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July 2011 Archives

NGC5394 and NGC5395.jpg

By Tushna Commissariat

It is commonly thought that astronomy and astrophotography are rather exclusive hobbies and that you require a lot of specialist equipment and training to pursue them. But an amateur astrophotographer, using only his ordinary digital SLR camera, a tripod and his love for the skies, has won the major astrophotography prize at the inaugural STARMUS festival.

Not only did Alex Cherney win the opportunity to attend and mingle with the who’s who of astronomy at the STARMUS festival – an astronomy and space-science festival held in the Canary Islands this June – but the Australian amateur astronomer also won an hour using one of the largest optical telescope on the planet – the 10.4 m Gran Telescopio Canarias (GranTeCan), in the Canary Islands in Spain.

Cherney’s prize-winning collection of time-lapse sequences of the Milky Way, seen over the Southern Ocean, beat a bevy of global participants for the best entry as judges felt his scenes were “chosen with the eye of an artist” and that his “subtle panning and excellent control of colour and contrast revealed technical skills of the highest order”. Cherney uses only his Nikon D700 DSLR camera and produced a compilation of images taken over 31 hours of exposure time.

This is notably the first time an amateur astronomer has been allowed access to the GranTeCan and Cherney was keen to make the most of the opportunity. After much deliberation, he decided to use his hour to observe and photograph Arp84, a pair of interacting galaxies – NGC5394 and NGC5395. (Image above courtesy: Alex Cherney)

“I wanted an object that would look nice given the parameters of the telescope and has not been photographed in colour and great detail by a professional telescope,” he said. Noel Carboni, an astro-image-processing expert, met Cherney at the festival and helped to produce a colour image. Carboni feels this is the clearest image of Arp84 ever made. Cherney felt the experience of using the telescope was “incredible”, akin to taking a space flight. “It is very hard to describe what it is like to observe space with an instrument that is helping scientists seek answers to the origin of the universe.”

Cherney put his opportunity of being at the La Palma observatory to good use, producing another time-lapse video featuring GranTeCan and MAGIC (Major Atmospheric Gamma-ray Imaging Cherenkov Telescopes) as the backdrop for the night skies. Take a look at the stunning video below.

Outer Space from Alex Cherney on Vimeo.

Do the media cover science impartially?

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By James Dacey

A recently published review of the BBC’s science coverage concluded that, for the large part, its content is accurate and impartial. The review, published by the BBC Trust, consisted of an independent report from geneticist and popular-science author Steve Jones and a content analysis carried out by Imperial College London.

“[The BBC] is widely praised for its breadth and depth, its professionalism, and its clear, accurate and impartial manner,” writes Jones. “Science is well embedded into programming, on a diversity of platforms.”

Jones does, however, warn of instances where scientific debates have been misrepresented in an attempt to create balance or conflict. “Equality of voice calls for a match of scientists not with politicians or activists, but with those qualified to take a knowledgeable, albeit perhaps divergent, view of research,” Jones asserts.”Attempts to give a place to anyone, however unqualified, who claims interest can make for false balance: to give free publicity to marginal opinions and not to impartiality but its opposite.”

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But, while Jones’ report refers exclusively to the BBC, I am sure that similar conclusions could apply to other sections of the media. We want to know your opinion on this issue. On the whole, how do you find the media’s coverage of science? Please visit our Facebook page where you can take part in a poll. If you can participate, I would also encourage you to add a comment to tell us which topics you feel are covered particularly well, or particularly badly.

Artist image of the first Earth Trojan asteroid
This artist’s concept illustrates the first known Earth Trojan asteroid (Credit: Paul Wiegert, University of Western Ontario, Canada)

By Tushna Commissarat

Looks as if the Earth has a cohort – one that has been hitching a ride with our planet’s orbit for a while now. Astronomers sifting through data from NASA’s Wide-field Infrared Survey Explorer (WISE) mission have discovered the first known “Trojan” asteroid orbiting the Sun along with the Earth. It has been known since 1772 that stable small bodies can share the same orbit with a planet or a moon – as long as they remain at stable points in front of or behind the main body. Such Trojan asteroids have been found orbiting Jupiter, Mars, two of Saturn’s moons and Neptune, but had not been seen for the Earth until now. This is because they are difficult to detect, being relatively small and appearing near the Sun from the Earth’s point of view.

Trojans circle around “Lagrange points” – gravity wells where small objects can be relatively stable compared with two larger objects, in this case the Sun and the Earth. The points that the Earth’s Trojan – called 2010 TK7 – orbits around are known as the L4 and L5 points, and are 60° in front of and behind the Earth, respectively. As they constantly lead or follow in the same orbit as the planet, they can never collide with it; so you can breathe a sigh of relief if you were worried about a possible armageddon.

