BLOGS

Credit: Menno Schaefer/Adobe

Starlings flock in a so-called murmuration, a collective behavior of interest in biological physics — one of many subfields that did not always “belong” in physics.

Topics: Applied Physics, Cosmology, Einstein, History, Physics, Research, Science

"To be rather than to seem." Translated from the Latin Esse Quam Videri, which also happens to be the state motto of North Carolina. It is from the treatise on Friendship by the Roman statesman Cicero, a reminder of the beauty and power of being true to oneself. Source: National Library of Medicine: Neurosurgery

If you’ve been in physics long enough, you’ve probably left a colloquium or seminar and thought to yourself, “That talk was interesting, but it wasn’t physics.”

If so, you’re one of many physicists who muse about the boundaries of their field, perhaps with colleagues over lunch. Usually, it’s all in good fun.

But what if the issue comes up when a physics faculty makes decisions about hiring or promoting individuals to build, expand, or even dismantle a research effort? The boundaries of a discipline bear directly on the opportunities departments can offer students. They also influence those students’ evolving identities as physicists, and on how they think about their own professional futures and the future of physics.

So, these debates — over physics and “not physics” — are important. But they are also not new. For more than a century, physicists have been drawing and redrawing the borders around the field, embracing and rejecting subfields along the way.

A key moment for “not physics” occurred in 1899 at the second-ever meeting of the American Physical Society. In his keynote address, the APS president Henry Rowland exhorted his colleagues to “cultivate the idea of the dignity” of physics.

“Much of the intellect of the country is still wasted in the pursuit of so-called practical science which ministers to our physical needs,” he scolded, “[and] not to investigations in the pure ethereal physics which our Society is formed to cultivate.”

Rowland’s elitism was not unique — a fact that first-rate physicists working at industrial laboratories discovered at APS meetings, when no one showed interest in the results of their research on optics, acoustics, and polymer science. It should come as no surprise that, between 1915 and 1930, physicists were among the leading organizers of the Optical Society of America (now Optica), the Acoustical Society of America, and the Society of Rheology.

That acousticians were given a cold shoulder at early APS meetings is particularly odd. At the time, acoustics research was not uncommon in American physics departments. Harvard University, for example, employed five professors who worked extensively in acoustics between 1919 and 1950. World War II motivated the U.S. Navy to sponsor a great deal of acoustics research, and many physics departments responded quickly. In 1948, the University of Texas hired three acousticians as assistant professors of physics. Brown University hired six physicists between 1942 and 1952, creating an acoustics powerhouse that ultimately trained 62 physics doctoral students.

The acoustics landscape at Harvard changed abruptly in 1946, when all teaching and research in the subject moved from the physics department to the newly created department of engineering sciences and applied physics. In the years after, almost all Ph.D. acoustics programs in the country migrated from physics departments to “not physics” departments.

The reason for this was explained by Cornell University professor Robert Fehr at a 1964 conference on acoustics education. Fehr pointed out that engineers like himself exploited the fundamental knowledge of acoustics learned from physicists to alter the environment for specific applications. Consequently, it made sense that research and teaching in acoustics passed from physics to engineering.

It took less than two decades for acoustics to go from being physics to “not physics.” But other fields have gone the opposite direction — a prime example being cosmology.

Albert Einstein applied his theory of general relativity to the cosmos in 1917. However, his work generated little interest because there was no empirical data to which it applied. Edwin Hubble’s work on extragalactic nebulae appeared in 1929, but for decades, there was little else to constrain mathematical speculations about the physical nature of the universe. The theoretical physicists Freeman Dyson and Steven Weinberg have both used the phrase “not respectable” to describe how cosmology was seen by physicists around 1960. The subject was simply “not physics.”

This began to change in 1965 with the discovery of thermal microwave radiation throughout the cosmos — empirical evidence of the nearly 20-year-old Big Bang model. Physicists began to engage with cosmology, and the percentage of U.S. physics departments with at least one professor who published in the field rose from 4% in 1964 to 15% in 1980. In the 1980s, physicists led the satellite mission to study the cosmic microwave radiation, and particle physicists — realizing that the hot early universe was an ideal laboratory to test their theories — became part-time cosmologists. Today, it’s hard to find a medium-to-large sized physics department that does not list cosmology as a research specialty.

Opinion: That's Not Physics, Andrew Zangwill, APS

Climate of fear Anti-science protestors led to the closure of the High Flux Beam Reactor at the Brookhaven National Laboratory in the US 25 years ago using tactics that are widespread today. (Courtesy: iStock/DanielVilleneuve)

Topics: Biology, Cancer, Carl Sagan, Civilization, Climate Change, Philosophy, Physics

I typically don't comment on articles, but this one resonated with my memories of Carl Sagan desperately trying to raise the critical thinking skills of an entire essential nation with "The Demon-Haunted World: Science as a Candle in the Dark." The host of Cosmos would succumb to pneumonia as a consequence of bone marrow disease. I will be the age Carl was when he passed away this year, 62, but not as accomplished as he did in the six decades we all had access to him.

