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  • richardmitnick 11:21 am on May 4, 2021 Permalink | Reply
    Tags: , Clifford Johnson, Outreach, , Symmetry Magazine   

    From Symmetry: “On the marvels of physics” Clifford Johnson 

    Symmetry Mag

    From Symmetry

    Brianna Barbu

    Illustration by Sandbox Studio, Chicago with Corinne Mucha.

    Theoretical physicist Clifford Johnson answers Symmetry writer Brianna Barbu’s questions about his work in science and outreach, including advising on movies like Avengers: Endgame.

    Clifford Johnson, a theoretical physicist at the University of Southern California (US), is an accomplished scientist working on ways to describe the origin and fabric of the universe.

    He is also a multitalented science communicator and one of the rare scientists that can boast his own IMDb page.

    Johnson’s efforts to engage the public with science have spanned blogging, giving public lectures, appearing on television and web shows, writing and illustrating a graphic novel, and acting as a science advisor for television shows and blockbuster films including Star Trek: Discovery and Avengers: Endgame.

    In the spirit of his 2017 popular science book The Dialogues, I hopped on a Zoom call with Johnson for a dialogue of my own. What follows is an edited version of our conversation about how and why he came to study quantum physics, why he decided to create a graphic novel about science, the ups and downs of Hollywood consulting, and why public engagement with science matters.

    S.How did you decide to study physics?

    CJ:From a very early age, I was asking questions about how the world works and trying to figure out how things worked by tinkering with old radios and things. Then at some point, I learned that there’s a career where you can make a living from that sort of curiosity—being a scientist.

    And then some family friend asked me what kind of scientist I wanted to be. I didn’t realize there were different kinds. So I found a dictionary and I went through page by page and read the definitions of “chemist,” “biologist,” all of the “-ists” and “-ologists.” And when I hit “physicist,” I thought, “this is the one,” because the entry said that physics underlies all the other sciences—which appealed to me because I wanted to keep my options open.

    You were awarded a National Science Foundation (US) CAREER Award in 1997 and received the 2005 Maxwell Medal and Prize for your early-career contributions to string theory and quantum gravity research. What drew you to theoretical physics and quantum gravity?

    CJ: I got interested in particle physics reading authors such as Paul Davies and Abraham Pais as a teenager. And then in my undergraduate studies at Imperial College, I began to learn about the issues of trying to quantize gravity, which led me to study string theory for my PhD at the University of Southampton. The universe really does seem to be fundamentally quantum mechanical. So, it’s a real problem if we don’t know quantum mechanically how to understand gravity, spacetime and where the universe comes from.

    You also do a lot of public engagement on top of your research. The American Association for Physics Teachers awarded you the 2018 Klopsteg Award for your outreach. How did you get started in science communication and outreach?

    CJ: I’ve been doing outreach in a way since I was 8 or 10 years old. I was that annoying kid who was always explaining things. In school, people would call me “the professor.” Everyone thought they were giving me a hard time, but secretly I thought it was an awesome nickname.

    Outreach, for me, is a natural part of being a scientist. Research is all about the story of how things work and where they came from. And what’s the point of knowing the story, if you can’t also get other people excited about it? If someone wants to know, I’m going to tell them. I got reasonably good at explaining things in a coherent way. Word got around, and I started presenting on radio and TV.

    Sometimes, people would get in touch from the media because of something they read on my blog. I co-founded a blog called Cosmic Variance with four other physicists in 2005, and also started a solo blog called Asymptotia in 2006. I’d write about interesting ideas and what was going on in research, as well as my other interests and day-to-day life. Blogging created communities where people would engage in conversation and we’d have great discussions, and then that would encourage us to write more.
    Why is engaging the public in science so important to you?

    It is very frustrating to me that science is often portrayed as a special thing done by a special group of people. It is a special thing, but anyone can be involved, and everyone should be involved. I often say that science should be put back into the culture where it belongs.

    Public outreach is important because a lot of people think they wouldn’t understand scientific issues, and so they leave it to a small group of people to make decisions. And that’s not democratic. We aren’t a democracy if people aren’t more familiar and comfortable with science and the people who do science.

    Your book The Dialogues is a graphic novel structured as a series of conversations about science, which you wrote and also illustrated yourself. How did that come together?

    CJ: I agonized over writing a book for the general public for a long time because I didn’t think there was any urgency to write one of the standard kinds of books that get written by people in my field. Not that there’s anything wrong with those books. But I thought that if we could break out of the narrow mold of how popular science books are supposed to be, we could reach so many more people.

    Though I was a comic book fan from a young age, I essentially snuck up on the on the graphic-novel concept backwards. The ratio between prose and illustration changed as I began to conceptualize what I really wanted to be able to do with the book. The illustration aspect began to eat the prose aspect and became a narrative in its own right. And then I realized it was going to be a graphic novel. Writers often say that you try and create the book that you want to see in the world—so I did, and I even took the time out to teach myself to draw at the level needed to do it.

    In all graphic novels, spacetime is created by the reader. When you’re looking at a series of comic panels, your mind constructs how space and time come alive on the page. So what better medium to talk about physics, the subject that is about spacetime, than graphic novels? I could take advantage of the medium to illustrate ideas, like arranging panels to swirl into the interior of a black hole and mess up the order to convey how space and time get messed up there.

    Do you plan to write another book?

    CJ: Yes. The plan is to do a new set of dialogues. Unfortunately, I’m still working on the time machine in the basement so I can manufacture more hours in the day. Sooner or later, I’ll get it to work.

    Okay, you know I had to ask this—what’s it like working with the Science and Entertainment Exchange and being a science advisor for movies and TV?

    CJ: Most of the work is not the glamorous, sitting-around-chatting-with-Spielberg kind of thing that people envision. There’s no industry standard for science consulting. The work can be anything from a writer getting in touch with me and asking if I’ll take a look at a script, or if I’ll talk with them about an idea they have. Or the directors call consultants in at the end and ask us to fix something before they start shooting, although by then it’s usually too late for a good conversation.

    If the science is going to be part of the DNA of the story, then it’s best if conversations happen early. The best stuff happens when there’s an environment where science can be an inspiration at the writing stage. For the Avengers: Endgame and Infinity War movies, one of the smart things the filmmakers did is they got in touch early on and then we brainstormed ideas. They did this with other scientists, too, gathering a lot of good material to draw from.

    How much of your advice gets used?

    CJ: Anywhere from zero to a hundred percent. I have no control over how much. When I give public talks, I talk about the trade-off between how much control you have and the size of the audience you can reach. I have complete control over the content of a public lecture to a few hundred people. I had zero control of what ended up in the final cut of Avengers, with an audience of many millions.

    In a few projects I advised on, there are even scenes where I wrote most of the words. I either went over the script and revised the science talk, or the writers left a hole for me to tell them how to say something, and then they used my suggestions verbatim. That’s not common, but it happens sometimes.

    Overall, the science is more likely to survive all the way to the screen if it’s for television, which is more of a writer’s medium. In television, the director works for the writers. In film, the writers work for the directors, who may or may not care about the science content.

    Can you give me some examples of projects where you had a significant impact?

    CJ: Season two of the show Agent Carter is a great model of how things between TV writers and science consultants are supposed to work. Entire characters and storylines on the show were invented based on things we brainstormed together in the writers’ room. A few times, I sketched an idea about what a machine might look like and they just went away and built the machine for the set!

