Tag Archives: physics

The mathematics of Disney’s ‘Moana’

The hit Disney movie “Moana” features stunning visual effects, including the animation of water to such a degree that it becomes a distinct character in the film. Courtesy of Walt Disney Animation Studios

Few people think to marvel over the mathematics when watching an animated feature but without mathematicians, the artists would not be able to achieve their artistic goals as a Jan. 4, 2017 news item on phys.org makes clear (Note: A link has been removed),

UCLA [University of California at Los Angeles] mathematics professor Joseph Teran, a Walt Disney consultant on animated movies since 2007, is under no illusion that artists want lengthy mathematics lessons, but many of them realize that the success of animated movies often depends on advanced mathematics.

“In general, the animators and artists at the studios want as little to do with mathematics and physics as possible, but the demands for realism in animated movies are so high,” Teran said. “Things are going to look fake if you don’t at least start with the correct physics and mathematics for many materials, such as water and snow. If the physics and mathematics are not simulated accurately, it will be very glaring that something is wrong with the animation of the material.”

Teran and his research team have helped infuse realism into several Disney movies, including “Frozen,” where they used science to animate snow scenes. Most recently, they applied their knowledge of math, physics and computer science to enliven the new 3-D computer-animated hit, “Moana,” a tale about an adventurous teenage girl who is drawn to the ocean and is inspired to leave the safety of her island on a daring journey to save her people.

A Jan. 3, 2017 UCLA news release, which originated the news item, explains in further nontechnical detail,

Alexey Stomakhin, a former UCLA doctoral student of Teran’s and Andrea Bertozzi’s, played an important role in the making of “Moana.” After earning his Ph.D. in applied mathematics in 2013, he became a senior software engineer at Walt Disney Animation Studios. Working with Disney’s effects artists, technical directors and software developers, Stomakhin led the development of the code that was used to simulate the movement of water in “Moana,” enabling it to play a role as one of the characters in the film.

“The increased demand for realism and complexity in animated movies makes it preferable to get assistance from computers; this means we have to simulate the movement of the ocean surface and how the water splashes, for example, to make it look believable,” Stomakhin explained. “There is a lot of mathematics, physics and computer science under the hood. That’s what we do.”

“Moana” has been praised for its stunning visual effects in words the mathematicians love hearing. “Everything in the movie looks almost real, so the movement of the water has to look real too, and it does,” Teran said. “’Moana’ has the best water effects I’ve ever seen, by far.”

Stomakhin said his job is fun and “super-interesting, especially when we cheat physics and step beyond physics. It’s almost like building your own universe with your own laws of physics and trying to simulate that universe.

“Disney movies are about magic, so magical things happen which do not exist in the real world,” said the software engineer. “It’s our job to add some extra forces and other tricks to help create those effects. If you have an understanding of how the real physical laws work, you can push parameters beyond physical limits and change equations slightly; we can predict the consequences of that.”

To make animated movies these days, movie studios need to solve, or nearly solve, partial differential equations. Stomakhin, Teran and their colleagues build the code that solves the partial differential equations. More accurately, they write algorithms that closely approximate the partial differential equations because they cannot be solved perfectly. “We try to come up with new algorithms that have the highest-quality metrics in all possible categories, including preserving angular momentum perfectly and preserving energy perfectly. Many algorithms don’t have these properties,” Teran said.

Stomakhin was also involved in creating the ocean’s crashing waves that have to break at a certain place and time. That task required him to get creative with physics and use other tricks. “You don’t allow physics to completely guide it,” he said.  “You allow the wave to break only when it needs to break.”

Depicting boats on waves posed additional challenges for the scientists.

“It’s easy to simulate a boat traveling through a static lake, but a boat on waves is much more challenging to simulate,” Stomakhin said. “We simulated the fluid around the boat; the challenge was to blend that fluid with the rest of the ocean. It can’t look like the boat is splashing in a little swimming pool — the blend needs to be seamless.”

Stomakhin spent more than a year developing the code and understanding the physics that allowed him to achieve this effect.

“It’s nice to see the great visual effect, something you couldn’t have achieved if you hadn’t designed the algorithm to solve physics accurately,” said Teran, who has taught an undergraduate course on scientific computing for the visual-effects industry.