“These asteroids dwell mostly in the daylight, making them very hard to see,” says Martin Connors of Athabasca University, Canada, lead author of a paper about the discovery published in Nature. “But we finally found one, because the object has an unusual orbit that takes it farther away from the Sun than is typical for Trojans. WISE was a game-changer, giving us a point of view difficult to have at the Earth’s surface.”

The WISE telescope scanned the entire sky in the infrared from January 2010 to February this year. The researchers began looking for data for an Earth-bound Trojan using data from NEOWISE – a WISE mission that focused in part on near-Earth objects (NEOs), such as asteroids and comets. NEOs are bodies that pass within 45 million kilometres of Earth’s path around the Sun. The NEOWISE project observed more than 155,000 asteroids in the main belt between Mars and Jupiter, and more than 500 NEOs, discovering 132 that were previously unknown. The team found two Trojan candidates – of these, 2010 TK7 was confirmed as an Earth Trojan after follow-up observations were made using the Canada–France–Hawaii Telescope in Hawaii.

2010 TK7 is roughly 300 metres in diameter, at a distance of about 80 million kilometres from Earth. It has an unusual orbit that traces a complex motion near the Lagrange points in the plane of the Earth’s orbit, although it also moves above and below the plane. The asteroid’s orbit is well defined and remains stable for at least 10,000 years. For the next 100 years, it will not come closer to the Earth than 24 million kilometres. An animation, with a Star Wars worthy soundtrack, showing the orbit can be found below. (Image and video credit: Paul Wiegert, University of Western Ontario, Canada.)

A handful of other asteroids also have orbits similar to Earth. Such objects could make excellent candidates for future robotic or human exploration. Unfortunately, asteroid 2010 TK7 has not been deemed worthy of exploration because it travels too far above and below the plane of Earth’s orbit, and so would require a large amount of fuel to reach it.

The Antiprotonic Decelerator at CERN (Courtesy: CERN)

By Hamish Johnston

For something that is rare in the universe, antimatter has certainly been in the news a lot lately.

The latest breakthrough involves antiprotonic helium and is published in Nature today. This exotic “atom” is formed when one electron in a helium atom is replaced with an antiproton, which is negatively charged.

For two decades physicists have known that antiprotonic helium is formed in a metastable state that sticks around for a few milliseconds before decaying. This should make it to possible to study its energy levels and measure the ratio of the antiproton mass to the electron mass. This could then be compared with the well-known proton-to-electron mass ratio to see if the proton and antiproton have different masses. Such an asymmetry goes against the Standard Model of particle physics and its discovery could help physicists understand why the universe is dominated by matter.

Now, physicists working on the Antiprotonic Decelerator at CERN have done just that. Masaki Hori of the Max Planck Institute of Quantum Optics in Garching, Germany, and an international team made laser-spectroscopy measurements and worked out the mass ratio to a remarkable degree of precision.

The experiment begins with pulses of antiprotons being injected into helium gas to create the exotic atoms. The team then fires laser pulses at the atoms to knock the antiproton from its metastable state to an unstable state, causing it to annihilate with the helium nucleus. This produces pions, which are easily detected. By varying the wavelength of the lasers to find the maximum rate of pion production, the team found the exact energy of the transition.

The big challenge for the researchers was that the atoms are moving about, which causes a Doppler broadening of the transition wavelength. Scientists get around this with normal atoms by firing two identical lasers in opposite directions at the target. The atom absorbs one photon from each beam – which is only likely to occur if the atom has no relative motion in the direction of the lasers, eliminating the Doppler broadening.

This is trickier to do with antiprotonic helium, and Hori and colleagues instead used lasers at two different frequencies to eliminate much of the Doppler broadening.

So after all that hard work, did they discover any new physics? I’m afraid not. The antiproton-to-electron mass ratio is the same as the proton-to-electron ratio to an impressive nine significant figures.

The work is described in Nature 475 484.

Magnetism 1
Magnetism 1 by Ahmed Mater al Ziad. (Copyright: Trustees of the British Museum)

By Hamish Johnston

One of the world’s most famous scenes is of hundreds of thousands of hajj pilgrims circling the Ka’bah – the giant granite cube draped in black silk that is the most sacred site in Islam.

The photograph above is not of that swirling scene in Mecca, Saudi Arabia, but of a bar magnet surrounded by iron filings. While familiar to anyone who has studied magnetism at school, the picture also does a remarkable job of capturing the essence of the Ka’bah circumambulatory.

The image is called Magnetism 1 and is by the Saudi artist Ahmed Mater. You can see the photograph and other historical and modern objects associated with the pilgrimage to Mecca in an upcoming exhibition at the British Museum in London. The exhibition is called “Hajj journey to the heart of Islam” and runs from 26 January to 15 April 2012.

While Mater is not a physicist, he does have a strong connection to the sciences because he is a medical doctor. Indeed, some of his other works have a distinctly medical theme – including works based on medical X-rays.

