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Home » Page 1201

Between the lines: Christmas special

Photo of Nazi rocketeer turned father of the US space programme Wernher von Braun standing next to a rocket
Nazi rocketeer turned father of the US space programme Wernher von Braun. (Courtesy: Library of Congress/Science Photo Library)

Murky business

In the autumn of 1944, with the Second World War rumbling towards its nightmarish conclusion, a small group of Western scientists embarked on one of the Allied campaign’s more dubious missions. Their task was to locate and capture scientists who had served the crumbling Nazi regime, ferret out their secrets and put them to work in the war against Japan (and, later, in the Cold War against the Soviet Union). But as the US journalist Annie Jacobsen documents in her book Operation Paperclip, this theoretically justifiable goal soon collided with some ugly realities. At best, the scientists targeted by the operation were “apolitical” types who had turned a blind eye to atrocities as long as the research funds kept flowing. Many others, like the Nazi rocketeer turned father of the US space programme Wernher von Braun, had much dirtier hands than either they or their new American chums cared to admit. And a few were out-and-out war criminals. As Jacobsen shows, the distinction between who got hired and who got hanged was disturbingly fine. In one of the book’s most unsettling passages, she describes how representatives of an American group charged with arresting a suspected war criminal found their efforts stymied by an officer from a different US agency, which was trying to give that same war criminal a government contract. This would be farcical if it were not so horrible: the scientist in question, Otto Ambros, was a chemical weapons expert who had tested poison gas on concentration camp inmates, and had also managed the synthetic rubber factory at Auschwitz. Thoroughly researched and compellingly written, Operation Paperclip is a masterful critique of the ethics of science in wartime, and would make a good companion to Philip Ball’s book Serving the Reich, which focuses on the role of civilian physicists in Nazi Germany (February p42).

  • 2014 Little, Brown $30.00hb/£12.99pb 592/576pp
A blood-speckled zombie reaches towards the viewer
Disquieting: Real and imagined horrors populate the pages of these books. (Courtesy: iStock/Renphoto)

The mathematical undead

Craig Williams teaches mathematics at a small liberal-arts college in western Massachusetts. Or at least he did, until the day a zombie shambled into his calculus class and started snacking on his students. Soon afterwards, the hero of Colin Adams’ delightfully silly novel/teaching aid Zombies and Calculus is holed up in an office with an assortment of sidekicks, including his biggest rival, his worst student, his onetime lover and the departmental secretary. Oh yes, and the rapidly zombifying local police chief, who got bitten in an earlier attack. At this point, Williams decides that what everyone really needs is a lesson on the mathematics of exponential growth (the better to model how the zombie epidemic is spreading), followed by a quick analysis of how much force is required to crack a zombie’s skull. This sets the pattern for the rest of the book, in which characters periodically take breaks from decapitating zombies in order to consider the finer points of exponential functions, differential equations and whether a fleeing university administrator can outrun the hordes of undead chasing him (spoiler alert: nope). It’s implausible, of course, but pleasingly surreal, and the mathematics is nicely done. If you are a current calculus student looking to spice up your revision, or a former one wanting to refresh your rusty u substitution skills, reading Zombies and Calculus is one of the most entertaining ways to do it.

  • 2014 Princeton University Press $24.95/£16.95hb 240pp
Three big-headed, big-eyed aliens with grey-green skin
(Courtesy: iStock/Zeppelie)

We come in peace

Do-it-yourself motor enthusiasts have long relied on Haynes manuals to guide them through the ins and ours of automotive repair. A few years ago, fans of space exploration got a Haynes manual of their own, when the company honoured the 40th anniversary of the Moon landings by publishing an “owner’s manual” for the Apollo 11 mission (July 2009 p3). Now Haynes has taken the space theme to its logical conclusion (and perhaps beyond) by producing a manual for resisting alien invasion. Written by Sean Page and illustrated by Ian Moores, the Haynes Alien Invasion Owners’ Resistance Manual includes a step-by-step guide for making your own tin-foil hat and plenty of handy tips like “If they vaporize you with phasers, you know they’re hostile” and “Don’t get drawn into any discussion on time dilation, string theory or why they cancelled the TV series Firefly”. It’s all clearly tongue-in-cheek, and good for a few chuckles, but in some areas of the manual, the humour does have a bit of an edge to it. In particular, a page containing genuine, pro-UFO-sighting quotes from a British Royal Air Force chief, a Chinese general and two former US presidents (among others) brings to mind Poe’s Law of the Internet, which states (roughly) that there is no parody so absurd that someone won’t mistake it for the real thing.