While Teran loves spectacular visual effects, he said the research has many other scientific applications as well. It could be used to simulate plasmas, simulate 3-D printing or for surgical simulation, for example. Teran is using a related algorithm to build virtual livers to substitute for the animal livers that surgeons train on. He is also using the algorithm to study traumatic leg injuries.

Teran describes the work with Disney as “bread-and-butter, high-performance computing for simulating materials, as mechanical engineers and physicists at national laboratories would. Simulating water for a movie is not so different, but there are, of course, small tweaks to make the water visually compelling. We don’t have a separate branch of research for computer graphics. We create new algorithms that work for simulating wide ranges of materials.”

Teran, Stomakhin and three other applied mathematicians — Chenfanfu Jiang, Craig Schroeder and Andrew Selle — also developed a state-of-the-art simulation method for fluids in graphics, called APIC, based on months of calculations. It allows for better realism and stunning visual results. Jiang is a UCLA postdoctoral scholar in Teran’s laboratory, who won a 2015 UCLA best dissertation prize.  Schroeder is a former UCLA postdoctoral scholar who worked with Teran and is now at UC Riverside. Selle, who worked at Walt Disney Animation Studios, is now at Google.

Their newest version of APIC has been accepted for publication by the peer-reviewed Journal of Computational Physics.

“Alexey is using ideas from high-performance computing to make movies,” Teran said, “and we are contributing to the scientific community by improving the algorithm.”

Unfortunately, the paper does not seem to have been published early online so I cannot offer a link.

Final comment, it would have been interesting to have had a comment from one of the film’s artists or animators included in the article but it may not have been possible due to time or space constraints.

Atomic force microscope with nanowire sensors

Measuring the size and direction of forces may become reality with a nanotechnology-enabled atomic force microscope designed by Swiss scientists, according to an Oct. 17, 2016 news item on phys.org,

A new type of atomic force microscope (AFM) uses nanowires as tiny sensors. Unlike standard AFM, the device with a nanowire sensor enables measurements of both the size and direction of forces. Physicists at the University of Basel and at the EPF Lausanne have described these results in the recent issue of Nature Nanotechnology.

A nanowire sensor measures size and direction of forces (Image: University of Basel, Department of Physics)

A nanowire sensor measures size and direction of forces (Image: University of Basel, Department of Physics)

An Oct. 17, 2016 University of Basel press release (also on EurekAlert), which originated the news item, expands on the theme,

Nanowires are extremely tiny filamentary crystals which are built-up molecule by molecule from various materials and which are now being very actively studied by scientists all around the world because of their exceptional properties.

The wires normally have a diameter of 100 nanometers and therefore possess only about one thousandth of a hair thickness. Because of this tiny dimension, they have a very large surface in comparison to their volume. This fact, their small mass and flawless crystal lattice make them very attractive in a variety of nanometer-scale sensing applications, including as sensors of biological and chemical samples, and as pressure or charge sensors.

Measurement of direction and size

The team of Argovia Professor Martino Poggio from the Swiss Nanoscience Institute (SNI) and the Department of Physics at the University of Basel has now demonstrated that nanowires can also be used as force sensors in atomic force microscopes. Based on their special mechanical properties, nanowires vibrate along two perpendicular axes at nearly the same frequency. When they are integrated into an AFM, the researchers can measure changes in the perpendicular vibrations caused by different forces. Essentially, they use the nanowires like tiny mechanical compasses that point out both the direction and size of the surrounding forces.

Image of the two-dimensional force field

The scientists from Basel describe how they imaged a patterned sample surface using a nanowire sensor. Together with colleagues from the EPF Lausanne, who grew the nanowires, they mapped the two-dimensional force field above the sample surface using their nanowire “compass”. As a proof-of-principle, they also mapped out test force fields produced by tiny electrodes.

The most challenging technical aspect of the experiments was the realization of an apparatus that could simultaneously scan a nanowire above a surface and monitor its vibration along two perpendicular directions. With their study, the scientists have demonstrated a new type of AFM that could extend the technique’s numerous applications even further.

AFM – today widely used

The development of AFM 30 years ago was honored with the conferment of the Kavli-Prize [2016 Kavli Prize in Nanoscience] beginning of September this year. Professor Christoph Gerber of the SNI and Department of Physics at the University of Basel is one of the awardees, who has substantially contributed to the wide use of AFM in different fields, including solid-state physics, materials science, biology, and medicine.

