Tag Archives: physics

Physics of the Wild Cards fictional universe, a paper by physicist Ian Tregillis and author George RR Martin

I don’t often get a chance to mention superstar authors such as George RR Martin here but it does happen when science fiction authors and physics are concerned.

Caption: A coordinate system for the polar model of the Wild Cards system and an example of the viral vector trajectories. Credit: Ian Tregillis

A January 23, 2025 news item on phys.org announces the research paper,

Many science fiction authors try to incorporate scientific principles into their work, but Ian Tregillis, who is a contributing author of the Wild Cards book series when he’s not working as a physicist at Los Alamos National Laboratory, took it one step further: He derived a formula to describe the dynamics of the fictional universe’s viral system.

In independent research published in the American Journal of Physics, from AIP Publishing, Tregillis and George R.R. Martin derive a formula for viral behavior in the Wild Cards universe.

A January 23, 2025 American Institute of Physics (AIP) news release (also on EurekAlert), which originated the news item, describes both the ‘Wild Cards universe’ and the speculative physics in more detail,

Wild Cards is a science fiction series written by a collection of authors and edited by Martin and Melinda M. Snodgrass. Sitting at over 30 volumes, the books are about an alien virus called the Wild Card that mutates human DNA. Martin is credited as a co-author of the paper, making it his first peer-reviewed physics publication.

The idea to explore the science behind the fictional virus came from a series of blog posts on the Wild Cards website.

“Like any physicist, I started with back-of-the-envelope estimates, but then I went off the deep end. Eventually I suggested, only half-jokingly, that it might be easier to write a genuine physics paper than another blog post,” Tregillis said. “Being a theoretician, I couldn’t help but wonder if a simple underlying model might tidy up the canon.”

The formula he derived is a Lagrangian formulation, which considers the different ways a system can evolve. It’s also a fundamental physics principle, which also makes the fictional example a powerful teaching tool.

Tregillis shared that deriving this physical model was a fun but open-ended puzzle. After some trial and error of models based on fractals or thermodynamic analogies, he and Martin settled on the Lagrangian approach.

“We translated the abstract problem of Wild Card viral outcomes into a simple, concrete dynamical system. The time-averaged behavior of this system generates the statistical distribution of outcomes,” he said.

While the Wild Card virus can be modeled by physics, Tregillis emphasized that it isn’t a hard-and-fast rule in the canon.

“Good storytelling is about characters: their wants, needs, obstacles, challenges, and how they interact with their world,” Tregillis said. “The fictional virus is really just an excuse to justify the world of Wild Cards, the characters who inhabit it, and the plot lines that spin out from their actions.”

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

Ergodic Lagrangian dynamics in a superhero universe by I. L. Tregillis and George R. R. Martin. Am. J. Phys. Volume 93, Issue 2 February 2025 127–136 DOI: https://doi.org/10.1119/5.0228859

This paper is open access.

One other thing, Wild Cards, a current television programme which has nothing to do with George RR Martin or physics, stars Vanessa Morgan and Giacomo Gianniotti in a Canadian Broadcasting Corporation (CBC) production about a con artist and a police officer solving crimes toghether can be seen here.

Say ain’t so! van Gogh’s ‘The Starry Night’ is not a masterpiece when it comes to flow physics according to researchers

Researchers at Virginia Commonwealth University (VCU; US) have challenged the findings in recent research that was highlighted here in a December 16, 2024 posting “van Gogh’s sky is alive with real-world physics.”

An April 1, 2025 news item (not an April Fool’s joke) on phys.org announces a conclusion that contradicts the original findings,

The Dutch master Vincent van Gogh may have painted one of Western history’s most enduring works, but “The Starry Night” is not a masterpiece of flow physics—despite recent attention to its captivating swirls, according to researchers from Virginia Commonwealth University and the University of Washington [state not district].

Credit: Pixabay/CC0 Public Domain [downloaded from https://phys.org/news/2025-04-vincent-van-gogh-starry-night.html].

An April 1, 2025 Virginia Commonwealth University (VCU) news release (also on EurekAlert) by Leila Ugincius, which originated the news item, goes on to further refute the claim about Starry Night and flow physics, Note: Links have been removed,

The post-Impressionist artist painted the work (often referred to simply as “Starry Night”) in June 1889, and its depiction of a pre-sunrise sky and village was inspired in part by the view from van Gogh’s asylum room in southern France. The painting is part of the permanent collection of the Museum of Modern Art in New York City.

Last year, a paper published in the September issue of Physics of Fluids – “Hidden Turbulence in van Gogh’s ‘The Starry Night’” – received considerable notice by positing that the eddies, or swirls, painted by van Gogh adhere to Kolmogorov’s theory of turbulent flow, which explains how air and water swirls move in a somewhat chaotic pattern. “[van Gogh] was able to reproduce not only the size of whirls/eddies, but also their relative distance and intensity in his painting,” the paper read.

However, those conclusions are unfounded, according to Mohamed Gad-el-Hak, Ph.D., the Inez Caudill Eminent Professor in VCU’s Department of Mechanical and Nuclear Engineering, and James J. Riley, Ph.D., the inaugural Paccar Professor of Mechanical Engineering at the University of Washington. Their report –  “Is There Hidden Turbulence in Vincent van Gogh’s ‘The Starry Night’?” – appears in the latest issue of Journal of Turbulence.

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

Is there hidden turbulence in Vincent van Gogh’s The Starry Night? by James J. Riley
& Mohamed Gad-el-Hak. Journal of Turbulence Pages 1–2. DOI: https://doi.org/10.1080/14685248.2025.2477244 Published online: 18 Mar 2025

This paper is behind a paywall.

Explaining topological insulators with dance

This must have been some high school physics class. A November 5, 2024 news item on ScienceDaily explains how physics topological insulators and dance intersected for three classes,

Science can be difficult to explain to the public. In fact, any subfield of science can be difficult to explain to another scientist who studies in a different area. Explaining a theoretical science concept to high school students requires a new way of thinking altogether.

This is precisely what researchers at the University of California San Diego did when they orchestrated a dance with high school students at Orange Glen High School in Escondido as a way to explain topological insulators.

The experiment, led by former graduate student Matthew Du and UC San Diego Associate Professor of Chemistry and Biochemistry Joel Yuen-Zhou, was published in Science Advances.