  • 2014 Haynes £16.99hb 128pp
A fiery sunset over a snowy mountainous island
Solutions to climate change: If the aliens don’t get us, the carbon dioxide may. (Courtesy Peter Menzel/Science Photo Library)

No quick fix

According to Hinchliffe’s Rule, whenever the title of an academic paper is phrased as a question with a yes/no answer, the answer always turns out to be “no”. At first glance, Mike Hulme’s book Can Science Fix Climate Change? seems like a good example. In the book, Hulme, a climate scientist at King’s College London, strongly criticizes the idea that the Earth’s warming climate can (or should) be modified by injecting sunlight-blocking aerosols into the upper atmosphere. Such a technological “fix” would, he argues, be “undesirable” (because reducing temperature isn’t the same thing as controlling climate) “ungovernable” (because there is no mechanism for agreeing who would control the thermostat) and “unreliable” (because of the risks of unintended consequences). Of these three arguments, the second one is the most convincing. Because the benefits of such an intervention would be unevenly spread, Hulme notes that powerful states (and perhaps also non-state actors, such as corporations or eccentric billionaires) would have tremendous incentives to act in ways that favoured them. Injecting aerosols into the atmosphere is not, however, the only possible strategy for adjusting the Earth’s climate, and Hulme does not object to milder, more localized forms of “geoengineering” such as carbon capture and storage or painting roofs white to reflect sunlight. This suggests that the real answer to the question “Can science fix climate change?” is not a simple “no”, but rather something that depends on your definition of “science” or “fix”. A better, longer book might have weighed up the pros and cons of other scientific solutions, rather than focusing exclusively on the downsides of a single (rather barmy) one.

  • 2014 Polity Press £9.99pb 144pp

Your inner scientist awaits

If you’ve already taught your dog quantum physics and relativity, what do you do for an encore? For Chad Orzel, whose first two popular-science books (How to Teach Quantum Physics to Your Dog and How to Teach Relativity to Your Dog) were based on imagined conversations with his German shepherd mix, the answer was simple: move on to humans. Specifically, humans who think they don’t like science very much. In his latest book, Eureka! Discovering Your Inner Scientist, Orzel sets out to convince people who regard science as “difficult” (or “nerdy”, or “esoteric”, or whatever) that they, too, are capable of thinking like scientists, and of applying the scientific method to whatever pursuits they find pleasant and meaningful. Pursuits like cooking, for example. As Orzel points out, successful chefs must master a repertoire of basic techniques, and then learn how to apply them in new situations. When they do this, he explains, they are following a path similar to that of the American physicist Luis Alvarez, who used techniques from particle physics to solve some notable problems in archaeology and geoscience. Readers who are already sold on the idea that science is useful and interesting are not, of course, Orzel’s primary audience here, but scientists will nevertheless find the stories in the book agreeably diverting – even if, ultimately, they are not completely convinced that what they do is comparable to baking a cake, playing basketball or bidding in a card game.

  • 2015/2014 Basic Books £11.49/$17.99pb 368pp

Mixing maths and art

“Alice believes that Bob assumes that Alice believes that Bob’s assumption is incorrect.” If you didn’t follow the logic in that statement, it’s not your fault: it is, in fact, impossible for Alice to hold such a belief, because it is inherently self-contradictory. This conundrum is one of many fascinating little puzzlers found in John Barrow’s latest book, 100 Essential Things You Didn’t Know You Didn’t Know About Maths and the Arts. Like its predecessor, in which Barrow, a mathematician at the University of Cambridge, expounded on 100 essential unknowns related to maths and sport, the book is well written and varied, with chapters on such diverse subjects as systems of finger counting, computability and betting. There’s just one problem: many of the chapters (including the Alice and Bob example above) have, at best, a very tangential connection to art. So why does “the arts” appear in the book’s title? According to Barrow, the answer is that mathematics and art are natural bedfellows, since they both involve the exploration and study of patterns. However, in reading the book, one gets the impression that Barrow’s real reason is simply that he finds them both interesting. Either way, it is probably best to ignore the words on the book’s cover and just enjoy the titbits inside.

  • 2014 The Bodley Head £10.00hb 320pp

Physicists create ‘anelloni’ – a new kind of pasta

Rigatoni, fettucine, tagliatelle, penne? We think they’ve had their day.

It’s time to say hello to “anelloni” – a new kind of pasta created by two physicists from the University of Warwick in the UK. Consisting of giant loops, it’s the brainchild of Davide Michieletto and Matthew Turner, who invented the pasta in an attempt to demonstrate the complicated shapes that ring-shaped polymer molecules can adopt.

