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Science cleans up at the Oscars

Still of Stephen and Jane from the film The Theory of Everything
The Theory of Everything depicts Stephen Hawking’s relationship with first wife Jane. (Courtesy: Universal Pictures International)

By Tushna Commissariat

In a sweeping win for science-themed films at this year’s Oscars, British actor Eddie Redmayne has won the best actor award for his portrayal of the theoretical physicist Stephen Hawking in the film The Theory of Everything. Redmayne, 33, plays Hawking in the biographical film that was inspired by the memoir Travelling to Infinity: My Life with Stephen written by Hawking’s former wife Jane, who is portrayed in the film by the British actress Felicity Jones. The Theory of Everything was also nominated for best picture, original score and adapted screenplay, while Jones was nominated in the best actress category. Redmayne’s success at the Oscars comes after his win in the best actor category at this year’s Bafta awards, which also saw The Theory of Everything pick up best film. The movie chronicles Jane’s relationship with Hawking – from the early days of their courtship to Hawking’s diagnosis of amyotrophic lateral sclerosis at the age of 21 and his success in physics until the two divorced in 1995. I was lucky enough to attend an early screening of the film, and I thought it was a very worthy candidate for the awards season. You can read my review of the film here.

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Could the Sun be trapping asymmetric dark matter?

Unexplained discrepancies between mathematical models of the Sun and astronomical observations could be resolved by the presence of dark matter in the Sun, according to the latest work from an international team of researchers. The team’s model – which looks at dark matter that has a particular, momentum-dependent interaction with normal matter – explains the observed data much better than more conventional dark-matter models. The researchers believe that the particles they postulate could potentially be seen either by direct detectors or in particle accelerators.

In recent years, scientists have reduced their estimates of the proportion of elements heavier than hydrogen and helium in the Sun. These new estimates, based on reinterpretations of spectroscopic data, create a problem. When applied to conventional mathematical models of the solar structure, they create multiple conflicts with the values of various quantities that are measured by looking at periodic changes in size of the Sun caused by acoustic pressure waves. This study of the internal structure of the Sun via acoustic waves is known as helioseismology. To resolve these inconsistencies, researchers are seeking new ways that heat can reach the surface of the Sun from its core. One possibility is that the Sun might contain dark matter that it captures as it passes through the galactic halo. Such matter could carry heat from the core to the cooler outer layers of the Sun.

Particle pick and mix

Particle physicists have postulated numerous candidates for dark matter, ranging from weakly interacting massive particles (WIMPs) and axions to supersymmetric particles such as neutralinos. In most of these, the probability of two particles interacting (an interaction cross-section) is independent of the momentum exchanged in such a collision. However, more recently, newer theories have been constructed containing asymmetric dark matter – where dark matter could have its own antimatter counterpart. Some of these models permit an interaction cross-section that depends on the square of the exchanged momentum. Astroparticle physicist Aaron Vincent of Durham University in the UK, together with colleagues at Imperial College London and the Institut de Ciències de l’Espai in Spain, looked at how models of asymmetric dark matter that interacted in various ways with normal matter would affect the relationship between theoretical solar models and observations.

The researchers looked at multiple properties of the Sun measured from various sources, using accepted mathematical models to infer the speed of the acoustic waves throughout the Sun, the depth of the convective envelope and the intensity of neutrinos given off. They compared these values with those predicted first by the standard solar model and then by models that incorporated dark matter interacting with the baryonic (regular) matter in three possible ways. In two of the three ways, the interaction cross-section was independent of momentum, while the third considered a cross-section that was proportional to the square of the momentum exchanged. In each case, they chose parameters, such as the mass of the dark-matter particle, to provide the best possible fit to the observational data.

Perfect fit

They found that the model with the momentum-dependent interaction cross-section gave an excellent fit if the dark-matter particle had a mass of about 3 GeV, whereas neither the solar standard model nor the other two dark-matter models could produce anything even remotely consistent with the observed values. Particles where the interaction cross-section shows this type of momentum dependence have a larger mean free path inside the Sun and can therefore transport heat more effectively to its outer layers. Vincent explains that such an interaction would probably not involve one of the four known fundamental forces, saying “this would be some new interaction between dark matter and the standard model”.