A November 5, 2024 University of California at San Diego (UC San Diego) news release (also on EurekAlert), which originated the news item, provides more detail about how the researchers employed dance to teach physics concepts, Note: A link has been removed,

“I think the concept is simple,” stated Yuen-Zhou. “But the math is much harder. We wanted to show that these complex ideas in theoretical and experimental physics and chemistry are actually not as impossible to understand as you might initially think.”

Topological insulators are a relatively new type of quantum material that has insulating properties on the inside, but have conductive properties on the outside. To use a Southern California staple, if a topological insulator was a burrito, the filling would be insulating and the tortilla would be conducting.

Since topological insulators are able to withstand some disorder and deformation, they can be synthesized and used under conditions where imperfections can arise. For this reason, they hold promise in the areas of quantum computing and lasers, and in creating more efficient electronics.

To bring these quantum materials to life, the researchers made a dance floor (topological insulator) by creating a grid with pieces of blue and red tape. Then to choreograph the dance, Du created a series of rules that governed how individual dancers moved.

These rules are based on what is known as a Hamiltonian in quantum mechanics. Electrons obey rules given by a Hamiltonian, which represents the total energy of a quantum system, including kinetic and potential energy. The Hamiltonian encodes the interactions of the electron in the potential energy of the material.

Each dancer (electron) had a pair of flags and was given a number that corresponded to a movement:

  •  1 = wave flags with arms pointing up
  •  0 = stand still
  • -1 = wave flags with arms pointing down

Subsequent moves were based on what a neighboring dancer did and the color of the tape on the floor. A dancer would mimic a neighbor with blue tape, but do the opposite of a neighbor with red tape. Individual mistakes or dancers leaving the floor didn’t disrupt the overall dance, exhibiting the robustness of topological insulators.

In addition to topology, Yuen-Zhou’s lab also studies chemical processes and photonics, and it was in thinking of light waves that they realized the movement of a group of people also resembled a wave. This gave Yuen-Zhou the idea of using dance to explain a complex topic like topological insulators. Implementing this idea seemed like a fun challenge to Du, who is currently a postdoctoral scholar at the University of Chicago and takes salsa lessons in his free time.

Du, who comes from a family of educators and is committed to scientific outreach, says the project gave him an appreciation for being able to distill science into its simplest elements.

“We wanted to demystify these concepts in a way that was unconventional and fun,” he stated. “Hopefully, the students were able to see that science can be made understandable and enjoyable by relating it to everyday life.”   

Full list of authors: Matthew Du, Juan B. Pérez-Sánchez, Jorge A. Campos-Gonzalez-Angulo, Arghadip Koner, Federico Mellini, Sindhana Pannir-Sivajothi, Yong Rui Poh, Kai Schwennicke, Kunyang Sun, Stephan van den Wildenberg, Alec Barron and Joel Yuen-Zhou (all UC San Diego); and Dylan Karzen (Orange Glen High School).

This research was supported by an National Science Foundation CAREER grant (CHE 1654732).

Here’s what it looked like,

series of overhead images of dancers on dance floor grid
Snapshots showing dancers on the edge of the topological insulator moving in a clockwise direction. Courtesy of University of California at San Diego

You may find this helps you to understand what’s happening in the pictures,

Before getting to a link and citation for the paper, here’s the paper’s abstract,

Topological insulators are insulators in the bulk but feature chiral energy propagation along the boundary. This property is topological in nature and therefore robust to disorder. Originally discovered in electronic materials, topologically protected boundary transport has since been observed in many other physical systems. Thus, it is natural to ask whether this phenomenon finds relevance in a broader context. We choreograph a dance in which a group of humans, arranged on a square grid, behave as a topological insulator. The dance features unidirectional flow of movement through dancers on the lattice edge. This effect persists when people are removed from the dance floor. Our work extends the applicability of wave physics to dance. [emphasis mine]

I wonder if we’re going to see some ‘wave physics’ inspired dance performances.

Finally, here’s a link to and a citation for the paper,

Chiral edge waves in a dance-based human topological insulator by Matthew Du, Juan B. Pérez-Sánchez, Jorge A. Campos-Gonzalez-Angulo, Arghadip Koner, Federico Mellini, Sindhana Pannir-Sivajothi, Yong Rui Poh, Kai Schwennicke, Kunyang Sun, Stephan van den Wildenberg, Dylan Karzen, Alec Barron, and Joel Yuen-Zhou. Science Advances 28 Aug 2024 Vol 10, Issue 35 DOI: 10.1126/sciadv.adh7810

This paper is open access.

I think this is the first year I’ve stumbled across two stories about physics and dance in one year. Here’s the other one, “Happy Canada Day! Breakdancing at the 2024 Paris Summer Olympics: physics in action + heat, mosquitoes, and sports” in a July 1, 2024 posting.

Physicists study Bach, Mozart, and jazz

This November 5, 2024 news item on phys.org takes a while before revealing how science is involved in the research,

Physicists at the Max Planck Institute for Dynamics and Self-Organization (MPI-DS) have investigated to which extent a piece of music can evoke expectations about its progression. They were able to determine differences in how far compositions of different composers can be anticipated. In total, the scientists quantitatively analyzed more than 550 pieces from classical and jazz music.

It is common knowledge that music can evoke emotions. But how do these emotions arise and how does meaning emerge in music? Almost 70 years ago, music philosopher Leonard Meyer suggested that both are due to an interplay between expectation and surprise.

In the course of evolution, it was crucial for humans to be able to make new predictions based on past experiences. This is how we can also form expectations and predictions about the progression of music based on what we have heard. According to Meyer, emotions and meaning in music arise from the interplay of expectations and their fulfillment or (temporary) non-fulfillment.

A team of scientists led by Theo Geisel at the MPI-DS and the University of Göttingen have asked themselves whether these philosophical concepts can be quantified empirically using modern methods of data science. …

Physicists at the MPI-DS have investigated the variability in music pieces by different composers. They found a high initial autocorrelation of pitches, which ends relatively abruptly after a certain time, thus making further anticipation impossible. (image generated with AI) [less] © MPI-DS [downloaded from https://phys.org/news/2024-11-bach-mozart-jazz-scientists-quantitative.html]

A November 5, 2024 Max Planck Institute for Dynamics and Self-Organization press release (also on EurekAlert), which originated the news item, offers technical details about the work,

… In a paper published recently in Nature Communications, they used time series analysis to infer the autocorrelation function of musical pitch sequences; it measures how similar a tone sequence is to previous sequences. This results in a kind of “memory” of the piece of music. If this memory decreases only slowly with time difference, the time series is easier to anticipate; if it vanishes rapidly, the time series offers more variation and surprises. 