With its name derived from anello – the Italian word for “ring” – the new pasta is exclusively unveiled in an article that Michieletto and Turner have written in the December 2014 issue of Physics World magazine, which also contains their secret recipe for making it.

The two researchers created the large loops of pasta using just two eggs and 200 g of plain flour. When cooked and thrown together in a bowl, the pasta rings get hugely tangled up, in much the same way that real ring-shaped polymers become massively intertwined with each other.

Michieletto explains more about ring-shaped polymers in the video above, which was filmed at Physics World headquarters in Bristol. As he explains, whereas it’s easy when faced with a bowl of normal spaghetti to suck or pull a single strand out, it’s much harder to extract a single piece of pasta from a pile of anelloni, which get horribly tangled up.

While the new kind of pasta is just a bit of fun, Michieletto and Turner’s real work involves carrying out computer simulations of ring-shaped polymers. These studies have shown that if the molecules are long enough, they are likely to get so tangled up that they would appear frozen in place. If this were true in real life – and there is some evidence to suggest that it is – then they believe they would have discovered a new state of matter, which the pair dub a “topological glass”.

PWDec14cover-200You can find out more about the new pasta and polymer mysteries in the December issue of Physics World. If you’re a member of the Institute of Physics (IOP), you can now enjoy immediate access to the new issue with the digital edition of the magazine. If you’re not yet in the IOP, you can join now to get full access to Physics World as well as many other member benefits. The Michieletto and Turner article is also available online here.

For the record, here’s a run-down of all the highlights of the December issue:

• Driving the innovation agenda – The Fraunhofer Centre for Applied Photonics is the first UK branch of Germany’s famed applied-research organization. Margaret Harris travels to Glasgow to find out how it will boost Scotland’s laser industry.

• Driving the innovation agenda – Arti Agrawal says that more needs to be done to address the gender gap in science.

• Literature of the lab – Robert P Crease surveys novels with scenes set in physics laboratories, and wants your suggestions of others.

• The pyramid detectives – Lucina Melesio explores how physicists are mapping the internal structures of ancient pyramids in Mexico and Central America using muons – potentially revealing hidden chambers that could finally lead archaeologists to where ancient rulers are buried.

•  A taste for anelloni – The behaviour of ring-shaped polymers is one of the last big mysteries in polymer physics. Davide Michieletto and Matthew S Turner illustrate just why they are so hard to understand – using some delicious home-cooked pasta that they dub “anelloni”.

•  Listening to the world – Philippe Blondel reviews Sonic Wonderland: a Scientific Odyssey of Sound by Trevor Cox.

•  A strong model, with flaws – Sabine Hossenfelder reviews Cracking the Particle Code of the Universe: the Hunt for the Higgs Boson by John W Moffat.

•  Artistic influences – Dan Falk reviews Colliding Worlds: How Cutting-Edge Science is Redefining Contemporary Art by Arthur I Miller.

• Social physics and antisocial science – Martin Zaltz Austwick reviews Social Physics: How Good Ideas Spread – the Lessons from a New Science by Alex Pentland.

•  A cabinet of invisible curiosities – Ulf Leonhardt reviews Invisible: the Dangerous Allure of the Unseen by Philip Ball.

•  Elegant constructions – Margaret Harris reviews Beautiful Geometry by Eli Maor and Augen Jost.

•  Finding balance in a new lab – Setting up a new laboratory is a formidable challenge for early-career researchers. Sarah Bohndiek shares a few lessons she learned in her first
year as a group leader.

A taste for anelloni

ring-shaped pasta
Anelloni: a new form of ring-shaped pasta that is a great analogy for ring-shaped polymers. (Courtesy: Davide Michieletto)

For Italians, there’s nothing better to cheer you up than a bowlful of handmade pasta drizzled with extra-virgin olive oil and sprinkled with some good-quality Parmesan cheese. A mouthful of spaghetti perfectly rolled around your fork, they would argue, is without equal in the culinary world and can evoke a feeling of joy in even the hardest of souls. Indeed, rolling spaghetti around a fork is an art that every Italian is expected to learn from a young age. Mastering this skill takes years of practice, however, and children who’ve not yet got the knack will try to eat spaghetti by sucking up each spaghetto one at a time.

Vulgar and embarrassing though that might be, it is perfectly possible to eat a bowl of spaghetti in this way because each individual strand has two ends, meaning each can be pulled free from a pile of others. But what would happen if you were to eat a bowl of spaghetti in which each strand was not linear, but shaped into a ring? “Ring spaghetti” can’t be bought in the shops – in fact, as far as we’re aware, it’s never previously been served at any Italian dining table (though tiny pasta hoops can be bought). So to find out what happens, we decided to create our own ring spaghetti – or “anelloni” as we’ve decided to call it (anello in Italian meaning “ring”). Actually, we made our rings not from strands of spaghetti, which have a circular cross-section, but from linguine, which is flatter, but it makes no difference to anyone wishing to check the difference between ring-shaped and linear pasta. If you fancy trying the experiment in your own kitchen, we’ve included a simple recipe for anelloni (see below).

