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Flash Physics: Opportunity Rover goes crater diving, new deputy director of US Department of Energy, underwater transistors

NASA’s Opportunity Rover to drive into crater and explore Mars gully

NASA’s Opportunity Mars Rover, which began yet another extended mission this month, will visit the interior of a crater on Mars and drive down an ancient gully carved out by a fluid (that may have been water) – a first for a Mars rover. Opportunity, which is the longest active rover on Mars, launched on 7 July 2003 and landed on Mars on 24 January 2004, on a planned mission of 90 Martian days, which is equivalent to 92.4 Earth days. “We have now exceeded the prime-mission duration by a factor of 50,” notes John Callas, Opportunity’s project manager. “Milestones like this are reminders of the historic achievements made possible by the dedicated people entrusted to build and operate this national asset for exploring Mars.” Opportunity began its latest extended mission in a part of the western rim of Endeavour Crater – the rover reached the edge of this crater in 2011 after more than seven years of investigating a series of smaller craters. The gully chosen as the next major destination slices west-to-east through the rim about half a kilometre south of the rover’s current location. The Opportunity team will drive the rover down the full length of the gully, onto the crater floor. The second goal of the extended mission is to compare rocks inside Endeavour Crater with the dominant type of rock Opportunity examined on the plains that it explored en route to the current spot.

Steve Binkley takes over as DOE deputy director as Patricia Dehmer retires

Steve Binkley has been appointed as the US Department of Energy’s deputy director for science as of this November, as the current director Patricia Dehmer will retire on 10 November. Binkley – who is currently head of the department’s Advanced Scientific Computing Research programme – will oversee six different research programmes including high-energy physics, nuclear physics, fusion-energy sciences and more, as well as evaluating existing and proposed new facilities. Dehmer has had a long and distinguished career at the department and during her time as the director of the DOE’s Office of Basic Energy Sciences she oversaw a doubling of the programme’s budget and $3bn in major construction projects, including the Spallation Neutron Source, the Linac Coherent Light Source, and the National Synchrotron Light Source II.

N-type electrochemical transistor works underwater

Schematic of the new n-type organic electrochemical transistor
Water proof: schematic of the new n-type organic electrochemical transistor showing the gold electrodes (yellow), parylene C (grey) and the neat polymer red. (Courtesy: Alexander Giovannitti/Nature Communications)

An n-type organic electrochemical transistor (OECT) that works underwater has been created by an international team of researchers. OECTs show great promise as biological sensors because they can convert ionic signals in liquid media into electronic signals. One challenge facing the development of practical sensing devices is that OECTs have been limited to being “p-type” devices based on electrical conduction by holes. If OECTs could also be based on n-type devices that use electrons to conduct electricity, then better and more versatile sensors could be created. The problem, however, is that n-type materials tend to be unstable in water. Now Alexander Giovannitti of Imperial College London and colleagues have created OECTs from a new semiconductor polymer that supports both n- and p-type conduction and is also stable in water. Giovannitti said that the new OECTs “might be able to detect abnormalities in sodium and potassium ion concentrations in the brain, responsible for neuron diseases such as epilepsy”. The OECTs are described in Nature Communications.

 

  • You can find all our daily Flash Physics posts in the website’s news section, as well as on Twitter and Facebook using #FlashPhysics. Tune in to physicsworld.com later today to read today’s extensive news story on a new type of high-resolution lens for microscopes.

The 2016 Physics World Focus on Neutron Science is out now

By Michael Banks

pwneut16cover-200Neutron scientists in Europe are facing a number of headwinds in the coming decade. One is the uncertainty caused by the recent UK vote to leave the European Union. Another is the impending closure of ageing reactors across the continent such as the Orphée reactor in Paris and the BER II reactor in Berlin, which could both shut down by 2020.

A recent report by an expert group of researchers – the Neutron Landscape Group – paints a worrying challenge for neutron scientists. It forecasts that the continent’s supply of neutrons could drop by as much as a half over the next decade – a shortfall in capacity that is unlikely to be met by the upcoming European Spallation Source in Lund, Sweden.