In total, the researchers Theo Geisel and Corentin Nelias analyzed more than 450 jazz improvisations and 99 classical compositions in this way, including multi-movement symphonies and sonatas. They found that the autocorrelation function of pitches initially decreases very slowly with the time difference. This expresses a high similarity and possibility to anticipate musical sequences. However, they found that there is a time limit, after which this similarity and predictability ends relatively abruptly. For larger time differences, the autocorrelation function and memory are both negligible.

Of particular interest here are the values of the transition times of the pieces where the more predictable behavior changes into a completely unpredictable and uncorrelated behavior. Depending on the composition or improvisation, the scientists found transition times ranging from a few quarter notes to about 100 quarter notes. Jazz improvisations typically had shorter transition times than many classical compositions, and therefore were usually less predictable. Differences could also be observed between different composers. For example, the researchers found transition times between five and twelve quarter notes in various compositions by Johann Sebastian Bach, while the transition times in various compositions by Mozart ranged from eight to 22 quarter notes. This implies that the anticipation and expectation of the musical progression tends to last longer in Mozart’s compositions than in Bach’s compositions, which offer more variability and surprises.

For Theo Geisel, the initiator and head of this research project, this also explains a very personal observation from his high school days: “In my youth, I shocked my music teacher and conductor of our school orchestra by saying that I often couldn’t show much enthusiasm for Mozart’s compositions,” he says. “With the transition times between highly correlated and uncorrelated behavior, we have now found a quantitative measure for the variability of music pieces, which helps me to understand why I liked Bach more than Mozart.”

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

Stochastic properties of musical time series by Corentin Nelias & Theo Geisel. Nature Communications volume 15, Article number: 9280 (2024) DOI: https://doi.org/10.1038/s41467-024-53155-y Published: 28 October 2024

This paper is open access.

There was a Theodor Geisel who in the US and Canada was better known as Dr. Seuss.

11th century Arab-Muslim optical scientist laid groundwork for modern-day physics

An April 15, 2024 news item on phys.org announces research into how an Arab scientist’s studies into optics established the basis for modern day physics,

Scientists from the University of Sharjah [United Arab Emirates] and the Warburg Institute [University of London, UK] are poring over the writings of an 11th-century Arab-Muslim polymath to demonstrate their impact on the development of optical sciences and how they have fundamentally transformed the history of physics from the Middle Ages up to modern times in Europe.

Caption: Ibn al-Haytham (“Alhasen”) on the left pedestal of reason [while Galileo is on the right pedestal of the senses] as shown on the frontispiece of the Selenographia (Science of the Moon; 1647) of Johannes HeveliusIbn al-Haytham (“Alhasen”) on the left pedestal of reason [while Galileo is on the right pedestal of the senses] as shown on the frontispiece of the Selenographia (Science of the Moon; 1647) of Johannes Hevelius Credit: Public domain provided by the author

A May 6, 2024 University of Sharjah press release on EurekAlert, which originated the news item, delves further into the topic, Note 1: Why there’s such a large discrepancy in the publication dates for the press release is a mystery to me; Note 2: Links have been removed,

Their research focuses on the legacy of al-Ḥasan Ibn al-Haytham known in Latin as “Alhazen” and particularly his most influential work titled Book of Optics, reputed in Arabic as Kitab al-Manazir and first circulated in Europe via its Latin translation dubbed ‘Perspectiva’. Ibn al-Haytham was born in the southern Iraqi city of Basra in 965 during the Abbasid Caliphate.

The divisions IV-V of this authoritative book have been recently translated into English from Arabic and published by the Warburg Institute under the title “The Optics of Ibn al-Haytham, Books IV–V: On Reflection and Images Seen by Reflection”. Having already rendered divisions I-III into English, the Warburg Institute is bringing together a wide-ranging network of scientists “for a collaborative humanities-science investigation of [Ibn] al-Haytham and the questions his work provokes.“

The role of Alhazen [Ibn al-Haytham] in these processes is simultaneously well-known, but limited; only half of his scientific works have English translation and a quarter are not yet edited.”

Introducing the new translation, the Warburg Institute describes Ibn al-Haytham as “perhaps the greatest mathematician and physicist of the medieval Arabic/Islamic world. His reputation is based not only on the vast amount of material he was able to process, but also on his rigorous scientific methodology.

“He (Ibn al-Haytham) deals with both the mathematics of rays of light and the physical aspects of the eye in seven comprehensive books. His reinstatement of the entire science of optics sets the scene for the whole of the subsequent development of the subject … influencing figures such as William of Ockham, [Johannes] Kepler, [René] Descartes, and Christaan Huygens.”

Professor Nader El-Bizri of Sharjah University’s College of Arts, Humanities, and Social Sciences has just published an academic review of the Warburg Institute’s translation of Ibn al-Haytham. The article, printed in the International Journal of the Classical Tradition, highlights the strong influence the Arab-Muslim optical scientist has exerted over the ages up to the present day.

Ibn al-Haytham’s Book of Optics, Prof. El-Bizri writes, “constituted a monumental foundational opus in the history of science and the visual arts from the Middle Ages to the early modern period in the European milieu and the Islamicate context … The reception of Ibn al-Haytham’s Optics in the European milieu took place from the High Middle Ages via Gerard of Cremona’s Toledo circle in terms of its Latinate translations, and subsequent influence on Franciscan, Dominican, and Jesuit opticians across Europe.“

It influenced François d’Aguilon’s Opticorum libri sex within the Antwerp Jesuit mathematical school and had a direct impact on Johannes Hevelius’s Selenographia. The Optics was also consulted by Girard Desargues, René Descartes, Johannes Kepler and Christaan Huygens.”

Prof. El-Bizri works closely with the Warburg Institute assisting its attempts to reintroduce Ibn al-Haytham to the west. “A remarkable thinker, not only did Ibn al-Haytham revolutionize optical thought by mathematising its study, [but] his thinking also went on to have similar revolutionary effects in medieval Europe.”