Faced with a dish of ring-shaped pasta like our anelloni, it turns out to be much harder to pull one piece of pasta free than if you were eating a plate of spaghetti, making the meal take longer. How much longer will depend on the length of the rings – and on your dexterity! We haven’t actually tried an experiment with anelloni of different sizes, but calculations show that as rings become longer, they can get more and more entangled with each other, with 100% of rings getting tangled up in the limit of infinitely long chains.

Running rings around pasta

Well, this is all very interesting, we hear you say – but what has pasta got to do with physics? Actually, strands of spaghetti (or linguine) are a very good macroscopic analogy of polymers – those long-chain molecules that make up everything from plastics to proteins. Normal spaghetti can be seen as an analogy for conventional “linear” polymers, such as polyethylene or polystyrene, while our novel ring-shaped pasta resembles ring polymers. These ring polymers are hard (though not impossible) to make synthetically, but they are more commonly found in nature.

For example, while DNA is a long double helix, pieces of DNA, known as plasmids, can be found as closed rings inside bacteria. Meanwhile, tiny single-celled organisms known as Kinetoplastida keep all their mitochondrial DNA as a mass of rings that are interlocked rather like the loops of metal on a medieval knight’s chainmail armour (mitochondria being objects in which chemical energy from food is turned into a form the cell can use). These rings, which are double-stranded sections of DNA, are different from rings of our anelloni pasta, which get tangled up but can, in principle, be pulled apart, even if it’s hard to do so. In fact, when Kinetoplastida divides, the only way it can physically separate the loops is to use a particular enzyme to cut each ring, which can then de-link from its neighbour before joining itself up again.

The thing about ring-shaped polymers, though, is that they’re very poorly understood – in fact, they’re one of the last big mysteries in polymer physics. Physicists are now pretty clear about how individual linear poly-mer molecules move: each chain slides along like a snake moving through tall grass in a process dubbed “reptation”. Similarly, suck on a strand of spaghetti and it’ll slither through the others in the bowl and up into your mouth. But reptation doesn’t apply to rings because they have no free ends. There are theories conjecturing how rings move and what shape they adopt, but none really captures the whole story.

Computer simulation of ring-shaped polymers heavily tangled up
1 Knotty issue Computer simulations can give us a better understanding of the dynamic motion of ring polymers, which move ever more slowly as the chains get longer and more tangled up. (Courtesy: Davide Michieletto)

In our work, we are interested in knowing what shapes ring polymers adopt when placed in a gel of linear polymers, which we model as a 3D lattice of obstacles. As each ring polymer must form a continuous loop that weaves itself between the obstacles, the ring polymers don’t stay circular but end up adopting some curious shapes dubbed “lattice animals” because they can, rather amusingly, look like real animals. While the idea of ring polymers forming these lattice-animal shapes is rather cute, the fact that individual ring polymers must stay as isolated loops (known as “un-knots” in the language of topology) is what makes studying these materials really hard.

Ring polymers are free to adopt different configurations and don’t necessarily stay circular but can crumple up into different shapes. Unlike linear polymers, in which you can just examine all the local interactions between individual segments, or “monomers”, of the molecule in isolation, for ring polymers you have to keep track of the overall topological state of the chain. Judging the likelihood of a ring polymer adopting a particular configuration is therefore much more tricky and what makes studying these molecules hard.

Recent computational studies of the dynamics of ring polymers have revealed that these macro-molecules can entangle in a very different way from their linear cousins. Because of their topology, ring polymers can form horribly complicated structures, in which one ring is threaded through another, which is threaded through another and so on to form what we call “hierarchical threadings”. The most tightly bound ring in this giant network can only get free if the other rings are pulled apart one by one in a particular order.

Towards a topological glass

The bottom line is that the individual ring polymers in a network find it very hard to move freely even though they don’t actually form any knots, which are topological states that can only be undone by cutting the ring (see figure 1, above). In fact, recent simulations that we’ve carried out suggest that if they are long enough, ring polymers become so sluggardly that they could eventually appear frozen into place. If this were to occur – and we have evidence, though no definite proof, that it does – we would have identified a new state of matter, which we have called a “topological glass” (2014 ACS Macro Lett. 3 255 and 2013 Europhys. Lett. 102 58005).