That said, there are plans to help overcome the impending neutron gap, including proposals to plug it by building compact, specialist sources. Improvements to accelerator technology and instruments could also help by boosting the number of usable neutrons. Scientists at the US Spallation Neutron Source, for example, are pioneering a method to improve its proton beam energy using plasma processing, while the National Institute of Standards and Technology’s world-leading neutron microscope will soon open up to users.

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The physics of Luke Cage’s skin, meet the 'mathekniticians', lessons from the only girl in a physics class

By Hamish Johnston

Marvel’s Luke Cage is a superhero television series that has just debuted on Netflix. Cage’s superpower is that his skin is impervious to bullets and other projectiles fired at him by villains. But could it be possible to create a skin-like layer that would allow someone to emerge unscathed from machine gun fire? The Nerdist’s Kyle Hill has the answer in the above video.

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Correlation between galaxy rotation and visible matter puzzles astronomers

A new study of the rotational velocities of stars in galaxies has revealed a strong correlation between the motion of the stars and the amount of visible mass in the galaxies. This result comes as a surprise because it is not predicted by conventional models of dark matter.

Stars on the outskirts of rotating galaxies orbit just as fast as those nearer the centre. This appears to be in violation of Newton’s laws, which predict that these outer stars would be flung away from their galaxies. The extra gravitational glue provided by dark matter is the conventional explanation for why these galaxies stay together. Today, our most cherished models of galaxy formation and cosmology rely entirely on the presence of dark matter, even though the substance has never been detected directly.

These new findings, from Stacy McGaugh and Federico Lelli of Case Western Reserve University, and James Schombert of the University of Oregon, threaten to shake things up. They measured the gravitational acceleration of stars in 153 galaxies with varying sizes, rotations and brightness, and found that the measured accelerations can be expressed as a relatively simple function of the visible matter within the galaxies. Such a correlation does not emerge from conventional dark-matter models.

Mass and light

This correlation relies strongly on the calculation of the mass-to-light ratio of the galaxies, from which the distribution of their visible mass and gravity is then determined. McGaugh attempted this measurement in 2002 using visible light data. However, these results were skewed by hot, massive stars that are millions of times more luminous than the Sun. This latest study is based on near-infrared data from the Spitzer Space Telescope. Since near-infrared light is emitted by the more common low-mass stars and red giants, it is a more accurate tracer for the overall stellar mass of a galaxy. Meanwhile, the mass of neutral hydrogen gas in the galaxies was provided by 21 cm radio-wavelength observations.

McGaugh told physicsworld.com that the team was “amazed by what we saw when Federico Lelli plotted the data.”

The result is confounding because galaxies are supposedly ensconced within dense haloes of dark matter. Furthermore, the team found a systematic deviation from Newtonian predictions, implying that there is some other force is at work beyond simple Newtonian gravity.

It’s an impressive demonstration of something, but I don’t know what that something is
James Binney, University of Oxford

“It’s an impressive demonstration of something, but I don’t know what that something is,” admits James Binney, a theoretical physicist at the University of Oxford, who was not involved in the study.

This systematic deviation from Newtonian mechanics was predicted more than 30 years ago by an alternate theory of gravity known as modified Newtonian dynamics (MOND). According to MOND’s inventor, Mordehai Milgrom of the Weizmann Institute in Israel, dark matter does not exist, and instead its effects can be explained by modifying how Newton’s laws of gravity operate over large distances.

“This was predicted in the very first MOND paper of 1983,” says Milgrom. “The MOND prediction is exactly what McGaugh has found, to a tee.”

However, Milgrom is unhappy that McGaugh hasn’t outright attributed his results to MOND, and suggests that there’s nothing intrinsically new in this latest study. “The data here are much better, which is very important, but this is really the only conceptual novelty in the paper,” says Milgrom.

No tweaking required

McGaugh disagrees with Milgrom’s assessment, saying that previous results had incorporated assumptions that tweak the data to get the desired result for MOND, whereas this time the mass-to-light ratio is accurate enough that no tweaking is required.