You can see Mater working on his magnetic creations here.

By Hamish Johnston

“Bookies bashed by giant god-particle gamble,” says a press release from the Irish bookmaker Paddy Power.

It seems that the bookie has received several “substantial” bets that the Higgs boson will be discovered in 2011 – a flutter that Paddy Power was offering at odds of 12/1 on, but has now slashed to a paltry 1/3.

These bets were probably inspired by the positive results from the Large Hadron Collider (LHC) being reported at the Europhysics Conference of High-Energy Physics that is running in Grenoble, France.

In particular, it looks as if a low-mass Higgs in the 130–150 GeV/c2 region may be emerging from LHC data. You can read all about this and other Higgs news in this on-the-spot report by our particle-physics specialist Matthew Chalmers.

Paddy Power is now offering odds that favour finding the Higgs sometime this year. At 1/3, a £3 bet will pay out a measly £4 if the Higgs is discovered before January. In contrast, the same bet last week would pay a whopping £39.

The bookie is also taking bets on the mass of the Higgs, offering the following odds:

6/1 130 GeV/c2 or lower
13/8 131–140 GeV/c2
5/2 141–150 GeV/c2
7/4 Higher than 150 GeV/c2

And if you think the Higgs will be not be found this year, the odds are 4/1 for discovery in 2012 and 5/1 in 2013 or later.

Pioneer 10
Artist’s impression of Pioneer 10 (Courtesy: NASA)

By Hamish Johnston

For more than a decade physicists have known that the space probes Pioneer 10 and Pioneer 11 are following trajectories that cannot be explained by conventional physics – leading some to speculate that this is the result of new and exciting physics.

Called the “Pioneer anomaly”, both spacecraft seem to be experiencing an extra tug towards the Sun as they move through the solar system. There has been much written about the origins of the extra acceleration, which is 10 billion times weaker than the Earth’s gravitational pull. Explanations have run the gamut from the gravitational attraction of dark matter, to modifications of Einstein’s general theory of relativity, to string theory and/or supersymmetry.

Now it seems that the answer could be much more mundane: heat generated onboard the spacecraft creates a thrust by escaping in an asymmetrical manner. That’s the conclusion of a paper to appear in Physical Review Letters and written by Slava Turyshev of the Jet Propulsion Laboratory in California and colleagues Viktor Toth, Jordan Ellis and Craig Markwardt.

The quartet’s painstaking analysis of telemetry data suggests that the anomalous acceleration of both spacecraft is decreasing with time. While the exact nature of this decrease is not certain, there is a good chance that it is exponential. This would be consistent with the decay of radioactive material with a half-life of about 27 years. Both spacecraft have radioactive power sources that are still running – so mystery solved.

Well, not quite. Both spacecraft are powered by plutonium-238, which has a half-life of about 88 years. However, the team believes that the more rapid drop in acceleration could be the result of degradation and changes to the thermal properties of the spacecraft over time. When these factors are considered, claim the researchers, a half-life of 27 years seems reasonable.

Studying the acceleration of Pioneer 10 and 11 has been a daunting task. Turyshev and others have sifted and processed decades-old data – and in some cases data have been found to be corrupt or missing. So it’s nice to see that the hard work is paying off, even if the answer is a bit dull.

Indeed, in 2004 Turyshev co-wrote an article for Physics World about the Pioneer anomaly that says “Dispassionately, the most likely cause of the anomalous acceleration of the Pioneer spacecraft is on-board systematics”.

A preprint of Turyshev’s latest paper is available here.

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By Tushna Commissariat

This past year has seen a fair amount of excitement in the particle-physics community, with bumps and jumps and leaks and debates, but sadly without any spectacular discoveries. In fact, since the both the CDF and D0 experiments at the US Fermi National Accelerator Laboratory (Fermilab) reported the production of the top quarks in 2009, it’s been rather quiet on the particle front. So it was quite refreshing to hear that researchers at the CDF collaboration at Fermilab announced the observation of a new particle – the neutral “Xi-sub-b”. This particle is basically a baryon – a Standard Model particle that is formed of a combination of three quarks.

Common examples of baryonic particles are the proton – a combination of two up quarks and a down quark and the neutron – a combination of two down quarks and an up quark. This new addition consists of a strange quark, an up quark and a bottom quark (s-u-b). While its existence was predicted by the Standard Model, the observation of the neutral Xi-sub-b is significant because it strengthens our understanding of how quarks form matter. This new particle fits into the bottom baryons group, which are six times heavier than the proton and neutron because they all contain a heavy bottom quark. The particles are produced only in high-energy collisions, and are rare and very difficult to observe.

