro-turbine.

He says that this act of greenness is pointless because it only cuts your daily consumption of energy by less than 0.01%. That, by the way, is enough energy to run a car for about one second.

“But every little counts”, you may be thinking. That’s true, but in his book Sustainable Energy — without the hot air , the Cambridge professor argues that folks should focus on making meaningful changes like turning the thermostat down or improving their home insulation. Indeed, he managed to cut his heating gas consumption by a factor of four by doing so.

“Obsessively switching off the phone-charger is like bailing out the Titanic with a teaspoon”, he quips.

And what about roof-top micro-turbines? “An utter waste of resources”, he says. Indeed, a typical micro-turbine would, on average, generate enough electricity to power four idle phone chargers — bailing out the Titanic with a tablespoon. However, the Sun is strong enough in the UK for heating water and a roof-top system could supply about half a family’s hot water needs, he says.

MacKay was on BBC Radio 4 today explaining why we should pay more attention to exactly how much energy we consume and how that energy could be generated — in cold , hard units of kilowatt hours per day (a horrible unit, I know). You can listen to the interview here.

Also interviewed was Rebecca Willis of the UK government’s Sustainable Development Commission, who didn’t seem too impressed with MacKay’s book.

She seemed to be saying that turning sustainability into a technical debate “turns people off”.

The BBC’s Tim Harford — an economist by training — accused the Commission of promoting “style over substance” in its literature. For example, it recommends micro-turbines so that people can feel “connected” to electricity generation. After reading MacKay’s book, Harford said he felt “betrayed” by the Commission.

You can read MacKay’s entire book online here

Tesla’s twilight years

By Hamish Johnston

You just can’t pick up the papers these days without coming across an eccentric physicist.

Now it’s Nikola Tesla, who is the hero of a book that has just been short-listed for this year’s Orange Prize for Fiction.

The Invention of Everything Else by Samantha Hunt is a fictional account of Tesla’s twilight years in New York City.

Tesla was one of the most famous inventors at the turn of the last century. He was a pioneer in wireless communications and the wireless transmission of energy. And of course, the SI unit of magnetic field strength is name after him.

He had many strange ways — apparently he only stayed in a hotel room if its number was a multiple of three — and neglected to secure the rights to many of his inventions. As a result, he lived out his later years in poverty and obscurity.

“Historic” budget

By James Dacey

Since Obama came to office, scientists in the US seem to be pretty happy with the way he is divvying up national funds.

Yesterday, it was the turn of the UK Government to announce its annual spending plans as Chancellor of the Exchequer, Alistair Darling delivered the budget in Westminster.

If the morning papers are to reflect public opinion, it is fair to say that the “historic” tax increases and plans to borrow a further £348 bn over the next 2 years have gone down like a lead balloon.

“Darling’s Great Squeeze”, The Guardian
“Alistair’s living in wonderland”, Daily Mail
“They’ve ruined Britain”, The Daily Express

However, as part of the budget statement, Darling also revealed that £2.5 billion would be invested in “industries of the future”, including digital communications and biotech; £1.5 billion specifically for low carbon technologies; and the creation of a £750 million venture capital fund to help technology start-up firms prosper.

Early reactions from the scientific community have been positive.

“This is a budget that does recognise the need to invest in science and technology,” said Sir Martin Rees, President of the Royal Society.

Robert Kirby-Harris, chief executive at the Institute of Physics was also up beat:

“The Chancellor has called upon UK science to play a key role in ensuring we have a world-leading economic future. Money is being directed by the Government towards the industries which will help us to deliver on this agenda. This is commendable and we are confident that the UK science base is up to the challenge.”

Given the perilous economic conditions, it remains to be seen whether this investment will be to much or too little…

By Margaret Harris

The “On-Ramps Into Academia” programme aims to make the transition from industry to academia easier for women in science.

