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November 2011 Archives


By James Dacey

Hindsight is a wonderful thing. It’s an overused expression but one that undoubtedly applies in the case of science. Time and again throughout the history of science a seemingly immutable theory has been overthrown by a new one as new evidence or new ideas come to light. In many cases, the new theory can appear so blindingly obvious that it seems incredible to think that our forebears could have failed to discover it themselves.

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But as any good scientist knows, in hindsight, many ideas that seemed rock solid at the time, turn out to be concealing flaws beneath the surface. But this is how science progresses. Any would-be Einstein does not simply stare into a crystal ball and wait for that revolutionary idea to miraculously emerge. No, scientists rigorously examine an existing theory from a range of different angles, looking for chinks in the armour that every so often can allow a theory to be damaged or even toppled. This then paves the way for new science.

Non-scientists, however, do not always have the tools to test these theories. This is certainly the case for science at the cutting edge, where we have few clear answers and the required tools to probe these questions can be very expensive – costing billions of dollars in some cases. So how far can a non-scientist trust what he or she is told by a scientist about a subject? This important question is addressed by the author Alan B Whiting in his new book Hindsight and Popular Astronomy, which was recently reviewed in Physics World.

In his book, Whiting looks back at several books about astronomy written for popular audiences in the late-19th and early-20th centuries, including titles by Sir John Herschel and Sir Arthur Stanley Eddington. With the full benefit of hindsight, Whiting looks at the science presented in these books and considers which theories have stood the test of time. But Whiting is not interested in laughing at these authors for “getting it wrong”. Instead, he is interested in the manner in which these scientists presented the science: did these authors present these theories as undisputable scientific fact; or did they acknowledge that there were still uncertainties? It turns out that these authors ranged widely from the humble to the “often wrong, but never in doubt”.

The book makes for a very interesting read and it highlights many of the qualities and pitfalls of popular-science writing. We have all read pieces of science writing where the author has presented the science as if it is incontestable knowledge. But this is only one flaw among many. In this week’s Facebook poll, we want you to share your feelings on this topic by answering the following question:

What is your biggest pet peeve about popular-science writing?

Talking down to readers
Blurring fact and speculation
Using clichés and overblown language
Giving bad or unclear explanations

Of course, you may have other pet peeves, so feel free to share these by posting a comment on the Facebook poll.

In last week’s poll we asked you where you would most like to go for a nerdy day trip from a shortlist of six places of particular interest to physicists.

Unsurprisingly, CERN was the most popular choice, with 51% of respondents saying they would most like to visit the famous particle-physics lab on the Franco–Swiss border. The second most popular choice was The Very Large Telescope in Chile, which was the choice of 27% of voters. In third place (which, incidentally, was my personal preference) was the Baikonur Cosmodrome, the world’s first space-launch facility in Kazakhstan, which received 9% of the vote. The other three choices, which failed to stir much interest, were: the Trinity test site where the first atomic bomb was detonated, New Mexico, US; Bletchley Park code-breaking centre, Buckinghamshire, UK; and Woolsthorpe Manor, birthplace of Isaac Newton, Lincolnshire, UK.

Thank you for all your responses and we look forward to hearing from you again in this week’s poll.

By Matin Durrani

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One of the big advantages of a physics degree is that it opens the door to a wide range of different careers.

In fact, relatively few physicists stay within the confines of academic research, with plenty heading off into IT, finance, industry and teaching.

And, of course, there are lots of other unusual jobs that physicists end up doing, from opera singing to beach-animal sculpture-making, some of which appear in our regular “Once a physicist” column, a selection of which can be read via this link.

Plenty of physicists also end up working in the environmental sector and it was pleasing to see that the new head of the UK’s Natural Environment Research Council (NERC) is a physicist too.

Appointed today by the Department for Business, Innovation and Skills, the new NERC boss is Duncan Wingham, who graduated with a BSc in physics from the University of Leeds in 1979 and obtained a PhD from the University of Bath, also in physics, in 1984.

Most of Wingham’s career since then has been at University College London (UCL), where he was chair of space and climate physics and later head of Earth sciences from 2005 to 2010.

