Category Archives: Quantum Physics

QED stands for quantum electrodynamics, which describes how light and matter interact and links the theories of quantum mechanics and special relativity; not exactly an easy field to understand - or to explain - unless you are Richard Feynman. The book QED is a collection of transcripts of a series of lectures Richard gave to the general public; for people without any technical or academic background to quantum or theoretical physics about his field and work.

The extraordinary thing about these lecturers is how easy to follow and understand they are, in spite of the complexity of the subject matter covered. Richard had a gift for explaining intricate ideas in human terms, without dumbing them down.

All too often, marketing messages are obscured by flowery language, smug jargon, and clever ideas that make it difficult for ones audience to understand what it is that you are actually trying to say and what it is that you would like your audience to do after receiving your message.

All too often, this confusion is a result of the marketer or advertiser not being sure of what it is they want to say or why they are saying it.

If Richard Feynman could get non-physicists to understand what quarks are and what we do and dont know about how electrons and protons behave (even when they are behaving badly), then there is no excuse for corporate communication that fails to communicate a clear message and call to action.

If you are unable to communicate clearly and convincingly, it is probably because you dont know what it is you are actually trying to say.

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#PulpNonFiction: Advertisers, be clear about what you want to say and why! - Bizcommunity.com

In 2001 at the Brookhaven National Laboratory in Upton, New York, a facility used for research in nuclear and high-energy physics, scientists experimenting with a subatomic particle called a muon encountered something unexpected.

To explain the fundamental physical forces at work in the universe and to predict the results of high-energy particle experiments like those conducted at Brookhaven, Fermilab in Illinois, and at CERNs Large Hadron Collider in Geneva, Switzerland, physicists rely on the decades-old theory called the Standard Model, which should explain the precise behavior of muons when they are fired through an intense magnetic field created in a superconducting magnetic storage ring. When the muon in the Brookhaven experiment reacted in a way that differed from their predictions, researchers realized they were on the brink of a discovery that could change sciences understanding of how the universe works.

Earlier this month, after a decades-long effort that involved building more powerful sensors and improving researchers capacity to process 120 terabytes of data (the equivalent of 16 million digital photographs every week), a team of scientists at Fermilab announced the first results of an experiment called Muon g-2 that suggests the Brookhaven find was no fluke and that science is on the brink of an unprecedented discovery.

UVA physics professor Dinko Poani has been involved in the Muon g-2 experiment for the better part of two decades, and UVA Today spoke with him to learn more about what it means.

Q. What are the findings of the Brookhaven and Fermilab Muon g-2 experiments, and why are they important?

A. So, in the Brookhaven experiment, they did several measurements with positiveand negative muons an unstable, more massive cousin of the electron under different circumstances, and whenthey averaged their measurements,they quantified a magnetic anomaly that is characteristic of the muon more precisely than ever before. According torelativistic quantum mechanics, the strength of the muons magnetic moment (a property it shares with a compass needle or a bar magnet) should be two in appropriate dimensionless units, the same as for an electron. The Standard Model states, however, that its not two, its a little bit bigger, and that difference is the magnetic anomaly. The anomaly reflects the coupling of the muon to pretty much all other particles that exist in nature. How is this possible?

The answer is that space itself is not empty; what we think of as a vacuum contains the possibility of the creation of elementary particles, given enough energy. In fact, these potential particles are impatient and are virtually excited, sparking in space for unimaginably short moments in time. And as fleeting as it is, this sparking is sensed by a muon, and it subtly affects the muons properties. Thus, the muon magnetic anomaly provides a sensitive probe of the subatomic contents of the vacuum.

To the enormous frustration of all the practicing physicists of my generation and younger, the Standard Model has been maddeningly impervious to challenges. We know there are things that must exist outside of it because it cannot describe everything that we know about the universe and its evolution. For example, it does not explain the prevalence of matter over antimatter in the universe, and it doesnt say anything about dark matter or many other things, so we know its incomplete. And weve tried very hard to understand what these things might be, but we havent found anything concrete yet.