I saw an intriguing press release yesterday about a new programme, called “On-Ramps Into Academia”, that aims to help women who have PhDs and at least three years’ experience in industry make a transition back to an academic career. The programme’s first workshop is in Seattle, Washington this October (there’s an online application here , and applying before 15 May is encouraged), and participants can expect practical advice, networking and support from senior women researchers who have already switched to successful academic careers.

The rationale behind the workshops — which are funded by the US National Science Foundation — seems to make sense. The release quoted one of the programme’s co-investigators saying that current strategies to recruit more female scientists to work in US universities are a “zero-sum game”, because most rely on wooing them from one university to another. The new programme, by contrast, is similar to schemes in fields like law and business that aim to bring experienced women back into the workplace after extended absences (e.g. maternity leave).

Still, I had to wonder exactly what “industry” jobs would be suitable preparation for academia, and whether physicists might be at a disadvantage compared to scientists in disciplines like engineering or chemistry, where industry-academia links tend to be more widespread.

By João Medeiros

Just attended one of the best talks so far, here at the “Science beyond Fiction” conference in Prague — a really exciting, wacky and speculative talk by Artur Ekert, on quantum information science.

To Ekert, the questions that are used to “sell” quantum information science to “deciders” and funding bodies are usually of two kinds. A first argument, more scientifically motivated, sells the point that the true power of quantum computation is yet to be achieved, a computational capacity that will likely teach us much more about the fundamentals of nature. The second, more pragmatic approach, appeals to the exploration of the true fundamental limits in exploring quantum systems and what constraints they put on technology.

On the issue of framing the subject of quantum computation, Ekert says that it is really interesting how people from different cultural backgrounds react to the topic.

For instance when discussing the matter with computer scientists, Ekert uses a more philosophically inclined, logic based approach. According to him, computer scientists are naturally not really fond of atoms and messy quantum systems.

The question he asks his computer scientist collaborators is whether it is possible to construct a logic gate operating on a single bit, such that the same two consecutive operations produce a flip of the bit. Classically, of course, you cannot. But this is a possibility when using quantum systems.

Indeed, one of the fundamental differences between quantum and classical computational systems exists in the respective nature of the logical operations allowed by each system.

The bottomline realization is that information and computation are intimately linked to physics. Information is physical. This conclusion was to many computer scientists a shock and it marked the intellectual revolution that kickstarted quantum information science.

Physicists now realize that if you change the physics you change the nature of information. This has been a surprising revelation to many computer scientists, who since the work of Alan Turing have been playing with classical computer logic without a physical foundation, a logical framework which somehow worked.


Ekert also pointed out that quantum computation is one of the truly interdisciplinarity subjects.

Not only it has brought together mathematicians, computer scientists and physicists, but it has also brought people together within physics, scientists that beforehand would not talk to each other simply because they were using completely different jargon and codes. A common denominator was found in the language of quantum logic gates.

Ekert, who is based in Singapore, compared this situation with the way that sometimes Koreans and Chinese use to communicate: not by speaking, but via written characters.


Ekert also mentioned that recent advances in the study of the quantum aspects of life, such as the study of the role of quantum coherence in photosynthesis, opens the door to discover quantum computation already happening in natural systems. This is a most fascinating topic that will be featured in an upcoming feature by Paul Davies for PW.


The final aspect discussed by Ekert was the philosophical aspect of quantum computation, an side of science which has not been avoided by physicists. According to Ekert, quantum Information has elevated the questions about the nature of reality, randomness, complexity to the level of bona-fide scientific conundrums that should be addressed, rather than ignored.

Ekert himself is partial to question about the nature of randomness, the question of whether it is really possible to have events that have no underlying cause? What is so interesting about this question is that it essential goes against one’s understanding of science, which is intrinsically motivated by the notion of causality of phenomena in nature.


In the next issue of PW, Ekert authors a feature about Girolamo Cardano, the “gambling scholar”. Cardano was a Renaissance mathematician which by himself discovered the basic notions of probability and complex numbers, two of the fundamental pillars of quantum theory.