Wingham was also founding director of the NERC’s Centre for Polar Observation and Modelling from 2000 to 2005, which, among other things, discovered the widespread mass loss from the West Antarctic Ice Sheet and its origin in accelerated ocean melting.

He is also currently chairman of the NERC’s science and innovation board and has been lead investigator of the European Space Agency’s CryoSat and CryoSat-2 satellite missions.

Wingham replaces Alan Thorpe, who was also a physicist.

We’ll be publishiing a special issue of Physics World magazine next March on Earth sciences and we’re filming some videos at the American Geophysical Union’s meeting next month – so stay tuned for more Earth-sciences coverage.

By Hamish Johnston

Last week’s particle-physics conference in Paris began with the news that CERN’s Large Hadron Collider (LHC) may have produced the first glimpse of direct CP violation in a charmed-muon decay.

If that wasn’t enough to get particle physicists mildly excited, Friday’s joint announcement by the ATLAS and CMS experiments should do the trick.

Physicists working on the LHC’s two biggest experiments have pooled their data from 2011 (or at least the bits they have managed to analyse so far) to obtain the best mass exclusion yet for the Higgs boson.

The data reveal that the mass of the Higgs is unlikely to fall in the range 140–480 GeV/c2. This is news because most of this energy range had not been excluded by previous colliders, including the Tevatron at Fermilab. When combined with work at other colliders, the ATLAS and CMS data suggest that the Higgs mass falls into a window between about 110–140 GeV/c2, or is greater than about 480 GeV/c2.

Perhaps the most intriguing feature of the data is a sharp change at about 120 GeV/c2. In his blog, Tommaso Dorigo explains the significance of this fluctuation, and argues that it could be the first indication of the Higgs mass, which he believes is 119 GeV/c2. You can read Dorigo’s analysis here.

In the video above, physicists from the CMS experiment talk about the mass-exclusion results.

In other LHC news, researchers from the CMS experiment have published a paper in Physical Review Letters detailing the most extensive search for supersymmetry to date. Supersymmetry (or SUSY) is an attractive concept because it offers a solution to the “hierarchy problem” of particle physics, provides a way of unifying the strong and electroweak forces, and even contains a dark-matter particle. An important result of the theory is that every known particle has at least one superpartner particle, or “sparticle”.

Sadly, those waiting for a revolution in particle physics will have to wait a little longer, because no evidence for such sparticles has been found by CMS. You can read the paper here free of charge.

23 November Higgs update from CERN: Physicists on the ATLAS experiment have published a paper in Physical Review Letters that excludes the Standard Model Higgs mass from 340-450GeV/c2 at 95% confidence. You can read the paper here.



Image of Gavin Pretor-Pinney with his book and award

Image of Gavin Pretor-Pinney with his book and award on the left and the front cover of the UK edition of The Wavewatcher’s Companion on the right. (Courtesy: The Royal Society)

By Tushna Commissariat

The Royal Society announced its 2011 Royal Society Winton Prize for Science Books today and the winning book is Gavin Pretor-Pinney’s The Wavewatcher’s Companion. Sir Paul Nurse, president of the Royal Society, presented the prize to Pretor-Pinney at an award ceremony held at the society’s headquarters in London.

The society’s annual book prize, originally established in 1988, aims at encouraging the writing, publishing and reading of science books – especially those that deal with complex subjects in a style that can be absorbed by a non-specialist audience. The society also awards the Royal Society Young People’s Book Prize for books that communicate science to a younger audience.

The winner of the Winton Prize is selected by a panel that first chooses a longlist of about 12 books followed by a shortlist of six books, before the winner is announced. The authors of the short-listed books each receive £1000 and the winner receives £10,000.

In The Wavewatcher’s Companion, Pretor-Pinney, who also happens to be the founder of the Cloud Appreciation Society, talks about another formation in nature that caught his eye – waves – and explores why it is they appear everywhere around us. On winning the prize, Pretor-Pinney said “I’m really grateful to the jury, the Royal Society and Winton Capital Management. What interests me in science is that it follows from being curious about the world around us. I hope my book motivates others to be curious too!”