Fabio Iocco of the South American Institute for Fundamental Research in São Paolo, Brazil, is impressed. Iocco says that what Vincent and colleagues have accomplished is to take a certain type of dark matter “to try and see if it solves an observational problem, and apply it in a new context which is absolutely well posed – it’s been overlooked for a long time because it’s very difficult to do”.

The researchers hope to develop their model further in forthcoming work. “There’s probably a zoo of different possible particles that would give this interaction, but it’s not clear yet whether any of those would really work when you work out the details,” says Vincent. The team also hopes that forthcoming experimental work at the Large Hadron Collider at CERN and in underground dark-matter detectors such as Super Cryogenic Dark Matter Search (SuperCDMS) will either confirm the existence of such a particle or refute it. “We’re very close to finding out whether this really is an indication of dark matter or whether we have stumbled upon something that mathematically looks like dark matter but is actually something more subtle going on in the Sun,” he adds.

The research is to be published in Physical Review Letters. A preprint is available on the arXiv preprint server.

Oscar-nominated physics, putting the jump into popping corn and more

 

By Tushna Commissariat

There is nothing quite like a bowl of hot, buttery popcorn – and it seems as if even physicists are enthralled by it as they dig into the pops and jumps of this tasty snack. A recent article in the New York Times caught our attention this week, as it talked about how a French research duo used high-speed video cameras and a hot plate to see just why a kernel of corn not only pops, but also leaps up as it puffs. The team found that as the kernel’s hull is breached, we hear the popping sound and this is swiftly followed by the jump that happens when a puffy bit of the inside pushes out and makes the corn jump, a bit like a muscle twitch. Take a look at the lovely slow-motion video above of individual kernels leaping about like perfect puffy ballet dancers.

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Geoengineering schemes to combat climate change still risky, say reports

Dramatic reductions in the emissions of greenhouse gases are essential to help mitigate the effects of climate change, according to two reports issued last week by the National Research Council of the US National Academy of Sciences. Written by a 22-strong committee, the reports argue that removing carbon dioxide from the atmosphere is the most promising approach to tackle climate change, but conclude that the use of geoengineering to reduce the amount of solar energy that reaches the atmosphere is too risky. That type of geoengineering, the reports state, should instead be restricted to small-scale experiments rather than full deployment.

Dual approach

The reports identify two specific geoengineering approaches that could have a significant impact on the climate: injecting aerosols into the stratosphere – to mimic the effect of large volcanic eruptions – and brightening clouds to make them more reflective. Although these methods are cheaper than removing carbon dioxide from the air and would not require “major technological innovation”, the reports note that any future decisions on managing solar radiation – known as albedo modification – will be judged mainly on questions of risk. Indeed, many of the processes most relevant to albedo modification – such as those controlling the formation of clouds and aerosols – are among the most difficult to measure and monitor. Nor can current observational techniques monitor the environmental effects of the approach.

Marcia McNutt, a former director of the US Geological Survey who chaired the committee, says the fact that scientists are even thinking about using geoengineering to mitigate climate change should be a “wake-up call”. “The longer we wait, the more likely it will become that we will need to deploy some forms of carbon-dioxide removal to avoid the worst impacts of climate change,” she insists.

Conflicting views

However, some climate scientists urge the need for caution. “No reputable scientist I know thinks placing tiny reflecting particles in the stratosphere is a good idea, although some support studying it,” says Philip Duffy, president and executive director of the Woods Hole Research Center, an institution that focuses on climate change. Pennsylvania State University climatologist Michael Mann takes an equally sceptical view. “I believe that we should continue to fund studies of geoengineering approaches,” he says, “if only for one purpose: to expose just how dangerous many of these schemes might be.”

Marine geochemist Scott Doney of the Woods Hole Oceanographic Institution, who helped write the reports, thinks that deploying geoengineering – or even carrying out field research into it – is not on the immediate agenda and would require further discussion. “This is not just an academic science conversation, it needs to involve society: NGOs, governments and industry,” he says. “We’re saying that we should not move forward with deployment now – and not with field research until we have more detailed conversations on governance issues.”