Ordinary glassy materials are made by cooling a viscous liquid, with the amount of movement dropping exponentially as temperature falls; it becomes a glass only once the material is cool enough that the molecules in it have stopped moving. A topological glass made from ring polymers would be rather different: the motion would slow down exponentially not just with temperature but with ring length too. Despite not yet having definite proof that such a state exists, we have shown with our simulations that ring polymers certainly start to slow down in exactly the way you’d expect if it were a true topological glass. What’s holding us back from getting a definitive answer is computer power: as the rings get longer and more tangled up, the time it takes to probe the motion rises exponentially, though we’ve recently bid for more supercomputer time to push our simulations to the limit.

“Topological phases” are all the rage in condensed-matter physics these days, with researchers studying exotic materials such as topological insulators (materials that don’t conduct electrically in the bulk but do along the edge) and rod-shaped liquid-crystal molecules that contain topological defects. What would be nice about a topological glass is that its properties would be governed purely by topology, rather than the system-specific chemical details that often control when and how classical glasses form. Physicists love that kind of universal behaviour – in fact, obtaining a universal description of glasses has been a central goal in condensed-matter physics for several decades. What’s more, ring polymers could also inspire the design of novel materials that could have applications that we cannot yet even imagine.

So while we are not entirely sure yet that topological glasses really do exist, what we do know from our research is that when it comes to eating pasta, the Italians were right all along – you’re better off sticking to spaghetti, which you can eat nice and quickly. Make yourself a bowl of anelloni and it’s likely to have gone cold by the time you’ve pulled all the rings apart and struggled your way to the messy end.

A recipe for anelloni

Photo of sheets of pasta
Sheets of pasta from which ring-shaped “anelloni” can be cut. (Courtesy: Davide Michieletto)

Serves two.

Ingredients

2 eggs
200 g plain flour
Extra-virgin olive oil
Aged Parmesan

Method

  • Shape the flour into a mound on a clean surface and make a large well in the middle.
  • Add the eggs bit by bit to the flour and mix until you get a smooth dough, taking care to avoid the dough becoming clumpy.
  • Knead rigorously by hand for 15–20 min until the dough is smooth and elastic.
  • Flatten the dough out with a rolling pin to form a thin sheet.
  • Cover one half of the sheet with a piece of baking paper so that the dough doesn’t stick as you take one end of the sheet and fold it over itself, making sure it overlaps by about 1 cm.
  • Moisten the overlapped region with water and then seal the sheet together to create a flat, open cylindrical shape (see image above).
  • Using scissors, cut thin strips along the dough at 90° to the sealed edge to form closed rings of pasta, or anelloni (see image above).
  • Cook for 3–5 min in plenty of boiling water.
  • Enjoy it with a generous drizzling of olive oil and lots of Parmesan!

Photo of rings of pasta laid out on a table
Pasta cut into large “anelloni” rings. (Courtesy: Davide Michieletto)

Slamming physics at Fermilab, dancing to Yuri Gagarin and lifting off from 'Cape Kebaberal'

 

By Hamish Johnston

Giving a fired-up talk at a physics conference is a good way for aspiring researchers to make themselves known to the community, but unless you have a natural gift, lots of practice is required. That’s why many universities and labs host “slams” to encourage staff and students to talk about their research to a broader audience. Above is a video of the sold-out Fermilab Physics Slam 2014, which was held last week at the lab on the outskirts of Chicago.

(more…)

Medical-isotope breakthrough made at Canadian lab

The first commercial shipment of medical isotopes produced using a new particle-accelerator-based technique has been made by scientists at the Canadian Light Source (CLS). Molybdenum-99 (Mo-99) decays to create technetium-99m (Tc-99m), which is used to tag radiopharmaceuticals and plays a unique and vital role in medical imaging. Unlike nuclear reactors, which currently make most of the world’s Mo-99, the system is small enough to be deployed within a large hospital and could thereby improve the supply of the short-lived isotopes.

The material is made at the Medical Isotope Project (MIP) facility at the CLS, which is located at the University of Saskatchewan in Saskatoon. According to Mark de Jong, director of accelerators at the CLS, the facility is the first of its kind anywhere in the world, and uses a small high-power industrial electron linear accelerator to produce a flux of high-energy X-rays through bremsstrahlung radiation. The X-rays strike a target made of enriched Mo-100, in the process “knocking out” a neutron from the nuclei of some of the target atoms to produce Mo-99.

No fission required

“The main advantage of this method is the complete avoidance of any use of uranium or fission, with all the problems that arise from both volatile short-lived isotopes, as well as disposing of the long-lived radioactive waste,” says De Jong.