The judging panel included Richard Holmes, biographer and a previous winner of the prize; Jenny Clack FRS, Professor and Curator of Vertebrate Palaeontology at the University of Cambridge; Robert Llewellyn, writer, actor and TV presenter; and Professor Cait MacPhee, Professor of Biological Physics at the University of Edinburgh.

The six books shortlisted were:

*Alex’s Adventures in Numberland by Alex Bellos

*Through the Language Glass: How Words Colour Your World by Guy Deutscher

*The Disappearing Spoon by Sam Kean

*The Wavewatcher’s Companion by Gavin Pretor-Pinney

*Massive: The Missing Particle That Sparked the Greatest Hunt in Science by Ian Sample

*The Rough Guide to the Future by Jon Turney

“At the heart of the scientific enterprise is a desire to explore our world, and to understand it better. The Wavewatcher’s Companion used relatively straightforward science to transform our perspective on the world around us, both visible and invisible, in a completely radical way. From mexican waves to electromagnetic waves, it gave us a new delight and fascination in our immediate surroundings,” said Holmes, chair of the judges. He went on to say that the panel was “inspired to see waves everywhere” after reading the book and that it was a “delightful winner”.

The first chapter of each shortlisted book is available to download free of charge here.

When East meets West

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Wroclaw

Centennial Hall in Wrocław, where the meeting took place

By Susan Curtis

I was recently in the Polish city of Wrocław to attend the second Asian-European Physics Summit, where one message emerged loud and clear – scientists from West and East need to collaborate with each other more.

The summit brought together representatives of the European Physical Society with those from the Association of Asian Physical Societies. The latter is an umbrella organization that represents the physical societies of countries such as Japan, China, Korea, Australia and India.

Physicists at the meeting argued that working together is the best way to push the boundaries of scientific discovery, while policy-makers recognized that the drive for ever-more-sophisticated research facilities can only be realized by combining global resources.

There was good news in Wrocław from speakers from Japan, Korea and China, who reported that science funding is increasing across Asia. While Japan already has a reputation for research excellence, China and Korea are making big investments in basic research in a bid to move up the value chain from product supply to a knowledge-based economy. They are keen to work with European research centres to speed up that transition, and to learn from Europe’s approach to developing a structured and collaborative research infrastructure.

A good example of how that’s happening in practice is Korea’s activity in fusion research. Having established its capability with the KSTAR research tokamak, Korea has become a key member of the ITER consortium, which is building a proof-of-concept fusion reactor in the south of France. Korea plans to exploit the experience gained at ITER to build a commercial nuclear-fusion facility sometime between 2022 and 2036.

But collaborations like that are few and far between. Asian scientists have traditionally viewed the US as the best place to develop a physics career, so much so that Asia is suffering a brain drain as talented scientists relocate for better pay and research opportunities. And while some Asian scientists come to Europe to work on particular projects, very few European researchers spend significant time in Asia.

In January 2009 the EU set up a project called KORANET to investigate the reasons why. One obvious problem is the eight- or nine-hour time gap, combined with the cultural and linguistic differences that make it hard for Asian scientists to live and work Europe, and for Europeans to move to Asia. More practical problems also discourage mobility, such as finding suitable accommodation and ensuring continuity of pensions provision and healthcare insurance.

One idea suggested by KORANET is for European research organizations to set up “branches” in Asia. A particularly successful initiative has been the Sino-German Center for Research Promotion, a joint venture formed 10 years ago to co-ordinate and encourage collaborative activities between China and Germany. The Max Planck Society has also established 24 partner groups in China, which allows Chinese students and postdocs to gain research experience in Europe before returning to work in well funded, well equipped Chinese facilities.

For their part, delegates at the ASEPS event said that more exchange opportunities should be developed for small research programmes as well as for large projects, and that a network of local contact points should be set up to help scientists who are working in an unfamiliar part of the world.

To encourage student mobility – which will be crucial for future collaboration – delegates were keen to ensure mutual recognition of degrees, and suggested a joint summer school to address some of the key challenges facing young physicists, such as the need for sustainable energy technologies.