So, with this experiment, were challenging the Standard Model with increasing levels of precision. If the Standard Model is correct, we should observe an effect that is completely consistent with the model because it includes all the possible particles that are thought to be present in nature, but if we see a different value for this magnetic anomaly, it signifies that theres actually something else. And thats what were looking for: this something else.

This experiment tells us that were on the verge of a discovery.

Q. What part have you been able to play in the experiment?

A. I became a member of this collaboration when we had just started planning for the follow-up to the Brookhaven experiment around 2005, just a couple of years after the Brookhaven experiment finished, and we were looking at the possibility of doing a more precise measurements at Brookhaven. Eventually that idea was abandoned, as it turned out that we could do a much better job at Fermilab, which had better beams, more intense muons and better conditions for experiment.

So, we proposed that around 2010, and it was approved and funded by U.S. and international funding agencies. An important part was funded by a National Science Foundation Major Research Instrumentation grant that was awarded to a consortium of four universities, and UVA was one of them. We were developing a portion of the instrumentation for the detection of positrons that emerge in decays of positive muons. We finished that work, and it was successful, so my group switched focus to the precise measurements of the magnetic field in the storage ring at Fermilab, a critical part of quantifying the muon magnetic anomaly. My UVA faculty colleague Stefan Baessler has also been working on this problem, and several UVA students and postdocs have been active on the project over the years.

Q. Fermilab has announced that these are just the first results of the experiment. What still needs to happen before well know what this discovery means?

A. It depends on how the results of our analysis of the yet-unanalyzed run segments turn out. The analysis of the first run took about three years. The run was completed in 2018, but I think now that we weve ironed out some of the issues in the analysis, it might go a bit faster. So, in about two years it would not be unreasonable to have the next result, which would be quite a bit more precise because it combines runs two and three. Then there will be another run, and we will probably finish taking data in another two years or so. The precise end of measurements is still somewhat uncertain, but I would say that about five years from now, maybe sooner, we should have a very clear picture.

Q. What kind of impact could these experiments have on our everyday lives?

A. One way is in pushing specific technologies to the extreme in solving different aspects of measurement to get the level of precision we need. The impact would likely come in fields like physics, industry and medicine. There will be technical spinoffs, or at least improvements in techniques, but which specific ones will come out of this, its difficult to predict. Usually, we push companies to make products that we need that they wouldnt otherwise make, and then a new field opens up for them in terms of applications for those products, and thats what often happens. The World Wide Web was invented, for example, because researchers like us needed to be able to exchange information in an efficient way across great distances, around the world, really, and thats how we have, well, web browsers, Zoom, Amazon and all these types of things today.

The other way we benefit is by educating young scientists some of whom will continue in the scientific and academic careers like myself but others will go on to different fields of endeavor in society. They will bring with them an expertise in very high-level techniques of measurement and analysis that arent normally found in many fields.

And then, finally, another outcome is intellectual betterment. One outcome of this work will be to help us better understand the universe we live in.

Q. Could we see more discoveries like this in the near future?

A. Yes, there is a whole class of experiments besides this one that look at highly precise tests of the Standard Model in a number of ways. Im always reminded of the old adage that if you lose your keys in the street late at night, you are first going to look for them under the street lamp, and thats what were doing. So everywhere theres a streetlight, were looking. This is one of those places and there are several others, well, I would say dozens of others, if you also include searches that are going on for subatomic particles like axions, dark matter candidates, exotic processes like double beta decay, and those kinds of things. One of these days, new things will be found.

We know that the Standard Model is incomplete. Its not wrong, insofar as it goes, but there are things outside of it that it does not incorporate, and we will find them.

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Q&A: Are We on the Brink of a New Age of Scientific Discovery? - University of Virginia

In last weeks podcast,, our guest host, neurosurgeon Michael Egnor, interviewed idealist philosopher of science and physicist Bruce Gordon on how the quantum physics that underlies our universe makes much more sense if we have a non-materialist view of reality. Even then, it challenges our conventional view of how nature must work:

A partial transcript, Show Notes, and Additional Resources follow.