The framework of our current duress was already here in the form of celebrity worship, gossip columns, and talk shows where sensationalism equaled eyeballs, just as the Internet rouses the primitive lizard portion of our brains to be afraid, get angry, and "buy-purchase-consume" products (a friend who's a sound engineer likes to say that a lot).

Underhand tactics by environmental activists led to the closure of a famous physics facility 25 years ago. We can still learn much from the incident, says Robert P Crease.

Fake facts, conspiracy theories, nuclear fear, science denial, baseless charges of corruption, and the shouting down of reputable health officials. All these things happened 25 years ago, long before the days of social media, in a bipartisan, celebrity-driven episode of science denial.  Yet the story offers valuable lessons for what works and what does not (mostly the latter) for anyone wanting to head off such incidents.

The episode in question concerned one of the more valuable scientific facilities in the US, the High Flux Beam Reactor (HFBR) at the Brookhaven National Laboratory. As I mentioned in a previous column and in my book The Leak, the HFBR was a successful research instrument that was used to make medical isotopes and study everything from superconductors to proteins and metals. “Experimentalists saw the reactor as the place to go,” recalls the physicist William Magwood IV, then at the US Department of Energy.

But in 1997, lab scientists discovered a leak of water from a pool located in the same building as the reactor, where its spent fuel was stored. The leak contained tritium, a radioactive isotope of hydrogen that decays with a half-life of about 12 years, releasing low-energy electrons that can be stopped by a few sheets of paper. The total amount of tritium in the leak was about that in typical self-illuminating “EXIT” signs.

The protestors’ tactics are a familiar part of today’s political environment: tell people they are in danger and insist that anyone who says otherwise is lying.

The article goes on to recount the actor Alec Baldwin using his celebrity to put a ten-year-old child on the Montell Williams Show to claim that the tritium and the research facility caused his cancer. It wasn't true, but it was LOUD, drowning out the experts who are used to spirited peer review and erudite discussions of research, not tears and gnashing of teeth.

Montell Williams ended his talk show after announcing that he had multiple sclerosis. Alec Baldwin, though I enjoyed his SNL skits, has other pressing issues.

I have a physicist friend who's using tritium in his research with optical tweezers, separating isotopes to detect and treat cancers, among other applications. I am opting not to give his website as those same elements described in the article about Brookhaven National Labs have metastasized into our current societal mass psychosis. If his research leads to your cancer cure, you can thank him later.

Twenty-five years ago, we weren't as far along in climate disruption as we are now. Twenty-five years ago, CNN was 19 years old, and its clones, Fox and MSNBC, were 3 years old. Five years after the Y2K scare (exquisitely setting us up for election 2000 and 9/11), humanity further siloed itself into warring tribes, first posting on Internet bulletin boards, MySpace. Then, the logical progression was to Facebook, Twitter (now X), and its myriad progeny.

A side note: CERN would go on to discover the Higgs Boson because we, in the spirit of fiscal stewardship, closed the superconducting collider in Waxahachie, Texas, 48 kilometers south of Dallas. Peter Higgs and François Englert owe their 2013 Physics Nobel Prize to Switzerland. U-S-A. U-S-A.

How much further along in cancer research and nuclear energy as an alternative to fossil fuels would we be if, prior to Facebook and the former Twitter, we exercised a little critical thinking and common sense? I'm not talking about tritium, but fission reactors, which we know how to build (fusion, though cleaner and less radioactive, is still far off), but the environmental activists have terrorized anyone from building newer and safer facilities that might have had some positive impact on our warming climate. To paraphrase a famous saying, "Don't let the perfect be the enemy of the good." Our air quality improved during the pandemic, so the logic leads to upgrading public transportation to something matching other countries that rely on it more than we do, or within our borders, the subway systems in New York, New Jersey, Philadelphia, or Washington, DC. You end up doing nothing of any importance. We could replace the fission reactors one by one as fusion comes online.

That is what enrages and disappoints me.

The American reactor that was closed by fake news, Robert P Crease, Physics World

Credit: Fanatic Studio/Gary Waters/Getty Images

Topics: Education, Existentialism, Philosophy, Physics

Physicists and philosophers recently met to debate a theory of consciousness called panpsychism.