In the future, Ekert will write again for PW about quantum information science.

Cycling into the light

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Fighting climate change with X-rays

By James Dacey

In the final day of my synchrotron sojourn I headed deep into the heart of the facility to meet some of the scientists hard at work.

In this dimly-lit environment, intense X-ray beamlines shoot off at tangents from the 844m electron beam as it screeches around the main storage ring - the giant polo you see from the air above Grenoble.

Researchers flock here from across the ESRF 12 member states (and beyond) to use these X-rays for probing all sorts of matter - to (hopefully) reveal new information about its fundamental properties.

Within this unusual office space, bicycle is the preferred way of getting around - as at many of the big-name particle colliders.

Highlight of the day for me was whizzing round on my red bike to beamline 15 - the most intense in the facility - to hear about the project taking place there. It had some very interesting environmental implications…

The researchers, from Germany and France, are using the X-rays to probe water-based crystal structures known as “hydrates”, which are capable of storing both hydrogen and carbon dioxide within their structures.

“If we can understand the chemistry and physics of how these hydrates form, this would be a great help for developing carbon sequestration technologies and feasible hydrogen-fuelled cars,” Felix Lehmkühler, one of the researchers, told me over lunch.

Since their latest publication, the researchers have been looking the effect of adding new compounds to their hydrates - the aim is to develop a structure that could store these important gases at everyday temperatures and pressures.

The good news for researchers like Lehmkühler is that the ESRF will be pouring 177 million Euros into upgrading all beamlines and research facilities over the next 6 years.

Meanwhile yesterday, over in California, the US Department of Energy were unveiling “the world’s brightest X-ray source” at the SLAC Accelerator laboratory.

“The science that will come from the LCLS will be as astounding and as unexpected as was the science that came from the lasers of a few decades ago,” said DOE Office of Science acting director, Patricia Dehmer.

With over 50 synchrotrons spread across five continents, and a road map in place to develop the first African facility, synchrotron research seems to be in a very healthy state right now!

One too many Brits

By Hamish Johnston

One of the things that makes the British great is their love of eccentricity.

Which is why I was not particularly surprised when I came across a reference in Saturday’s Daily Telegraph to “the British physicist Richard Feynman”. The passage was in a review of Jim Baggot’s book Atomic: The First War of Physics.

Feynman was as American as they come — he was born in New York City and spent most of his career at Caltech near Los Angeles.

However, he was famously eccentric so I can understand why a Brit reading about his antics would assume Feynman is British.

I don’t think I am the only person to have spotted the error — but for some reason it has yet to be corrected in the online version

By the way, Physics World will be publishing its own review of the book shortly.

By João Medeiros

I’m in Prague attending the European Future Technologies Conference — “Science Beyond Fiction”. It has so far been prolific in ideas and science-fictionish future promises, despite a bumpy start.

Viviane Reding, the European Commissioner for Information Society and Media, and Mirek Topolanek, the Czech PM, were the high profile names planned to open the proceedings. They were, however, conspicuous by their absence.

Topolanek, understandably, is perhaps more concerned with his political future than with the future of science right now, after losing a no-confidence motion in Parliament last month. The Czechs also presently hold the EU presidency, so the overbooking of Topolanek’s diary is understandable. One can only hope that he can multitask.

Reding, on the other hand, used cutting-edge European technology to address the delegates via a prosaic video-stream. Given that she is the Commissioner for Information Society and Media, the symbolism is laudable.

Speaking on a blue background of distorted stars and clouds dangerously resembling a psychedelic motif, Reding proposed to boost Europe´s high-risk research into future technologies by doubling the current level of funding by 2015.

“Europe must be inventive and bold - especially in times of crisis. Research seeds innovation which is key for Europe’s long-term global competitiveness. Scientific and revolutionary breakthroughs constitute enormous opportunities and we must bring the best brains together to make the most of them,” said Reding. “Combining efforts of the 27 EU countries and stepping up cooperation with global partners is essential for Europe to take the lead in future information technologies that can yield radically new solutions for European citizens in domains such as health, climate change, the ageing population, sustainable development or security.”