A small working group will take these ideas forward so that real progress can be reported at the next ASEPS meeting, which is due to take place in Asia at some point over the next two years.

In the meantime, don’t forget to check out our Physics World special report on China, which can be read via this link.

Unleash your geeky day-tripper

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By James Dacey

Be it a day spent relaxing at the beach, a long stroll through the rolling countryside, or an afternoon blowing all your wages at an out-of-town shopping centre: you simply cannot beat a fun day out every once in a while. But there are some people out there who crave a little more intellectual nourishment from their hard-earned days off. Well, a solution is at hand, thanks in part to the science blogger and Guardian columnist, Ben Goldacre, who came up with the concept of NerdyDayTrips.

hands smll.jpg The story begins with Goldacre asking his followers on the social-networking site Twitter to suggest half-day trips to unusual destinations in London, listing his interests as “industrial archaeology, urban-explorer type stuff”. The response was huge and it inspired a medical journalist, Jo Brodie, to begin collating the various ideas and organizing them into a searchable list. By September this year the concept had evolved into its current form: a giant world map dotted with tourist attractions and other curious sights that meet with the nerd seal of approval.

So, we thought we would borrow this idea by coming up with a short-list of locations that might be of particular interest to the physicist day-tripper. We want to know your thoughts on this via our latest Facebook poll, in which we ask the following question:

If money were no object, which of these nerdy places would you most like to visit on a day trip?

The CERN particle-physics laboratory, France/Switzerland
The Trinity test site where the first atomic bomb was detonated, New Mexico, US
Bletchley Park code-breaking centre, Buckinghamshire, UK
The Baikonur Cosmodrome, the world’s first space-launch facility, Kazakhstan
Woolsthorpe Manor, birthplace of Isaac Newton, Lincolnshire, UK
The Very Large Telescope, Cerro Paranal, Chile

To cast your vote, please visit our Facebook page. But it’s a big old world, populated by varied demographics of geeks, so please feel free to suggest other physics sites not included on our list. Do this by posting a comment on the Facebook poll.

In last week’s poll, we looked at the issue of physics education. We asked what people considered to be is the “single most important quality of a great physics teacher”. The question was prompted by the recent announcement by the UK government of a new £2m-a-year scholarship programme to help persuade 100 graduates to become physics teachers in English high schools.

The results were conclusive, as 70% of respondents believe that the single most important quality is for a teacher to have an enthusiastic and entertaining teaching style. Some 25% of respondents disagreed, as they believe that a deep knowledge of the subject is more important. Our final three options attracted very little support: 2% felt that prior experience working as a physicist is most important; 2% opted for the teacher having a proven track record of getting good grades out of their students; and just 1% believe that an ability to maintain classroom discipline is the most important attribute.

The poll also attracted a fair number of comments. For instance, Glilium Ho, one of the respondents who opted for enthusiasm and entertainment in the classroom, believes that knowing about physics is of little value to education if it cannot be communicated to others. “To have a deep knowledge is important, but to be able to pass down the knowledge to the others is the most important thing. So that others, too, can stand on the shoulders of giants and look further,” he wrote.

Another interesting comment came from Dileep Sathe from Mumbai, India, who accepts that not everyone will appreciate the theoretical aspects of physics, so flashy experiments are important to maintain students’ interest. “If you are presented with cool experiments every few weeks, you’ll be more likely to give the theory of the phenomenon a chance, instead of just not caring at all,” he wrote.

Thank you for all of your responses and we look forward to hearing from you again on our Facebook page.

SESAME
Shamin Kharrazi talks about plans for the Iranian Light Source Facility

By Michael Banks

You may remember a few weeks ago when I wrote about Turkey’s plans to build a 3 GeV synchrotron in Ankara. In fact the next decade will see two other new synchrotrons springing up in the Middle East.

One – SESAME – is near Amman, Jordan, and I visited the facility earlier this week to hear how progress is moving towards completion by 2015 (see this story for more details).

Synchrotrons accelerate electrons to high energy and then make the particles generate flashes of X-rays as they travel around a circular ring. The X-rays are then sent down beamlines where they are used in a range of experiments from condensed-matter physics to biology.