Furthermore, McGaugh says he is “trying to be open-minded”, by pointing out that exotic forms of dark matter like superfluid dark matter or even complex galactic dynamics could be consistent with the data. However, he also feels that there is implicit bias against MOND among members of the astronomical community.

“I have experienced time and again people dismissing the data because they think MOND is wrong, so I am very consciously drawing a red line between the theory and the data.”

Much of our current understanding of cosmology relies on cold dark matter, so could the result threaten our models of galaxy formation and large-scale structure in the universe? McGaugh thinks it could, but not everyone agrees.

Way too complex

Binney points out that dark-matter simulations struggle on the scale of individual galaxies because “the physics of galaxy formation is way too complex to compute properly,” he says, the implication being that it is currently impossible to say whether dark matter can explain these results or not. “It’s unfortunately beyond the powers of humankind at the moment to know.”

That leaves the battle between dark matter and alternate models of gravitation at an impasse. However, Binney points out that dark matter has an advantage because it can also be studied through observations of galaxy mergers and collisions between galaxy clusters. Also, there are many experiments that are currently searching for evidence of dark-matter particles.

McGaugh’s next step is to extend the study to elliptical and dwarf spheroidal galaxies, as well as to galaxies at greater distances from the Milky Way.

The research is to be published in Physical Review Letters and a preprint is available on arXiv.

Spotlight on the International Year of Light (IYL 2015)

As science-inspired global initiatives go, it’s fair to say that the International Year of Light and Light-based Technologies (IYL 2015) burned brighter than its organizers could have imagined. IYL 2015 set out to raise awareness of the crucial roles light can play in areas such as sustainable development, education and health, and it did so through festivals, workshops, publications and a plethora of other activities. A final report published this week details some of IYL 2015’s key achievements and describes some of the year’s most memorable activities.

Among the highlights identified in the report is the Physics World film series “Light in our Lives”, a set of short documentaries about the role of light in people’s everyday lives. We commissioned the films as an official IYL 2015 media partner, embracing the collaborative and international dimensions of the year by working with filmmakers across the world. They include a film about how LED lanterns are enabling students to study after sunset in a rural community in India, and another about how lighting technologies are bringing a modern twist to Day of the Dead celebrations in Mexico City.

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Flash Physics: Enhancing iron-based superconductors, gender disparity among ESO proposals, how to make ferroelectric water

Enhancing iron-based superconductors

A new method that doubles the amount of electrical current an iron-based material can carry without losing its superconducting properties – while also increasing the material’s critical temperature – has been developed by an international team of researchers based in the US and Japan. Iron-based superconductors can conduct electricity without resistance at relatively high temperatures (when compared with conventional superconductors, which must be chilled to near absolute zero to become superconducting). The researchers bombarded the material with protons at low energy, thereby simultaneously increasing its current-carrying capacity and critical temperature – a first for an iron-based superconductor, according to team-leader Qiang Li, at the US Department of Energy’s (DOE) Brookhaven National Laboratory. The researchers also used electron microscopes to view microstructural defects – which cause the lattice to locally compress or expand – that appeared in an iron-based superconducting material after the material was bombarded with low-energy protons. Their new technique could be used to improve the performance of superconducting wires and tapes. The research is published in Nature Communications.

Gender disparity found among ESO telescope-time proposals

Proposals submitted by female principal investigators for telescope time at European Southern Observatory (ESO) facilities are much less likely to be accepted than their male colleagues. A study carried out by Ferdinando Patat, an astronomer at ESO, looked at 13,000 proposals from about 3000 principal investigators over an eight-year span, finding that success rates were 16% for women and 22% for men. The study follows a recent finding that female postdoctoral-fellowship applicants at a US geoscience institution were half as likely as their male counterparts to receive glowing recommendation letters.