Michael Egnor: When I was in college, I was a biochemistry major and I took some courses in quantum mechanics. It was noted in the course that when you look at the most fundamental properties of subatomic particles, matter seems to disappear. That the reality of the subatomic particles is that theyre mathematical concepts. It utterly fascinated me that, at its basic structure, reality is an idea which fits very nicely with idealism. Dr. Gordon is an expert on idealism and on the philosophy of science. What do you think about all this?

Bruce Gordon (pictured): Well, certainly my own path to idealism was paved by my reflections on the metaphysics of quantum physics. So Im deeply sympathetic to the questions that youre raising.

Quantum physics is a highly mathematical theory that describes the nature of reality at the atomic and subatomic level. The mathematical descriptions of quantum physics have a variety of experimentally confirmed consequences that I would say preclude the possibility of a world of mind-independent material substances governed by material causation.

We live in a reality that seems very much to be described by classical Newtonian kinds of mathematical descriptions. However, at the most fundamental level thats not the case.

Note: Newtons Laws of Motion, formulated by Isaac Newton, describe in simple terms that can be rendered in mathematics the way objects and force behave in the visible world around us. For example, Newtons First Law can be phrased: objects tend to keep on doing what theyre doing (unless acted upon by an unbalanced force). Newtons First Law, (Physics Classroom).

No law of nature makes moving objects stop. They stop because forces act on them. Otherwise, they would just keep moving. Similarly, no law of nature makes still objects stay put. They stay put because no force is acting on them, causing them to move.

The world we can see around us works on these kinds of principles. But down at the level of, say, electrons, the types of rules followed while strict are quite different.

Bruce Gordon: Lets take a look at some interesting quantum experiments that point toward the mind-dependent character of reality Fundamentally, weve got a situation in which reality at the quantum level does not exist until it is observed. I think one of the most fascinating ones is the quantum eraser experiment.

When youre not observing reality, it seems to behave in accordance with the Schrdinger wave equation, and various relativistic expressions of that. But when you are observing it

Note: The Schrdinger wave equation is a partial differential equation that describes the dynamics of quantum mechanical systems via the wave function. Electrical4u.com The equation describes, using mathematics, what quantum systems do when no one is trying to measure them.

Bruce Gordon: So what does the delayed choice quantum eraser experiment do? Well, it tries to measure which path a particle would have taken after interference in the wave function has been created that is inconsistent with that particles behavior. So youve got a splitter of some sort. Its going to divide the quantum wave function and send it along two different paths. Then youre going to make a measurement along one of the paths to see whats happening.

That interference can be turned off or on by choosing whether or not to look at which path the particle has taken after the interference already exists.

Now if you dont look, you get an interference phenomenon at the end. If you do look, the wave function instantaneously collapses and you detect the particle along that pathway. So choosing to look erases the wave function and gives the system a particle history.

Bruce Gordon: This experiment has been performed under what would be called Einstein Locality Conditions. In other words, no signal could have passed subject to the limiting velocity of the speed of light between the components of the system to cause the effect that youre observing.

The very fact that we can make a causally disconnected choice of whether wave or particle phenomena are manifested in a quantum system essentially shows that there is no measurement-independent and causally connected, substantial material reality at the micro physical level. It is created by the measurement itself.

Michael Egnor: What counts as a measurement?

Bruce Gordon: What can count as a measurement is any sort of interaction that would localize the wave function and yield a determinant local result. That could involve a conscious observer, or it might not involve a conscious observer.

Michael Egnor (pictured): What sort of measurement wouldnt involve a conscious observer? Does it matter how much you pay attention? If Im a little preoccupied, do I not get much interference, but maybe a little? Because it really implies that there is an actual something that is observation and its an on or off thing, its yes or no. Theres no in between

Say, for example, that Im a physicist who is looking at a quantum system, and Im actually looking at the oscilloscope, or whatever our modern instrument is, when its happening. Everybody would say, Well, thats an observation for sure.

But lets say that Im not in the room and Im just taping it but I plan to look at it later. Is that an observation? If I change my mind and decide not to look at it, does that change the system?

Im fascinated by what we mean by an observation because in reality, an observation is a continuum. I mean, I could be watching something, then my mind wanders. Im thinking about lunch. Does that make the system go back into indeterminacy? Then it becomes determined again when I focus on it?