However, a talk given by Shamin Kharrazi at the SESAME users’ meeting also outlined plans Iran has to build its very own synchrotron – the Iranian Light Source Facility (ILSF) – by 2020.

A conceptual design review for the 100 m diameter facility has just been completed and it is estimated that construction will begin by 2015.

Plans for the ILSF, like its Turkish equivalent, are still firmly on the drawing board, but researchers in Iran are hoping the facility will get funding. Kharrazi remarked that around seven years ago synchrotron radiation was not widely known to the authorities in Iran. Now, in a matter of only a few years, the country has plans for its own facility.

Indeed, over the past few years Iran has been building a community of those who could use their own national facility as well as SESAME. At times this has been painstaking and even involved researchers searching via Google for others around Iran who work with X-rays.

Kharrazi reassured SESAME users that Iran will still play an integral part in that project. “We think that by 2020 there will be enough demand for Iran to have its own synchrotron and also use SESAME,” says Kharrazi. “Just like France has the Soleil synchrotron as well as the ESRF.

A letter from space

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By Michael Banks

In a video interview with Physics World in June, Michael Schreiber, editor-in-chief of the journal EPL, marked the 25th anniversary of the publication by hoping that it would, one day, receive a submission from the International Space Station (ISS) (see video above).

We thought he was joking, but that day has now come. On 27 October Russian astronaut Sergey Aleksandrovich Volkov, who is currently aboard the ISS, submitted a paper via e-mail to EPL, which is jointly published by the Institute of Physics and the European Physical Society.

The paper was about measuring the speed of sound in a plasma under microgravity conditions. In an EPL editorial, Schreiber wrote that the journal has now left the confines of the globe “by publishing what is, I believe, the first manuscript ever submitted from beyond the globe, namely from the International Space Station”.

That all important caveat (“I believe”) proved its worth as it transpires that a paper was already submitted from the ISS in 2004 to the journal Radiology – published by the Radiological Society of North America.

Still, the EPL paper is perhaps the first physics-related article to be submitted from space. But Schreiber has even loftier ambitions: hoping for a paper from a space-trip to Mars to coincide with EPL’s golden jubilee in 2036.

What makes a great physics teacher?

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By James Dacey

This week, the UK government has announced a £2m-a-year scholarship programme to help persuade 100 graduates to become physics teachers. Each graduate who wins a scholarship will be awarded a £20,000 (roughly $32,000) tax-free bursary provided they have got a place to study for a postgraduate certificate in education (PGCE) in England.

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It seems that the architects of the new scheme are keen to attract the brightest physics graduates into teaching. Applicants for the scholarships will require a first-class or upper-second degree and be intending to complete a physics or physics-with-maths PGCE. The new scheme may also help to persuade older graduates to move into teaching from other professions, in the knowledge that they will no longer need to study for a year without a salary.

The scheme is designed to address the lack of specialists teaching physics in English high schools. According to the UK Institute of Physics (IOP), about 1000 new specialist physics teachers in England will be needed every year for the next 15 years to ensure that the subject is taught entirely by specialists. Last year 275 fewer trainees were recruited to physics teaching-training courses than were needed to start plugging the gap. More information about the scheme is included in Michael Banks’s news article from Tuesday.

In this week’s poll, we want you to draw on your own experiences of studying physics at high school by answering the following question:

What do you believe is the single most important quality of a great physics teacher?

A deep knowledge of the subject
Prior experience working as a professional physicist
An enthusiastic and entertaining teaching style
A proven track record of their students getting good grades
An ability to maintain classroom discipline

To cast your vote, please visit our Facebook page. And feel free to explain your choices and share your own school experiences – by posting a comment on the Facebook poll.

In last week’s poll, we appealed strongly to your inner geek by asking you to select your favourite from a list of the most familiar physical constants. And it seems that the issue is close to the hearts of our Facebook followers, as the poll attracted more responses than any previous poll.

The clear winner, collecting 42% of the votes, was Planck’s constant. In second place was the speed of light in a vacuum, which received 21% of the responses, and in third place was the gravitational constant with 14%. Avagadro’s number, Boltzmann’s constant and the charge on an electron took 4th, 5th and 6th places, respectively.