Once produced, the neutral Xi-sub-b travels a fraction of a millimetre before it decays into lighter particles. Combing through almost 500 trillion proton–antiproton collisions produced by researchers isolated 25 examples in which the particles emerging from a collision bore the signature of the neutral Xi-sub-b. The analysis established the discovery at a level of 7 sigma, clearing the 5 sigma threshold quite easily. (Image courtesy: Fermilab)

A paper detailing their results will be available on the arXiv preprint server soon.

By Matin Durrani

With the world’s leading particle physicists meeting in Grenoble right now to discuss the latest results from the Large Hadron Collider at CERN and the Tevatron machine at Fermilab in the US, I couldn’t resist pointing out a great new video from Fermilab’s Don Lincoln about what the Higgs boson is all about and why it’s interesting.

Rather than launching straight into the nature of the Higgs boson, Lincoln begins quite rightly with the Higgs field – the energy field that permeates the entire universe and interacts with subatomic particles to give them their mass.

In doing so, Lincoln draws a comparison between a barracuda gliding effortlessly through water and Don’s rather rotund buddy “Eddie” who is “no stranger to doughnuts”.

The water serves the role of the Higgs field and the barracuda, “being supremely streamlined”, interacts – like a low-mass particle – only slightly with the field and can glide through it very easily. Eddie, in contrast, moves only very slowly through the water, being like a massive particle that interacts a lot with the water.

In other words, if the Higgs field didn’t exist, then neither the top quark nor the electron, for example, would have any mass at all.

To explain the Higgs boson itself, Lincoln continues his water theme – explaining how just as water is made of individual H2O molecules, so the Higgs field is made up of countless Higgs bosons.

Meanwhile, for the real news from the International Europhysics Conference on High Energy Physics in Grenoble, stay tuned to, where our reporter is prowling the conference halls and lecture rooms for the latest news.

And finally, if you want more on the hunt for the Higgs, don’t forget this great article from Physics World magazine by prolific blogger and CERN particle physicist Tommaso Dorigo or our own video. It’s from March but still well worth watching.

By Margaret Harris

How often do you use physics in your job?

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Have your say by voting in our Facebook poll.

The poll allows you to choose from several options, from “practically every day” to “I obey the laws of physics, but I don’t use them at work”.

You’re also welcome to explain your answers further in the comments section or – if you’re a recent physics graduate – to e-mail us at to tell us more about how you’re using physics in your job. We’ll use the results in our October special section on careers for physics graduates.

For the moment, though, let’s return to last week’s poll. We asked whether a shift towards privatized space missions would be good for science, and readers who are simultaneously celebrating the safe return of Atlantis and mourning the last shuttle flight and can take a little comfort from the result. Some 72% of respondents said “yes”, with 28% voting “no”.

Messing with your brain

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By Louise Mayor

Last night I attended an event at the Royal Society in London celebrating 100 years of superconductivity. Hosted by Oxford Instruments and the Institute of Physics, the evening’s entertainment included talks by top scientists Stephen Blundell, Mark Lythgoe, Steven Cowley and Jonathan Flint.

A take-home message from Blundell was that it took 50 years from the discovery of superconductivity until we got to the point of commercializing the science – something that funding bodies and policy-makers should keep in mind. But as well as such sensible opinions, there were some unusual goings-on that I won’t forget in a hurry.

One such highlight was the video below. Lythgoe showcased what we’ve learned about the human brain through magnetic resonance imaging (MRI), which only has such high resolution due to superconducting magnets. Lythgoe challenged the audience to watch the following video and count how many times the people in white T-shirts pass the ball between each other. Have a go yourself, but try not to be distracted by the people in black T-shirts, who will try to confuse you by running around and throwing a second ball.

So, how many times did the white ball get passed? The answer is 15. Well done if you got that right – it shows you have good attention. However, this was an example of a selective attention test. Did you see the gorilla?

In a particularly curious moment, a group of people stood up and made their way to the front of the room; in hindsight they were conspicuously young and gender-balanced compared with the rest of the crowd. It was explained that we were in for a musical treat – a music/art performance called Brainwaves, one of the composers having been inspired by an MRI scan. The experience was immersive, with visual effects from design studio loop.Ph, and Mira Calix and Anna Meredith’s electronic music sounding menacing and grating next to the more soothing tones of the Aurora string quartet. I’ve never been in an MRI scanner, but watch for yourself and see what you think.

None of the evening’s events would have taken place were it not for that serendipitous discovery of superconductivity 100 years ago. This April, Physics World produced a special issue to celebrate the centenary, a free PDF of which can be downloaded by following this link.

Should space missions be privatized?

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By James Dacey

With the last space shuttle mission launched last week, would a shift towards privatized space missions be good for science?

Have your say by voting in our Facebook poll.

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Last week we asked for your opinion on another astronomy issue. We wanted to know where you think the Square Kilometre Array should be built. This $1.5bn project will be the biggest and most advanced radio telescope ever built. Sites in southern Africa and Australia/New Zealand have been shortlisted to host the central core of the array.