Novel nanoparticle boosts six different medical-imaging techniques

A new type of nanoparticle could allow patients to be imaged in six different ways with an injection of just one contrast agent, reports an international research team. If put into clinical use, the technology could give doctors the ability to combine the strong points of a number of imaging techniques, providing a clearer overall picture of patient organs and tissue.

Many ways and means

The nanoparticles – averaging 74 nm in diameter – comprise a core surrounded by a porphyrin-phospholipid (PoP) wrapper. Each part has properties that facilitate different imaging modes. The core component fluoresces blue when struck with near-infrared light, allowing imaging with the potential for deep-tissue penetration. In addition, the core’s ytterbium component, which is dense in electrons, enables detection by CT scanning. The outer PoP shell has biophotonic properties that make it suitable for use with both fluorescence and photoacoustic imaging. At the same time, the copper affinity of the porphyrin wrapper allows the nanoparticles to be easily coated in radioactive copper-64 for the purposes of PET and Cerenkov-luminescence imaging. The team initially tested each imaging method in vitro and subsequently in a turkey breast to determine the level of signal attenuation with tissue depth. Turkey breast was chosen as a medium comparable to that of human breast tissue, as lymph-node mapping is a current challenge in the assessment of breast cancer. The nanoparticles were then used to image the lymph nodes of live mice, demonstrating the potential of this approach.

Multiscale imaging

“Photoacoustic imaging provides information about endogenous blood vessels, while CT provides information about local bone structure,” says team member Jonathan Lovell, a biomedical engineer at the University of Buffalo in the US. The CT and PET scans were seen to afford the deepest tissue penetration, while fluorescence imaging provided additional information on the uptake of the nanoparticles into cells.

Along with the nanoparticles’ convenient compatibility with the different imaging methods, the researchers also point out that their nanoparticles are both inexpensive and simple to manufacture in comparison with other contrast agents. “Another advantage of this core/shell imaging contrast agent is that it could enable biomedical imaging at multiple scales, from single-molecule to cell imaging, as well as from vascular and organ imaging to whole-body bioimaging,” adds Guanying Chen of the University of Buffalo’s Institute for Lasers Photonics and Biophotonics and the Harbin Institute of Technology in China.

All in one

An imaging machine capable of performing all six scans at once does not currently exist, but the researchers are optimistic that devices capable of exploiting some or all of the nanoparticles’ potential will soon be developed. “Creating a higher-order integrated scanner is not a simple task, but luckily there has been a lot of research and development into just that topic recently,” says Lovell, noting that integrating just some of the six methods – such as the optical techniques, for example – might provide a simpler device that would still be suitable for clinical applications.

Tumour mapping

David Cormode, a radiologist from the University of Pennsylvania who was not involved in the work, is impressed with the nanoparticles’ unique potential as a flexible contrast agent. “I look forward to future work where the agent is used for targeted imaging,” he says, while noting that “safety and excretion will have to be studied prior to translation to patients”.

In addition to confirming the suitability of the nanoparticles for clinical use, the team is also seeking additional applications for the technology. One avenue of investigation would involve the addition of a targeting molecule to the surface of the nanoparticles, allowing them to be taken in by cancer cells to allow better mapping of tumours.

The work is published in Advanced Materials.

Read all about it

By Michael Banks

Cover of the book "Tricked!" by Paul FramptonThe 71-year-old theoretical physicist Paul Frampton, who was arrested in Argentina in 2012 with 2 kg of cocaine in his luggage, has released his own version of events.

The British-born physicist was in Argentina after thinking he had struck up a correspondence on the Internet with Czech-born lingerie model Denise Milani.

However, when he arrived, Milani was nowhere to be seen and Frampton was apparently asked by someone else to carry a suitcase for her, which turned out to contain the drugs.

Despite protesting his innocence, Frampton was sentenced in November 2012 to 56 months in jail in Buenos Aires, some of which he spent under house arrest.

Now, in a 45-page e-book – Tricked!: the Story of an Internet Scam – Frampton outlines “the true story of an adventure that I would rather not have had”. According to the book’s blurb, it provides an “important lesson” that is “essential reading for everybody who uses the Internet”.

It could be the best £3.83 you ever spend.