    Another project where I was involved very early on was the first season of National Geographic’s series Genius, about the life and work of Einstein. Not only did I teach the writers a lot about relativity, but I helped pick pieces of science that they could unpack thematically for episodes and helped them write scenes so that the science could really be on show.

    Maybe most importantly, they took seriously my encouragement to show that Einstein discussed his ideas with others around him, to help break that “lone genius” mythology that often drives people away from thinking they can be scientists.

    What are the most important things for films and TV shows to get right when it comes to science?

    CJ: Some people get hung up on getting all the facts right, but I’d rather focus on things like representing the scientific process correctly, as opposed to making it seem like magic—representing the thought processes and the people doing those thought processes.

    I care about whether the scientists are portrayed like real people with narratives that help you relate to them and understand them. When I’m working with artists and media people creating images of scientists, I encourage them to make those people more real, make them more accessible, show that they’re human beings.

    You do so much! How do you balance your work, your outreach and the rest of your life?

    CJ: I think the most important skill to learn is dealing with interruption and knowing how to put something on hold and then come back to it. I’ve gotten better at doing a lot of stuff in my head in preparation for that short time I’m going to have where I will be able to sit at my desk and do my physics.

    I hope that I am helping to dispel the myth that if you’re good at outreach, it means that you’re not good—or not interested—in research at the highest level. That’s often used to discourage people from spending time on outreach and engagement, or as an excuse to dismiss people of color or women in the field. The fact that I have been very successful at research and teaching and also science outreach shows that it is possible to be a significant player in both realms.

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

    Symmetry is a joint Fermilab/SLAC publication.

  • richardmitnick 10:53 am on April 7, 2021 Permalink | Reply
    Tags: "First results from Fermilab’s Muon g-2 experiment strengthen evidence of new physics", , , , , , Symmetry Magazine   

    From Symmetry: “First results from Fermilab’s Muon g-2 experiment strengthen evidence of new physics” 

    Symmetry Mag


    FNAL Muon g-2 experiment at DOE’s Fermi National Accelerator Laboratory (US). Photo by Reidar Hahn, Fermilab.

    The long-awaited first results from the Muon g-2 experiment at the US Department of Energy’s Fermi National Accelerator Laboratory show fundamental particles called muons behaving in a way that is not predicted by scientists’ best theory, the Standard Model of particle physics. This landmark result, made with unprecedented precision, confirms a discrepancy that has been gnawing at researchers for decades.

    The strong evidence that muons deviate from the Standard Model calculation might hint at exciting new physics. Muons act as a window into the subatomic world and could be interacting with yet undiscovered particles or forces.

    “Today is an extraordinary day, long awaited not only by us but by the whole international physics community,” says Graziano Venanzoni, co-spokesperson of the Muon g-2 experiment and physicist at the Italian National Institute for Nuclear Physics. “A large amount of credit goes to our young researchers who, with their talent, ideas and enthusiasm, have allowed us to achieve this incredible result.”

    A muon is about 200 times as massive as its cousin, the electron. Muons occur naturally when cosmic rays strike Earth’s atmosphere, and particle accelerators at Fermilab can produce them in large numbers. Like electrons, muons act as if they have a tiny internal magnet. In a strong magnetic field, the direction of the muon’s magnet precesses, or wobbles, much like the axis of a spinning top or gyroscope. The strength of the internal magnet determines the rate that the muon precesses in an external magnetic field and is described by a number that physicists call the g-factor. This number can be calculated with ultra-high precision.

    As the muons circulate in the Muon g-2 magnet, they also interact with a quantum foam of subatomic particles popping in and out of existence. Interactions with these short-lived particles affect the value of the g-factor, causing the muons’ precession to speed up or slow down very slightly. The Standard Model predicts this so-called anomalous magnetic moment extremely precisely. But if the quantum foam contains additional forces or particles not accounted for by the Standard Model, that would tweak the muon g-factor further.

    “This quantity we measure reflects the interactions of the muon with everything else in the universe. But when the theorists calculate the same quantity, using all of the known forces and particles in the Standard Model, we don’t get the same answer,” says Renee Fatemi, a physicist at the University of Kentucky and the simulations manager for the Muon g-2 experiment. “This is strong evidence that the muon is sensitive to something that is not in our best theory.”

    The predecessor experiment at DOE’s Brookhaven National Laboratory, which concluded in 2001, offered hints that the muon’s behavior disagreed with the Standard Model. The new measurement from the Muon g-2 experiment at Fermilab strongly agrees with the value found at Brookhaven and diverges from theory with the most precise measurement to date.

    The accepted theoretical values for the muon are:

    g-factor: 2.00233183620(86) [uncertainty in parentheses]

    anomalous magnetic moment: 0.00116591810(43)

    The new experimental world-average results announced by the Muon g-2 collaboration today are:

    g-factor: 2.00233184122(82)

    anomalous magnetic moment: 0.00116592061(41)

    The first result of the Muon g-2 experiment at Fermilab confirms the result from the experiment performed at DOE’s Brookhaven National Laboratory(US) two decades ago. Together, the two results show strong evidence that muons diverge from the Standard Model prediction. Credit: Ryan Postel, Fermilab/Muon g-2 collaboration.

    The combined results from Fermilab and Brookhaven show a difference with theory at a significance of 4.2 sigma, a little shy of the 5 sigma (or standard deviations) that scientists require to claim a discovery but still compelling evidence of new physics. The chance that the results are a statistical fluctuation is about 1 in 40,000.

    The Fermilab experiment reuses the main component from the Brookhaven experiment, a 50-foot-diameter superconducting magnetic storage ring.

    DOE’s Fermi National Accelerator Laboratory(US) G-2 magnet from DOE’s Brookhaven National Laboratory(US) finds a new home in the FNAL Muon G-2 experiment. The move by barge and truck.

    In 2013, it was transported 3200 miles by land and sea from Long Island to the Chicago suburbs, where scientists could take advantage of Fermilab’s particle accelerator and produce the most intense beam of muons in the United States. Over the next four years, researchers assembled the experiment; tuned and calibrated an incredibly uniform magnetic field; developed new techniques, instrumentation, and simulations; and thoroughly tested the entire system.

    The Muon g-2 experiment sends a beam of muons into the storage ring, where they circulate thousands of times at nearly the speed of light. Detectors lining the ring allow scientists to determine how fast the muons are precessing.

    In its first year of operation, in 2018, the Fermilab experiment collected more data than all prior muon g-factor experiments combined. With more than 200 scientists from 35 institutions in seven countries, the Muon g-2 collaboration has now finished analyzing the motion of more than 8 billion muons from that first run.

    “After the 20 years that have passed since the Brookhaven experiment ended, it is so gratifying to finally be resolving this mystery,” says Fermilab scientist Chris Polly, who is a co-spokesperson for the current experiment and was a lead graduate student on the Brookhaven experiment.

    Data analysis on the second and third runs of the experiment is under way, the fourth run is ongoing, and a fifth run is planned. Combining the results from all five runs will give scientists an even more precise measurement of the muon’s wobble, revealing with greater certainty whether new physics is hiding within the quantum foam.

    “So far we have analyzed less than 6% of the data that the experiment will eventually collect. Although these first results are telling us that there is an intriguing difference with the Standard Model, we will learn much more in the next couple of years,” Polly says.

    “Pinning down the subtle behavior of muons is a remarkable achievement that will guide the search for physics beyond the Standard Model for years to come,” says Fermilab Deputy Director of Research Joe Lykken. “This is an exciting time for particle physics research, and Fermilab is at the forefront.”