It was a close-run affair as 57% of respondents opted for Australia/New Zealand and 43% went for southern Africa.

The founding board of the SKA project has unveiled the process and timeline for selection of the host site for the telescope. A final decision on the location is expected to be made in early 2012 by the SKA board of directors.

By Hamish Johnston

In this month’s issue of Physics World, Martin McCall and Paul Kinsler outline plans for an “event cloak” – a device that would be perfect for the ultimate bank heist. Now, physicists in the US are the first to build one.

McCall and Kinsler are theoretical physicists at Imperial College London and their article offers a recipe for a device that allows selected events to go undetected.

Now it seems that Alexander Gaeta and colleagues at Cornell University have built a working event cloak – albeit different from the McCall and Kinsler’s proposal.

The device comprises two “split time lenses” (STLs). The first STL takes a beam of light and splits it into two parts, one that is delayed in time and the other that is advanced in time. This creates a gap in time and any event occurring within this gap cannot be detected by the beam. The second STL then does the reverse on the beam, closing the gap in time.

An easy way of understanding this process is the “stream of cars” analogy in McCall and Kinsler’s article.

Indeed, McCall told “We were very pleased to see that our concept has been realized experimentally – it doesn’t quite use the same technique we proposed, but I think it can fairly claim to be the first experimental observation of the signature of a space–time cloak”.

The July issue of Physics World is devoted to the physics of invisibility and you can download a free PDF copy here.

A paper describing the cloak has been uploaded to the arXiv preprint server and the authors say it will be published in Nature. The latter means that Gaeta and colleagues are unable to speak about the paper.

Last launch of Atlantis- Space Shuttle Program NASA-Bill Ingalls.jpg

By Tushna Commissariat

Despite gloomy weather conditions that threatened to cancel the launch altogether, NASA’s shuttle Atlantis has launched from the Kennedy Space Center. Marking the last and final flight of the Space Shuttle Programme – STS-135 – Atlantis and a four-person crew are on a 12-day mission to deliver more than 3.5 tonnes of supplies to the International Space Station (ISS). This final stock should keep the station running for a year. Although the countdown stopped briefly at 31 s before the launch, the shuttle had a “flawless” lift-off, according to NASA. It has now settled down into its preliminary orbit ahead of its rendezvous with the ISS this Sunday morning.

The image above is of the shuttle, taken shortly after the rotating service structure was rolled back yesterday at Launch Pad 39A at the Kennedy Space Centre in Florida (Credit: NASA/Bill Ingalls). Below is an image of the mission patch for this final iconic flight (Credit: NASA).

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“The shuttle’s always going to be a reflection of what a great nation can do when it commits to be bold and follow through,” said astronaut Chris Ferguson, commander of the mission, from the cockpit of Atlantis minutes before the launch. “We’re completing a chapter of a journey that will never end. Let’s light this fire one more time, and witness this great nation at its best.”

Atlantis was the fourth orbiter built and had its maiden voyage on 3 October 1985. Atlantis had a number of firsts to its name – it was the first shuttle to deploy a probe to another planet, to dock to the ISS and the first with a glass cockpit! It conducted a final servicing mission to the Hubble Space Telescope in May 2009.

NASA has decided to retire its shuttle programme with this last flight because the vehicles are too costly to maintain. It now intends to contract out space transport to private companies. The hope is that this will free NASA resources to invest in a other programmes that will potentially send humans beyond the space station to the Moon, Mars and maybe even asteroids.

Atlantis is also carrying some rather unusual passengers – some simple yeast cells. The aim is to study the yeast cells as their genetic make up is remarkably similar to that of a human cell. This makes it an ideal system for studying genetic defects and understanding how these defects may manifest in human disease. In two separate experiments – conducted at the ISS – researchers will study the effect of microgravity on cell growth.

The video below has the crew of Atlantis talking about the “vibrancy of the ISS as a stepping stone for NASA’s plans for future human exploration beyond low Earth orbit”.

Jagged peaks at ILL in Grenoble
Behind the bike sheds: the view from ILL

By Hamish Johnston

Yesterday I made a flying visit to what is arguably the world’s most famous lab for neutron science – the Institut Laue-Langevin (ILL). Nestled between jagged mountains at the edge of the French Alps, the reactor at ILL has been reliably churning out neutrons since the reactor in Grenoble first went critical in 1971.

Like all neutron sources, the majority of the facility’s 40 or so instruments don’t study the neutron itself – but rather use beams of neutrons to work out the structure and composition of objects as varied as railway tracks and human proteins.


However, ILL is unique in that a significant chunk of the research that goes on there (about 15%) is devoted to the study of the neutron. To do this, ILL physicists make ultracold neutrons, or UCNs, which move so slowly that they would be overtaken in a race by a decent human sprinter.