The Warburg Institute is investing in rendering the writings of Ibn al-Haytham on optics into English, which Prof. El-Bizri describes as “voluminous”. “Ibn al-Haytham’s Book of Optics indicates with evidence the impact of Arabic sciences and philosophy on the history of science and the architectural and visual arts in Europe, as well as demonstrating how science and the arts influence each other in the manner the studies of optics in their mathematized physics inspired the invention of projective geometric constructions of perspective as a novel Renaissance method of painting and architectural design.”

Prof. El-Bizri adds “The impact of this book is fundamental not only in the history of science from the High Middle Ages till the early-modern period in Europe, but it was also foundational for architecture and the visual arts in the Italian Renaissance and up till the late Baroque era. Moreover, it has further significance in modern conceptions of the mathematization of physics, the reliance on experimentation in science, and the philosophical analysis of perception.”

Asked about the importance of translating Ibn al-Haytham into English despite the lapse of nearly 1000 years, Prof. El-Bizri says the Arab-Muslim scientist’s theories and methodologies, specifically those dealing with optics are still considered “seminal” in the literature. Ibn al-Haytham has had a “foundational impact on the history of science and the arts in Europe.”

The influence of Ibn al-Haytham’s writings in the European milieu, according to Prof. El-Bizri, cannot be overlooked. The Arab-Muslim scientist had “a notable effect on Biagio Pelacani da Parma’s Questiones super perspectiva communi, Leon Battista Alberti’s De pictura, Lorenzo Ghiberti’s Commentarii, culminating in the first printed Latin version in the publication of Friedrich Risner’s Opticae thesaurus in the sixteenth century.“

Then, in the seventeenth century, it influenced François d’Aguilon’s Opticorum libri sex within the Antwerp Jesuit mathematical school and had a direct impact on Johannes Hevelius’s Selenographia.”.

In the Book of Optics, notes Prof. El-Bizri, Ibn al-Haytham establishes an “inventive and precise scientific experimental method (al-iʿtibār al-muḥarrar) with its controlled verificative repeated testing, as framed by isomorphic compositions between physics and mathematics.”

He adds that Ibn al-Haytham in his Optics “aims at elucidating the nature of visual perception through studies on the anatomy and physiology of the eyes, the optic nerves and the frontal part of the brain, along with cognitive psychology and the analysis of psychosomatic ocular motor kinaesthetic acts”

Here’s a link to and a citation for the paper, Note: This is one of the more unusual citation I have hrere,

The Optics of Ibn al-Haytham, Books IV–V: On Reflection and Image by N. El-Bizri. Seen by Reflection, translated from the Arabic by Abdelhamid I. Sabra and prepared for publication by Jan P. Hogendijk (Warburg Institute Studies and Texts, 8), London: University of London Press in association with the Warburg Institute, 2023, pp. xiv+343, ISBN 978-1908590589, £90. Int class trad 31, 116–119 (2024). https://doi.org/10.1007/s12138-024-00654-4 Published: 20 February 2024 Issue Date: March 2024

This paper is behind a paywall.

I was a little curious about the Warburg Institute and found out more on their About Us webpage,

The Warburg Institute is one of the world’s leading centres for the study of art and culture. Its collections, courses and programmes are dedicated to the study of global cultural history and the role of images in society. Founded in Hamburg at the turn of the twentieth century by historian Aby Warburg (1866-1929), the Institute was established to trace the roots of the Renaissance in ancient civilisations and ended up changing the way we see the world around us.

The Warburg Institute owes its mission—and its very existence—to the open movement of people, collections and ideas. Sent into exile when the Nazis came to power, the Institute was transferred to England in 1933 and became part of the University of London in 1944. It has served, during a turbulent century, as a creative crucible for scholars, curators, artists and all those whose work sits outside traditional academic structures.

The Warburg’s unique Library, Archive and Photographic Collection form a holistic, associative engine for exploring the histories of the arts and sciences—linking the textual and the visual, the intellectual and the social, the scientific and the magical. Following an extensive renovation of the Institute’s building in Bloomsbury, new spaces for exhibitions and events have restored the Institute’s original emphasis on discovery, display and debate and are bringing its holdings and programmes to new audiences.

Building on Aby Warburg’s belief that the memory of the past activates the present, the Warburg examines the movement of culture across barriers – of time, space and discipline -to inspire, inform and connect.

There you have it.

Happy Canada Day! Breakdancing at the 2024 Paris Summer Olympics: physics in action + heat, mosquitoes, and sports

Happy July 1, 2024, also known as, Canada Day!

Onto breakdancing (or breaking), which for the first time will be an official event at the 2024 Paris Summer Olympics. Amy Pope, principal lecturer, physics and astronomy, Clemson University (South Carolina, US), has written a June 12, 2024 essay for The Conversation that describes breakdancing as physics in action, (h/t June 13, 2024 news item in phys.org), Note: Links have been removed,

Two athletes square off for an intense dance battle. The DJ starts spinning tunes, and the athletes begin twisting, spinning and seemingly defying gravity, respectfully watching each other and taking turns showing off their skill.

The athletes converse through their movements, speaking through a dance that celebrates both athleticism and creativity. While the athletes probably aren’t consciously thinking about the physics behind their movements, these complex and mesmerizing dances demonstrate a variety of different scientific principles.

Breaking, also known as breakdancing, originated in the late 1970s in the New York City borough of the Bronx. Debuting as an Olympic sport in the 2024 Summer Olympics, breaking will showcase its dynamic moves on a global stage. This urban dance style combines hip-hop culture, acrobatic moves and expressive footwork.

Since its inception, breaking has evolved into a competitive art form. An MC narrates the movements, while a DJ mixes songs to create a dynamic atmosphere. The Olympics will feature two events: one for men, called B-boys, and one for women, called B-girls. In these events, athletes will face off in dance battles.

… Success in this sport requires combining dance moves from three basic categories: top rock, down rock and freeze.

And now for the physics of it all, from Pope’s June 12, 2024 essay, Note: Links have been removed,

Top rock moves [emphasis mine] are performed while standing up, focusing on fancy footwork and hand movements. These movements are reminiscent of hip-hop dancing.

Top rock moves rely on having lots of friction between an athlete’s shoes and the floor. Friction is the force [emphasis miine] that resists when you slide something across a surface.

This friction allows the athlete to take very quick steps and to stop abruptly. The dancers must intuitively understand inertia, or the fact that their bodies will continue in the direction they’re moving unless they are acted upon by an external force. To stop abruptly, athletes need to engage their muscles, getting their shoes to grip the ground to stop themselves from continuing forward.