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

    Symmetry is a joint Fermilab/SLAC publication.

  • richardmitnick 1:15 pm on March 30, 2021 Permalink | Reply
    Tags: "The mystery of the muon’s magnetism", , , , , , , , Symmetry Magazine   

    From Symmetry: “The mystery of the muon’s magnetism” 

    Symmetry Mag
    From Symmetry

    Brianna Barbu

    A super-precise experiment at DOE’s Fermi National Accelerator Laboratory(US) is carefully analyzing every detail of the muon’s magnetic moment.


    Modern physics is full of the sort of twisty, puzzle-within-a-puzzle plots you’d find in a classic detective story: Both physicists and detectives must carefully separate important clues from unrelated information. Both physicists and detectives must sometimes push beyond the obvious explanation to fully reveal what’s going on.

    And for both physicists and detectives, momentous discoveries can hinge upon Sherlock Holmes-level deductions based on evidence that is easy to overlook. Case in point: the Muon g-2 experiment currently underway at the US Department of Energy’s Fermi National Accelerator Laboratory.

    The current Muon g-2 (pronounced g minus two) experiment is actually a sequel, an experiment designed to reexamine a slight discrepancy between theory and the results from an earlier experiment at DOE’s Brookhaven National Laboratory(US), which was also called Muon g-2.

    DOE’s Fermi National Accelerator Laboratory(US) G-2 magnet from DOE’s Brookhaven National Laboratory(US) finds a new home in the FNAL Muon G-2 experiment. The move by barge and truck.

    Fermi National Accelerator Laboratory(US) Muon g-2 studio. As muons race around a ring at the , their spin axes twirl, reflecting the influence of unseen particles.

    The discrepancy could be a sign that new physics is afoot. Scientists want to know whether the measurement holds up… or if it’s nothing but a red herring.

    The Fermilab Muon g-2 collaboration has announced it will present its first result on April 7. Until then, let’s unpack the facts of the case.

    The mysterious magnetic moment

    All spinning, charged objects—including muons and their better-known particle siblings, electrons—generate their own magnetic fields. The strength of a particle’s magnetic field is referred to as its “magnetic moment” or its “g-factor.” (That’s what the “g” part of “g-2” refers to.)

    To understand the “-2” part of “g-2,” we have to travel a bit back in time.

    Spectroscopy experiments in the 1920s (before the discovery of muons in 1936) revealed that the electron has an intrinsic spin and a magnetic moment. The value of that magnetic moment, g, was found experimentally to be 2. As for why that was the value—that mystery was soon solved using the new but fast-growing field of quantum mechanics.

    In 1928, physicist Paul Dirac—building upon the work of Llewelyn Thomas and others—produced a now-famous equation that combined quantum mechanics and special relativity to accurately describe the motion and electromagnetic interactions of electrons and all other particles with the same spin quantum number. The Dirac equation, which incorporated spin as a fundamental part of the theory, predicted that g should be equal to 2, exactly what scientists had measured at the time.

    The Dirac equation in the form originally proposed by Dirac is


    But as experiments became more precise in the 1940s, new evidence came to light that reopened the case and led to surprising new insights about the quantum realm.

    Credit: Sandbox Studio, Chicago with Steve Shanabruch.

    A conspiracy of particles

    The electron, it turned out, had a little bit of extra magnetism that Dirac’s equation didn’t account for. That extra magnetism, mathematically expressed as “g-2” (or the amount that g differs from Dirac’s prediction), is known as the “anomalous magnetic moment.” For a while, scientists didn’t know what caused it.

    If this were a murder mystery, the anomalous magnetic moment would be sort of like an extra fingerprint of unknown provenance on a knife used to stab a victim—a small but suspicious detail that warrants further investigation and could unveil a whole new dimension of the story.

    Physicist Julian Schwinger explained the anomaly in 1947 by theorizing that the electron could emit and then reabsorb a “virtual photon.” The fleeting interaction would slightly boost the electron’s internal magnetism by a tenth of a percent, the amount needed to bring the predicted value into line with the experimental evidence. But the photon isn’t the only accomplice.

    Over time, researchers discovered that there was an extensive network of “virtual particles” constantly popping in and out of existence from the quantum vacuum. That’s what had been messing with the electron’s little spinning magnet.

    The anomalous magnetic moment represents the simultaneous combined influence of every possible effect of those ephemeral quantum conspirators on the electron. Some interactions are more likely to occur, or are more strongly felt than others, and they therefore make a larger contribution. But every particle and force in the Standard Model takes part.

    The theoretical models that describe these virtual interactions have been quite successful in describing the magnetism of electrons. For the electron’s g-2, theoretical calculations are now in such close agreement with the experimental value that it’s like measuring the circumference of the Earth with an accuracy smaller than the width of a single human hair.

    All of the evidence points to quantum mischief perpetrated by known particles causing any magnetic anomalies. Case closed, right?

    Not quite. It’s now time to hear the muon’s side of the story.

    Not a hair out of place—or is there?

    Early measurements of the muon’s anomalous magnetic moment at Columbia University (US) in the 1950s and at the European physics laboratory CERN [European Organization for Nuclear Research (Organisation européenne pour la recherche nucléaire)(EU)] in the 1960s and 1970s agreed well with theoretical predictions. The measurement’s uncertainty shrank from 2% in 1961 to 0.0007% in 1979. It looked as if the same conspiracy of particles that affected the electron’s g-2 were responsible for the magnetic moment of the muon as well.

    But then, in 2001, the Brookhaven Muon g-2 experiment turned up something strange. The experiment was designed to increase the precision from the CERN measurements and look at the weak interaction’s contribution to the anomaly. It succeeded in shrinking the error bars to half a part per million. But it also showed a tiny discrepancy—less than 3 parts per million—between the new measurement and the theoretical value. This time, theorists couldn’t come up with a way to recalculate their models to explain it. Nothing in the Standard Model could account for the difference.

    It was the physics mystery equivalent of a single hair found at a crime scene with DNA that didn’t seem to match anyone connected to the case. The question was—and still is—whether the presence of the hair is just a coincidence, or whether it is actually an important clue.

    Physicists are now re-examining this “hair” at Fermilab, with support from the DOE Office of Science (US), the National Science Foundation (US) and several international agencies in Italy, the UK, the EU, China, Korea and Germany.

    In the new Muon g-2 experiment, a beam of muons—their spins all pointing the same direction—are shot into a type of accelerator called a storage ring. The ring’s strong magnetic field keeps the muons on a well-defined circular path. If g were exactly 2, then the muons’ spins would follow their momentum exactly. But, because of the anomalous magnetic moment, the muons have a slight additional wobble in the rotation of their spins.

    When a muon decays into an electron and two neutrinos, the electron tends to shoot off in the direction that the muon’s spin was pointing. Detectors on the inside of the ring pick up a portion of the electrons flung by muons experiencing the wobble. Recording the numbers and energies of electrons they detect over time will tell researchers how much the muon spin has rotated.

    Using the same magnet from the Brookhaven experiment with significantly better instrumentation, plus a more intense beam of muons produced by Fermilab’s accelerator complex, researchers are collecting 21 times more data to achieve four times greater precision.

    The experiment may confirm the existence of the discrepancy; it may find no discrepancy at all, pointing to a problem with the Brookhaven result; or it may find something in between, leaving the case unsolved.

    Seeking the quantum underworld

    There’s reason to believe something is going on that the Standard Model hasn’t told us about.

    The Standard Model is a remarkably consistent explanation for pretty much everything that goes on in the subatomic world.