The various different types of AFM are most often carried out using cantilevers made from crystalline Si as the mechanical sensor. “Moving to much smaller nanowire sensors may now allow for even further improvements on an already amazingly successful technique”, Martino Poggio comments his approach.

I featured an interview article with Christoph Gerber and Gerd Binnig about their shared Kavli prize and about inventing the AFM in a Sept. 20, 2016 posting.

As for the latest innovation, here’s a link to and a citation for the paper,

Vectorial scanning force microscopy using a nanowire sensor by Nicola Rossi, Floris R. Braakman, Davide Cadeddu, Denis Vasyukov, Gözde Tütüncüoglu, Anna Fontcuberta i Morral, & Martino Poggio. Nature Nanotechnology (2016) doi:10.1038/nnano.2016.189 Published online 17 October 2016

This paper is behind a paywall.

Replicating brain’s neural networks with 3D nanoprinting

An announcement about European Union funding for a project to reproduce neural networks by 3D nanoprinting can be found in a June 10, 2016 news item on Nanowerk,

The MESO-BRAIN consortium has received a prestigious award of €3.3million in funding from the European Commission as part of its Future and Emerging Technology (FET) scheme. The project aims to develop three-dimensional (3D) human neural networks with specific biological architecture, and the inherent ability to interrogate the network’s brain-like activity both electrophysiologically and optically. It is expected that the MESO-BRAIN will facilitate a better understanding of human disease progression, neuronal growth and enable the development of large-scale human cell-based assays to test the modulatory effects of pharmacological and toxicological compounds on neural network activity. The use of more physiologically relevant human models will increase drug screening efficiency and reduce the need for animal testing.

A June 9, 2016 Institute of Photonic Sciences (ICFO) press release (also on EurekAlert), which originated the news item, provides more detail,

About the MESO-BRAIN project

The MESO-BRAIN project’s cornerstone will use human induced pluripotent stem cells (iPSCs) that have been differentiated into neurons upon a defined and reproducible 3D scaffold to support the development of human neural networks that emulate brain activity. The structure will be based on a brain cortical module and will be unique in that it will be designed and produced using nanoscale 3D-laser-printed structures incorporating nano-electrodes to enable downstream electrophysiological analysis of neural network function. Optical analysis will be conducted using cutting-edge light sheet-based, fast volumetric imaging technology to enable cellular resolution throughout the 3D network. The MESO-BRAIN project will allow for a comprehensive and detailed investigation of neural network development in health and disease.

Prof Edik Rafailov, Head of the MESO-BRAIN project (Aston University) said: “What we’re proposing to achieve with this project has, until recently, been the stuff of science fiction. Being able to extract and replicate neural networks from the brain through 3D nanoprinting promises to change this. The MESO-BRAIN project has the potential to revolutionise the way we are able to understand the onset and development of disease and discover treatments for those with dementia or brain injuries. We cannot wait to get started!”

The MESO-BRAIN project will launch in September 2016 and research will be conducted over three years.

About the MESO-BRAIN consortium

Each of the consortium partners have been chosen for the highly specific skills & knowledge that they bring to this project. These include technologies and expertise in stem cells, photonics, physics, 3D nanoprinting, electrophysiology, molecular biology, imaging and commercialisation.

Aston University (UK) Aston Institute of Photonic Technologies (School of Engineering and Applied Science) is one of the largest photonic groups in UK and an internationally recognised research centre in the fields of lasers, fibre-optics, high-speed optical communications, nonlinear and biomedical photonics. The Cell & Tissue Biomedical Research Group (Aston Research Centre for Healthy Ageing) combines collective expertise in genetic manipulation, tissue engineering and neuronal modelling with the electrophysiological and optical analysis of human iPSC-derived neural networks. Axol Bioscience Ltd. (UK) was founded to fulfil the unmet demand for high quality, clinically relevant human iPSC-derived cells for use in biomedical research and drug discovery. The Laser Zentrum Hannover (Germany) is a leading research organisation in the fields of laser development, material processing, laser medicine, and laser-based nanotechnologies. The Neurophysics Group (Physics Department) at University of Barcelona (Spain) are experts in combing experiments with theoretical and computational modelling to infer functional connectivity in neuronal circuits. The Institute of Photonic Sciences (ICFO) (Spain) is a world-leading research centre in photonics with expertise in several microscopy techniques including light sheet imaging. KITE Innovation (UK) helps to bridge the gap between the academic and business sectors in supporting collaboration, enterprise, and knowledge-based business development.