In other words, Europe needs catch up with the US, China and Japan.

Unlimited computing power, computers mimicking the brain, mind controlled wheelchairs and friendly robotic companions are all part of this European sized mega super project. This initiative comes in the context of the Future and Emerging Technologies (FET) programme to promote long-term and high risk research in quantum computing and communications, nanoelectronics, neuro- and bio- information science, advanced robotics and complex systems.

Some of the research that resulted from FET sponsorship is in show here at an Exhibition.

On the “friendly robotic companions” category, I saw NAO, an extremely self-conscious robot that talked non-stop whilst pushing boxes around (or in the words of the researchers involved, “learning physics”). It did not really convince me, but kudos for looking so helpless and cute.

I was also the only volunteer to test drive a simulator type head-set - immersive journalism at its best — and had to control a joystick to run over black squares on a virtual road. I’m still trying to figure out why.

The issues of high-risk research and funding of basic science, of course, were already timely featured in PW’s May issue, on the excellent article by Mark Buchanan, “In search of black swans”
Glad to see that PW is driving the European science agenda.

Highlight of the day: Anton Zeilinger’s talk on Quantum Information (more on that later)

Us and them: ‘e’ is the smallest exoplanet yet and ‘d’ is in the habitable zone

By Hamish Johnston

Imagine my excitement last week when I received an email press release proclaiming:

“At 11:00 BST/12:00 CEST [21 April], a press conference will highlight a major and truly unique discovery in the field of exoplanets, made possible with ESO telescopes.”

“That’s got to be the first sighting of an exomoon”, I thought — a satellite of planet orbiting a star other that the Sun.

I now know I was jumping the gun on exomoons (more on this later) — it turns out that astronomers have found the smallest exoplanet yet, which is a mere 1.9 times more massive than Earth.

Now, I’m not trying to demean this discovery, but hundreds of exoplanets have already been discovered and this one just happens to be the smallest yet. And I’m guessing that in a few month’s time, a smaller exoplanet will be found.

Perhaps the most interesting thing about this exoplanet is that astronomers know it orbits the star Gliese 581 in the company of at least three other exoplanets.

Three of these planets (including the smallest) are too close to the star to harbour life, but the team has also revealed today that the fourth is inside the “habitable zone”, where life could exist. Indeed, at the press conference the team speculated that the planet could be home to “a large and deep ocean” and described it as the first serious “water world candidate” to be found.

The good old days

By Hamish Johnston

The Sun normally follows an 11-year cycle — waxing and waning in terms of its power output and the number of solar flares and sunspots at its surface.

But our star seems to be stuck in a slump — it should have hit a minimum in 2007-8 and should now be climbing rapidly to its next maximum in about 2013.

Despite a few false starts towards increased activity, the Sun is “bumping along the bottom”, according to solar physicist Mike Lockwood of Southampton University who was on BBC Radio 4 this morning.

You can listen to the interview here.

Lockwood pointed out that the power output of the sun is at a “record low”, but added that we shouldn’t expect a new ice age because solar power fluctuations are measured in hundredths of a percent.

Although solar output is expected to have some effect on Earth’s climate, Lockwood said that exactly how and why is currently a topic of debate.

No sleep at the synchrotron

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By James Dacey

Phew, they certainly don’t believe in wasting any time here at the European Synchrotron Radiation Facility (ESRF).

Day one of my synchrotron sojourn involved a medley of information from key staff, a whistle-stop tour of the 844m storage ring, an afternoon excursion to one of the most intense neutron sources on the planet…

… finished off by dinner with the ESRF scientists.

I think this sense of urgency must be fuelled by the annual turnover of over 6000 scientists who travel from across the 12 member countries (and beyond) to use the facility.