How to make ferroelectric water

Illustration of water molecules trapped in the mineral beryl
Spontaneous polarization: illustration of water molecules (in red and blue spheres) trapped in the mineral beryl. (Courtesy: B P Gorshunov/Nature Communications)

Water becomes ferroelectric when trapped in a solid, according to Martin Dressel and colleagues at the University of Stuttgart, the Moscow Institute of Physics and Technology and several other institutes in Russia and the Czech Republic. Water molecules have large electric-dipole moments and there are strong interactions between molecules. These properties could result in ferroelectric order in water, whereby the dipole moments of water molecules point in the same direction to create a spontaneous electric polarization. Normally, this does not happen because hydrogen bonding between water molecules screens dipole–dipole coupling and suppresses ferroelectric order. Now, Dressel and colleagues have created a ferroelectric material by trapping water molecules within tiny channels in the mineral beryl. The molecules are separated by 46 μm, which is far enough apart to suppress hydrogen bonding – but near enough for the dipole–dipole interaction to cause ferroelectric order at temperatures below about 10 K. Writing in Nature Communications, the team says the ferroelectricity of water molecules may play a key role in the functioning of biological systems and find applications in fuel and memory cells, light emitters and other nanoscale electronic devices”.

 

  • You can find all our daily Flash Physics posts in the website’s news section, as well as on Twitter and Facebook using #FlashPhysics. Tune in to physicsworld.com later today to read today’s extensive news story on galaxy rotation and the link to dark matter.

What is a topological metal?

Among the more familiar examples of topological materials are topological insulators and topological superconductors. In this video, Zahid Hasan of Princeton University in the US introduces the theory behind the first known example of a topological metal – a semi-metal containing quasiparticles known as Weyl fermions.

This video is part of our 100 Second Science series, in which researchers give concise presentations covering the spectrum of physics.

Gender bias found in recommendation letters

Female postdoctoral fellowship applicants are half as likely as their male counterparts to receive glowing recommendation letters, according to a study by researchers at Columbia University’s Lamont-Doherty Earth Observatory (LDEO). Led by Kuheli Dutt, assistant director of academic affairs and diversity at the observatory, the researchers also found that both male and female scientists tend to write stronger recommendation letters for men than for women. The findings add more evidence of implicit, or unconscious, bias that women are perceived as weaker in the sciences than men.

While previous studies have shown that those who evaluate applications for postdoctoral fellowships or other scientific positions tend to have implicit bias against women, the new study focuses on the other side of that application – the person writing a recommendation letter. The new analysis focused on geoscience research positions – and specifically postdoctoral-fellowship applications for positions at the LDEO. Dutt and colleagues analysed 1224 recommendation letters – redacted of personal information – that were written between 2007 and 2012 by 1101 researchers from 54 countries.

The researchers looked at the tone of each overall letter and classified it as either “excellent”, “good” or “doubtful”. Terms like “outstanding”, “genius” and “groundbreaking research” were classified as excellent letters, for example. To compile a “tone-terminology manual”, the researchers spoke to 18 senior scientists who either currently serve on or have in the past served on postdoctoral-fellowship selection committees.

Meaningful dialogue

Out of the 1224 letters, 862 were written for male applicants and 362 for female applicants. The researchers found that for male applicants, 24% were rated as excellent, 73% good and 3% doubtful. For letters for female applicants, 15% were excellent, 83% good and 2% doubtful. “We’re not assigning blame on anyone,” says Dutt. “Everyone has implicit biases. It’s more about using these results, and the fact that they’re consistent with implicit bias, to engage in meaningful dialogue or to open up conversations that would lead to rectifying the problem.”

Dutt and her colleagues acknowledge that they were unable to statistically rule out the possibility that male applicants may have been better qualified than females. “That being said, [the results] fit with the literature,” says physicist Zahra Hazari from Florida International University. “This is one of many studies that have found things of this ilk.”

Reflecting on beliefs

According to Hazari, who is a member of the American Physical Society’s Committee on the Status of Women in Physics and was not involved in the study, the findings “amplify the issue of gender bias” because it comes from both sides of the application process – from the recommender and the evaluator. “We can’t change the stereotypes or the views overnight,” says Hazari. “But what we can do is reflect on our own beliefs and how we’ve internalized the beliefs that are out there. By thinking about them, we can neutralize some of the effect.”

The work is published in Nature Geoscience.