After several days of irradiation at the CLS facility, the target is shipped 800 km to the Winnipeg Health Sciences Centre’s Radio-Pharmacy Department, where it is dissolved and the Tc-99m is extracted. Transport across long distances is possible because Mo-99 has a half-life of 66 hours, but significant losses do occur. The half-life of Tc-99m is just 6 hours, so it must be produced as near as possible to where it will be used.

De Jong says that future implementations will not necessarily require such long-distance shipping. “The electron linear accelerator is small enough to be located close to where the Mo-99 is required, possibly even within major hospitals, reducing the losses caused by decay in shipping Mo-99. In the present fission-based production, more than 80% of the Mo-99 produced has decayed before it reaches the hospitals,” he adds.

Reactor shutdowns

The MIP was created in the wake of serious Mo-99 shortages in 2007 and 2009, which were both related to two unscheduled shutdowns of the ageing NRU nuclear reactor at Atomic Energy of Canada’s Chalk River Laboratories. NRU provides most of Mo-99 for North America, and isotope production is an important industry in Canada. In 2010, fearful of damage to the industry, the Canadian government launched a call under its Non-nuclear-reactor-based Isotope Supply Program (NISP) to encourage alternative isotope production using either photo-neutron production of Mo-99, or direct production of Tc-99m using proton cyclotrons. The CLS proposal was one of two photo-neutron production projects funded, the other being run by Winnipeg-based Prairie Isotope Production Enterprise (PIPE).

“Once the work to approve the processes involved – Mo-99 production, target dissolution and Tc-99m extraction – is completed by Health Canada, the facility should produce enough for the hospitals serving a population of more than two million people. The health approvals are the next phase that we are working on with our colleagues at PIPE. We hope to have the New Drug Application (NDA) submitted to the authorities by the end of 2015, with routine clinical use possible by the end of 2016,” says De Jong.

Other options

In 2012 scientists at the Vancouver-based TRIUMF national laboratory for particle and nuclear physics pioneered two methods for producing Tc-99m using Mo-100 targets and medical cyclotron-based accelerator technology. Cyclotrons are particle accelerators that rely on electricity and magnets to create isotopes by accelerating ions and bombarding non-radioactive materials.

“Our process is suitable for large population bases, using medical cyclotrons already installed and operational in our major hospitals throughout the country. We have demonstrated that cyclotrons in Vancouver, London and Hamilton have sufficient capacity to supply their respective hospital catchments with Tc-99m,” says TRIUMF’s Melissa Baluk.

Celebrating innovation

Photo of Baroness Neville-Rolfe
Clever thinking: Baroness Neville-Rolfe celebrates the winners of the 2014 Institute of Physics innovation awards. (Courtesy: Richard Lewis)

“Commercializing physics” is the theme of the November issue of Physics World and it was therefore timely that last night saw a special ceremony at the House of Commons to celebrate the winners of this year’s Innovation Awards from the Institute of Physics (IOP), which publishes the magazine.

The awards, which are now in their third year, are given by the Institute to firms in the UK and Ireland “that have built success on the innovative application of physics”.

Four firms were honoured this year: Gas Sensing Solutions, which makes carbon-dioxide sensors; Gooch & Housego, for an opto-acoustic device that can modulate laser beams for industrial processing; nuclear-power firm Magnox for a clever way of refuelling a reactor at the Wylfa power station; and MBDA for a novel “missile-system upgrade”.

(more…)

Top physics books for 2014

Top-10-Book-2014-200x200By Margaret Harris

Is it time for end-of-the-year lists already? At Physics World HQ, the answer is a definite “yes”, and we’re kicking off the season with our annual list of the year’s best physics books.

As in previous years, the entries on our “Book of the Year” shortlist are all well written, novel and scientifically interesting for a physics audience. They represent the best of the 57 books that Physics World reviewed in 2014, being highly commended by external experts (the diverse group of professional physicists and freelance science writers who review books for the magazine) and by members of our own editorial staff, who helped winnow the field down to a shortlist of 10.

This is the sixth year we’ve picked a “Book of the Year”, and I don’t think I’ve ever seen a stronger shortlist. Frankly, 2014 has been a fantastic year for science books, and for physics books in particular. You’ll see that quality reflected in the list below, where first-person accounts of the latest discoveries rub shoulders with historical analyses of the foundations of the field. There’s room in our shortlist for books about acoustic physics, exoplanets, geophysics, materials science, radiation safety and scientific ethics – plus a whimsical tour of the physics of fantasy and science fiction.