For anyone curious about the FET funding scheme, there’s this from the press release,

Horizon 2020 aims to ensure Europe produces world-class science by removing barriers to innovation through funding programmes such as the FET. The FET (Open) funds forward-looking collaborations between advanced multidisciplinary science and cutting-edge engineering for radically new future technologies. The published success rate is below 1.4%, making it amongst the toughest in the Horizon 2020 suite of funding schemes. The MESO-BRAIN proposal scored a perfect 5/5.

You can find out more about the MESO-BRAIN project on its ICFO webpage.

They don’t say anything about it but I can’t help wondering if the scientists aren’t also considering the possibility of creating an artificial brain.

Babies have more general physics knowledge than experts realized

A Feb. 10, 2016 news item on ScienceDaily sheds some light on babies and their knowledge of physics,

We are born with a basic grasp of physics, just enough not to be surprised when we interact with objects. Scientists discovered this in the past two decades. What they did not know yet was that, as early as five months of age, this ‘naive’ physics also extends to liquids and materials that do not behave like solids (for example, sand), as demonstrated by a new study.

A Feb. 10, 2016 SISSA (International School of Advanced Studies) press release (also on EurekAlert), which originated the news item, describes the conclusions and the research in more detail,

If we hold a ball and then let go of it and the ball remains suspended in mid-air, even a baby a few months old will be surprised. Just like an adult, the baby expects the ball to fall to the floor. Even at such a young age humans already have some rudimentary knowledge of the behaviour of solids. Now a new study extends this knowledge to add liquids and other non-solids to the “naïve physics” of infants.

“This new study developed out of previous experiments”, explains Alissa Ferry, SISSA research scientist and among the authors of the paper, “in which we observed that infants were surprised when a liquid failed to behave as a liquid (in those experiments we “cheated” by disguising solids as liquids)”. Their surprise, explains Ferry, demonstrates that their expectations for a liquid had not been met. “However, what we couldn’t establish was whether the infants knew how a liquid should behave or whether they just expected it to be different from a solid”.

Ferry and colleagues (the first author is Susan Hespos of Northwestern University in Illinois, USA, where the experiments were conducted) therefore devised a new set of tests with a greater range of materials and “interactions”. In a first “habituation” phase, the infants were shown the contents of a glass by tilting the glass in front of them. The glass either contained a solid (which, when not moving, had identical appearance to water) or some water. When the glass was tilted back and forth, the two materials behaved differently: the solid remained perfectly still whereas the water moved. This phase served to teach the infants whether they were looking at a solid or a liquid.

Next, the infants were shown an identical glass to the one seen in the previous phase (making them believe that it was the same glass) which contained either the material they had already seen or the other material. At this point, the infants watched the experimenter either pour the contents (liquid or solid) of the glass into another glass containing a grid or submerge the grid in the liquid (or rest it on top of the solid) inside the glass.

“In the previous experiments we merely poured the contents of the glass. This time we added a grid to find out whether the infants really understood the loose cohesiveness of liquids, which can pass through a perforated surface and recompose in the vessel unlike solids which, being highly cohesive, cannot pass through a grid” explains Ferry.

In the habituation phase, in fact, the infants could know how liquids change shape with movement, but it was unknown if they could use this knowledge to understand other properties of liquids, like loose cohesiveness. “If infants understand the properties of liquids, then they should be surprised when, what they think is a liquid gets trapped on a grid”.

And the analysis of the infants’ behaviour shows that when they expected a liquid they were surprised to see it blocked by the grid (or see the grid unable to penetrate the material). Conversely, if they thought they were looking at a solid, then they were surprised when they saw it pass through the grid.

The investigators also used other materials like sand and small glass spheres. “Even in these cases the infants showed that they knew the behaviour of substances”, concludes Ferry. “This is especially interesting because, while we can imagine that 5-month-old infants already have had extensive direct experience with liquids and especially water through meals, baths and 9 months in the amniotic liquid, it’s unlikely that they’ve had many encounters with sand or glass balls, suggesting that infants have a naïve understanding of the physics of nonsolid substances”.

Here’s a link to and a citation for the paper,

Five-Month-Old Infants Have General Knowledge of How Nonsolid Substances Behave and Interact by Susan J. Hespos, Alissa L. Ferry, Erin M. Anderson, Emily N. Hollenbeck, anb Lance J. Rips. Psychological Science February 2016 vol. 27 no. 2 244-256 doi: 10.1177/0956797615617897 Published online: January 7, 2016

This paper is behind a paywall.