Many of these scientists are PhD students from wide-ranging disciplines, including biology, chemistry and the earth sciences, who come along with thier pre-prepped samples and probe them with this brilliant light source to hopefully reveal some interesting things.

Passing through the central coffee square, you certainly get the impression that this is a lively, creative environment for young researchers to come and share ideas with peers from across Europe.

In the morning I also managed to catch up with Harald Reichert, the new head of research at the ESRF, who compared the facility to a Swiss army knife. “We serve almost every branch of science, all you need is a good idea,” he told me.

After scurrying along the beamlines (I’ll be spending more time there today), I then spent the afternoon at the Institut Laue-Langevin (ILL), which neighbours the ESRF.

A neutron source, the ILL was founded over 40 years ago as the first large research collaboration between France and Germany after World War II, and in many ways it sees itself as the older, wiser brother of the ESRF.

And time on the neutron beam seems to be equally as precious as time with the ESRF X-rays; the head of science, Andrew Harrison, told of how he used to try and sleep amongst the machinery back in his student days.

I saw some pretty cool experiments including a group who were using the neutron beam to look at how different types of molecule react at a surface of water. “Across nature, surfaces are being created then destroyed again,” said the group leader.

To test a surface under stable conditions, they had created a water fountain whose flat surface was perfectly renewed every second - you really couldn’t tell anything was changing!

In search of a giant polo

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Buzzing around Grenoble

By James Dacey

I’ve come to France this week to acquaint myself with one of the world’s “big 3” synchrotrons — the European Synchrotron Research Facility (ESRF) in Grenoble.

The serious science starts today but j’adore my European getaways so I arrived a day early for a bit of exploring.

Doing the classic tourist thing I headed to the highest point, in this case — via a cable car — to La Bastille, a series of fortifications dating back to the middle ages.

There were some fantastic views of the city sprawling out along the flood plain of the Isere.

Unfortunately, Mont Blanc to the east was covered in cloud, but I got some great shots looking down at the ESRF - aka “the giant polo” (below).

One other wonderfully French feature was “apiview” - a viewing slot fronted by a tank of bees (above).

The idea is to gain an original view of Grenoble and its surroundings by looking out “as if one were a bee” - it is part of a local project to combine art with science.

Right, I’m of now to interview Harold Reichert, the director of research here at the facility.

The giant polo
Map of physics in 1997…

By Michael Banks

Producing maps of science seem to be a popular pastime for researchers these days.

Only last month we reported a map made by using over a billion so-called “click-throughs” - produced when going from a web portal like Elseiver’s Science Direct to the full text of a paper or to the abstract on the journal’s website.

Now physicists have made a map using the Physics and Astronomy Classification Scheme (PACS) codes produced by the American Institute of Physics (AIP).

PACS codes contain four numbers and two letters, which are used to classify papers according to the research they contain. Each paper usually includes two or three PACS numbers listed just after the abstract.

The first two numbers of a PACS code denote the subject area, which are grouped in tens. For example, 20-29 is nuclear physics and 30-39 is atomic and molecular physics while 60-69 is condensed matter: structure, mechanical and thermal properties.

Then within nuclear physics, say, there are up to 10 subfields such as nuclear structure (21) and nuclear astrophysics (26). These subfields are also split in tens, so nuclear structure runs from 21.10 (properties of nuclei; nuclear energy levels) to 21.90 (other topics in nuclear structure).

Bear with me a little longer, nearly there. Next is where the letters come in. Within, say, 21.10 there are then a list of topics, such as 21.10.Tg (lifetimes, widths) or 21.10.Dr (binding energies and masses).

Taking papers from the last two decades in the AIP’s database, Mark Herrera from the University of Maryland, David Roberts from Los Alamos National Laboratory and Natali Gulbachce from the Northeastern University in Boston, have created a map using the links between different PACS numbers.