Bruce Gordon: Not necessarily, if youve got decoherence happening in the quantum metaphysics of the world around you. So how do we bring this into relationship with idealism?

In fact, I was going to talk about some other experiments to kind of further massage peoples intuitions with respect to the nature of the reality that undergirds these sorts of phenomena. Let me talk about at least a couple more. Then well come back to the question of, Whats going on when were not looking?

Michael Egnor: Right. Is the moon there if no ones looking at it?

Next: So is the moon there if no one is looking at it? Or is there no there there?

Here are stories from Bruce Gordons previous podcast with host Michael Egnor, where he defends idealism as a reasonable way of making sense of nature:

Why idealism is actually a practical philosophy. Not what you heard? Philosopher of science and pianist Bruce Gordon says, think again. Is reality fundamentally more like a mind than a physical object? Many are sure of the answer without understanding the question.

and

A physicist and philosopher examines panpsychism. Idealism says everything is an idea in the mind of God. Panpsychism says everything participates in consciousness (thus is not just an idea). Bruce Gordon thinks that, for a thing to be conscious, there must be something that it is like to be that thing. Can panpsychism demonstrate that?

Podcast Transcript Download

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In Quantum Physics, Reality Really Is What We Choose To Observe - Walter Bradley Center for Natural and Artificial Intelligence

Multiple opportunities for research under expert guidance

Physics students are known for their agile, curious minds, and its pretty apparent that Shrestha relishes research he completed two projects as a summer scholar, a directed study, and a senior research project, Photoionization of Barium and Lanthanum in an ion trap, under the direction of Associate Professor of Physics Steven Olmschenk.

But that wasnt quite enough to slake his appetite. He also completed an independent study on quantum information theory and a directed study on how to give planetarium shows. Persistence and careful analysis are the keys to a good researcher, says Olmschenk. Rahul is currently working with me on a senior research project, which is focused on photoionization loading of the ion trap. As in all his previous research in my lab, his engagement with the project is at the highest level. He is carefully analyzing the ablation production of ions and neutral atoms to ascertain the effect of the photoionization light. He is a fantastic researcher.

Shrestha has been enthusiastic about being a scientist since he was a child. But with all this experience under his belt, his perspective has changed about what that means.

The mini objectives and side projects that lead to a better understanding of the experiment, and the endless troubleshooting of problems, which feels like playing a game of whack-a-mole, help us inch our way towards the eventual goal, he says. I have come to appreciate the explorative part of research and learned to take pride in my understanding of the experiment.

Taking on Denisons yearbook gave Shrestha an opportunity to exercise a different set of creative chops. He signed on board with the staff his first year and now leads the entire project, which involves managing other students and building his own skills in software like Photoshop, Illustrator, and InDesign.

He also learned a life lesson about the importance of asking for help. I am one of those who always wants to do everything by themselves, and I know thats not how being a leader works. I had to pick between giving up on it and getting out of my comfort zone.

Groups like this are a great way for students to find friends and peer mentors. Shrestha met then-senior physics major Patrick Banner 18 on the yearbook staff. He has been, to this day, a source of constant support for me, from writing a summer research proposal to applying to graduate schools, says Shrestha, who also became close to yearbook advisor Jamie Hale in the University Communications office. Over the years, he has turned into a friend.

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Multiple Realities | Physics - Denison University

Ravneet Singh

Tribune News Service

Patiala, April 20

The Punjab Government has appointed Professor Arvind of the Indian Institute of Science Education and Research, Mohali (IISER), the new Vice-Chancellor of Punjabi University, Patiala.

Reviving and rebuilding the university by adding fresh courses to bring it on a par with international institutions remains on top of Professor Arvinds agenda.

Professor Arvind has been serving as a physics professor at the Mohali institute since March 3, 2010. He is a known theoretical quantum physicist working on science education, science communication and developing science paedagogy in Punjabi and is credited with over 100 technical and non-technical publications, including True experimental reconstruction of quantum states and processes via convex optimisation published this year.