Creating new manufacturing technologies with photonic sintering

There’s a nice of explanation of nanoparticle sintering, a process which is central to producing new materials, according to a Dec. 1, 2015 Oregon State University (OSU) news release (also on EurekAlert),

Engineers at Oregon State University have made a fundamental breakthrough in understanding the physics of photonic “sintering,” which could lead to many new advances in solar cells, flexible electronics, various types of sensors and other high-tech products printed onto something as simple as a sheet of paper or plastic.

Sintering is the fusing of nanoparticles to form a solid, functional thin-film that can be used for many purposes, and the process could have considerable value for new technologies.

Photonic sintering has the possible advantage of higher speed and lower cost, compared to other technologies for nanoparticle sintering.

The news release goes on to provide some technical details and information about commercialization efforts,

In the new research, OSU experts discovered that previous approaches to understand and control photonic sintering had been based on a flawed view of the basic physics involved, which had led to a gross overestimation of product quality and process efficiency.

Based on the new perspective of this process, which has been outlined in Nature Scientific Reports, researchers now believe they can create high quality products at much lower temperatures, at least twice as fast and with 10 times more energy efficiency.

Removing constraints on production temperatures, speed and cost, the researchers say, should allow the creation of many new high-tech products printed onto substrates as cheap as paper or plastic wrap.

“Photonic sintering is one way to deposit nanoparticles in a controlled way and then join them together, and it’s been of significant interest,” said Rajiv Malhotra, an assistant professor of mechanical engineering in the OSU College of Engineering. “Until now, however, we didn’t really understand the underlying physics of what was going on. It was thought, for instance, that temperature change and the degree of fusion weren’t related – but in fact that matters a lot.”

With the concepts outlined in the new study, the door is open to precise control of temperature with smaller nanoparticle sizes. This allows increased speed of the process and high quality production at temperatures at least two times lower than before. An inherent “self-damping” effect was identified that has a major impact on obtaining the desired quality of the finished film.

“Lower temperature is a real key,” Malhotra said. “To lower costs, we want to print these nanotech products on things like paper and plastic, which would burn or melt at higher temperatures. We now know that is possible, and how to do it. We should be able to create production processes that are both fast and cheap, without a loss of quality.”

Products that could evolve from the research, Malhotra said, include solar cells, gas sensors, radiofrequency identification tags, and a wide range of flexible electronics. Wearable biomedical sensors could emerge, along with new sensing devices for environmental applications.

In this technology, light from a xenon lamp can be broadcast over comparatively large areas to fuse nanoparticles into functional thin films, much faster than with conventional thermal methods. It should be possible to scale up the process to large manufacturing levels for industrial use.

This advance was made possible by a four-year, $1.5 million National Science Foundation Scalable Nanomanufacturing Grant, which focuses on transcending the scientific barriers to industry-level production of nanomaterials. Collaborators at OSU include Chih-hung Chang, Alan Wang and Greg Herman.

OSU researchers will work with two manufacturers in private industry to create a proof-of-concept facility in the laboratory, as the next step in bringing this technology toward commercial production.

Here’s a link to and a citation for the paper,

On the self-damping nature of densification in photonic sintering of nanoparticles by William MacNeill, Chang-Ho Choi, Chih-Hung Chang, & Rajiv Malhotra.  Scientific Reports 5, Article number: 14845 (2015)  doi:10.1038/srep14845 Published online: 07 October 2015

This is an open access paper.

Access (virtual) to a quantum lab for everybody

I love the idea behind this project “find a way to make research equipment available to everyone” and that’s what the researchers at the University of Vienna (Austria) hope they have achieved according to a Sept. 16, 2015 University of Vienna press release (also on EurekAlert),

Topical research experiments are often too expensive or too complex to be rebuilt and incorporated in teaching. How can one, nevertheless, make modern science accessible to the public? This challenge was tackled in the research group Quantum Nanophysics led by Markus Arndt at the University of Vienna. For the first time, two research laboratories were created as complete, photorealistic computer simulations allowing university and high-school students as well as the general public to virtually access unique instruments. “One could describe it as a flight simulator of quantum physics”, says Mathias Tomandl who designed and implemented the essential elements of the simulation in the course of his PhD studies.