More than 400 years ago, Galileo showed that many everyday phenomena—such as a ball rolling down an incline or a chandelier gently swinging from a church ceiling—obey precise mathematical laws. For this insight, he is often hailed as the founder of modern science. But, Galileo recognized that not everything was amenable to a quantitative approach. Such things as colors, tastes, and smells “are no more than mere names,” Galileo declared, for “they reside only in consciousness.” These qualities aren’t really out there in the world, he asserted, but exist only in the minds of creatures that perceive them. “Hence, if the living creature were removed,” he wrote, “all these qualities would be wiped away and annihilated.”

Since Galileo’s time, the physical sciences have leaped forward, explaining the workings of the tiniest quarks to the largest galaxy clusters. But explaining things that reside “only in consciousness”—the red of a sunset, say, or the bitter taste of a lemon—has proven far more difficult. Neuroscientists have identified a number of neural correlates of consciousness—brain states associated with specific mental states—but have not explained how matter forms minds in the first place. As philosopher Colin McGinn put it in a 1989 paper, “Somehow, we feel, the water of the physical brain is turned into the wine of consciousness.” Philosopher David Chalmers famously dubbed this quandary the “hard problem” of consciousness.*

Scholars recently gathered to debate the problem at Marist College in Poughkeepsie, N.Y., during a two-day workshop focused on an idea known as panpsychism. The concept proposes that consciousness is a fundamental aspect of reality, like mass or electrical charge. The idea goes back to antiquity—Plato took it seriously—and has had some prominent supporters over the years, including psychologist William James and philosopher and mathematician Bertrand Russell. Lately, it is seeing renewed interest, especially following the 2019 publication of philosopher Philip Goff’s book Galileo’s Error, which argues forcefully for the idea.

Is Consciousness Part of the Fabric of the Universe? Dan Falk, Scientific American

Topics: Nobel Laureate, Nobel Prize, Physics

Prize announcement. NobelPrize.org. Nobel Prize Outreach AB 2023. Tue. 3 Oct 2023. <https://www.nobelprize.org/prizes/physics/2023/prize-announcement/>

3 October 2022

The Royal Swedish Academy of Sciences has decided to award the Nobel Prize in Physics 2023 to

Pierre Agostini
The Ohio State University, Columbus, USA

Ferenc Krausz
Max Planck Institute of Quantum Optics, Garching and Ludwig-Maximilians-Universität München, Germany

Anne L’Huillier
Lund University, Sweden

“for experimental methods that generate attosecond pulses of light for the study of electron dynamics in matter.”

Experiments with light capture the shortest of moments.

The three Nobel Laureates in Physics 2023 are being recognized for their experiments, which have given humanity new tools for exploring the world of electrons inside atoms and molecules. Pierre Agostini, Ferenc Krausz, and Anne L’Huillier have demonstrated a way to create extremely short pulses of light that can be used to measure the rapid processes in which electrons move or change energy.

Fast-moving events flow into each other when perceived by humans, just like a film that consists of still images is perceived as a continual movement. If we want to investigate really brief events, we need special technology. In the world of electrons, changes occur in a few tenths of an attosecond – an attosecond is so short that there are as many in one second as there have been seconds since the birth of the universe.

The laureates’ experiments have produced pulses of light so short that they are measured in attoseconds, thus demonstrating that these pulses can be used to provide images of processes inside atoms and molecules.

In 1987, Anne L’Huillier discovered that many different overtones of light arose when she transmitted infrared laser light through a noble gas. Each overtone is a light wave with a given number of cycles for each cycle in the laser light. They are caused by the laser light interacting with atoms in the gas; it gives some electrons extra energy that is then emitted as light. Anne L’Huillier has continued to explore this phenomenon, laying the ground for subsequent breakthroughs.

In 2001, Pierre Agostini succeeded in producing and investigating a series of consecutive light pulses, in which each pulse lasted just 250 attoseconds. At the same time, Ferenc Krausz was working with another type of experiment, one that made it possible to isolate a single light pulse that lasted 650 attoseconds.

The laureates’ contributions have enabled the investigation of processes that are so rapid they were previously impossible to follow.

“We can now open the door to the world of electrons. Attosecond physics gives us the opportunity to understand mechanisms that are governed by electrons. The next step will be utilizing them,” says Eva Olsson, Chair of the Nobel Committee for Physics.

The sea floor near Australia’s Casey station in Antarctica has been found to have levels of pollution comparable to those in Rio de Janeiro’s harbor. Credit: Torsten Blackwood/AFP via Getty

Topics: Antarctica, Biology, Chemistry, Environment, Physics, Research

Antarctica is often described as one of the most pristine places in the world, but it has a dirty secret. Parts of the sea floor near Australia’s Casey research station are as polluted as the harbor in Rio de Janeiro, Brazil, according to a study published in PLoS ONE in August.