For example, when a paper quotes two PACS codes, these topics are then linked. Running all this data through an algorithm then sorts and finds clusters of nodes and groups them.

The above images show the full maps from 1997 and 2006 with subfields of a subject area shown (that is the first two numbers in a PACS code). The nodes represent the subject area, and its size is proportional to the amount of single PACS codes it contains. The thickness of the links indicates how many papers have PACS codes corresponding to both nodes.

According to the researchers, the map lets you see how areas shrink and grow and how they merge with one another.

For example, in 1997 crystallography (61) was one central node, but in 2006 it had split into five (as deduced by the algorithm). Even though each one is strongly linked with the others, the algorithm didn’t deem it one single node, which may indicate five separate fields emerging within this area.

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Coup d’etat in physics?

By James Dacey

Even its fiercest critics will struggle to argue that open-access publishing has not brought about a revolution in the way scientists engage with the latest research findings.

Driving the reformation in physics and maths is the arXiv preprint server, which was pioneered by Paul Ginsparg at the Los Alamos National Laboratory and is currently hosted by Cornell University.

Now the revolution continues apace as a new innovation will enable frontline physics to be winged straight into the palms of researchers.

ArXiview is a new iPhone application billed as “a very easy way to surf the last few weeks of arXiv postings.”

This new innovation was designed by Dave Bacon, a theoretical physicist at the University of Washington, during a recent spell between jobs.

I ran a quick search of the Apple store website and found a couple of rival arXiv app’s but this seems to be the first to enable users to order results by date.

It remains to be seen whether arXiview will be a bit hit amongst physicists but I can already picture a handful of the uber keen ones wowing their colleagues at conferences as they reel off the days latest findings.

Thankfully, long gone are the days where findings took months, years even, to see the light of day. But let’s just hope this mania for faster, round-the-clock access to physics doesn’t start to chip away at the rigour and depth of the subject.

So what next in the research revolution - Stephen Hawkings tweeting about his favourite formulae?

Earthquake shockwaves (credit: IREA-CNR)

By Michael Banks

Researchers have released the first satellite images showing the effect of the L’Aquila earthquake that struck central Italy earlier this month.

Measuring 6.3 on the Richter scale, the earthquake killed over 290 people with an epicentre only a few kilometres away from the Gran Sasso National Laboratory located between L’Aquila and Teramo, which is best known for studying the properties of neutrinos and searching for dark matter.

Scientists at the Instituto per il Rilevamento Elettromagnetico dell’ Ambiente in Napoli have now started analysing data taken from the Environmental Satellite (Enivsat) operated by the European Space Agency (ESA).

Launched in 2001, Enivsat carries ten instruments for Earth observation, which can measure, for example, sea surface temperatures and the amount of sunlight transmitted, reflected and scattered by the Earth’s atmosphere.

Enivsat’s on board radar can detect changes in the Earth’s surface with millimetre accuracy. Data taken just after the earthquake on 6 April and compared to an image made a few months before show a set of nine fringes originating a few kilometres from L’Aquila.

Each fringe on this ‘interferogram’ represents a ground movement of 2.8 cm, meaning the ground moved by 25 cm at the centre of the earthquake a few kilometres from L’Aquila.

The results from Envisat have also been confirmed by the movement of five GPS receivers located around the affected area that were moved as a result of the earthquake.

ESA is also making the satellite’s data taken in the L’Aquila region freely available for scientists to analyse, which is available to download here.

Radio all-stars

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Techno. Science. Art

By James Dacey

One aim of this International Year of Astronomy (IYA2009) is to ground astronomy in popular culture and inspire people to consider the role that star-gazing has played throughout history.

“Astronomy is not just a modern science but a fundamental reflection of how all people, past and present, understand themselves in relation to the Universe,” reads the Astronomy and World Heritage website.

Inspired by this grandiose mission, artist and researcher Michael Takeo Magruder has represented the influence of broadcast technology on the near-Earth environment by creating a visual representation of the Radiosphere.