The press release goes on to describe the process for using the laboratory and some real life events promoting the lab,

A learning path guides the visitors of the virtual quantum lab through the world of delocalized complex molecules. A series of lab tasks and essential background information on the experiments enable the visitors to gradually immerse into the quantum world. The engaging software was developed together with university and high-school students and was fine-tuned by periodic didactic input. The teaching concept and the accompanying studies have now been published in the renowned scientific journal Scientific Reports.

Wave-particle dualism with large molecules

The virtual laboratories provide an insight into the fundamental understanding and into the applications of quantum mechanics with macromolecules and nanoparticles. In recent years, the real-life versions of the experiments verified the wave-particle dualism with the most complex molecules to date. Now, everyone can conduct these experiments in the virtual lab for the first time.

The quantum lab on tour through Austria

Currrently, a light version of the virtual lab can be experienced as an interactive exhibit in the special exhibition “Das Wissen der Dinge” in the Natural History Museum Vienna. In the travelling exhibition “Wirkungswechsel” of the Science-Center-Netzwerk the exhibit will be available at various locations throughout Austria.

Here’s a video produced by the researchers to demonstrate their virtual quantum lab,

For more information about the exhibitions,

Special exhibition “Das Wissen der Dinge”: http://www.nhm-wien.ac.at/ausstellung/sonderausstellungen/das_wissen_der_dinge_1

Travelling exhibition “Wirkungswechsel”: http://www.wirkungswechsel.at/

Here’s a link to and a citation for the paper,

Simulated Interactive Research Experiments as Educational Tools for Advanced Science by Mathias Tomandl, Thomas Mieling, Christiane M. Losert-Valiente Kroon, Martin Hopf, & Markus Arndt. Scientific Reports 5, Article number: 14108 (2015) doi:10.1038/srep14108 Published online: 15 September 2015

This paper is open access.

Complex networks to provide ‘grand unified theory’

Trying to mesh classical physics and quantum physics together in one theory which accounts for behaviour on the macro and quantum scales has occupied scientists for decades and it seems that mathematicians have discovered a clue so solving the mystery. A Sept. 13, 2015 news item on Nanotechnology Now describes the findings,

Mathematicians investigating one of science’s great questions — how to unite the physics of the very big with that of the very small — have discovered that when the understanding of complex networks such as the brain or the Internet is applied to geometry the results match up with quantum behavior.

A Sept. 9, 2015 Queen Mary University of London press release, which originated the news item, describes the collaboration between Queen Mary and Karlsruhe Institute of Technology mathematicians,

The findings, published today (Thursday) in Scientific Reports, by researchers from Queen Mary University of London and Karlsruhe Institute of Technology, could explain one of the great problems in modern physics.

Currently ideas of gravity, developed by Einstein and Newton, explain how physics operates on a very large scale, but do not work at the sub-atomic level. Conversely, quantum mechanics works on the very small scale but does not explain the interactions of larger objects like stars. Scientists are looking for a so called ‘grand unified theory’ that joins the two, known as quantum gravity.

Several models have been proposed for how different quantum spaces are linked but most assume that the links between quantum spaces are fairly uniform, with little deviation from the average number of links between each space. The new model, which applies ideas from the theory of complex networks, has found that some quantum spaces might actually include hubs, i.e. nodes with significantly more links than others, like a particularly popular Facebook user.

Calculations run with this model show that these spaces are described by well-known quantum Fermi-Dirac, and Bose-Einstein statistics, used in quantum mechanics, indicating that they could be useful to physicists working on quantum gravity.

Dr Ginestra Bianconi, from Queen Mary University of London, and lead author of the paper, said:

“We hope that by applying our understanding of complex networks to one of the fundamental questions in physics we might be able to help explain how discrete quantum spaces emerge.

“What we can see is that space-time at the quantum-scale might be networked in a very similar way to things we are starting to understand very well like biological networks in cells, our brains and online social networks.”

Here’s a link to and a citation for the paper,

Complex Quantum Network Manifolds in Dimension d > 2 are Scale-Free by Ginestra Bianconi & Christoph Rahmede. Scientific Reports 5, Article number: 13979 (2015) doi:10.1038/srep13979 Published online: 10 September 2015

This is an open access paper.

US National Institute of Standards and Technology and molecules made of light (lightsabres anyone?)