The poll also attracted a lot of comments. For instance, Lulú Hernández, who studied at the Escuela Superior De Física Y Matematicas (IPN) in Mexico, stands firmly beside her choice. “Planck’s constant is the best constant of nature, used to measure the energy of the photon, define the limits of quantum phenomena, among many other applications,” she says [translated from Spanish]. Another respondent, Kate Scaryboots Oliver, wrote simply: “Good ol’ Planck. never lets you down. Unlike c [the speed of light in a vacuum].”

Thank you for all of your responses and we look forward to hearing from you again on the Physics World Facebook page.

Big Bang Theory
Geek chic: From left to right, Raj, Howard, Leonard and Sheldon of The Big Bang Theory build a fighting robot. (Courtesy: Warner Bros Television Entertainment)

By Hamish Johnston
Sheldon Cooper is an unlikely poster boy for any cause – he’s gangly, self-absorbed and sociopathic. Indeed, the fictional theoretical physicist is more like an alien observer of the human race, than someone to aspire to.

But according to an article in the Observer, the popular character in TV’s The Big Bang Theory – played by Jim Parsons – and his entourage of geeky physics pals are responsible for “a remarkable resurgence of physics among A-level [high school] and university students.” Tom Whitmore, 15, told the paper: “The The Big Bang Theory is a great show and it’s definitely made physics more popular”.

According to the paper, the number of British students studying physics at university has jumped by 10% since 2008 when the show was first broadcast in the UK. However, the article does point out – as Sheldon surely would – that the number of pupils doing physics A-levels (senior high-school courses) in the UK had been rising since 2006. Also, the recent popularity of TV/radio presenter and physicist Brian Cox, and all the publicity surrounding the Large Hadron Collider, are put forth in the article as contributing factors in the physics boom.

If UK students are being turned on to physics by the The Big Bang Theory, the irony will not be lost on physics societies worldwide, which have spent much time and effort on trying to re-brand physics as a cool subject studied by normal people who go on to success in the wider world. It could be that a better way to get teens interested in physics is to appeal to their “inner geek”.

You can read the Observer article here.

cn.jpg By Hamish Johnston

Darmstadtium (Ds), roentgenium (Rg) and copernicium (Cn) are here to stay now that the International Union of Pure and Applied Physics (IUPAP) has approved the names of these three new elements.

The good news came yesterday at the General Assembly of IUPAP, which is running this week at the Institute of Physics (IOP) in London.

Robert Kirby-Harris, chief executive of the IOP and secretary-general of IUPAP, said, “The naming of these elements has been agreed in consultation with physicists around the world and we’re delighted to see them now being introduced to the periodic table.”

The approval ends the long process of naming a new element, which typically begins with its discovery at a nuclear physics lab. Indeed, these latest three were all discovered at the GSI lab near the German city of Darmstadt – which lent its name to Ds.

Both Rg and Ds were first spotted in 1994 and have 111 and 110 protons, respectively. With an atomic number of 112, Cn first burst on the scene in 1996.

Why has it taken so long for official approval? After GSI announced a discovery, it had to be reproduced at another facility – and then both the International Union of Pure and Applied Chemistry (IUPAC) and IUPAP had to be convinced of the discovery. Then, the scientists who made the discovery suggest a name to the IUPAC/IUPAP Joint Working Party on the Discovery of Elements, which then recommends that the name be adopted. Finally, the name must be adopted by the General Assembly of IUPAP.

If you’d like to know more about how these and other elements were found, we’ve just published an article by Paddy Regan, a nuclear physicist at the University of Surrey who works on the RISING collaboration at GSI. You can read it here.


View Larger Map

By Hamish Johnston

In 2008 zoologist Sabine Begall from the University of Duisburg-Essen in Germany and colleagues shocked the bovine world with the claim that cattle prefer to align their bodies along the Earth’s magnetic field – that is along the north–south direction. The team used images from Google Earth to study the orientation of 8500 cattle from 208 pastures around the world to come to their conclusion, which was described in the Proceedings of the National Academies of Science.