Down rock moves [emphasis mine] are performed while on the floor. Athletes may spin in circles with their head, back, elbows or shoulders touching the ground and their feet in the air. B-boys and B-girls rely heavily on an internal knowledge of physics to complete these moves.

Consider the physics of a backspin. A backspin occurs when the athlete is on their back with their feet lifted in the air, rotating around a specific area of their back.

Sitting on the floor, the athlete’s left foot stays in contact with the floor while they spread their right leg wide, gathering linear momentum [emphasis mine] as they sweep their right leg toward their left foot in a wide arc. Then, they release their left leg from contact with the ground and roll onto their back.

Now that only their back is in contact with the ground, the linear momentum from their leg turns into angular momentum [emphasis mine], which rotates the athlete around an axis that extends upward from their back’s contact point with the ground. This move turns magical when they bring their legs and arms inward, toward the axis of rotation. This principal is called conservation of angular momentum.

When an athlete brings their mass in more closely to the axis of rotation, the athlete’s rotations speed up. Extending their legs and arms once again and moving their mass away from the axis of rotation will cause the competitor to slow their rotation speed down. Once they slow down, they can transition to another move.

Freeze [emphasis mine] occurs when athletes come to a stop in a funky pose, often occurring in time to the music and in an upside-down position. To freeze effectively, the athlete must have full control over their center of mass, placing it right above the point of their body that is in contact with the floor. The center of mass is the average position of all the parts of an athlete, weighted according to their masses. The “balance point” where the entire mass of the athlete seems to be concentrated is the center of mass.

Athletes are most stable when their center of mass is as close to the ground as possible. You will see many competitors freeze with arms bent in an effort to lower their center of mass. This lowered center of mass reduces their distance from the floor and minimizes the tendency of their body to rock to one side or the other due to torque.

Torque is a twisting force [emphasis mine], like the force used to turn a wrench. The torque depends on two things: the amount of force you apply, and how far from the pivot point you apply the force. With an athlete’s center of mass closer to the ground, the athlete decreases the distance between the pivot point – the ground – and where the force of gravity is applied – the athlete’s center of mass.

Athletes need great strength to halt their motion mid-movement because they have to apply a force to resist the change in inertia.

It’s not just about the moves, clothing is a factor, Pope’s June 12, 2024 essay,

Many sports require a specific uniform. Breaking doesn’t – an athlete can wear whatever they want – but the right outfit will maximize their chance of success.

The athlete wants a shirt that minimizes the friction between their body and the ground during a spin. Lettering or images on the back of the shirt will add friction, which hinders an athlete’s ability to perform some down rock moves. An athlete may choose to wear long sleeves if they plan to slide on their elbows, as bare skin in contact with the floor provides more friction.

Athletes also have to think about the headgear they wear. …

There’s a bit more information about the breakdancing competition on the 2024 Olympics website.I cannot find a full list of athletes for the August 9, 2024 (B-Girls) and August 10, 2024 (B-Boys) competitions. There is this June 2, 2024 article (from the Associated Press) on the CBC (Canadian Broadcasting Corporation) online news website,

Victor Montalvo (B-boy Victor), United States: A breaker who describes himself as a student of old school b-boys from the founding era of hip-hop, the 30-year-old Montalvo, who is from Kissimmee, Florida, qualified for Paris by besting all other b-boys at the 2023 WDSF World Breaking Championship in Belgium.

Sunny Choi (B-girl Sunny), United States: The 35-year-old Choi, a cheerful Queens, New York-bred breaker, has long been an ambassador for b-girls globally. She qualified for the Paris Games with her win at the 2023 Pan American Games in Chile.

Philip Kim (B-boy Phil Wizard), Vancouver, Canada: Consistently ranked in the top three b-boys in the international breaking competitive community, Kim secured a spot for Paris when he came out on top at last year’s Pan American Games.

Dominika Banevič (B-girl Nicka), Lithuania: Banevič was the youngest in her category at last year’s WDSF World Breaking Championship, when she punched her ticket to Paris. Banevič turns 17 this month.

I thought the competition would be dominated by Americans and certainly wasn’t expecting to see a Lithuanian (Dominika Banevič or ‘Nicka’) listed as a competitor to watch. The Canadian (Philip Kim or ‘Phil Wizard’) is also a surprise. Who knew Vancouver was home to a leading B-boy?

Two comments: heat and mosquitoes (dengue and other fevers)

The organizers of the Paris 2024 Summer Olympics are to be complimented for their work towards making the games ‘green’ but that is a complex process.

Heat

For example, the Canadian Broadcasting Corporation (CBC) ran a news item on The National news telecast on June 17, 2024 (see telecast for embedded video clip) regarding concerns about and preparations for heat,

Preparing for extreme heat at the Paris Olympics

Paris Olympic organizers plan to make this summer’s games the greenest ever, but that includes offering less air conditioning to cut down on energy use. [emphases mine] As temperatures rise globally, some suggest the organizers should take extreme heat into account when awarding cities with the next big Olympic games.

Some of the reporting in the CBC news item is based on information from a June 18, 2024 University of Portsmouth (UK) press release, Note: Links have been removed,

Leading athletes are warning that intense heat at the Paris Olympics in July-August 2024 could lead to competitors collapsing and in worst case scenarios dying during the Games. [emphasis mine]

Eleven Olympians, including winners of five World Championships and six Olympic medals, have come together with climate scientists and leading heat physiologists Professor Mike Tipton and Dr Jo Corbett from the University of Portsmouth to unpack the serious threat extreme heat poses for athletes in a new Rings of Fire report.

Dr Corbett, Associate Professor of Environmental Physiology in the School of Sport, Health and Exercise Science at the University of Portsmouth, said: “A warming planet will present an additional challenge to athletes, which can adversely impact on their performance and diminish the sporting spectacle of the Olympic Games,. Hotter conditions also increase the potential for heat illness amongst all individuals exposed to high thermal stress, including officials and spectators, as well as athletes.”

“For athletes, from smaller performance-impacting issues like sleep disruption and last-minute changes to event timings, to exacerbated health impacts and heat related stress and injury, the consequences can be varied and wide-ranging. With global temperatures continuing to rise, climate change should increasingly be viewed as an existential threat to sport,” said Lord Sebastian Coe, President of World Athletics and four-time Olympic medallist.