    Standard Model of Particle Physics from “Particle Fever” via Symmetry Magazine

    But there are still a number of unsolved mysteries in physics that it doesn’t address.

    Dark matter, for instance, makes up about 27% of the universe. And yet, scientists still have no idea what it’s made of. None of the known particles seem to fit the bill. The Standard Model also can’t explain the mass of the Higgs boson, which is surprisingly small. If the Fermilab Muon g-2 experiment determines that something beyond the Standard Model—for example an unknown particle—is measurably messing with the muon’s magnetic moment, it may point researchers in the right direction to close another one of these open files.

    A confirmed discrepancy won’t actually provide DNA-level details about what particle or force is making its presence known, but it will help narrow down the ranges of mass and interaction strength in which future experiments are most likely to find something new. Even if the discrepancy fades, the data will still be useful for deciding where to look.

    It might be that a shadowy quantum figure lurking beyond the Standard Model is too well hidden for current technology to detect. But if it’s not, physicists will leave no stone unturned and no speck of evidence un-analyzed until they crack the case.

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

    Symmetry is a joint Fermilab/SLAC publication.

  • richardmitnick 8:54 pm on March 29, 2021 Permalink | Reply
    Tags: "The data wranglers", A degree in particle physics or astrophysics can lead to a career in data science., , , Symmetry Magazine   

    From Symmetry: “The data wranglers” 

    Symmetry Mag
    From Symmetry

    Liz Kruesi

    Credit: Sandbox Studio, Chicago with Corinne Mucha.

    A degree in particle physics or astrophysics can lead to a career in data science.

    Particle physicist Abhigyan Dasgupta says there are many reasons he left academia after earning his PhD: He wanted to avoid a nomadic life spent following elusive opportunities. He wanted a good work-life balance.

    “I realized what I was enjoying about my day-to-day life was analyzing physics data,” he says. “But I realized I could do it with other kinds of data as well.”

    Physics and astronomy PhDs who stay on the academic track find themselves chasing a limited number of positions pursued by a large number of extremely talented candidates. Despite this, many graduate programs in physics and astronomy do not introduce students to careers outside of research institutions, and so it’s up to the students to figure out what to do next.

    As he neared the end of his doctoral program, Dasgupta started considering his options. He eventually came across the Insight Fellows Program, which trains academic-track scientists for careers in data science. The founder of the program, Jake Klamka, is a physicist who conducted research at both the Department of Energy’s Fermi National Accelerator Laboratory(US) and European Organization for Nuclear Research (Organisation européenne pour la recherche nucléaire)(EU) [CERN].

    Dasgupta applied, was accepted, and then started the seven-week program right after finishing his PhD in 2019.

    A plethora of skills transfer from physics to data science, Dasgupta says. Physicists know how to take enormous amounts of raw data and use it to address a question—often approaching it from multiple angles before finding the answer.

    “My job still reminds me of physics in many ways,” says Dasgupta, who now works as a data scientist for the video game company Activision Blizzard. “It’s just that instead of electrons and muons as my individual data, it’s users or revenue or something else.”

    Credit: Sandbox Studio, Chicago with Corinne Mucha.

    Finding the stories in the data

    Data scientists have many roles, but in the broadest sense, they “collect and analyze data and present the results to business subject-matter experts so they can make data-driven decisions,” says Aga Leyko.

    A particle-physicist-turned-data-scientist, Leyko works at a leading professional services company focusing on the healthcare industry. As she explains, data science is a broad career trajectory that uses skills such as data analysis, simulation and visualization. Leyko used these same skills for her PhD thesis, in measuring elementary particles’ properties using a multi-terabyte-sized set of data from particle interactions at the Large Hadron Collider at CERN.

    Data science also uses non-technical skills, such as problem-solving, she says. “What makes physicists really good data scientists is their ability to see through complex issues, their attention to details, and their focus on finding tangible solutions.”

    At a computer-gaming studio, data scientists study player behavior and how it interacts with the company’s revenue steam. At a large technology company, data scientists answer questions about sales tactics. Data science projects often require multiple phases and multiple tools, and they can take from weeks to years to complete.

    The first step in a new data science project is figuring out what the problem is—translating a business question into a data-science project. The next step is acquiring and preparing the raw data.

    The importance of this second step is not always obvious to those without a background in physics or astronomy, says Chaoyun Bao, a managing strategy consultant in data science at IBM who came to the field after a postdoctoral position in astrophysics.

    “When I was doing my PhD, I was analyzing a lot of sensor data,” which involves dealing with distractions ranging from radio noise to faulty electronics. “So I knew that real-world data is going to have a lot of noise, it’s going to [involve] a lot of digging around,” she says. “You know data is not going to be perfect, and you’re not going to make decisions based on perfect information.”

    Along the same lines, Leyko recalls of her time working in particle physics at CERN: “You would interrogate every single data point before you came to any conclusion.”

    Leyko began her PhD work in 2010, when the LHC started back up after a faulty magnet took it out of commission. Verifying that everything was functioning properly was of especially great importance. “I never assume that everything in the data is correct,” Leyko says.

    Leyko’s extra level of caution with data has been incredibly helpful to her career in healthcare consulting, she says. At one point she noticed a dataset she was working with just looked wrong, so she checked it out. A simple distribution plot confirmed her suspicions. It turned out a program had automatically changed any missing birthdates in the dataset to January 1, 1900—and as a result, the ages of clients seemed to peak at a value over 100 years old.

    Once a data scientist is confident in their data, they can transform it into meaningful information. This is where writing code, making plots, using predictive models, investigating a subset of data, and using other analytical tools learned throughout a physics education are incredibly useful. It’s also where the problem-solving comes in: Perhaps even more important than knowing how to use the tools is knowing which tool to use when.

    “You can teach someone how to run specific commands,” says Dasgupta, “but it takes longer to teach someone the intuition behind ‘I have this data, how can I get something useful out of that?’”

    And then there’s one more step beyond the analysis: “To be a good data scientist, you have to be able to communicate your results,” Bao says.

    It’s an inversion of the first step, translating a business question into a data problem; this time, the data scientists must translate their coding and analysis into interesting insights and business actions, she says.

    Dasgupta agrees that this is an essential part of the job. “It’s being able to explain and tell the story of data really well.”

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

    Symmetry is a joint Fermilab/SLAC publication.

  • richardmitnick 12:23 pm on March 7, 2021 Permalink | Reply
    Tags: "How English became the language of physics" Is it Really?, "Scientific Babel: How Science Was Done Before and After Global English" by Michael Gordin, , Around 1970 about 70% of world publication in science was written in English and about 25% was written in Russian., , , Because the American educational system becomes so prominent and later on also the British English becomes an obligatory conference language. It becomes a common denominator., , By the mid-1800s science in Europe was split fairly equally between English; French; and German., , Germany’s esteemed position in the scientific community changed dramatically with the rise of the Nazi Party before World War II., In the first half of the 20th century Germany was an important educational hub for physics., , , Symmetry Magazine, The salience and prominence of physics that emerged in the West—linked to the development of the Manhattan Project and its legacy—produced a very strong shift towards English., There was also a strong scientific community in the Soviet Union. But right after the world war the Soviet government shut down their few scientific journals published in languages other than Russian., Today more than 90% of the indexed articles in the natural sciences are published in English. That wasn’t always the case.   

    From Symmetry: “How English became the language of physics” Is it Really? 