The geometry of “Data_set” is derived from the positions of all the stars listed by astronomers in catalogues like Hipparcos. Star types are represented by shape, with living stars appearing as spheres, brown dwarves as incomplete spheres, and white dwarves as compressed crosses.

These stellar nodes are then connected to a central spherical body representing our solar system, by lines coloured according to the spectral class of the individual stars.

to heighten the sensory experience, images and sounds - streamed live from the BBC world service - are layered on top of the 3-D light show.

“The televised broadcast of the Berlin Olympics in 1936 was humanity’s first media transmission powerful enough to pass through Earth’s ionosphere and travel into deep space… in the 73 years since that defining moment, our communications have reached nearly two thousand other known star systems,” reads the press release.

“Data_set” has been created especially for IYA2009 and is hosted now at the Thinktank Planetarium in Birmingham, UK.

The Supra-Thermal Ion Imager

By Hamish Johnston

Where does Earth’s atmosphere end and space begin?

The answer is 118 km above sea level, at least according to physicists in Canada and the US.

In 2007 the team sent their Supra-Thermal Ion Imager into space aboard the JOULE-II rocket. The instrument was able to detect the precise altitude at which the rocket left the cocoon of Earth’s atmosphere and was subject to the blast of charged particles found in space.

They have just published a paper describing their findings. You can read more about it here

On location at Brookhaven

By Hamish Johnston

‘What is a petaflop?’

That was the only wrong ‘question’ given by contestants in a round of the US game show Jeopardy that focussed on the Brookhaven National Lab in New York.

The ‘answers’ were posed by video by two presenters who seemed to be on a grand tour of the facility.

You can test your knowledge of what goes on at Brookhaven in this clip of the show.

Sadly, one of the answers wasn’t:

‘He is a philosopher and historian of science at Brookhaven who writes an entertaining yet erudite column for the best physics magazine in the world.’

Who is…?

By Hamish Johnston

Physicists like a bit of gossip — especially if it’s about when the Large Hadron Collider will be back in action after its catastrophic failure last year.

That’s why I was fascinated by a post on Peter Woit’s Not Even Wrong blog suggesting that the LHC start-up will be delayed by four weeks beyond its current September 2009 target.

Woit refers to a “draft” of the latest repair schedule that was presented by LHC operations leader Roger Bailey at a recent conference in Oxford. The document clearly shows that the first beam will be circulated during week 43 of 2009 — which begins on Monday 19 October.

By contrast, the schedule released in February says the beam should be commissioned the week of 21 September.

The draft schedule seems to suggest that the problem is related to repairing sector 34, the section of the accelerator where the disaster occurred.

I asked CERN spokesman James Gillies what was going on. He said like any major project, “time is lost and time is gained” in various aspects of the repairs and there is no point in putting out a new schedule every time this happens.

He also said that CERN is now looking for ways to make up the extra time identified by Bailey and he said that the repair team are confident of having the LHC running towards the end of September as planned.

The Gran Sasso National Laboratory (credit: LNGS)

By Michael Banks

Researchers at the Gran Sasso National Laboratory in central Italy are best known for their experiments that are designed to study the properties of neutrinos and search for dark matter.

The underground lab, however, also lies around 20 kilometres away from the town of L’Aquila, which was hit by an earthquake in the early hours of Monday morning. Measuring 6.3 on the Richter scale, the earthquake has so far killed over 200 people. But there are reports saying that Giampaolo Giuliani, a physicist based at Gran Sasso, predicted the earthquake would happen more than a month ago.

Predicting earthquakes is a tricky business as a feature we ran in January points out. But developing a system that could predict when and where they happen, although being a pipe dream at the moment, could save thousands of lives per year.

Reports yesterday say Giuliani predicted the earthquake would happen after nearby sensors picked up excess radon gas escaping from the ground last month.