The Tokyo Games became known as the “hottest in history,” with temperatures exceeding 34°C and humidity reaching nearly 70 per cent, leading to severe health risks for competitors. The Paris Games have the potential to surpass that, with climate change driven by the burning of fossil fuels contributing to record heat streaks during the past months.

2023 was the hottest year on record according to the EU’s [European Union] Copernicus Climate Change Service and 2024 has continued this streak. April 2024 was warmer globally than any previous April in the record books, said experts at Copernicus.

The Rings of Fire report discusses the deadly heatwave in France in 2003 – which killed over 14,000 people – and subsequent years of record-breaking temperatures, exceeding 42°C. It underscores the heightened risk of extreme heat during the Paris Olympics, especially considering the significant rise in the region’s temperatures since the city last hosted the Games a century ago.

You can find the Rings of Fire report here and the Corpernicus Climate Change Service here.

Mosquitoes and dengue and other fevers

Obviously, the world is changing as you can see in this June 18, 2024 Institut Pasteur press release (also on EurekAlert),

Olympics: how many days does it take for mosquitoes in Greater Paris to transmit arboviruses, and what preventive measures are needed?

The number of imported cases of dengue in the Greater Paris region increased significantly in the first few months of 2024. In the run-up to the Olympic Games, with huge numbers of international visitors set to come to Paris – especially from endemic dengue countries –, we need to be vigilant. Scientists from the Institut Pasteur, in collaboration with the Regional Mosquito Control Agency (ARD) and the National Reference Center for Arboviruses (Inserm-Irba), have demonstrated that the tiger mosquito, now present in Greater Paris, is capable of transmitting five viruses (West Nile, chikungunya, Usutu, Zika and dengue) within different time frames ranging from 3 to 21 days, at an external temperature of 28°C. These results highlight the importance of stepping up surveillance of imported cases of arboviruses this summer. The study was published on May 16 [2024] in Eurosurveillance.

Between January 1 and April 19, 2024, 1,679 imported dengue cases were reported in mainland France, 13 times more than the number reported over the same period the previous year (source SPF). It is likely that this number will increase during the Olympic Games, as more people come to Paris from countries that are endemic regions for other arboviruses. The vector for dengue transmission is Aedes albopictus, more commonly known as the tiger mosquito. Arboviruses are transmitted when a female mosquito bites a virus carrier and ingests viral particles. One particular feature of arboviruses is that they can replicate in mosquitoes (unlike other viruses such as influenza, which are destroyed when ingested by mosquitoes). The viral particles multiply and spread within the mosquito, reaching the salivary glands in a few days. When the female mosquito bites another human, she injects the virus while taking her blood meal.

The tiger mosquito is now present in 78 départements in mainland France, and this together with other climate change-related factors is facilitating vector-borne transmission. Scientists from the Institut Pasteur’s Arboviruses and Insect Vectors Unit, in collaboration with the Regional Vector Control Agency (ARD) and the National Reference Center for Arboviruses (Inserm-Irba), therefore decided to analyze the ability of Aedes albopictus in Greater Paris to transmit five arboviruses at a temperature of 28°C, which is likely in the region at this time of year, and counted the number of days between initial infection and the possibility of the virus being transmitted through a further mosquito bite. As well as the dengue, chikungunya and Zika viruses, which we already know can be transmitted by the tiger mosquito, the scientists studied the Usutu and West Nile viruses, which are naturally transmitted by another mosquito species, Culex pipiens (known as the “common mosquito”). Culex pipiens mosquitoes transmit viruses to humans after feeding on birds, which act as viral reservoirs.

Tiger mosquito susceptible to five arboviruses

Working in a BSL3 laboratory, the scientists studied the ability of tiger mosquitoes to transmit these five viruses and determined the extrinsic incubation period required for the virus to reach the mosquito’s salivary glands in sufficient quantities to infect a human. At 28°C, West Nile virus needs three days before it can be transmitted to humans by mosquitoes. The incubation period is 3 to 7 days for chikungunya and Usutu, and 14 to 21 days for dengue and Zika.(1) 

This information is crucial to gage the additional risk represented by the upcoming Olympic Games in Paris, which will see significant intermingling of populations combined with the return of travelers from endemic regions and a season conducive to mosquito proliferation. The findings can also be used to develop suitable control strategies.

“If a case of dengue is detected in the Greater Paris region, we now know that disinsection is required within 21 days. We can use these results to adjust our time frame for action and optimize our approach,” explains Anna-Bella Failloux, Head of the Institut Pasteur’s Arboviruses and Insect Vectors Unit, who led the study. “Depending on the temperatures we experience in and around Paris this summer, our findings will be essential for adjusting control measures as needed.”

What precautions should be taken in the run-up to the Olympics?

Health care professionals are trained to detect the symptoms of arboviruses if people indicate that they have recently been to an endemic country. The difficulty of surveillance is that many cases are asymptomatic: although dengue is a notifiable disease, up to 80% of cases lead to few or no symptoms. If a diagnosis of one of these diseases is confirmed, an inquiry is carried out by France’s Regional Health Agencies to determine where the individuals live or spent time in the days before the diagnosis, so that they can identify the areas where disinsection is needed. Anyone coming back from a foreign trip who experiences fever or aches is advised to see their family physician immediately and indicate the region they recently returned from.

“The alert system in France is effective. The applicable procedure and measures are already well established because France’s overseas territories in endemic regions have provided us with expertise in these diseases and know-how on epidemiological monitoring. My team is affiliated with the Arbo-France network, and we are contacted as soon as an arbovirus is detected,” continues Anna-Bella Failloux.

Since 2006, vector control measures in France have led to increased surveillance of tiger mosquitoes between May 1 and November 30 each year. This involves monitoring mosquito populations in areas where they are likely to be present; disease surveillance coordinated by Santé publique France based on reporting of viruses such as dengue, chikungunya and Zika by health care professionals; and raising awareness among people living in areas where mosquitoes have been reported. France’s Regional Health Agencies (ARS) and their operators are responsible for managing reporting, monitoring the presence of mosquitoes and taking rapid action in response to human cases of infection (vector control).

This research, which focused on mosquitoes in the Greater Paris region for this first study, will soon be extended to the rest of mainland France. Extrinsic incubation periods vary from one tiger mosquito population to the next because of differences in their genetic makeup and in local temperatures. 