Craft, science, early industry

Like the legend of Isaac Newton seeing an apple fall, the story of young James Watt carefully observing steam coming from a tea kettle has become part of British folklore. A popular painting shows him being watched by an aunt, whose puzzled and disapproving expression holds dramatic irony: unlike us, she doesn’t know that her nephew would go on to invent the modern steam engine and so change the world.

The title notwithstanding, Ben Russell’s main theme in James Watt: Making the World Anew is not Watt the man. Rather, he uses Watt as a “lens” through which to examine how the process of “making things” evolved during the industrial revolution. He does, indeed, guide us through the varied phases of Watt’s long and productive life, but also invites us to study a somewhat neglected aspect of the industrial revolution: the part played by craftsmen such as clockmakers, instrument makers, potters, blacksmiths and millwrights. As Russell points out, without the people who actually made things, the ideas that inspired progress would have remained just ideas.

Watt himself was both a thinker and a doer. His most famous invention – the steam engine with a separate condenser – drew on both attributes and demonstrates his ability to go on thinking (and doing) long after most people would have given up. He realized that contemporary engines wasted a great deal of heat every time water was injected into the cylinder to condense the steam, and began to experiment with ways to reduce the waste, using his skill as an instrument maker in improvising apparatus for the purpose. He found that the problem was not caused by heat escaping through the cylinder walls, as he had first thought, but by the cast-iron cylinder cooling and having to be reheated at every stroke. The solution was to send the steam to a separate vessel to be condensed; then the cylinder would remain hot and the condenser could be kept cool, thus wasting far less heat. So stated, it sounds simple, but the idea came to Watt only after he had gained understanding of the properties of steam – specific heat, latent heat and elasticity – through his experiments and his discussions with the natural philosopher, Joseph Black.

Although trained as a maker of scientific instruments, Watt turned his hand to all manner of crafts wherever he saw potential markets. Despite being tone-deaf, he made and sold flutes and guitars. No-one matched Watt’s almost superhuman versatility but, as Russell points out, ambitious craftsmen everywhere were developing new techniques and identifying new materials – anything that could give them an edge over their competitors. In doing so, they improved existing products and found ways to make new ones. Some, notably Josiah Wedgwood, were able to anticipate the needs of society in a spectacularly successful way. Others fell prey to the whims of fashion. When, in the late 1700s, people abandoned fancy shoe buckles in favour of cheaper and more practical shoelaces, 20,000 buckle-makers petitioned the Prince of Wales, and the Birmingham Gazette ran a despairing article in May 1790 contrasting the “manly buckle” with “that most ridiculous of all ridiculous fashions, the effeminate shoestring”.

An important part of the ambitious craftsman’s business was to deal with people – to negotiate contracts, chase slow payers and discipline recalcitrant workers. Though far from shy when in congenial company, Watt hated this rough stuff. He was, however, keen to strike good bargains and to secure his legal ownership of inventions, and was lucky to find a partner, the manufacturer Matthew Boulton, who was a master of such arts. It was Boulton who persuaded Watt to patent the principles of his separate condenser rather than the means of applying them. This patent eventually made Watt a very rich man, but only after he and Boulton had pursued many people who had infringed the patent or withheld royalty payments, and, in the end, got a significant proportion of them to pay.

Anyone who opens this book expecting to read a story is likely to be disappointed. Russell gives us instead a course of lectures, meaty ones, that draw on a great many sources. (He lists 787 references.) The text is copiously illustrated but is not all easy going, and at times one may wish for some smooth paraphrasing rather than clunky quotes from original letters and papers. It’s good, authentic stuff though, and we learn some surprising facts (surprising to me, at least). For example, waterwheels persisted far longer during the industrial revolution than I had thought. Moreover, they were sometimes used together with steam engines in a hybrid arrangement, rather like that in today’s petrol/electric cars. In some installations the steam engine would be brought in only when the water supply failed; in others the steam engine actually fed water to the water wheel.

Perhaps from a wish to emphasize the importance of craft work in the industrial revolution (as a companion to the importance of science which has already been much written about), Russell has made a strange omission. He tells us nothing about Birmingham’s Lunar Society, of which Watt and Boulton were leading members along with Joseph Priestley, Erasmus Darwin and Josiah Wedgwood. (The society was an informal group that met monthly around the time of the full moon for dinner, gossip, and scientific talk. Its members strongly supported each other and, together, wielded great influence.) The omission is especially odd as Russell has included an illustration of society members sitting round a table drinking coffee.