    Symmetry Mag
    From Symmetry

    Meredith Fore

    Credit: Sandbox Studio, Chicago with Steve Shanabruch.

    Today more than 90% of the indexed articles in the natural sciences are published in English. That wasn’t always the case.

    During Michael Gordin’s childhood, his mother—who grew up speaking French and Moroccan Arabic—mostly conversed with his father in his father’s native Hebrew. But both of Gordin’s parents spoke to Gordin and his brothers in English, even though Gordin’s father was less nimble in the language.

    “It wasn’t until much later that I came to realize what a sacrifice that was for them, to not feel quite at ease when speaking to their kids,” Gordin says, “because they wanted their kids to have the opportunities that came with speaking a language” that more people spoke.

    As Gordin got older, he became more and more interested in languages: specifically, in how people choose which languages to use, and how sometimes a more widespread language is favored over a less common one for the sake of greater opportunity and access.

    Gordin is now a professor at Princeton University(US) who specializes in the history of the modern physical sciences, particularly in Russia and the Soviet Union. In 2010, he began to write a book about how, in the mid-20th century, Russian became one of the significant languages of science. But he quickly ran into a problem.

    “You can’t just write about one language; it’s an ecology, where all the languages of science are interacting,” he says. “So I decided to just devote myself entirely to exploring the issue of the friction that happens when people have to use a different language” that is not their native tongue.

    In 2015, he published Scientific Babel: How Science Was Done Before and After Global English, an account of how languages have waxed and waned in popularity among the scientific community since the Renaissance—and how English became the dominant language of science.

    Credit: Sandbox Studio, Chicago with Steve Shanabruch.

    A dead language gets a second life

    During the Renaissance, a trove of ancient scientific texts was rediscovered by Western Europeans, providing a repository of ancient knowledge. Scholars immediately translated them from ancient Greek to the written language that most educated Europeans knew: Latin, the language of the Catholic church. This led to a resurgence of written Latin, despite all its native speakers having been dead for a millennium.

    But a few hundred years later, Latin faded out of general use once more. By the mid-1800s science in Europe was split fairly equally between English; French; and German.

    “If you were a native speaker of French, English or German, you had to learn passively the other two,” Gordin says. “You had to be able to at least read articles and maybe understand someone speaking to you, but you only had to actively produce content in your own language. It was very common to have correspondence between scientists where one writes in English and the other writes in German.”

    In the first half of the 20th century Germany was an important educational hub for physics. Not only was it producing its own trailblazers—such as Werner Heisenberg, Albert Einstein and Maria Goeppert Mayer—it also attracted prominent physicists from other countries to study and work at its universities. Lise Meitner, born in Austria, Robert Oppenheimer, born in America, and Enrico Fermi, born in Italy, all spent time as researchers in German science institutes in the 1920s.

    Germany’s esteemed position in the scientific community changed dramatically with the rise of the Nazi Party before World War II. Foreign students and researchers were denied visas. Thousands of Jewish scientists, including Meitner, were forced to resign from their universities, and academics were forbidden from traveling abroad.

    Meitner, for one, stayed in Berlin, where she had built her career, as long as she could. But she was eventually forced to flee to the Netherlands. Soon afterward she settled in Sweden.

    She wrote to fellow physicist Max van Laue about the experience of finding herself, at the age of 60, suddenly dependent on the goodwill of a country whose language she had never spoken. “One never enjoys equal rights and is always internally alone,” she wrote. “One always speaks a foreign language—I don’t mean the external formulation of language, I mean mentally. One is without a homeland. I wish that you never experience this, nor even that you understand it.”

    The exile and persecution of scientists in Germany had a profound effect on individuals like Meitner—and on the field of physics, Gordin says. There was a shift away from Germany—and war-torn France as well—coupled with a shift toward the universities and national laboratories in the United States.

    “The salience and prominence of physics that emerged in the West—linked to the development of the Manhattan Project and its legacy—produced a very strong shift towards English,” he says. “And now, when scientists go on postdocs, they want to go to the US.”

    It was also a turning point for the role of the US in scientific education.

    “That is enormously influential because it’s where people go to graduate school, where they send their students to study,” Gordin says. “It’s where the conferences are heavily funded, because the Americans had more money after the war. Because the American educational system becomes so prominent and later on also the British English becomes an obligatory conference language. It becomes a common denominator.”

    How translation burst the Russian bubble

    There was also a strong scientific community in the Soviet Union. But right after the world war the Soviet government shut down their few scientific journals published in languages other than Russian.

    “So now you have one of the most powerful countries in the world publishing a ton of science but publishing it in a language most scientists don’t read,” Gordin says. “There is a strongly felt need in the ’50s and ’60s that American scientists need to know what Soviet scientists are doing. But they don’t have enough people who read Russian.”

    Concerned about Soviet military technology, the Atomic Energy Commission, the Office of Naval Research and the National Science Foundation began to fund projects translating Soviet physics journals from Russian into English.

    These projects were an important factor in English becoming overwhelmingly dominant. Non-American Western scientists didn’t need to learn Russian to read what the Soviets were doing. At no or little cost to their own governments and institutes, they could simply read the American English translations.

    Around 1970 about 70% of world publication in science was written in English and about 25% was written in Russian (all other languages combined made up about 5%). Today, more than 90% of the indexed articles in the natural sciences are published in English.

    “You want to communicate with a broader audience, but you also want to allow people to express themselves in a language they feel comfortable in,” Gordin says. “Now we don’t have that compromise; we just have one language.”

    History shows that this won’t necessarily always be the case.

    “It would take a lot of shocks,” Gordin says, “but something like a global plague”—he takes a meaningful pause—“could do something, or radical climate effects, or a massive war could disrupt the system so much that it reorients around an alternative equilibrium,” displacing English as the dominant scientific language.

    Even if things change, Gordin says, English will be the language of science for a long time.

    If all native Anglophones were to vanish tomorrow, and if you wanted to learn any science, you would need to know English, he says. “And that’s why Latin lasted so long after the Protestant Reformation: It was so important for the repository of knowledge that it had to be kept alive.”

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

    Symmetry is a joint Fermilab/SLAC publication.

  • richardmitnick 12:03 pm on November 10, 2020 Permalink | Reply
    Tags: , , Kaon+ and Kaon-, , , Symmetry Magazine   

    From Symmetry: “Meet the kaon” 

    Symmetry Mag
    From Symmetry

    Nathan Collins



    Nearly 75 years after the puzzling first detection of the kaon, scientists are still looking to the particles for hints of physics beyond their current understanding.

    All Clifford Charles Butler and George Rochester knew for sure was that they’d discovered something new. Photographs from their cloud-chamber experiments at the University of Manchester (UK) revealed the tracks of two particles that behaved unlike anything they’d seen before.

    When the two physicists published their results in 1947 in the journal Nature, they could have had only the dimmest notion that their discovery would in time upend the world’s understanding of elementary particle physics.

    Observations of kaons, as the particles came to be known, and other similar particles led physicists on a path toward the discoveries of new quantum properties of matter, new particles—including quarks—and the downfall of a once-sacrosanct construct called CP symmetry [charge conjugation parity symmetry], an exact relationship between the laws of physics for matter and those for antimatter. Today, high-precision experiments with kaons are helping researchers probe the limits of the same Standard Model the particles helped usher in.

    Standard Model of Particle Physics via http://www.plus.maths.org .

    But back in Butler and Rochester’s day, physicists were mostly left scratching their heads, says Helen Quinn, an emerita professor of physics and astrophysics at the US Department of Energy’s SLAC National Accelerator Laboratory.