There is, however, no reliable proof that radon emitted by smaller tremors could be used to predict an earthquake. Guiliani was also apparently told to remove videos and information from the internet warning that an earthquake could hit the region.

Physics World is currently looking into the full details of Guiliani’s story, so stay posted for updates.


By Matin Durrani

When Tim Berners-Lee dreamt up the World Wide Web 20 years ago last month, the former physicist-turned-CERN-software-engineer could not possibly have envisaged what his invention would unleash - from iTunes to Google StreetView and from Spotify to Ebay.

There’s no way either that he could have ever envisaged the idea of Twitter — the website that invites people to answer the question “What are you doing?” in fewer than 156 characters.

Twitter’s been all the rage this year with everyone from BBC Radio Five Live presenter Richard Bacon to actor Stephen Fry signing up, boring everyone who chooses to “follow” their “twitterings” about their every move. Even Barack Obama is on Twitter, except that he doesn’t write his entries - he has minions to do it for him.

But whether Twitter turns out to be a short-lived phenomenon or something that proves truly durable and lasting, the fact is it’s here and we on Physics World couldn’t resist joining in. You can find us here

You’ll be delighted to hear though that we won’t be letting you know every time one of us goes to the kitchen to make tea or has another chew on one of the Physics World pens.

What we are doing though is letting you know via Twitter every time something new is posted on our site - be it  a news story, blog entry or longer feature.

So now you’ve got even less excuse not to keep coming back! Apparently you can even follow Twitter via your mobile phone.


By Hamish Johnston

You can’t have an International Year without a commemorative stamp — so here are a few beauties issued by Canada Post to celebrate this International Year of Astronomy.

The top stamp features the Dominion Astrophysical Observatory, which is high on a hill overlooking Saanich, British Columbia.

Not to be confused with the Dominion Observatory in Ottawa, or the Dominion Radio Astrophysical Observatory in Penticton, the Saanich facility opened in 1918 and its telescope is still used today. The observatory is also home of the Herzberg Institute of Astrophysics.

The background of both stamps feature photographs of nebulae taken by the Canada-France-Hawaii Telescope, which is perched on top of an dormant volcano — Mauna Kea — in Hawaii. The top is the Horsehead nebula and the bottom is the Eagle nebula.


The bottom stamp also features the Canada-France-Hawaii Telescope itself, which is so high up that snow shovels are on hand. A little bit of Canada in Hawaii, I suppose.

The first Dirac House

By Hamish Johnston

Did he live here for 21 years?

The salmon-coloured house in the centre of the photo is 15 Monk Road, the birthplace of Paul Dirac.

This view of suburban Bristol is from our back window and would have been somewhat different in 1902 when Dirac was born. The houses had been built a year earlier and I’m guessing the gardens would have been devoid of trees and large shrubs.

Dirac lived in this house until he was about ten (according to his latest biographer Graham Farmelo) or 21 — according to the historical plaque on the house (right).

I sometimes wonder what the current owners make of this plaque — are they worried that Dirac left some antimatter lurking under the floorboards?

Bacon put the sizzle into science

By Hamish Johnston

If you do experiments; collaborate with other scientists; or benefit from government research grants you may want to thank this chap — the English lawyer and political schemer Francis Bacon (1561-1626).

Bacon lived at a pivotal time when the West was moving out of the renaissance and its reverence of the ancient Greek thinkers — and towards evidence-based methods of understanding nature. Bacon was one of the driving forces in the development of what we now call the “scientific method”.

This morning on BBC Radio 4’s In Our Time, Melvyn Bragg and company discussed Bacon’s role (sorry, couldn’t resist another pun) in the shaping of modern science.

By Hamish Johnston

Our good friends in the journals department have just published two special issues containing 850 papers on low temperature physics — all of which are free to read online.

The papers were presented at the 25th International Conference on Low Temperature Physics (LT25), which took place in August 2008 in Amsterdam.

You can get stuck into this rich seam of research papers here

Matin Durrani was there and blogged from the event.