James Watt epitomises the fusion of craft with science that brought about the industrial revolution and created the profession of engineering. Anyone with more than a passing interest in the comparatively neglected role of craft in this process will find this book good value.

  • 2014 Reaktion Books £17.95/$29.95hb 256pp

European Physical Society cautions against Horizon 2020 budget cuts

The European Physical Society (EPS) has hit out at plans to remove €2.7bn from the €80bn budget of Horizon 2020 – the European Union’s main research funding programme – and use the money instead to help finance a new European Union economic-stimulus initiative. In a letter to European Commission president Jean-Claude Juncker – signed by EPS president John Dudley and EPS president-elect Christophe Rossel – it warns that ignoring the “importance of research and development as key drivers of prosperity is sending the wrong message to the scientific communities who are essential for Europe’s future”.

The economic-stimulus initiative – which was announced in December last year by Juncker and is officially called the European Fund for Strategic Investment (EFSI) – aims to bolster weaker European economic regions and boost employment. To fund the EFSI, the Horizon 2020 budget would be cut by €70m this year, €860m in 2016, €871m in 2017, €479m in 2018, €150m in 2019 and €270m in 2020. Among the biggest losers would be the European Institute of Innovation and Technology (EIT) in Budapest with total cuts of €350m, while the European Research Council (ERC), which gives grants to individual researchers, would have its funds slashed by €221m.

Official approval?

Juncker has sought to ease concerns among researchers by saying that the EFSI investments will also benefit research. While the European Commission has stated it would like the EFSI to become operational in the coming months, the plan still needs official approval from the European Parliament and the European Council. The EPS letter to Juncker, dated 16 February, does not directly ask Junker to reconsider his plan to divert Horizon 2020 money to the EFSI but hints at the political implications, noting that the EPS comprises 42 member societies spanning Europe and represents the interests of 130,000 physicists. “We urge you to send a clear signal to the scientific community of your continued commitment to supporting scientific research and co-operation in Europe,” the letter says.

The letter also highlights the benefits physics plays to the European economy by employing 15.4 million people across the continent in 2010 and generating €3800bn in turnover. The EPS is particularly concerned about cuts to the ERC budget, saying it would lead to the axing of as many as 150 ERC grants, which would remove funds for 150 European scientists. “This loss of support will lead to a decline in Europe’s capacity to attract top-rank researchers and compete on a global scale,” the letter states.

Protest proclamations

Several other scientific and academic organizations have also either written letters of protest to Juncker or issued public statements, including the European Association for Chemical and Molecular Sciences, the League of European Research Universities and the European University Association.

Rüdiger Voss, head of international relations at CERN, told physicsworld.com that the European Parliament “can only accept or reject the EFSI as a whole”, noting that it would be difficult to reduce or remove the specific cuts to Horizon 2020. “Science is the ultimate driver of innovation and economic development, with a much larger multiplicative effect than direct investments to stimulate the economy,” he says. “It may appear short-sighted to divert significant funds from Horizon 2020 to the EFSI.”

Ove Poulsen, a retired optical physicist at Aarhus University in Denmark who was president of the EPS from 2005 to 2007, says it is hard to gauge the potential negative effects of the cuts on physics research. “Noting the central role of the physical sciences in emerging technology development, in problem solving of a societal nature and a growing impact in future energy scenarios, the proposed cuts surely will be felt by the European physics community,” he says.

‘Golden stars’ pulsate in a strange, non-chaotic way

The first stars known to pulsate in a fractal manner have been discovered by physicists in the US and Germany. According to the researchers, the variable stars may be the first “strange non-chaotic attractors” seen outside the laboratory. The objects were found in data from the Kepler space telescope by looking for stars with two characteristic pulsation frequencies that have a “golden ratio” of approximately 1.62. The discovery could shed light on the physics that drives variable stars and also help astronomers come up with better classification systems for these objects.