Find out more:

Video: “We are going to have to learn to live with tiger mosquitoes” – Anna-Bella Failloux

Disease-carrying mosquitoes – French Ministry of Employment, Health and Solidarity (sante.gouv.fr)

  1. It is important to point out that for Usutu and West Nile, the ability of tiger mosquitoes to transmit these viruses to humans in real-life conditions, outside the experimental setting, is yet to be demonstrated, as they are naturally transmitted by Culex pipiens, another mosquito species.

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

Aedes albopictus is a competent vector of five arboviruses affecting human health, greater Paris, France, 2023 by Chloé Bohers, Marie Vazeille, Lydia Bernaoui, Luidji Pascalin, Kevin Meignan, Laurence Mousson, Georges Jakerian, Anaïs Karchh, Xavier de Lamballerie, Anna-Bella Failloux. Euro Surveill. 2024; 29 (20): pii=2400271. DOI: https://doi.org/10.2807/1560-7917.ES.2024.29.20.2400271

This paper is open access.

I covered the movement of dengue fever and malaria into the Northern Hemisphere in an August 10, 2023 posting,

The World Health Organization (WHO) notes that dengue fever cases have increased exponentially since 2000 (from the March 17, 2023 version of the WHO’s “Dengue and severe dengue” fact sheet),

Global burden

The incidence of dengue has grown dramatically around the world in recent decades, with cases reported to WHO increased from 505 430 cases in 2000 to 5.2 million in 2019. A vast majority of cases are asymptomatic or mild and self-managed, and hence the actual numbers of dengue cases are under-reported. Many cases are also misdiagnosed as other febrile illnesses (1).

One modelling estimate indicates 390 million dengue virus infections per year of which 96 million manifest clinically (2). Another study on the prevalence of dengue estimates that 3.9 billion people are at risk of infection with dengue viruses.

The disease is now endemic in more than 100 countries in the WHO Regions of Africa, the Americas, the Eastern Mediterranean, South-East Asia and the Western Pacific. The Americas, South-East Asia and Western Pacific regions are the most seriously affected, with Asia representing around 70% of the global disease burden.

Dengue is spreading to new areas including Europe, [emphasis mine] and explosive outbreaks are occurring. Local transmission was reported for the first time in France and Croatia in 2010 [emphasis mine] and imported cases were detected in 3 other European countries.

The researchers from the University of Central Florida (UCF) couldn’t have known when they began their project to study mosquito bites and disease that Florida would register its first malaria cases in 20 years this summer, …

It seems pretty clear that there’s increasing concern about mosquito-borne diseases no matter where you live.

It looks like mega-sports events attract more visitors than you might expect.

News and events at the Perimeter Institute for Theoretical Physics (Waterloo, Ontario, Canada)

I believe this is an April (?) 2024 newsletter and it’s definitely from Canada’s Perimeter Institute for Theoretical Physics (PI). Received via email, I was able to find this online copy (Note: I’m not sure how long this copy will remain online) and am excerpting a few items for inclusion here,

The current state of theoretical physics

Join the latest episode of Conversations at Perimeter as Neil Turok [director of the Perimeter Institute, 2008 – 2019] delves into the intriguing topic of the simplicity of nature.

Watch podcast here

Public Lecture – May 8 [2024]

Free tickets to attend the event in person will be available on Monday, April 22, at 9:00 AM EDT. Live-stream will also be available on the PI YouTube channel. 

Check details here

Quantum Lectures playlist

Explore quantum physics with our YouTube Quantum Lectures playlist. Discover the universe’s secrets from basics to advanced topics

Start watching now!

I found this poster for the free May 8, 2024 PI event,

[downloaded from https://www.eventbrite.ca/e/hydrogen-to-higgs-boson-particle-physics-at-the-large-hadron-collider-tickets-877493876807]

It (the May 8, 2024 PI hybrid [live or streaming] event) may be of more interest than usual as Peter Higgs of the Higgs Boson died on April 8, 2024, from the Hydrogen to Higgs Boson: Particle Physics at the Large Hadron Collider eventbrite webpage,

Hydrogen to Higgs Boson: Particle Physics at the Large Hadron Collider

Explore particle physics with Dr. Clara Nellist at the Perimeter Institute on May 8, as she discusses CERN’s groundbreaking research.

Date and time

Starts on Wednesday, May 8 [2024] · 6pm EDT

Location

Perimeter Institute for Theoretical Physics
31 Caroline Street North Waterloo, ON N2L 2Y5

Agenda

6:00 p.m.

Doors Open

Perimeter’s main floor will be open for ticket holders, with scientists available to answer science questions until the show begins.

7:00 p.m. – 8:00 p.m.

Public Lecture

The public lecture will begin at 7:00pm, including a live stream for virtual attendees. This will include a full presentation as well as a Q&A session.

8:00 p.m. – 8:30 p.m.

Post-Event Discussion

Following the lecture, discussion will continue in the atrium, where you can ask questions to the presenter as well as other researchers in the crowd.

About this event

About the Speaker:

Dr Clara Nellist – Particle Physicist and Science Communicator, is currently working at CERN [European Organization for Nuclear Research] on the ATLAS experiment, with research focusing on top quarks and searching for dark matter with machine learning. Learn more about her work on her Instagram here.

About the Event:

Registration to attend the event in person will be available on Monday, April 22 at 9:00 AM EDT.

Tickets for this event are 100% free. [emphasis mine] As always, our public lectures are live-streamed in real-time on our YouTube channel – available here: https://www.youtube.com/@PIOutreach

The existence of the Higgs boson was confirmed (or as close to confirmed as scientists will get) in 2012 (see my July 4, 2012 posting “Tears of joy as physicists announce they’re pretty sure they found the Higgs Boson” for an account of the event. Peter Higgs and and François Englert were awarded the 2013 Nobel Prize in Physics.

If you are planning to attend the lecture in person, free tickets will be made available on Monday, April 22, at 9:00 AM EDT. Go here and, remember, these tickets go quickly.

Dendritic painting: a physics story

A March 4, 2024 news item on phys.org announces research into the physics of using paints and inks in visual art, Note: A link has been removed,

Falling from the tip of a brush suspended in mid-air, an ink droplet touches a painted surface and blossoms into a masterpiece of ever-changing beauty. It weaves a tapestry of intricate, evolving patterns. Some of them resemble branching snowflakes, thunderbolts or neurons, whispering the unique expression of the artist’s vision.