The contamination is likely to be widespread across Antarctica’s older research stations, says study co-author Jonathan Stark, a marine ecologist at the Australian Antarctic Division in Hobart. “These contaminants accumulate over long time frames and don’t just go away,” he says.

Stark and his colleagues found high concentrations of hydrocarbons — compounds found in fuels — and heavy metals, such as lead, copper, and zinc. Many of the samples were also loaded with polychlorinated biphenyls, highly carcinogenic chemical compounds that were common before their international ban in 2001.

When the researchers compared some of the samples with data from the World Harbor Project — an international collaboration that tracks large urban waterways — they found that lead, copper, and zinc levels in some cases were similar to those seen in parts of Sydney Harbour and Rio de Janeiro over the past two decades.

Widespread pollution

The problem of pollution is not unique to Casey station, says Ceisha Poirot, manager of policy, environment, and safety at Antarctica New Zealand in Christchurch. “All national programs are dealing with this issue,” she says. At New Zealand’s Scott Base — which is being redeveloped — contamination left from past fuel spills and poor waste management has been detected in soil and marine sediments. More of this historical pollution will emerge as the climate warms, says Poirot. “Things that were once frozen in the soil are now becoming more mobile,” she says.

Most of Antarctica’s contamination is due to historically poor waste management. In the old days, waste was often just dumped a small distance from research stations, says Terence Palmer, a marine scientist at Texas A&M University–Corpus Christi.

Research stations started to get serious about cleaning up their act in 1991. In that year, an international agreement known as the Protocol on Environmental Protection to the Antarctic Treaty, or the Madrid Protocol, was adopted. This designated Antarctica as a “natural reserve, devoted to peace and science,” and directed nations to monitor environmental impacts related to their activities. But much of the damage had already been done — roughly two-thirds of Antarctic research stations were built before 1991.

Antarctic research stations have polluted a pristine wilderness, Gemma Conroy, Nature.

Credit: Freddie Pagani for Physics Today

Topics: African Americans, Diversity in Science, Electrical Engineering, Materials Science, Physics

Students should strategically consider where to apply to graduate school, and faculty members should provide up-to-date job resources so that undergraduates can make informed career decisions.

The number of bachelor’s degrees in physics awarded annually at US institutions is at or near an all-time high—nearly double what it was two decades ago. Yet the number of first-year physics graduate students has grown much more slowly, at only around 1–2% per year. The difference in the growth rates of bachelor’s recipients and graduate spots may be increasing the competition that students face when interested in pursuing graduate study.

With potentially more students applying for a relatively fixed number of first-year graduate openings, students may need to apply to more schools, which would take more time and cost more money. As the graduate school admissions process becomes more competitive, applicants may need even more accomplishments and experiences, such as postbaccalaureate research, to gain acceptance. Such opportunities are not available equally to all students. To read about steps one department has taken to make admissions more equitable, see the July Physics Today article by one of us (Young), Kirsten Tollefson, and Marcos D. Caballero.

We do not view the increasing gap between bachelor’s recipients and graduate spots as necessarily a problem, nor do we believe that all physics majors should be expected to go to graduate school. Rather, we assert that this trend is one that both prospective applicants and those advising them should be aware of so students can make an informed decision about their postgraduation plans.

The “itch” for graduate school has always been a constant with me. I wanted especially to go after meeting Dr. Ronald McNair after his maiden voyage on Challenger in 1984. Little did I know that he would perish two years later in the same vehicle. Things happened to set the itch aside: marriage, kids, sports leagues. Life can delay your decision, too. My gap was 33 years: 1984 to 2017.

The recent decision by the Supreme Court to overturn another precedent: Affirmative Action in college admissions, affects graduate schools as well as undergraduate admissions. After every effort of progress, whether in race (a social construct) relations, labor, or gender, history, if they allow us to study it, has always shown a backlash. The group that is in power wants to remain in power, and the inequity those of us lower on the totem poll are pointing out they see as the result of the "natural order," albeit by government fiat.

My pastor at the time could have called our congressman and gotten me an appointment. My grades weren't too bad, and being the highest-ranking cadet in the city and county probably would have helped my CV. I chose an HBCU, NC A&T State University, in my undergrad because Greensboro to Winston-Salem was and is a lot closer than the Air Force Academy in Colorado. I would have been away from my parents for an entire agonizing year of no contact: cell phones and video chatting weren't a thing. I also wasn’t a fan of my freshman year being called a “Plebe” (lower-born). I do support the decisions students and their parents make as the best decision for their future. I do not support an unelected body trying to do "reverse political Entropy," turning back the clock of progress to 1953. We are, however, in 2023, and issues like climate change can be solved by going aggressively towards renewables: Texas experienced some of the hottest days on the planet, and their off-the-national grid held because of solar and wind, in an impressive display of irony.