As I recall, lightsabres are a Star Wars invention. I gather we’re a long way from running around with lightsabres  but there is hope, if that should be your dream, according to a Sept. 9, 2015 news item on Nanowerk,

… a team including theoretical physicists from JQI [Joint Quantum Institute] and NIST [US National Institute of Stnadards and Technology] has taken another step toward building objects out of photons, and the findings hint that weightless particles of light can be joined into a sort of “molecule” with its own peculiar force.

Here’s an artist’s conception of the light “molecule” provided by the researchers,

Researchers show that two photons, depicted in this artist’s conception as waves (left and right), can be locked together at a short distance. Under certain conditions, the photons can form a state resembling a two-atom molecule, represented as the blue dumbbell shape at center. Credit: E. Edwards/JQI

Researchers show that two photons, depicted in this artist’s conception as waves (left and right), can be locked together at a short distance. Under certain conditions, the photons can form a state resembling a two-atom molecule, represented as the blue dumbbell shape at center. Credit: E. Edwards/JQI

A Sept. 8, 2015 NIST news release (also available on EurekAlert*), which originated the news item, provides more information about the research (Note: Links have been removed),

The findings build on previous research that several team members contributed to before joining NIST. In 2013, collaborators from Harvard, Caltech and MIT found a way to bind two photons together so that one would sit right atop the other, superimposed as they travel. Their experimental demonstration was considered a breakthrough, because no one had ever constructed anything by combining individual photons—inspiring some to imagine that real-life lightsabers were just around the corner.

Now, in a paper forthcoming in Physical Review Letters, the NIST and University of Maryland-based team (with other collaborators) has showed theoretically that by tweaking a few parameters of the binding process, photons could travel side by side, a specific distance from each other. The arrangement is akin to the way that two hydrogen atoms sit next to each other in a hydrogen molecule.

“It’s not a molecule per se, but you can imagine it as having a similar kind of structure,” says NIST’s Alexey Gorshkov. “We’re learning how to build complex states of light that, in turn, can be built into more complex objects. This is the first time anyone has shown how to bind two photons a finite distance apart.”

While the new findings appear to be a step in the right direction—if we can build a molecule of light, why not a sword?—Gorshkov says he is not optimistic that Jedi Knights will be lining up at NIST’s gift shop anytime soon. The main reason is that binding photons requires extreme conditions difficult to produce with a roomful of lab equipment, let alone fit into a sword’s handle. Still, there are plenty of other reasons to make molecular light—humbler than lightsabers, but useful nonetheless.

“Lots of modern technologies are based on light, from communication technology to high-definition imaging,” Gorshkov says. “Many of them would be greatly improved if we could engineer interactions between photons.”

For example, engineers need a way to precisely calibrate light sensors, and Gorshkov says the findings could make it far easier to create a “standard candle” that shines a precise number of photons at a detector. Perhaps more significant to industry, binding and entangling photons could allow computers to use photons as information processors, a job that electronic switches in your computer do today.

Not only would this provide a new basis for creating computer technology, but it also could result in substantial energy savings. Phone messages and other data that currently travel as light beams through fiber optic cables has to be converted into electrons for processing—an inefficient step that wastes a great deal of electricity. If both the transport and the processing of the data could be done with photons directly, it could reduce these energy losses.

Gorshkov says it will be important to test the new theory in practice for these and other potential benefits.

“It’s a cool new way to study photons,” he says. “They’re massless and fly at the speed of light. Slowing them down and binding them may show us other things we didn’t know about them before.”

Here are links and citations for the paper. First, there’s an early version on arXiv.org and, then, there’s the peer-reviewed version, which is not yet available,

Coulomb bound states of strongly interacting photons by M. F. Maghrebi, M. J. Gullans, P. Bienias, S. Choi, I. Martin, O. Firstenberg, M. D. Lukin, H. P. Büchler, A. V. Gorshkov.      arXiv:1505.03859 [quant-ph] (or arXiv:1505.03859v1 [quant-ph] for this version)

Coulomb bound states of strongly interacting photons by M. F. Maghrebi, M. J. Gullans, P. Bienias, S. Choi, I. Martin, O. Firstenberg, M. D. Lukin, H. P. Büchler, and A. V. Gorshkov.
Phys. Rev. Lett. forthcoming in September 2015.

The first version (arXiv) is open access and I’m not sure whether or not the Physical review Letters study will be behind a paywall or be available as an open access paper.