Professor Arvind said the university needed to recover and move forward. On the academic front, my vision is to restore the old glory of the institution and build on those areas. I plan to bring in new disciplines, including liberal arts education, five-year integrated courses and data sciences, to put it on a par with international institutions. I will like to revamp the course work and course structure as well, he said.

On the financial crisis faced by the university, he said there was a need to work on curtailing expenditure, do redeployment and re-training of manpower. The universitys academic culture has declined. I think those on the campus are awaiting restoration of good culture, he said.

Professor Arvind is the national coordinator of theme-1 (photonics) of the National Multi-Institutional Networked Programme on Quantum Enabled Science and Technology (QuST) launched by the Department of Science and Technology, New Delhi, in 2018. He is also a member of the DPR drafting committee for the National Mission on Quantum Technologies and Applications (NMQTA).

Earlier, he had worked at the Physics Department of Carnegie Mellon University, Pittsburgh, as special faculty from 2002-2004.

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IISER physicist Prof Arvind is Punjabi University VC - The Tribune

Ravneet SinghTribune News ServicePatiala, April 20

The state government has appointed Professor Arvind of Indian Institute of Science Education and Research, Mohali (IISER) as the new Vice Chancellor of Punjabi University, Patiala.

The professor now aims to revive and rebuild the university by adding courses in an attempt to put it at par with international institutions.

Professor Arvind has been working as professor, Physics, at the Indian Institute of Science Education and Research, Mohali. He isawell-known theoretical quantum physicist working on science education, science communication and developing science pedagogy in Punjabi and is credited with over 100 technical and non-technical publications, including True experimental reconstruction of quantum states and processes via convex optimisation published this year.

Talking to The Tribune, he said the university needs to be recovered, reconstructed and moved forward. From the academic front, my vision is to go back to the old glory of the institute when it was doing well, and build on those areas. I want to bring in new disciplines including liberal arts education, 5-year integrated courses and data sciences to put it at par with international institutions. I would like to revamp the course work and course structure as well, he said.

He added that on the front of financial crises, they might work on curtailing expenditure, do some redeployment and re-training in terms of manpower issues.

The universitys academic culture has declined. I think those on the campus are waiting for a good culture to restart, he said.

Professor Arvind is the National Coordinator of Theme-1 (Photonics) of the National Multi-Institutional Networked Programme on Quantum Enabled Science and Technology (QuST) launched by the Department of Science and Technology, New Delhi in 2018.

He is also a member of the DPR drafting committee for the National Mission on Quantum Technologies and Applications (NMQTA).

The professor has been working at the IISER, Mohali since March 3, 2010. Before this, he was an associate professor at the same institute from 2007. He has also worked at the Physics Department of Carnegie Mellon University, Pittsburgh as a special faculty from 2002-2004.

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Theoretical Physicist Prof Arvind appointed Punjabi Varsity Vice Chancellor - The Tribune

Every community guards a creation story, a theory of cosmic origins. In much of sub-Saharan West Africa, for the past few thousand years, itinerant storytellers known as griots have communicated these and other tales through song. Cosmologists also intone a theory of cosmic origins, known as the Big Bang, albeit through journal articles and math.

Chanda Prescod-Weinstein is a cosmologist who is adept with both equations and "the keeper of a deeply human impulse" to understand our universe. In her first book, "The Disordered Cosmos: A Journey into Dark Matter, Spacetime, & Dreams Deferred," Prescod-Weinstein also admits she is a griot, one who knows the music of the cosmos but sings of earthbound concerns. She is an award-winning physicist, feminist, and activist who is not only, as she says, the first Jewish "queer agender Black woman" to become a theoretical cosmologist, she is the first Black woman ever to earn a Ph.D. in the subject.

Prescod-Weinsteinis an assistant professor of physics and astronomy, and a core faculty member in the department of women's and gender studies at the University of New Hampshire. She thus enjoys a unique frame of reference from which to appraise science and her fellow scientists. She is an insider whom others nonetheless cast as an outsider, because of her identity, orientation, and the tint of her skin. From the outside, however, she admits a fuller view of her field. She perceives the "structures that were invisible to people," and reveals them.