The amazing thing is that UCNs can be collected and stored in containers like the one pictured on the right. There they can be observed for relatively long periods of time to see, for example, if they change (or oscillate) into antineutrons. Such an oscillation is forbidden by the Standard Model of particle physics and seeing it could point towards new physics.

In Grenoble I interviewed two leading UCN physicists, Peter Geltenbort and Oliver Zimmer, so stay tuned to for much more about UCNs. I was also lucky enough to have a tour of the reactor and one of ILL’s experimental halls guided by Peter and Oliver. You can see the photos that I took over on our Flickr page.

This year is the 40th anniversary of ILL and I recorded an interview with the facility’s scientific director Andrew Harrison. As well as telling me about the four new instruments being built at ILL, Andrew looked to the future and shared his vision of how ILL will play a complementary role to the European Spallation Source due to be built in Sweden in 2025. Again, stay tuned to for more from Andrew.

By Matin Durrani


It is perhaps a little-known fact that Griffin – the main character in H G Wells’ classic novel The Invisible Man – was a physicist. In the 1897 book, Griffin explains how he quit medicine for physics and developed a technique that made himself invisible by reducing his body’s refractive index to match that of air.

While Wells’ novel is obviously a work of fiction, the quest for invisibility has made real progress in recent years – and is the inspiration for this month’s special issue of Physics World, which you can download for free via this link.

Kicking off the issue is Sidney Perkowitz, who takes us on a whistle-stop tour of invisibility through the ages – from its appearance in Greek mythology to camouflaging tanks on the battlefield – before bringing us up to date with recent scientific developments.

Ulf Leonhardt then takes a light-hearted look at the top possible applications of invisibility science. Hold on to your hats for invisibility cloaks, perfect lenses and the ultimate anti-wrinkle cream.

Some of these applications might be years away, but primitive invisibility cloaks have already been built, with two independent groups of researchers having recently created cloaks operating with visible light that can conceal centimetre-scale objects, including a paper clip, a steel wedge and a piece of paper. But as Wenshan Cai and Vladimir Shalaev explain, these cloaks only work under certain conditions, namely with polarized light, in a 2D configuration and with the cloak immersed in a high-refractive-index liquid. It seems that the holy grail of hiding macroscopic objects viewed from any angle using unpolarized visible light is still some way off.

The special issue ends with a look at something even more fantastic-sounding – the possibility of creating a cloak that works not just in space but in space–time. Although no such “event cloak” has yet been built, Martin McCall and Paul Kinsler outline the principles of how it would work and describe what might be possible with a macroscopic, fully functioning device that conceals events from view. These applications range from the far-fetched, such as the illusion of a Star Trek-style transporter, to the more mundane, such as controlling signals in an optical routing system.

But, hey, that’s enough of me banging on about the special issue. Download it for free now and find out for yourself. And don’t forget to let us know what you think by e-mailing us at or via our Facebook or Twitter pages.

P.S. If you’re a member of the Institute of Physics, you can in addition read the issue in digital form via this link, where you can also listen to, search, share, save, print, archive and even translate individual articles. How’s that for value?

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The $1.5 billion Square Kilometre Array (SKA) will be the biggest and most advanced radio telescope ever built. Which of the two competing bids do you think should win?

  • Australia / New Zealand
  • Southern Africa

Have your say by voting in our Facebook poll

Yesterday, the founding board of the SKA project the unveiled the process and timeline for selection of the host site for the telescope. Sites in southern Africa and Australia/New Zealand have been shortlisted to host the central core of the SKA telescope, and a final decision on the location is expected to be made in early 2012 by the SKA board of directors.

“Selection of the host site for the SKA will be made in terms of characteristics for the best science as well as the capability and cost of supporting a very large infrastructure, taking the political and working environment into account,” said Richard Schilizzi, director of SKA.

Last week’s Facebook poll was a more light-hearted affair as we celebrated Physics World’s Invisibility Science special issue. We asked readers to choose their favourite use of invisibility as a plot device from a selection of science-fiction works. The clear winner was John McTiernan’s 1987 action thriller, Predator, which received 40% of the vote.

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By Tushna Commissariat

I have already raved on about the awesomeness of the Hubble Space Telescope in my blog entry about its 21st anniversary in April this year. Now, the telescope has crossed yet another milestone – on Monday 4 July the Earth-orbiting observatory logged its one-millionth science observation! The image above is a composite of all the various celestial objects ranging through stars, clusters, galaxies, nebulae, planets, etc that Hubble has catalogued over the years. Click on the image for a hi-res version. [Credit: NASA, ESA and R Thompson (CSC/STScI)]

The telescope has had a significant impact on all fields of science from planetary science to cosmology and has provided generations with breathtaking images of our universe ever since it was launched on 24 April 1990 aboard Discovery’s STS-31 mission.