Aspiring quantum physicists gather in Rome

Up and coming: Fulvio Flamini (left) and Mario Ciampini (right) with Alaina Levine. (Courtesy: Alaina Levine)

By Alaina Levine

Recently I had the pleasure of travelling to La Sapienza University of Rome, to serve as the keynote speaker for the first ever Young Italian Quantum Information Science Conference. I was invited as part of a visiting lectureship programme run by the International Society of Optics and Photonics (SPIE), which supports SPIE student chapters around the world by providing travel funds for speakers.

The conference was a satellite of the annual Italian Quantum Information Science Conference (IQIS) and involved 95 students and postdocs from Italy and beyond. The day-long event was a great opportunity for the up-and-comers of quantum information to shine – and their technical talks demonstrated their expertise and passion.

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Flash Physics: Vibrating iodine stars in molecular movies, Ukraine joins CERN, LIGO-India location chosen

Vibrating iodine stars in molecular movies

Real-time diffraction measurements of the changing structure of vibrating iodine molecules have been made by two independent groups of scientists. Phil Bucksbaum and colleagues at Stanford University and the SLAC National Accelerator Laboratory in California used X-ray diffraction to study the molecules, while Markus Gühr and colleagues at Potsdam University, the University of Nebraska and SLAC used electron diffraction. The X-ray experiment was done at SLAC’s Linac Coherent Light Source, which produces coherent X-ray pulses. The iodine molecules were first pumped with a laser pulse, putting some of the atoms in an excited vibrational state. The resultant X-ray diffraction pattern is of the molecule in its ground and excited state – and these two can be separated using mathematical manipulation. Gühr and colleagues did a similar experiment, but using electron pulses from a source also located at SLAC. In both cases, the researchers were able to track the vibrational motions of the atoms on time scales of tens of femtoseconds – essentially creating “molecular movies” of the motions. While measurements on similar timescales can be achieved using very short laser pulses, these studies relied on assumptions about the structure of the molecule – whereas the diffraction studies make no such assumptions. Both studies are described in Physical Review Letters.

Ukraine joins CERN as associate member

Ukraine has become an associate member of CERN following ratification from the country’s parliament. Ukraine and CERN first signed a co-operation agreement in 1993 and now more than 100 scientists from the country work at CERN, including on experiments at the lab’s Large Hadron Collider. Ukraine signed the associate-membership agreement with CERN on 3 October 2013, but it was not completely ratified until later last month. Associate members have no voting rights on CERN Council but take responsibility for a share of the annual budget for the lab – set at a lower limit of about $1m. Associate membership will enable scientists from Ukraine to work at CERN as well as allowing Ukrainian businesses to bid for CERN contracts.

LIGO-India location chosen

A map showing the global gravitational-wave observatory network
Across the globe: current operating facilities in the global gravitational-wave observatory network include the twin LIGO detectors – in Hanford, Washington, and Livingston, Louisiana – and GEO600 in Germany. The Virgo detector in Italy and the Kamioka Gravitational Wave Detector (KAGRA) in Japan are undergoing upgrades and are expected to begin operations in 2016 and 2018, respectively. LIGO-India has just received its first approval from the government. (Courtesy: LIGO)

The Indian arm of the Laser Interferometer Gravitational-wave Observatory – dubbed LIGO-India – will be built in the state of Maharashtra, at Dudhala village in Hingoli district. The announcement came on Tuesday this week after the State Cabinet agreed to hand over 40.68 hectares of government-owned land to the Department of Atomic Energy to build the cutting-edge observatory, according to a report in The Hindu. India’s Union Cabinet gave its “in-principle” approval for such an observatory to be built in the country in February this year, soon after the announcement of the first direct detection of gravitational waves was made by researchers working on the Advanced Laser Interferometer Gravitational-wave Observatory (aLIGO) in the US. The Indian Initiative in Gravitational-wave Observations (IndIGO) has been a member of the international LIGO collaboration since 2011. Once built, LIGO-India will join the global network of LIGO observatories, which currently includes the US, Germany, Italy and Japan.

 

  • You can find all our daily Flash Physics posts in the website’s news section, as well as on Twitter and Facebook using #FlashPhysics. Tune in to physicsworld.com later today to read today’s extensive news story on a gender bias study in geoscience.
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