A variable star dims and brightens as its size and sometimes its shape oscillates at one or more frequencies. Since it was launched in 2009, NASA’s Kepler mission has been a boon to astronomers studying variable stars because the telescope has been monitoring the brightness of more than 100,000 stars in its search for distant planets. However, John Learned of the University of Hawaii and Michael Hippke of the Institute for Data Analysis in Neukirchen-Vluyn in Germany noticed the first strange non-chaotic “golden star” when searching the Kepler data for evidence that advanced extraterrestrial civilizations modulate variable stars to communicate between galaxies.

Geometry of life and art

This star – called KIC 5520878 – is a type of periodic variable star known as an “RRc Lyrae” variable. It pulsates at a large number of frequencies that are all related to two frequencies – f1 and f2 – that have a golden ratio. The golden ratio or “golden mean” is an irrational number that has significance in geometry, biology and art. Its presence in a dynamical system can mean that the system behaves as a “strange non-chaotic attractor”. In this case, “strange” means that the system can be characterized as fractal, and “non-chaotic” means that the dynamics falls in the middle ground between order and chaos.

To study the dynamics of the star, Learned and Hippke joined forces with physicists at the University of Hawaii and the College of Wooster, including John Lindner. To verify that the star is indeed a strange non-chaotic attractor, the team did a “spectral scaling” analysis. First, the researchers did a Fourier transform of a time sequence of the brightness of the star that was acquired by Kepler over a four-year period, creating a power spectrum with peaks at a large number of frequencies. Then, they counted the number of peaks above a threshold value, repeating the process over a wide range of threshold values. Finally, they plotted the number of peaks above the threshold as a function of the threshold.

Norwegian link

They found that the number of peaks was pretty well constant until the threshold reached an inflection point (a point on a curve at which the sign of the curvature changes). When this occurred, the number dropped rapidly and obeyed a power law. According to the team, this behaviour is indicative of strange non-chaotic dynamics. Interestingly, Lindner points out that a similar analysis of the variability of the coastline of Norway yields the same power-law exponent of –1.5. The team also did an “attractor reconstruction”, whereby the time evolution of the brightness of the star is plotted. The researchers found the attractor to be a “warped torus” (see figure), which is indicative of a non-chaotic system defined by two frequencies and involving non-linear dynamics.

While several strange non-chaotic attractors have been created in the lab based on magnetic, electrochemical, electronic and atomic systems, Lindner and colleagues believe that KIC 5520878 is the first to be found in nature. The physicists then applied their analysis to three other RRc Lyrae variable stars that also have two frequencies with ratios close to the golden mean. They found exactly the same power-law relationship. Finally, they looked at two variable stars that have frequency ratios that are not the golden ratio – but rather are simple fractions – and found that these did not obey power laws.

Quasiperiodic instabilities

As well as offering astronomers a new way to classify variable stars, the strange non-chaotic nature of some stars could help scientists gain a better understanding of the physics underlying stellar pulsations. In a stable star the inward gravitational pressure is balanced by the outward pressure of light. In some regions of a star, however, an increase in temperature can make the star more opaque, thereby reducing the amount of light that can escape. This can cause a build-up of pressure that is relieved by the star expanding. It is this sort of instability that could be responsible for driving the pulsations in a non-linear manner involving two frequencies.

The team is now studying other variable stars that could be strange non-chaotic attractors, and Lindner points out that many RR Lyrae and Cepheids appear to have frequency ratios near the golden mean. “Currently, we suspect that the RRc Lyrae stars, a previously recognized subclass of about 9% of RR Lyraes, may all be golden and strange non-chaotic,” he says. He also says that an important open question is whether all golden-ratio stars exhibit strange non-chaotic behaviour.

The research is described in Physical Review Letters.

Physics World 2015 Focus on Medical Imaging now live

By Tami Freeman

Medical imaging is a multidisciplinary science encompassing a wide range of powerful techniques with applications in both patient care and fundamental biological studies. In this latest Physics World focus issue, we examine how imaging technologies such as X-ray computed tomography (CT), magnetic resonance imaging and other nuclear, ultrasound and optical imaging techniques have evolved in recent years. We also take a look at what improvements can be expected in the future.

Created in collaboration with our sister website medicalphysicsweb, the new focus issue on medical imaging can be accessed free of charge in digital-magazine format.

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