Hubble’s counter reading includes every observation of astronomical targets since its launch. The millionth observation made by Hubble was during a search for water in the atmosphere of an exoplanet almost 1000 light-years away from us. The telescope had trained its Wide Field Camera 3, a visible and infrared light imager with an on-board spectrometer on the planet HAT-P-7b, a gas giant planet larger than Jupiter orbiting a star hotter than our Sun. HAT-P-7b has also been studied by NASA’s Kepler telescope after it was discovered by ground-based observations. Hubble now is being used to analyse the chemical composition of the planet’s atmosphere.

“For 21 years Hubble has been the premier space-science observatory, astounding us with deeply beautiful imagery and enabling ground-breaking science across a wide spectrum of astronomical disciplines,” said NASA administrator Charles Bolden. He piloted the space shuttle mission that carried Hubble to orbit. “The fact that Hubble met this milestone while studying a far away planet is a remarkable reminder of its strength and legacy.”

Hubble has now collected more than 50 terabytes – the archive of that data is available to scientists and the public at

And take a look at this Physics World article by astrophysicist Mark Voit where he looks at the most iconic images Hubble has produced over the years – Hubble’s greatest hits

The NASA video below was created last year for the 20th Hubble anniversary celebration and tells you how you could send a message to Hubble that will be stored in its archive.

Gorilla inspired by the work of Roger Penrose

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By James Dacey

Say hello to Tensor. His striking pelt has been inspired by the English mathematical physicist Roger Penrose, who created a visual language for representing complex mathematical expressions.

Tensor has just appeared today in a quiet public garden in central Bristol, just around the corner from the offices of He is one of a band of 60 life-sized decorated gorillas that will be appearing around the city to celebrate Bristol Zoo’s 175th anniversary.

Last year, the organizers of this public art exhibition approached IOP Publishing (which publishes to ask if it would like to sponsor and design a gorilla for the show. The challenge was taken on by in-house artist Fred Swist, collaborating with art director Andrew Giaquinto, and the pair came up with the idea of using Penrose’s graphical tensor notation. These pictorial elements, used in physics and pure maths, comprise simple shapes connected by lines. For instance, they have been used to visualize interactions between particles and fields in spin networks.

“The project was quite challenging, as we were trying to render complex mathematical notations into striking and colourful visual forms, to appeal to a wider audience,” said Swist.

Tensor is among the more high-brow of the gorillas as his cooler mates include an Elvis gorilla, a Funky Gibbon, and a Spidermonkey in trademark red and blue. But in addition to entertaining Bristolians and visitors to the city, there is also a serious note to the Wow! Gorillas exhibition. It is designed to promote Bristol Zoo’s gorilla conservation project and Wallace and Gromit’s Grand Appeal, which raises funds for the Bristol Royal Hospital for Children. When the exhibition comes to a close in mid-September, the life-sized painted gorillas will be sold at a charity auction and the funds will be donated to these causes.

IOP Publishing celebrates a decade in Moscow
Celebrating in Moscow

By Hamish Johnston

Last week several of my colleagues were in Moscow to celebrate the 10th anniversary of IOP Publishing’s office in that city. A reception was held at the office in the P N Lebedev Institute and speeches given – including one by Jerry Cowhig, the former managing director of IOP Publishing (which publishes who had been a driving force in the firm’s Russian campaign.

The company’s first office in Russia (then still in the USSR) opened in St Petersburg (then Leningrad) in 1990. In his speech Jerry summed up the goal of the offices: “[To] bring western research into Russia…[and to] bring Russian research into the West.”

Another highlight of the event was an award for the outstanding paper published in 2010 by a Russian author in an IOP journal. The award was scooped by Nataliya Chistyakova and her co-authors from Moscow State University for their paper “Mössbauer study of isomorphous substitutions in Cu2Fe1-xCuxSnS4 and Cu2Fe1-xZnxSnS4 series” published in Journal of Physics: Conference Series.

As well as encouraging Russian physicists to publish in its own journals, IOP Publishing produces English versions of six Russian journals in partnership with the Russian publisher Turpion. These include two physics titles – Quantum Electronics and Physics-Uspekhi – with the other four covering mathematics and chemistry.

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By Tushna Commissariat

A recent Guardian article in its “Improbable Research” series drew my attention to the Journal of Special Topics, produced by undergraduate physics students at the the University of Leicester.

The Guardian article focused on a paper discussing the feasibility of playing football on Mars and how gravitational and environmental differences would affect the game. Not being a big football fan myself, what really had me amused was the mention of another paper called “Determining the smallest migratory bird native to Britain able to carry a coconut”. Fans of Monty Python and the Holy Grail will remember King Arthur suggesting that the coconuts in his possession could have been carried by a bird from the tropics and the ensuing debate about which migratory bird actually could carry said coconut. The authors found that the only bird that fits the bill (sort of) is the white stork.