    “Kaons didn’t fit any picture” physicists had at the time, she says. In fact, when physicists realized they needed a new quantum property to describe the particles, it “was called ‘strangeness,’ because the particles had always seemed a bit strange.”

    The particle zoo expands

    By the start of the 1940s, it seemed like physicists were getting a handle on the fundamental particles and their interactions. They knew about electrons, protons and neutrons, as well as neutrinos and even positrons, the “antiparticles” of electrons Paul Dirac had predicted in the 1920s. They understood that there were forces beyond gravity and electromagnetism, the strong and weak nuclear forces, and were working to better understand them.

    But puzzles emerged as unexpected new particles appeared. Physicists discovered muons in cosmic rays using a cloud chamber experiment in 1936.

    (The name “cloud chamber” comes from the fact that electrically charged particles travelling through water vapor form tiny trails of clouds in their wake.)

    Image of cloud chamber results. http://physicsopenlab.org/2017/05/18/particles-in-the-mist/

    They found pions by similar means in 1947.

    That same year, Butler and Rochester announced they’d found particles they called V+ and V0. From a set of “unusual fork[s]” in their data, they inferred the existence of two fairly massive particles, one positively charged and the other neutral, that had broken apart into other particles.

    The particles had a number of curious features. For one thing, they were heavy—around five times the mass of a muon—which led to another puzzle. Ordinarily, heavier particles have shorter lifetimes, meaning that they stick around for less time before decaying into other, lighter particles. But as experiments continued, researchers discovered that despite their heft, the particles had relatively long lifetimes.

    Another odd feature: The particles were easy to make, but physicists never seemed to be able to produce just one of them at a time. Smash a pion and a proton together, for example, and you could create the new particles, but only in pairs. At the same time, they could decay independently of each other.

    A strange new world

    In the 1950s, Murray Gell-Mann, Kazuo Nishijima, Abraham Pais and others devised a way to explain some of the curious behaviors kaons and other newly discovered particles exhibited. The idea was that these particles had a property called “strangeness.” Today, physicists understand strangeness as a fundamental, quantum number associated with a particle. Some particles have strangeness equal to zero, but other particles could have strangeness equal to +1, -1, or in principle any other integer.

    Importantly, strangeness has to remain constant when particles are produced through strong nuclear forces, but not when they decay through weak nuclear forces.

    In the example above, in which a pion and a proton collide, both of those particles have strangeness equal to 0. What’s more, that interaction is governed by the strong force, so the strangeness of the resulting particles has to add up to zero as well. For instance, the products could include a neutral kaon, which has strangeness 1, and a lambda particle, which has strangeness -1, which cancels out the strangeness of the kaon.

    That explained why strange particles always appeared in pairs—one particle’s strangeness has to be canceled out by another’s. The fact that they’re built through strong interactions but decay through weak interactions, which tend to take longer to play out, explained the relatively long decay times.

    These observations led to several more fundamental insights, says Jonathan Rosner, a theoretical physicist at the University of Chicago. As Gell-Mann and colleagues developed their theory, they saw they could organize groups of particles into bunches related by strangeness and electric charge, a scheme known today as The Eightfold Way. Efforts to explain this organization led to the prediction of an underlying set of particles: quarks.

    The long and short of it

    Another important feature of the strangeness theory: When scientists found that strange kaons could decay into, for example, ordinary pions, they surmised that the weak nuclear interaction, unlike the strong nuclear interaction, did not need to keep strangeness constant. This observation set in motion a series of theoretical and experimental developments that physicists are still grappling with today.

    Building on theories that suggested the neutral kaon ought to have an antiparticle with opposite strangeness to the standard neutral kaon, Gell-Mann and Pais reasoned that the neutral kaon could, through complex processes involving weak interactions, transform into its own antiparticle.

    The scheme has a significant consequence: It implies that there are two new particles—actually different combinations of the neutral kaon and its antiparticle—with different lifetimes. K-long, as it’s now called, lasts on average about 50 billionths of a second, while K-short lasts just under one-tenth of a billionth of a second before breaking apart. The prediction of these particles was among Gell-Mann’s favorite results, Rosner says, because of how easily they emerged out of basic quantum physics.

    A symmetry of nature, dethroned

    One of the important things about K-long and K-short, at least in Gell-Mann and Pais’s theory, was that they obeyed something called CP symmetry. Roughly, CP symmetry says that if one were to switch every particle with its antiparticle and flip space around into a sort of mirror-image universe, the laws of physics would remain the same. CP symmetry holds in all classical physics, and it was CP’s quantum variant that motivated Gell-Mann and Pais. (Technically, Gell-Mann and Pais were originally motivated by C symmetry alone, but they had to update their theory once experiments determined that weak interactions violated both charge conjugation and parity symmetry—but in such a way that CP itself seemed to remain a good symmetry.)

    Ironically, a result motivated by CP symmetry led to its downfall: In 1964, James Cronin, Val Fitch and collaborators working at Brookhaven National Laboratory discovered that the K-long could—very rarely—break up into two pions, a reaction that violates CP symmetry. Kaon decays did violate CP symmetry after all.

    The cosmic gift that keeps on giving

    By the early 1970s, Quinn says, physicists developing the Standard Model needed a way to incorporate CP violation. In 1973 Makoto Kobayashi and Toshihide Maskawa, building on work by Nicola Cabibbo, proposed the solution: The Standard Model needed an extra pair of quarks beyond what they had already theorized. They also predicted that certain quarks could decay through weak interactions into other quarks in ways that violate CP symmetry. Throughout the 1980s and ’90s, kaon experiments such as KTeV at Fermilab and NA48 at CERN—along with B-meson experiments such as BaBar at SLAC and Belle at KEK—probed how such interactions led to CP violation.

    Over the years, theorists had also made ever more precise predictions about the various ways kaons could break apart. So precise are these predictions, says Yau Wah, a physicist at the University of Chicago, that searching for rare kaon decays remains among the best ways to test the Standard Model.

    “The merit of [these tests] is because the Standard Model is too successful,” says Wah, who works on the K0TO experiment, a Japanese project to search for neutral kaons decaying into a pion, neutrino and antineutrino.

    In the next five years, Wah says, K0TO will likely be in a position to say whether the Standard Model’s tight predictions related to that decay are correct. If not, it could indicate new sources of CP violation beyond the Standard Model.

    Such studies are also a good way to probe physics at extremely high energy scales, since any deviations from current predictions would require new particles with enormous masses—perhaps a million times that of the proton, says Cristina Lazzeroni, a physicist at CERN’s NA62 experiment, which focuses on rare decays of charged kaons.

    Lazzeroni says NA62 has already found some evidence of positively charged kaons decaying into positively charged pions and two neutrinos, and that in the next five years they plan to probe Standard Model physics to a level of accuracy that will allow them to see whether there is new physics to be found.

    CERN NA62 innards

    CERN NA62

    What started in a simple cloud chamber three-quarters of a century ago is continuing in some of the most precise experiments ever done, and kaons are likely to keep on giving for years to come.

    See the full article here .


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  • richardmitnick 2:47 pm on September 29, 2020 Permalink | Reply
    Tags: "How big can a fundamental particle be?", , , , , , , Symmetry Magazine   

    From Symmetry: “How big can a fundamental particle be?” 

    Symmetry Mag
    From Symmetry<

    Sarah Charley

    Extremely massive fundamental particles could exist, but they would seriously mess with our understanding of quantum mechanics.