Physics majors who graduate and go to work are prepared for either teaching K-12 or engineering. I worked at Motorola, Advanced Micro Devices, and Applied Materials. I taught Algebra 1, Precalculus, and Physics. So, if it’s any consolation: physics majors will EARN a living and eat! As a generalist, you should be able to master anything you’d be exposed to.

Speaking of Harvard: when I worked at Motorola in Austin, Texas, one of my coworkers was promoted from process engineering to Section Manager of Implant/Diffusion/Thin Films. He attended Harvard, and I, A&T. I still worked in photo and etch, primarily as the etch process engineer on nights. I noticed he had a familiar green book on his bookshelf with yellow, sinusoidal lines on the cover.

Me: Hey! Isn't that a Halladay and Resnick?

Him: Why, yes! What do you know about it?

Me: I learned Physics I from Dr. Tom Sandin (who recently retired after 50 YEARS: 1968 - 2018). He taught Dr. Ron McNair, one of the astronauts on the Space Shuttle Challenger. Physics II was taught to me by Dr. Elvira Williams: she was the first African American woman to earn a Ph.D. in Physics in the state of North Carolina and the FOURTH to earn a Ph.D. in Theoretical Physics in the nation. Who were your professors?

Him: Look at the time! Got a meeting. Bye!

Life experiences, in the end, overcome legacy and connection. We need a diversity of opinions to solve complex problems. Depending on the same structures and constructs to produce our next innovators isn't just shortsighted: it's magical thinking.

I now do think that 18 might be a little too young for a freshman on any campus and 22 a little too early for graduate school.

Just make the gap a little less than three decades!

The gap between physics bachelor’s recipients and grad school spots is growing, Nicholas T. Young, Caitlin Hayward, and Eric F. Bell, AIP Publishing, Physics Today.

Topics: Nobel Laureate, Nobel Prize, Physics

The Royal Swedish Academy of Sciences has decided to award the Nobel Prize in Physics 2022 to

Alain Aspect
Université Paris-Saclay and
École Polytechnique, Palaiseau, France

John F. Clauser
J.F. Clauser & Assoc., Walnut Creek, CA, USA

Anton Zeilinger
University of Vienna, Austria

“for experiments with entangled photons, establishing the violation of Bell inequalities and pioneering quantum information science”

Entangled states – from theory to technology

Alain Aspect, John Clauser and Anton Zeilinger have each conducted groundbreaking experiments using entangled quantum states, where two particles behave like a single unit even when they are separated. Their results have cleared the way for new technology based on quantum information.

Press release: The Nobel Prize in Physics 2022. NobelPrize.org. Nobel Prize Outreach AB 2022. Tue. Oct 2022. < https://www.nobelprize.org/prizes/physics/2022/press-release/ >

Transport dewars like this carry crucial cryogens for scientific instruments.

Topics: Chemistry, Instrumentation, Nuclear Magnetic Resonance, Physics, Research

Scientists who need the gas face tough choices in the face of reduced supply and spiking prices.

Helium supplies, already dicey, got worse this past week when production shut down in Arzew, Algeria. The curtailment joins ongoing disruptions in supplies from Russia and the US Federal Helium Reserve as well as planned maintenance at facilities in Qatar. Helium users in several locations say they are struggling to get the gas they need to keep their scientific instruments running.

“The shortage is scaring most NMR spectroscopists,” says Martha Morton, the director of research instrumentation at the University of Nebraska–Lincoln. Nuclear magnetic resonance instruments and related tools use liquid helium to cool superconducting magnets.

War in Ukraine makes helium shortage more dire, Craig Bettenhausen, Chemical & Engineering News

At CERN in 1973, John Bell (left), who was working there at the time, interacts with Martinus Veltman (right), who was then a professor at Utrecht University in the Netherlands. Since early 2020, COVID-19 has hindered physicists’ ability to travel and discuss physics in person. (Courtesy of CERN.)

Topics: COVID-19, Existentialism, Physics, Research

An excerpt. The longer article piece is at the link following.

The COVID-19 pandemic has not only killed a large number of people—approximately 5.5 million worldwide at the time Physics Today went to press in mid-January—it has also disrupted life in a fundamental, nonperturbative manner, forcing large-scale changes in human behavior from without.

It was difficult at the beginning of 2020 to anticipate the great COVID-19 calamity awaiting the world. In February of that year, I was apparently among the first people to have urged the leadership of the American Physical Society to cancel its upcoming March Meeting in Denver, which APS finally did at the last moment after considerable hesitancy.