But then in January of this year, Jiri Hert from Charles University in the Czech Republic and colleagues reported that there is no evidence for such alignment in their Europe-wide study of some 3412 individual cows in 322 herds (arXiv:1101.5263). This work was later published in Journal of Comparative Physiology A. You can read our take on this development here.

Now, Begall and colleagues have hit back with a paper in that very same journal, where they re-analyse data used by Hert and coworkers. In their paper, Begall and team argue that about half of Hert’s data are noise – that the resolution of corresponding images are too poor, or the cattle are on slopes or in other locales that could affect their orientation.

In their paper, Begall et al. take a fresh look at Hert’s data and claim to see that “cattle significantly align their body axes in north–south direction”. Furthermore, the researchers say that they have uncovered evidence that resting cattle are even more likely to align themselves than their standing neighbours.

Hynek Burda, who works with Begall, described the exchange of views as “a holy war against magnetoreception”. We look forward to the next salvo from Hert’s army.

In the meantime, you could do a bit of research of your own. To get you started I’ve embedded a Google image of what appears to be cattle grazing in a field somewhere in England. But beware, apparently it can be difficult to tell the difference between sheep and cattle!

What is your favourite physical constant?

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By James Dacey

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A fascinating paper published in Physical Review Letters this week reports that one of the fundamental constants of our universe – the fine-structure constant (α) – may in fact vary depending on where you look in the heavens. The paper was actually available on the arXiv preprint server more than a year ago, and the implications of this bold claim were discussed at the time in a news article by physicsworld.com editor, Hamish Johnston. Along with other fundamental constants, the fine-structure constant determines the masses and binding energies of elementary particles, including dark matter – so it’s a big claim!

But in addition to the huge physical questions raised by this finding, it is also quite strange to think that such a familiar constant, 1/137, may not be so constant after all. Maybe I’m being a tad melodramatic about this, but I find it quite sad to think that this trusty constant, which was etched into my brain as an undergraduate, could somehow be subject to the whims of the universe just like the rest of us. But when it comes to holding an emotional attachment to the fundamental constants of physics, I somehow doubt that I am alone.

In this week’s poll we want to know: What is your favourite physical constant?
Planck’s constant
Gravitational constant
Boltzmann’s constant
Charge of the electron
Avagadro’s number
Speed of light in a vacuum

To cast your vote, please visit our Facebook page. And of course, there are plenty of other physical constants out there, so if your favourite does not appear on this list of big-hitters then please feel free to let us know in a comment on the Facebook poll.

In last week’s poll, we considered another feature of the human side of science – the art of writing scientific papers. We asked whether you think that papers would be more informative if they were written in a first-person narrative where researchers told the “story” of their research as well as the scientific results. We had a lot of responses and opinion was fairly evenly divided with 56% of respondents replying “yes” and 44% replying “no”.

The question came about because last week the Royal Society opened up its entire historical journal archive to the public, which included Newton’s first published scientific paper. In the old text, Newton presents his New Theory of Light and Colors in a relaxed first-person narrative, which gives the readers an insight into the great physicist’s thought processes. Today’s scientific papers stand in stark contrast to this, being written largely in the third person about experiments that took place with no apparent human input.

One respondent who voted “yes” is Abhinav Deshpande, a physics student at the Indian Institute of Technology in Kanpur. He commented: “Even though [the papers] wouldn’t necessarily be more informative, the story of how the discovery came about or how the key idea hit the author is an inspiring one for young, inexperienced readers like myself.”

But another student, Matthew O’Neil who is doing a degree in biochemistry at Keele University in the UK, has different ideas. He thinks that a first person narrative would make a paper less, not more, informative. “The idea of a scientific paper is to clearly and concisely inform the reader of methods, results, analysis and conclusions,” he commented.

Perhaps a third way has been found, however, by a respondent called Chi Ming Hung. He believes that, for clarity, the main body of a scientific paper should still be in the third person, but that it would be useful for authors to add a section about the “story” of the research, perhaps to the appendix. “This is useful in case somebody has similar ideas and need some inspiration and thus can benefit from the subjective train-of-thought behind the research.”

Thank you for all of your responses and we look forward to hearing from you again on the Physics World Facebook page.