Okinawa Institute of Science and Technology (OIST) researchers set out to analyze the physical principles of this fascinating technique, known as dendritic painting. They took inspiration from the artwork of Japanese media artist, Akiko Nakayama. The work is published in the journal PNAS Nexus.

Caption: Japanese artist Akiko Nakayama manipulates alcohol and inks to create tree-like dendritic patterns during a live painting session. Credit: Photo Credit: Akiko Nakayama

Yes, the ends definitely look tree-like (maybe cedar). A February 29, 2024 Okinawa Institute of Science and Technology (OIST) press release (also on EurekAlert but published March 1, 2024), which originated the news item, goes on to describe the forces at work and provides instructions for creating your own dendritic paintings, Note: Links have been removed,

During her [Akiko Nakayama] live painting performances, she applies colourful droplets of acrylic ink mixed with alcohol atop a flat surface coated with a layer of acrylic paint. Beautiful fractals – tree-like geometrical shapes that repeat at different scales and are often found in nature – appear before the eyes of the audience. This is a captivating art form driven by creativity, but also by the physics of fluid dynamics.

“I have a deep admiration for scientists, such as Ukichiro Nakaya and Torahiko Terada, who made remarkable contributions to both science and art. I was very happy to be contacted by OIST physicist Chan San To. I am envious of his ability ‘to dialogue’ with the dendritic patterns, observing how they change shape in response to different approaches. Hearing this secret conversation was delightful,” explains Nakayama.

“Painters have often employed fluid mechanics to craft unique compositions. We have seen it with David Alfaro Siqueiros, Jackson Pollock, and Naoko Tosa, just to name a few. In our laboratory, we reproduce and study artistic techniques, to understand how the characteristics of the fluids influence the final outcome,” says OIST Professor Eliot Fried of OIST’s Mechanics and Materials Unit, who likes looking at dendritic paintings from artistic and scientific angles.

In dendritic painting, the droplets made of ink and alcohol experience various forces. One of them is surface tension – the force that makes rain droplets spherical in shape, and allows leaves to float on the surface of a pond. In particular, as alcohol evaporates faster than water, it alters the surface tension of the droplet. Fluid molecules tend to be pulled towards the droplet rim, which has higher surface tension compared to its centre. This is called the Marangoni effect and is the same phenomenon responsible for the formation of wine tears – the droplets or streaks of wine that form on the inside of a wine glass after swirling or tilting.

Secondly, the underlying paint layer also plays an important part in this artistic technique. Dr. Chan tested various types of liquids. For fractals to emerge, the liquid must be a fluid that decreases in viscosity under shear strain, meaning it has to behave somewhat like ketchup. It’s common knowledge that it’s hard to get ketchup out of the bottle unless you shake it. This happens because ketchup’s viscosity changes depending on shear strain. When you shake the bottle, the ketchup becomes less viscous, making it easier to pour it onto your dish. How is this applied to dendritic painting?

“In dendritic painting, the expanding ink droplet shears the underlying acrylic paint layer. It is not as strong as the shaking of a ketchup bottle, but it is still a form of shear strain. As with ketchup, the more stress there is, the easier it is for the ink droplets to flow,” explains Dr. Chan.

“We also showed that the physics behind this dendritic painting technique is similar to how liquid travels in a porous medium, such as soil. If you were to look at the mix of acrylic paint under the microscope, you would see a network of microscopic structures made of polymer molecules and pigments. The ink droplet tends to find its way through this underlying network, travelling through paths of least resistance, that leads to the dendritic pattern,” adds Prof. Fried.

Each dendritic print is one-of-a-kind, but there are at least two key aspects that artists can take into consideration to control the outcome of dendritic painting. The first and most important factor is the thickness of the paint layer spread on the surface. Dr. Chan observed that well-refined fractals appear with paint layer thinner than a half millimetre.

The second factor to experiment with is the concentration of diluting medium and paint in this paint layer. Dr. Chan obtained the most detailed fractals using three parts diluting medium and one part paint, or two parts diluting medium and one part paint. If the concentration of paint is higher, the droplet cannot spread well. Conversely, if the concentration of paint is lower, fuzzy edges will form. 

This is not the first science-meets-art project that members of the Mechanics and Materials Unit have embarked on. For example, they designed and installed a mobile sculpture on the OIST campus. The sculpture exemplifies a family of mechanical devices, called Möbius kaleidocycles, invented in the Unit, which may offer guidelines for designing chemical compounds with novel electronic properties.

Currently, Dr. Chan is also developing novel methods of analysing how the complexity of a sketch or painting evolves during its creation. He and Prof. Fried are optimistic that these methods might be applied to uncover hidden structures in experimentally captured or numerically generated images of flowing fluids.

“Why should we confine science to just technological progress?” wonders Dr. Chan. “I like exploring its potential to drive artistic innovation as well. I do digital art, but I really admire traditional artists. I sincerely invite them to experiment with various materials and reach out to us if they’re interested in collaborating and exploring the physics hidden within their artwork.”

Instructions to create dendritic painting at home

Everybody can have fun creating dendritic paintings. The materials needed include a non-absorbent surface (glass, synthetic paper, ceramics, etc.), a brush, a hairbrush, rubbing alcohol (iso-propyl alcohol), acrylic ink, acrylic paint and pouring medium.

  1. Dilute one part of acrylic paint to two or three parts of  pouring medium, or test other ratios to see how the result changes
  2. Apply this to the non-absorbent surface uniformly using a hairbrush. OIST physicists have found out that the thickness of the paint affects the result. For the best fractals, a layer of paint thinner than half millimetre is recommended.
  3. Mix rubbing alcohol with acrylic ink. The density of the ink may differ for different brands: have a try mixing alcohol and ink in different ratios
  4. When the white paint is still wet (hasn’t dried yet), apply a droplet of the ink with alcohol mix using a brush or another tool, such as a bamboo stick or a toothpick.
  5. Enjoy your masterpiece as it develops before your eyes. 

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

Marangoni spreading on liquid substrates in new media art by San To Chan and Eliot Fried. PNAS Nexus, Volume 3, Issue 2, February 2024, pgae059 DOI: https://doi.org/10.1093/pnasnexus/pgae059 Published: 08 February 2024

This paper is open access.