(more…)

Device cools itself in the blazing-hot Sun

When the weather gets hot, everyone wants to stay cool. That often means turning on the air conditioning, which consumes vast amounts of energy – and money – in developed countries. But that could change, thanks to a new photonic device that can cool to below the ambient temperature while consuming no energy.

Cooling accounts for around 15% of the energy used in buildings in the US and contributes heavily to greenhouse-gas emissions. Worldwide, energy consumption related to cooling is expected to surpass that used for heating by 2070.

Open window

Objects can cool themselves without consuming energy by radiating energy in the form of infrared light. This process is not normally very efficient because objects can also be warmed by convective air currents and by absorbing radiation emitted by other objects and by the air. However, air absorbs and emits very little infrared radiation at wavelengths of around 8–13 μm. It is through this “window” that the Earth lowers its temperature at night – especially when the sky is clear – by sending radiation out into space.

To make practical use of this effect during the day, the surface of an object must emit radiation within this window, while at the same time reflecting sunlight to minimize the amount of heat it absorbs. The problem is that no known naturally occurring material can do both of these things.

Layered material

Now, physicist Shanhui Fan and colleagues at Stanford University have made a device that fits the bill. The team designed a structure of seven alternating layers of silicon dioxide – essentially glass – and hafnium dioxide. Both materials are transparent to visible light but emit radiation strongly at wavelengths of around 10 μm. These layers are stacked on a layer of silver to create a mirror that reflects visible light. Fan and his team used a computer simulation to choose thicknesses for the different layers that would maximize both how much sunlight the combined device reflects and how much infrared radiation it emits.

The researchers then mounted the device, which was just under 2 μm thick, onto a 20 cm-diameter circular silicon wafer, added a plastic sheet to block convective air flows, and placed the apparatus on the rooftop of a building at Stanford. They found that on a sunny day, the device cooled to between 4 and 5 degrees below the surrounding air temperature. The device therefore appears to be the first object known to achieve such cooling under direct sunlight without consuming energy.

Rooftop coverage

The researchers are now planning to test their invention over a larger section of rooftop. They say a device like theirs could someday cool a building through direct contact, or by cooling water that is then pumped through the building. While hafnium dioxide is a relatively expensive material, the team says that it could be substituted with cheaper titanium dioxide. The device can be made using commercial fabrication techniques, so under the right conditions it could be combined with conventional air conditioning driven by solar power to create low-cost, low-carbon cooling systems. It could also work alongside solar panels, the researchers say, because these panels are typically installed on rooftops facing the Sun, whereas the new device operates best when not facing the Sun.

In addition to cooling buildings, such devices could help solar panels work better, says engineer Min Gu of Swinburne University of Technology in Australia. Solar panels become less efficient as they heat up, so a way to keep them cool without consuming energy would be a huge boon. “It’s very encouraging for us. Now we can design something to integrate into a solar cell,” Gu says.

Physicist Claes-Göran Granqvist of Uppsala University in Sweden says that Fan’s team has demonstrated an “interesting effect”. But he notes that the researchers face additional challenges in creating a practical device. For instance, the device will not work well on cloudy days, when water vapour largely blocks the 8–13 μm atmospheric window. In addition, the thin plastic sheet the researchers used to block convective air currents may not stand up to high winds. “It’s a step forward, but there are many more steps to be taken,” says Granqvist.

The research is described in Nature.

  • The challenges of keeping cities cool are discussed by Roland Ennos of the University of Manchester in the feature article “Urban cool”.

Become a CERN physicist in your bedroom

Particle collision within the ATLAS detector. (Courtesy: CERN/Higgs Hunters)

Who discovered the Higgs boson? Was it Peter Higgs and a combination of other great minds? The experimentalists at CERN who analysed reams of data? The magnificent machinery of the Large Hadron Collider (LHC) itself? By the time that the next great breakthrough in particle physics comes along, the debate about who makes the discovery could become even more complex. That’s because a new citizen-science project is encouraging anyone with an Internet connection to search for new curiosities in the Higgs data.

“Higgs Hunters” launched this week and invites the public to sift through collision images from the LHC’s ATLAS detector. The task at hand is to look for the paths of charged particles that seem to appear out of thin air in what are known as off-centre vertices. As explained on the Higgs Hunters website, “some scientists think the Higgs could break apart into exotic particles entirely new to science”. On the Higgs Hunters website, citizen scientists help to count the number of particle tracks and can notify the science team if they spot anything out of the ordinary.