Images from Turkey

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Institute of Accelerator Technologies, Ankara University
(Credit: Michael Banks)

By Michael Banks

If my recent travel (see here and here) to Ankara, Turkey, left you wanting to see more images from the trip, then fear no more.

On the Physics World Flickr page, you can now peruse selected images from the visit to the Institute of Accelerator Technologies at Ankara University, as well as the Proton Accelerator facility operated by the Turkish Atomic Energy Authority.

Look out for further coverage from my trip to Turkey in future issues of Physics World.




Spectrum of a quasar

A look into the anatomy of a quasar’s spectrum (Credit: Michael Murphy, Swinburne University of Technology/NASA/ESA)

By Tushna Commissariat

A paper published in Physical Review Letters this week talks about how one of the fundamental constants of our universe – the fine-structure constant (α) – may vary across the universe. If you feel like you have heard something about this before, that is because the researchers have been looking into this particular phenomenon for almost a decade now.

They published a pre-print of this work on the arXiv server in August 2010, but the paper was only published in PRL yesterday, the delay perhaps reflecting how profound the finding could be.

The constant α is a combination of another three constants – the speed of light “c”, the charge of an electron “e” and Plank’s constant “h” – and is given by α = e2/hc.

John Webb and colleagues first looked at the light coming from very distant quasars in 1999, using the Keck Observatory in Hawaii and more recently the Very Large Telescope in Chile, to see if α really was a fundamental constant or if it varied with time or space. They use distant quasars simply as light sources that span across billions of light years. The spectrum of the quasar light carries an imprint of atoms in gas clouds that the light traverses through on its way to Earth. These spectral “fingerprint” absorption lines (known as “metal absorption lines”) are then compared with the same fingerprints found in laboratories here on Earth to infer any changes to α.

What the researchers found, after looking at the light from almost 300 quasars (as of 2010) was that α was decreasing in one direction as seen from the Earth and increasing in the exactly opposite direction. This asymmetry in the two hemispheres has been dubbed the “Australian dipole” by the researchers and has a statistical significance of about 4 σ. While some scientists were sceptical of the finding in 2010, others called it “the news of the year in physics”. If the discovery is confirmed, it would have profound implications on our understanding of the universe and on many of our current cosmological theories.

If you would like to refresh your memory about the paper or find out what it’s all about, take a look at the news story written by Hamish Johnston last year here, or take a look at the feature article written for Physics World by lead author of the paper, John Webb, here.


By Hamish Johnston

A major breakthrough in gecko physics occurred in 2002 when Kellar Autumn and colleagues at Lewis and Clark College in Oregon showed that the lizards use Van der Waals forces to stick to (and scurry up) smooth vertical walls.

Since then, researchers have worked hard to mimic the structures found on gecko feet. Indeed, Stanford University’s Sangbae Kim has already built a “Stickybot” robotic lizard that is capable of climbing walls. Stickybot solved an important problem facing a gecko-inspired climber – how to make a foot that sticks when you want it to, yet releases when the climber takes a step upwards. Kim’s solution is “directional adhesion”, whereby the stickiness of a foot depends on the directions of the forces applied to it.

Another approach to the stick/release problem involves using continuous treads of an adhesive material that resemble those you would find on an army tank or bulldozer. The main problem with such “tank” climbers is that a tail is needed to ensure that there is an inward force at the front of the tread so that it grabs onto the wall.

stickytank.jpg

Now, Jeff Krahn and colleagues at Simon Fraser University in Canada have invented a tank robot that doesn’t need a tail – something that greatly simplifies the robot’s design. You can see the robot in action in the video above.

Another feature of the robot, according to the researchers, is that it is the first tank robot to use treads with microstructures that mimic gecko feet (right). Previous climbing tanks had used flat, unstructured materials.

Krahn’s robot, however, has treads covered in tiny mushroom-like structures that protrude slightly from the surface. The caps of the mushrooms are about 10 µm in diameter, with the stalks being about half that size. According to Krahn, this overhang allows the treads to grab on to rough surfaces.

The robot is described in a paper published in Smart Materials and Structures.