The logistics of canceling a meeting of 10 000 people right before the event are not trivial. But given the crowd density in APS March Meetings, it is reasonable to assume that the 2020 event would have led to a few thousand COVID-19 cases just among the physicist attendees. Overall, it may have led to many tens of thousands, perhaps even hundreds of thousands, of cases, if not more. That estimate is based on research related to the now-infamous Boston Biogen superspreader conference in late February 2020. Within a month, roughly 100 people in Massachusetts who either went to the conference or were a household contact of someone who went tested positive. The genetic-code-based investigation estimated that the event led to 300 000 COVID-19 cases worldwide by the beginning of the following November. APS made the right call in canceling the meeting.

Commentary: A physicist’s perspective on COVID-19, Sankar Das Sarma, Physics Today

FIG. 1. Schematic of the motivation and the method for this paper.

Topics: Applied Physics, Chemistry, Physics, Plasma, Research

ABSTRACT

Cold atmospheric plasmas have great application potential due to their production of diverse types of reactive species, so understanding the production mechanism and then improving the production efficiency of the key reactive species are very important. However, plasma chemistry typically comprises a complex network of chemical species and reactions, which greatly hinders the identification of the main production/reduction reactions of the reactive species. Previous studies have identified the main reactions of some plasmas via human experience, but since plasma chemistry is sensitive to discharge conditions, which are much different for different plasmas, widespread application of the experience-dependent method is difficult. In this paper, a method based on graph theory, namely, vital nodes identification, is used for the simplification of plasma chemistry in two ways: (1) holistically identifying the main reactions for all the key reactive species and (2) extracting the main reactions relevant to one key reactive species of interest. This simplification is applied to He + air plasma as a representative, chemically complex plasma, which contains 59 species and 866 chemical reactions, as reported previously. Simplified global models are then developed with the key reactive species and main reactions, and the simulation results are compared with those of the full global model, in which all species and reactions are incorporated. It was found that this simplification reduces the number of reactions by a factor of 8–20 while providing simulation results of the simplified global models, i.e., densities of the key reactive species, which are within a factor of two of the full global model. This finding suggests that the vital nodes identification method can capture the main chemical profile from a chemically complex plasma while greatly reducing the computational load for simulation.

Simplification of plasma chemistry by means of vital nodes identification

Bowen Sun, Dingxin Liu, Yifan Liu, Santu Luo, Mingyan Zhang, Jishen Zhang, Aijun Yang, Xiaohua Wang, and Mingzhe Rong, Journal of Applied Physics

1 Soap, shampoo, and worm-like micelles Soaps and shampoos are made from amphiphilic molecules with water-loving (red) and water-hating (blue) parts that arrange themselves to form long tubes known as “worm-like micelles”. Entanglements between the tubes give these materials their pleasant, sticky feel. b The micelles can, however, disentangle themselves, just as entangled long-chain polymer molecules can slide apart too. In polymers, this process can be modeled by imagining the molecule sliding, like a snake, out of an imaginary tube formed by the surrounding spatial constraints. c Worm-like micelles can also morph their architecture by performing reconnections (left), breakages (down), and fusions (right). These operations occur randomly along the backbone, are in thermal equilibrium, and reversible. (Courtesy: Davide Michieletto)

Topics: Biology, DNA, Physics, Polymer Science, Research

DNA molecules are not fixed objects – they are constantly getting broken up and glued back together to adopt new shapes. Davide Michieletto explains how this process can be harnessed to create a new generation of “topologically active” materials.

Call me naïve, but until a few years ago I had never realized you can actually buy DNA. As a physicist, I’d been familiar with DNA as the “molecule of life” – something that carries genetic information and allows complex organisms, such as you and me, to be created. But I was surprised to find that biotech firms purify DNA from viruses and will ship concentrated solutions in the post. In fact, you can just go online and order DNA, which is exactly what I did. Only there was another surprise in store.

When the DNA solution arrived at my lab in Edinburgh, it came in a tube with about half a milligram of DNA per centimeter cube of water. Keen to experiment on it, I tried to pipette some of the solution out, but it didn’t run freely into my plastic tube. Instead, it was all gloopy and resisted the suction of my pipette. I rushed over to a colleague in my lab, eagerly announcing my amazing “discovery”. They just looked at me like I was an idiot. Of course, solutions of DNA are gloopy.

I should have known better. It’s easy to idealize DNA as some kind of magic material, but it’s essentially just a long-chain double-helical polymer consisting of four different types of monomers – the nucleotides A, T, C, and G, which stack together into base pairs. And like all polymers at high concentrations, the DNA chains can get entangled. In fact, they get so tied up that a single human cell can have up to 2 m of DNA crammed into an object just 10 μm in size. Scaled up, it’s like storing 20 km of hair-thin wire in a box no bigger than your mobile phone.