Upon digging around in the journal’s archive, I found a few other gems…

If you enjoyed the film Up, you might want to peruse the paper that asked how many helium balloons would actually be required to lift a small wooden house – like the one in the film – as well as a common brick house found in the UK. The authors found that it would take almost 10 million helium balloons to lift the small wooden house and 400 million helium balloons to lift a typical UK house! They note the downfalls of this particular method of relocation though, by concluding that the balloons would “deflate very quickly at high altitudes” and that the “foundations and drainage of the house would be removed, making the structure very unstable, if by some miracle the journey is possible.” Pity, balloons would make moving so much easier!

Fans of the American sitcom The Big Bang Theory may recall a character attempting to “See how long it takes a 500 kW oxygen-iodine laser to heat up my Cup-A-Noodles”. And later claims the necessary time is two seconds. In the paper “The Pot Noodle Proposal”, the authors conclude that, while it is possible to use the laser to heat the noodles, “the heat transfer process is very ineffective” because the pot would melt long before the noodles would heat up. So physics labs will have to hold on to their microwave ovens!

Another paper calculates just how fast an average ball point pen can write on paper and how temperature and so, geological location affects the speed achieved. The paper, titled “How fast can a pen write”, found that the speed is approximately 153 m/s at room temperature, with maximum speeds of 181 m/s and 192 m/s at Sahara-like and Siberia-like temperatures respectively. While the authors acknowledge that these speeds could not be humanly achieved, they point out that the ink viscosity, determined by the temperature, is the “bottom line”.

The last paper I will mention is one that had me in splits. “How radioactive is a banana?” looks at just how harmful the radioactivity of a banana can be. But wait a minute, you say, bananas are not radioactive, are they? Bananas contain potassium – which has a naturally occurring radioactive isotope, potassium-40. Luckily all you banana lovers can rest easy as the authors found that “a person would have to consume more than 37 billion bananas to cause any risk of death” from radioactivity alone. Also, “even surrounded by bananas, it would take over a billion to cause any harm”. So no need to stop gulping down that banana smoothie in the morning just yet.

For papers like these, which are probably being penned by future Ig Nobel prize winners, take a look these and other papers – they are sure to make you laugh and think!

Out in the outback

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Out and about in Boolardy
Antony Schinckel (centre right) and Barry Turner (centre left) with a finished ASKAP dish

By Matin Durrani in Boolardy, Australia

Our eight-seater plane landed safely on the sandy red airstrip at the remote Boolardy homestead deep inside Western Australia.

There to meet us was Barry Turner, site manager for the Murchison Radioastronomy Observatory, which is currently building two key astronomy facilities here in the Australian outback – the Murchsion Widefield Array and the Australian Square Kilometre Array Pathfinder (ASKAP) project.

ASKAP will, when complete next February, consist of 36 parabolic antennae, of which six are currently built. Apart from being 10 times more powerful than any existing radiotelescope in the world, ASKAP is also designed to show that Boolardy is a suitable location for Australia’s bid for the Square Kilometre Array – an even larger radiotelescope array that will, when complete, consist of some 3000 dishes.

ASKAP astronomers, including project director Antony Schinckel, naturally think their site is a worthy location for SKA, although they are at pains not to discuss or comment on the rival SKA bid from various nations in southern Africa.

After lunch and the obligatory safety briefing, which included warnings about possible venomous snakes, Schinckel drove us off by 4×4 van to the telescope site, which was bathed in pleasantly warm winter sunshine. (Summers, in contrast, can easily rocket above the 40 °C mark.)

On site were various constructions workers digging roads and levelling the site, but it was also interesting to see staff from the Chinese Electrical Technology Corporation, which is making the ASKAP dishes in China, shipping them to Australia and then building them here in the outback.

Their presence explains the Chinese menus in the Boolardy lunchroom, although quite what they make of Australia’s local delicacy – Vegemite – I am not sure.

The six completed dishes consist of a supporting structure that will house electroncs cables, topped by a steerable 12 m-diameter dish. So smooth are the dishes that they are no more than 0.6 mm out from a perfect parabolic shape.

Barry and Antony gave us a detailed run-down of the dishes, but with the Australian sun quickly setting, it was imperative that we did not hang around for too long so that we could fly away before sunset. By nightfall, the unlit landing strip would be so dark that taking off would be impossible.

And soon we were soaring above the ASKAP site for the 90-minute flight back to Perth. A fitting and illuminating end to my week-long trip to Australia.

Schinckel joined us on the flight. While my fellow European science journalists and I are to return to Europe, for Schinckel the work goes on. He and numerous other members of Australia’s SKA bid team are flying to Banff in Canada next week for a high-level discussion meeting where its bid – and that from southern Africa – are to be evaluated.

I get the feeling the Australian team is pretty confident of winning the SKA bid but, as I said earlier, they resolutely refuse to get drawn on the matter. We shall see who wins when the final decision is announced on 29 February next year.