    Illustration by Sandbox Studio, Chicago with Steve Shanabruch.

    Fundamental particles are objects that are so small, they have no deeper internal structure.

    There are about a dozen “matter” particles that scientists think are fundamental, and they come in a variety of sizes. For instance, the difference between the masses of the top quark and the electron is equivalent to the difference between the masses of an adult elephant and a mosquito.

    Still, all of these masses are extremely tiny compared to what’s physically possible. The known laws of physics allow for fundamental particles with masses approaching the “Planck mass”: a whopping 22 micrograms, or about the mass of a human eyelash. To go back to our comparisons with currently known particles, if the top quark had the same mass as an elephant, then a fundamental particle at the Planck mass would weigh as much as the moon.

    Could such a particle exist? According to CERN Theory Fellow Dorota Grabowska, scientists aren’t completely sure.

    “Particles with a mass below the Planck scale can be elementary,” Grabowska says. “Above that scale, maybe not. But we don’t know.”

    Scientists at particle accelerators such as the Large Hadron Collider at CERN are always on the look-out for undiscovered massive particles that could fill in the gaps of their models. Finding new particles is so important that the global physics community is discussing building larger colliders that could produce even more massive particles. US involvement in the LHC is supported by the US Department of Energy’s Office of Science and the National Science Foundation.

    CERN FCC Future Circular Collider map.

    ILC schematic, being planned for the Kitakami highland, in the Iwate prefecture of northern Japan.

    China Circular Electron Positron Collider (CEPC) map. It would be housed in a hundred-kilometer- (62-mile-) round tunnel at one of three potential sites. The documents work under the assumption that the collider will be located near Qinhuangdao City around 200 miles east of Beijing.

    If scientists found a fundamental particle with a mass above the Planck scale, they would need to revisit how they think about particle sizes. For the kind of research performed at the LHC, fundamental particles are all considered to be the same size—no size at all.

    “When we think about the pure mathematics, elementary particles are, by definition, point-like,” Grabowska says. “They don’t have a size.”

    Treating fundamental particles as points works well in particle physics because their masses are so small that gravity, which would have an effect on more massive objects, is not really a factor. It’s kind of like how truck drivers planning a trip don’t need to consider the effects of special relativity and time dilation. These effects are there, at some level, but they don’t have a noticeable impact on drive time.

    But a fundamental particle above the Planck scale would sit at the threshold between two divergent mathematical models. Quantum mechanics describes objects that are very tiny, and general relativity describes objects that are very massive. But to describe a particle that is both very tiny and very massive, scientists need a new theory called quantum gravity.

    Mathematically, physicists could no longer consider such a massive particle as a volume-less point. Instead, they would need to think about it behaving more like a wave.

    The particle-wave duality concept was born about 100 years ago and states that subatomic particles have both particle-like and wave-like properties. When scientists think about an electron as a particle, they consider that it has no physical volume. But when they think about it as a wave, it extends throughout all the space it’s granted, such as the orbit around the nucleus of an atom. Both interpretations are correct, and scientists typically use the one that best suits their area of research.

    The mass-to-radius ratio of these waves is important because it determines how they feel the effects of gravity. A super massive particle with tons of room to roam would barely feel the force of gravity. But if that same particle were confined to an extremely small space, it could collapse into a miniature black hole. Scientists at the LHC have searched for such tiny black holes—which would evaporate almost immediately—but so far have come up empty-handed.

    According to Grabowska, quantum gravity is tricky because there is no way to experimentally test it with today’s existing technology. “We would need a collider 14 orders of magnitude more energetic than the LHC,” she says.

    But thinking about the implications of finding such a particle helps theorists push the known laws of physics.

    “Our model of particle physics breaks down when pushed to certain scales,” says Netta Engelhardt, a quantum gravity theorist at the Massachusetts Institute of Technology. “But that doesn’t mean that our universe doesn’t feature these regimes. If we want to understand massive objects at tiny scales, we need a model of quantum gravity.”

    See the full article here .


    Please help promote STEM in your local schools.

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  • richardmitnick 1:46 pm on September 23, 2020 Permalink | Reply
    Tags: A chiral twin has been found for every matter and antimatter particle in the Standard Model—with the exception of neutrinos., An object that can coincide with its mirror-image twin in every coordinate such as a dumbbell or a spoon is not chiral., Another broken symmetry: the current predominance of matter over antimatter in our universe., , Chirality is of the universe., , Chirality was discovered in 1848 by biomedical scientist Louis Pasteur., Every time an elementary particle is detected an intrinsic property called its spin must be in one of two possible states., For a completely unknown reason the weak nuclear force only interacts with left-handed particles., Maybe the neutrino masses come from a special Higgs boson that only talks to neutrinos., , Physicists often talk about three mirror symmetries in nature: charge (which can be positive or negative); time (which can go forward or backward) and parity (which can be right- or left-handed)., , Researchers have only ever observed left-handed neutrinos and right-handed antineutrinos., Symmetry Magazine, Understanding the difference between right-chiral and left-chiral objects is important for many scientific applications., You will find chirality in things like proteins; spiral galaxies and most elementary particles.   

    From Symmetry: “Nature through the looking glass” 

    Symmetry Mag
    From Symmetry

    Oscar Miyamoto Gomez

    Illustration by Sandbox Studio, Chicago.

    Handedness—and the related concept of chirality—are double-sided ways of understanding how matter breaks symmetries.

    Our right and left hands are reflections of one another, but they are not equal. To hide one hand perfectly behind the other, we must face our palms in opposite directions.

    In physics, the concept of handedness (or chirality) works similarly: It is a property of objects that are not dynamically equivalent to their mirror images. An object that can coincide with its mirror-image twin in every coordinate, such as a dumbbell or a spoon, is not chiral.

    Because our hands are chiral, they do not interact with other objects and space in the exact same way. In nature, you will find this property in things like proteins, spiral galaxies and most elementary particles.

    These different-handed object pairs reveal some puzzling asymmetries in the way our universe works. For example, the weak force—the force responsible for nuclear decay— has an effect only on particles that are left-handed. Also, life itself—every plant and creature we know—is built almost exclusively with right-handed sugars and left-handed amino acids.

    “If you have anything with a dual principle, it can be related to chirality,” says Penélope Rodríguez, a postdoctoral researcher at the Physics Institute of the National Autonomous University of Mexico. “This is not exclusive to biology, chemistry or physics. Chirality is of the universe.”

    Reflections of life

    Chirality was discovered in 1848 by biomedical scientist Louis Pasteur. He noticed that right-handed and left-handed crystals formed when racemic acid dried out.

    He separated them, one by one, into two samples, and dissolved them again. Although both were chemically identical, one sample consistently rotated polarized light clockwise, while the other did it counterclockwise.

    Pasteur referred to chirality as “dissymmetry” at the time, and he speculated that this phenomenon—consistently found in organic compounds—was a prerequisite for the handed chemistry of life. He was right.

    In 1904, scientist Lord Kelvin introduced the word “chirality” into chemistry, borrowing it from the Greek kheír, or hand.

    “Chirality is an intrinsic property of nature,” says Riina Aav, Professor at Tallinn University of Technology in Estonia. “Molecules in our bodily receptors are chiral. This means that our organism reacts selectively to the spatial configuration of molecules it interacts with.”

    Understanding the difference between right-chiral and left-chiral objects is important for many scientific applications. Scientists use the property of chirality to produce safer pharmaceuticals, build biocompatible metallic nanomaterials, and send binary messages in quantum computing (a field called spintronics).