Make or break: building soft materials with DNA, Davide Michieletto is a Royal Society university research fellow in the School of Physics and Astronomy, University of Edinburgh

Image Source: Link below

Topics: Biology, Chemistry, COVID-19, Mathematics, Physics

The year 2020 has been defined by the COVID-19 pandemic: The novel coronavirus responsible for it has infected millions of people and caused more than a million deaths. Like HIV, Zika, Ebola, and many influenza strains, the coronavirus made the evolutionary jump from animals to humans before wreaking widespread havoc. The battle to control it continues. When a disease outbreak is identified—usually through an anomalous spike in cases with similar symptoms—scientists rush to understand the new illness. What type of microbe causes the infection? Where did it come from? How does the infection spread? What are its symptoms? What drugs could treat it? In the current epidemic, science has proceeded at a frenetic pace. Virus genomes are quickly sequenced and analyzed, case and death numbers are visualized daily, and hundreds of preprints are shared every day.

Some scientists rush for their microscopes and lab coats to study a new infection; others leap for their calculators and code. A handful of metrics can characterize a new outbreak, guide public health responses, and inform complex models that can forecast the epidemic’s trajectory. Infectious disease epidemiologists, mathematical biologists, biostatisticians, and others with similar expertise try to answer several questions: How quickly is the infection spreading? What fraction of transmission must be blocked to control the spread? How long is someone infectious? How likely are infected people to be hospitalized or die?

Physics is often considered the most mathematical science, but theory and rigorous mathematical analysis also underlie ecology, evolutionary biology, and epidemiology.¹ Ideas and people constantly flow between physics and those fields. In fact, the idea of using mathematics to understand infectious disease spread is older than germ theory itself. Daniel Bernoulli of fluid-mechanics fame devised a model to predict the benefit of smallpox inoculations² in 1760, and Nobel Prize-winning physician Ronald Ross created mathematical models to encourage the use of mosquito control to reduce malaria transmission.³ Some of today’s most prolific infectious disease modelers originally trained as physicists, including Neil Ferguson of Imperial College London, an adviser to the UK government on its COVID-19 response, and Vittoria Colizza of Sorbonne University in Paris, a leader in network modeling of disease spread.

This article introduces the essential mathematical quantities that characterize an outbreak, summarizes how scientists calculate those numbers, and clarify the nuances in interpreting them. For COVID-19, estimates of those quantities are being shared, debated, and updated daily. Physicists are used to distilling real-world complexity into meaningful, parsimonious models, and they can serve as allies in communicating those ideas to the public.

The math behind epidemics, Alison Hill, Physics Today

Alison Hill is an assistant professor in the Institute for Computational Medicine and the infectious disease dynamics group at Johns Hopkins University in Baltimore, Maryland. She is also a visiting scholar at Harvard University in Cambridge, Massachusetts.

Topics: African Americans, Diversity in Science, Physics

Throughout the week of 25 October, Black physicists, their allies, and the general public are invited to participate in #BlackInPhysics Week, a social media-based event dedicated to celebrating Black physicists and their contributions to the scientific community and to revealing a more complete picture of what a physicist looks like. Programming includes professional panels, a job fair, and an open mic night. If you are interested in learning more and registering for the events, check out blackinphysics.org or @BlackInPhysics on Twitter.

The lead organizers of #BlackInPhysics Week are Charles D. Brown II, an atomic and condensed-matter physicist; Jessica Esquivel, a particle physicist; and Eileen Gonzales, an astronomer studying brown dwarfs and exoplanets. Co-organizers include Jessica Tucker, a quantum information scientist; LaNell Williams, a biophysicist; Vanessa Sanders, a radiochemist; Bryan Ramson, a particle physicist; Xandria Quichocho, a physics education researcher; Marika Edwards, an astrophysicist, and engineer; Ashley Walker, an astrochemist; Cheyenne Polius, an astrophysicist; and Ciara Sivels, a nuclear engineer.

Brown, Esquivel, Gonzales, Quichocho, and Polius answered questions about #BlackInPhysics Week and described how physics became their passion.

Meet the organizers of #BlackInPhysics Week, Physics Today

Topics: Microscopy, Nanotechnology, NEMS, Physics, Research

ABSTRACT

Single-molecule microscopy has become an indispensable tool for biochemical analysis. The capability of characterizing distinct properties of individual molecules without averaging has provided us with a different perspective for the existing scientific issues and phenomena. Recently, super-resolution fluorescence microscopy techniques have overcome the optical diffraction limit by the localization of molecule positions. However, the labeling process can potentially modify the intermolecular dynamics. Based on the highly sensitive nanomechanical photothermal microscopy reported previously, we propose optimizations on this label-free microscopy technique toward localization microscopy. A localization precision of 3 Å is achieved with gold nanoparticles, and the detection of polarization-dependent absorption is demonstrated, which opens the door for further improvement with polarization modulation imaging.