*EurekAlert link added 10:34 am PST on Sept. 11, 2015.

Convergence at Canada’s Perimeter Institute: art/science and physics

It’s a cornucopia of convergence at Canada’s Perimeter Institute (PI). First, there’s a June 16, 2015 posting by Colin Hunter about converging art and science in the person of Alioscia Hamma,

In his professional life, Hamma is a lecturer in the Perimeter Scholars International (PSI) program and an Associate Professor at China’s Tsinghua University. His research seeks new insights into quantum entanglement, quantum statistical mechanics, and other aspects of the fundamental nature of reality.

Though he dreamed during his boyhood in Naples of one day becoming a comic book artist, he pursued physics because he believed – still believes – it is our most reliable tool for decoding our universe.

“Mathematics is ideal, clean, pure, and meaningless. Natural sciences are living, concrete, dirty, and meaningful. Physics is right in the middle, like the human condition,” says Hamma.

Art too, he says, resides in the middle ground between the world of ideals and the world as it presents itself to our senses.

So he draws. …

Perimeter Institute has provided a video where Hamma shares his ideas,

This is very romantic as in literature-romantic. If I remember rightly, ‘truth is beauty and beauty is truth’ was the motto of the romantic poets, Byron, Keats, and Shelley. It’s intriguing to hear similar ideas being applied to physics, philosophy, and art.

H/t to Speaking Up For Canadian Science regarding this second ‘convergence at PI‘. From the Convergence conference page on the Perimeter Institute website,

Convergence is Perimeter’s first-ever alumni reunion and a new kind of physics conference providing a “big picture” overview of fundamental physics and its future.

Physics is at a turning point. The most sophisticated experiments ever devised are decoding our universe with unprecedented clarity — from the quantum to the cosmos — and revealing a stunning simplicity that theory has yet to explain.

Convergence will bring together many of the world’s best minds in physics to probe the field’s most exciting ideas and chart a course for 21st century physics. The event will also celebrate, through commemorative lectures, the centenaries of two defining discoveries of the 20th century: Noether’s theorem and Einstein’s theory of general relativity.

Converge with us June 20-24. [Registration is now closed]

Despite registration being closed it is still possible to attend online,


Whether you’re at Convergence in person or joining us online, there are many ways to join the conversation:

You can find PI’s Convergence blog here.

A May 27, 2015 presentation on Bruno Pontecorvo in Vancouver (Canada)

A movie about Bruno Pontecorvo (a mover and shaker in the world of neutrino physics) is being hosted by ARPICO (Society of Italian Researchers and Professionals in Western Canada) on Wednesday, May 27, 2015. From a May 12, 2015 ARPICO announcement,

Maksimovic – The story of Bruno Pontecorvo

Prof. Samoil Bilenky will introduce a short movie on the life of Bruno Pontecorvo.

The movie will trace the main points of Bruno Pontecorvo’s life, a nuclear physicist, born in 1913 in Pisa (Italy) and dead in 1993 in Dubna (Russia).
Samoil Bilenky worked with Pontecorvo from 1975 until 1989 in Dubna where they developed the theory of neutrino masses and oscillations and proposed experiments on the search for neutrino oscillations.

The impact of Bruno Pontecorvo on neutrino physics is well recognized in the Scientific Community.

Prof. Samoil Bilenky obtained his doctoral degree at JINR (Joint Institute for Nuclear Research) in Dubna and collaborated with Bruno Pontecorvo for over a decade. He was also professor at the Moscow State University and later at SISSA (Scuola Internazionale Superiore di Studi Avanzati) in Italy. He has been a visiting scientist at TRIUMF (Canada’s National Laboratory for Particle and Nuclear Physics) in Canada, at DESY (Deutsches Elektronen-Synchrotron) in Germany, at the University of Valencia (Spain), the University of Turin (Italy) and at the TU Munich (Germany).
In 2002 prof. Samoil Bilenky received the Bruno Pontecorvo Prize and in 1999 he received the Humboldt Research Award.

Here are location and other event details,

The story of Bruno Pontecorvo
  • May 27, 2015 – 7:15pm
  • Activity Room, Main Level – 480 Broughton St, Vancouver, BC
  • Underground pay parking is available – EasyPark – Lot 64
    Everyone is invited to a no-host dinner with the Board of Directors afterwards.