    Broken mirrors

    Physicists often talk about three mirror symmetries in nature: charge (which can be positive or negative), time (which can go forward or backward) and parity (which can be right- or left-handed).

    Gravity, electromagnetism and the strong nuclear force are ambidextrous, treating particles equally regardless of their handedness. But, as physicist Chien-Shiung Wu experimentally proved in 1956, the weak nuclear force plays favorites.

    “For a completely unknown reason, the weak nuclear force only interacts with left-handed particles,” says Marco Drewes, a professor at Catholic University of Louvain in Belgium. “Why that might be is one of the big questions in physics.”

    Research groups are exploring the idea that such an asymmetry could have influenced the origin of the preferred handedness in biomolecules observed by Pasteur. “There is a symmetry breaking that gives birth to a molecular arrangement, which eventually evolves until it forms DNA, right-handed sugars and left-handed amino acids,” Rodríguez says.

    From an evolutionary perspective, this would mean that chirality is a useful feature for living organisms, making it easier for proteins and nucleic acids to self-replicate due to the preferred handedness of their constituent biomolecules.

    Missing twins

    Every time an elementary particle is detected, an intrinsic property called its spin must be in one of two possible states. The spin of a right-chiral particle points along the particle’s direction of motion, while the spin of a left-chiral particle points opposite to the particle’s direction of motion.

    A chiral twin has been found for every matter and antimatter particle in the Standard Model—with the exception of neutrinos. Researchers have only ever observed left-handed neutrinos and right-handed antineutrinos. If no right-handed neutrinos exist, the fact that neutrinos have mass could indicate that they function as their own antiparticles. It could also mean that neutrinos get their mass in a different way from the other particles.

    “Maybe the neutrino masses come from a special Higgs boson that only talks to neutrinos,” says, André de Gouvêa, a professor at Northwestern University. “There are many other kinds of possible answers, but they all indicate that there are other particles out there.”

    The difference between left- and right-handed could have influenced another broken symmetry: the current predominance of matter over antimatter in our universe.

    “Right-handed neutrinos could be responsible for the fact that there is matter in the universe at all,” Drewes says. “It could be that they prefer to decay into matter over antimatter.”

    According to de Gouvêa, the main lesson that chirality teaches scientists is that we should always be prepared to be surprised. “The big question is whether asymmetry is a property of our universe, or a property of the laws of nature,” he says. “We should always be willing to admit that our best ideas are wrong; nature does not do what we think is best.”

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

    Symmetry is a joint Fermilab/SLAC publication.

  • richardmitnick 3:50 pm on August 24, 2020 Permalink | Reply
    Tags: "LHC creates matter from light", , , E = mc², Forces that seem separate in our everyday lives—electromagnetism and the weak force—are united., From massless to massive, , Last year the ATLAS experiment at the LHC observed two photons- particles of light- ricocheting off one another and producing two new photons., , , , Scientists on an experiment at the Large Hadron Collider see massive W particles emerging from collisions with electromagnetic fields., Symmetry Magazine, The LHC is the only place where scientists have seen two energetic photons merging and transforming into massive W bosons., The reason photons can collide and produce W bosons in the LHC is that at the highest energies those forces combine to make the electroweak force.   

    From Symmetry: “LHC creates matter from light” 

    Symmetry Mag
    From Symmetry<

    Sarah Charley

    Scientists on an experiment at the Large Hadron Collider see massive W particles emerging from collisions with electromagnetic fields. How can this happen?

    Illustration by Sandbox Studio, Chicago

    The Large Hadron Collider plays with Albert Einstein’s famous equation, E = mc², to transform matter into energy and then back into different forms of matter. But on rare occasions, it can skip the first step and collide pure energy—in the form of electromagnetic waves.

    CERN LHC Map

    Last year, the ATLAS experiment at the LHC observed two photons, particles of light, ricocheting off one another and producing two new photons.


    This year, they’ve taken that research a step further and discovered photons merging and transforming into something even more interesting: W bosons, particles that carry the weak force, which governs nuclear decay.

    This research doesn’t just illustrate the central concept governing processes inside the LHC: that energy and matter are two sides of the same coin. It also confirms that at high enough energies, forces that seem separate in our everyday lives—electromagnetism and the weak force—are united.

    From massless to massive

    If you try to replicate this photon-colliding experiment at home by crossing the beams of two laser pointers, you won’t be able to create new, massive particles. Instead, you’ll see the two beams combine to form an even brighter beam of light.

    “If you go back and look at Maxwell’s equations for classical electromagnetism, you’ll see that two colliding waves sum up to a bigger wave,” says Simone Pagan Griso, a researcher at the US Department of Energy’s Lawrence Berkeley National Laboratory. “We only see these two phenomena recently observed by ATLAS when we put together Maxwell’s equations with special relativity and quantum mechanics in the so-called theory of quantum electrodynamics.”

    Inside CERN’s accelerator complex, protons are accelerated close to the speed of light. Their normally rounded forms squish along the direction of motion as special relativity supersedes the classical laws of motion for processes taking place at the LHC. The two incoming protons see each other as compressed pancakes accompanied by an equally squeezed electromagnetic field (protons are charged, and all charged particles have an electromagnetic field). The energy of the LHC combined with the length contraction boosts the strength of the protons’ electromagnetic fields by a factor of 7500.

    When two protons graze each other, their squished electromagnetic fields intersect. These fields skip the classical “amplify” etiquette that applies at low energies and instead follow the rules outlined by quantum electrodynamics. Through these new laws, the two fields can merge and become the “E” in E=mc².

    “If you read the equation E=mc² from right to left, you’ll see that a small amount of mass produces a huge amount of energy because of the c² constant, which is the speed of light squared,” says Alessandro Tricoli, a researcher at Brookhaven National Laboratory—the US headquarters for the ATLAS experiment, which receives funding from DOE’s Office of Science. “But if you look at the formula the other way around, you’ll see that you need to start with a huge amount of energy to produce even a tiny amount of mass.”

    The LHC is one of the few places on Earth that can produce and collide energetic photons, and it’s the only place where scientists have seen two energetic photons merging and transforming into massive W bosons.

    A unification of forces

    The generation of W bosons from high-energy photons exemplifies the discovery that won Sheldon Glashow, Abdus Salam and Steven Weinberg the 1979 Nobel Prize in physics: At high energies, electromagnetism and the weak force are one in the same.

    Electricity and magnetism often feel like separate forces. One normally does not worry about getting shocked while handling a refrigerator magnet. And light bulbs, even while lit up with electricity, don’t stick to the refrigerator door. So why do electrical stations sport signs warning about their high magnetic fields?

    “A magnet is one manifestation of electromagnetism, and electricity is another,” Tricoli says. “But it’s all electromagnetic waves, and we see this unification in our everyday technologies, such as cell phones that communicate through electromagnetic waves.”

    At extremely high energies, electromagnetism combines with yet another fundamental force: the weak force. The weak force governs nuclear reactions, including the fusion of hydrogen into helium that powers the sun and the decay of radioactive atoms.

    Just as photons carry the electromagnetic force, the W and Z bosons carry the weak force. The reason photons can collide and produce W bosons in the LHC is that at the highest energies, those forces combine to make the electroweak force.

    “Both photons and W bosons are force carriers, and they both carry the electroweak force,” Griso says. “This phenomenon is really happening because nature is quantum mechanical.”

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

    Symmetry is a joint Fermilab/SLAC publication.

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