FIG. 2. (a) Schematic of the measurement setup. BE: beam expander. M: mirror. WP: waveplate. LP: linear polarizer. BS: beam splitter. PD: photodetector/power meter. DM: dichroic mirror. ID: iris diaphragm. CCD: charge-coupled device camera. APD: avalanche photodiode detector. (b) The transduction scheme of the trampoline resonator. (c) SEM image of the trampoline resonator.

J. Appl. Phys. 128, 134501 (2020); https://doi.org/10.1063/5.0014905

Nanoelectromechanical photothermal polarization microscopy with 3 Å localization precision, Miao-Hsuan Chien and Silvan Schmid, Journal of Applied Physics

Nobel Prize in Physics, 2020

Topics: Nobel Laureate, Nobel Prize, Physics

The Nobel Prize in Physics 2020 was divided, one half awarded to Roger Penrose “for the discovery that black hole formation is a robust prediction of the general theory of relativity”, the other half jointly to Reinhard Genzel and Andrea Ghez “for the discovery of a supermassive compact object at the centre of our galaxy.”

The Nobel Prize in Physics 2020. NobelPrize.org. Nobel Media AB 2020. Tue. 6 Oct 2020. <https://www.nobelprize.org/prizes/physics/2020/summary/>

The spike protein of the SARS-CoV-2 virus (gray) is shown with three small antibodies (pink) attached to its receptor binding domains. The spike attaches at the left to the viral membrane (not shown). DIAMOND LIGHT SOURCE

Topics: Chemistry, COVID-19, Physics, Research

As the world anxiously awaits development of one or more vaccines to tame the SARS-CoV-2 virus, other research continues at a feverish pace to find effective treatments for the disease it causes, COVID-19. That work, in which physicists and chemists are deeply involved, has made significant strides in the past several months and has turned up a few surprises. Researchers at the University of Alberta reported at the August virtual meeting of the American Crystallographic Association that a dipeptide-based protease inhibitor used to treat a fatal coronavirus infection in cats also blocks replication of the SARS-CoV-2 virus in samples of monkey lung tissue. Joanne Lemieux, a biochemist at the university, says the antiviral, known as GC373, works by blocking the function of the main protease (M^pro), an enzyme that cleaves the polyproteins translated from viral RNA into individual proteins once it enters human cells.

Lemieux says GC373 has been shown to have no toxic effects in cats. Anivive, a California company that develops pet medicines, has applied for US Food and Drug Administration approval to begin trials in humans. Lemieux’s group crystallized the M^pro in combination with the drug and produced three-dimensional images of how the drug binds strongly to the active pocket on the enzyme. Although GC373 should be effective in its current form, the group is planning further crystallography experiments at the Stanford Synchrotron Radiation Lightsource (SSRL) and the Canadian Light Source to see if a reformulation could optimize it for human use, she says.

Cats and llamas could offer a path to coronavirus therapies, David Kramer, Physics Today

Dr. Peter Delfyett, Jr., National Society of Black Physicists

Topics: Diversity, Diversity in Science, Laser, Physics, Semiconductors

Dr. Peter Delfyett, former NSBP President and NSBP fellow, is the 2020 winner of the William Streifer Scientific Achievement Award. The William Streifer Scientific Achievement Award was established to recognize an exceptional single scientific contribution which has had a significant impact in the field of lasers and electro-optics in the past ten years. Dr. Delfyett has been selected, "For pioneering contributions to semiconductor diode based ultrafast laser science and technology." The Award is endowed by Xerox Corp and Spectra Diode Labs. The Award consists of an honorarium of $2,500 and a medal. The presentation is made at the IEEE Photonics Conference.

Learn more about this award and its previous winners.

Peter Delfyett wins the 2020 William Streifer Scientific Achievement Award, NSBP

#P4TC links:

Diaspora, 13 February 2012

Reducing the Impact of Negative Stereotypes on the Careers of Minority and Women Scientists, November 25, 2010

Green Book Blog: The Technology Dilemma, Zoë Dowling

Topics: Biology, Chemistry, COVID-19, Nanotechnology, Physics, Research, STEM

Amid coronavirus shutdowns, some grad students feel pressure to report to their labs
Michael Price, Science Magazine, AAAS

I feel their pain.

APS Physics: March.APS/about/coronavirus/

MRS: Materials Research Society/2020-Spring Meeting