(more…)

Listening to the world

Small waves lap the side of our boat, making relaxing sounds. Every now and then, the little icebergs melting around us add their clinking noises, while the larger bergs bump gently against the boat’s rubber tubes as we drift past a large glacier. When parts of the glacier’s front wall collapse, we all jump. The loud explosion is followed by a series of surface waves, gentle at first but carrying blocks of ice that weigh in excess of 50 tonnes. Underwater, the general hissing sound, interrupted by slapping from the waves and crackling from the ice, reaches high intensities as it echoes from the sides of the fjord.

The ocean off the coast of Svalbard, where I spent last summer measuring underwater noise, is definitely not the “silent world” of Jacques Cousteau fame. But this should not surprise us. Most of the world is, in fact, full of sound – sound that is always there for us to sense, if we can stop ourselves relying only on visual stimuli. Sonic Wonderland is the perfect reminder of this rich soundscape. Before being asked to review this book for Physics World, I had seen it in advertisements and decided that its price tag was a bit too high. Now, having read it, I wonder why I did not jump on it immediately, regardless of the price. What comes first out of this book is the sheer variety of acoustic processes, how mysterious and entrancing they can be, and how understanding the physics behind them adds another dimension to their enjoyment. Not only that, but reading it made me want to travel all over the world to discover the acoustic wonders that the author, Trevor Cox, explains so passionately and so well.

The book’s chapters logically go from the loudest to the quietest places on Earth, placing sound in its wider human or natural context. We learn about simple sounds and how they are distorted by their environment, from reverberation under bridges or in sewers to echoes and whispering galleries. Relevant examples are presented alongside interesting stories about how British birdsong nearly leaked war secrets to the Nazis during the Second World War; how unusual echoes in the castle at Chinon, France, can be used to make calumnious accusations; and how church bells could be heard far out at sea without the need for supernatural explanations. On a related note (pun unintended), the urban legend that playing music backwards leads to satanic indoctrination is safely laid to rest, as the author explains that this process produces only meaningless noise, regardless of what record is played.

In addition to these historical anecdotes, we also learn about acoustics in a range of different buildings, from the author’s house (and bathroom) to churches, mosques and concert halls around the world. We come to understand what makes a “good” sound and what can be done to avoid unwanted echoes and the hubbub usually associated with badly designed cafeterias. The sounds of instruments appear in several chapters, with sections on the saxophone, violins, brass and, of course, organs and bells – including the author’s first-hand account of experiencing Big Ben’s chimes from inside the tower.

Natural spaces have their own peculiar acoustics, and we learn about Stonehenge and other antique sites, as well as tidal bores, waterfalls and even simple bubbles. With clear diagrams (and sometimes the support of audio clips on the book’s accompanying website), Cox demystifies these natural noises, explaining how sands can “burp”, how rocks can “sing” and why city-dwelling birds need to sing louder or later to adapt to urban life. In most cases, he has gone to study these sounds himself – measuring them, analysing them, and beautifully reporting on how they work and what they mean. In my own recent holidays, I was lucky enough to hear the sound from stalagmites in French caves, and Cox’s presentation of the Great Stalactite Pipe Organ (including a very nice example on SoundCloud) shows how human ingenuity has made the most of these natural or near-natural sounds. Other examples of human-nature sonic collaborations include Blackpool’s High-Tide Organ, which uses natural tides to create eerie and surprising sounds, as well as sculptures in London and further afield. I also learned with interest that musical roads do not exist only in Jasper Fforde’s novels, and I now know where to experience them directly.

My speciality is underwater sounds, so as I was reading (and enjoying) the book, I was also on the lookout for items directly relevant to my own experiences. I was not disappointed. Bearded seals and snapping shrimps, loud ships and quiet submarines – they are all there, clearly presented and exactly as heard around the world’s oceans. The clinking of ice and the noise of small bubbles coming from the melting of icebergs were even illustrated with examples from Iceland and Svalbard, to which I could directly relate. By adding numbers to these measurements, Trevor Cox also reiterates the fact that decibels underwater are definitely not the same as decibels in air (because of the different reference levels). My conclusion is that while this book is primarily intended for a popular-science audience, there is enough to keep even field-hardened professionals firmly interested.

These few examples should make it clear that I loved this book. It is definitely worth the price, and even if it seems strange to read about sound instead of listening to it, Sonic Wonderland is the perfect arrangement. (It is also a great gift idea for the coming festive season.) Inspired by this book, I now listen to the rumbling of the bus, the noise of the city, and of course the birds and cows on my way home. More importantly, this book has given me new ideas of places to explore: I want to listen to the Severn Bore and to trees in the forest; I want to visit concert halls and go on soundwalks around my favourite cities. There is an entire world to explore, and it’s out there for us to listen to, and to enjoy.

  • 2014 The Bodley Head £20.00hb 320pp
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