"The Disordered Cosmos" is equal parts critical analysis, personal essay, and popular science. It is an introspective yet revelatory book about the culture of physics and the formative years of a scientific career.

Growing up during the 1990s in East Los Angeles, where at night the dominant lights flashed red and blue, Prescod-Weinstein owned a telescope but rarely saw the stars. She was a "born empiricist" who decided to become a physicist at the age of 10, after her single mother took her to see the documentary "A Brief History of Time." Her mother, the journalist and wage activist Margaret Prescod, continually nourished the young girl's passion. She took a teenage Prescod-Weinstein to Joshua Tree National Park, where they spent a night observing the Comet Hyakutake, unblinded by city lights.

After arriving at Harvard University to study physics, Prescod-Weinstein struggled academically, in part because of her own extracurricular advocacy for providing a living wage to campus workers. Yet a classmate tried to help her realize her childhood dream. He offered her a job at a new observatory atop Maunakea in Hawaii, where the view to the heavens was among the most limpid on Earth. There she could earn better than a living wage in the astronomers' efforts "to gather photons particles of light that will help them tell our cosmological story."

Prescod-Weinstein imagined dedicating herself to pure physics in this idyllic locale, with "beaches, amazing tans, and an opportunity to start over." But no physics is pure, no place such an idyll. Astronomers had started building their telescopes on Maunakea during the 1960s against the protests of native Hawaiians, for whom the summit is sacred. Her living wages, she realized, would have underwritten the erasure of another peoples' cosmology. "I promised myself that I would make more room in my life for my dreams of being a physicist," she wrote. "But not like this." She now supports the native Hawaiians who have vowed to protect their unceded lands against the impending construction of the Thirty Meter Telescope, which might yet become the world's largest.

Prescod-Weinstein not only narrates her struggle to become a cosmologist, she advocates for all peoples whom physicists have undervalued. She praises the assistants and janitors, mostly people of color, whose labor permits theorists to ponder the universe daily, because "part of science is emptying the garbage." She elevates her elders, such as Elmer Imes and Ibn Sahl, whose contributions others have disregarded because these forebears were not of European descent.

The beauty of mathematics and the majesty of the stars attracted Prescod-Weinstein to cosmology. They sustain her. Yet, she writes: "Learning about the mathematics of the universe could never be an escape from the earthly phenomena of racism and sexism."

So, Prescod-Weinstein unveils the majesty that oppression obscures. In the opening quarter of her book, she hurries readers through a tour of physics, rushing past Bose-Einstein condensates, axions, and inflatons to arrive at her own research into dark matter. It's a brilliant sprint, and the prize for finishers is some of her finest writing about race and science.

Prescod-Weinstein includes a thunderous essay about scientists' historical neglect of the biophysics of melanin and the repercussions today. Later, there is a chapter that she did not want to write about an episode from her life that she did not want to share. She had no choice, she explained, because "Rape is part of science and a book that tells the truth about science would be a lie if I were to leave out this chapter." Her account is so fierce and switches registers so regularly, as if gliding between chorus and verse, that the writing becomes incantatory. She saps the event's power to define her, transmuting pain into affecting prose.

Prescod-Weinstein is attuned to the language of physicists, especially the biases it elides, as when her colleagues speak of "colored physics," more commonly known as quantum chromodynamics, which she describes as "a theory that uses color as an analogy for physical properties that have nothing to do with color." She is adept at then rephrasing physics to redress those biases. Systemic racism is compared to weak gravitational lensing, the subtle distortion of light owing to the curvature space and time around distant galaxies. Cyclical time is intuitive to a person who menstruates. The wave-particle duality reveals the queer, nonbinary nature of quantum mechanics. Dark matter is not actually dark: "It's transparent more like a piece of glass than a chalkboard." Not only is the name antithetical to the science, some physicists have compared such invisible matter, crudely, to Black people.

"Studying the physical world requires confronting the social world," Prescod-Weinstein writes. "It means changing institutionalized science, so that our presence is natural and our cultures are respected." It also means confronting the privileged stories of science.

The demographics of physicists still reflect the iniquities of the past. And physics remains diminished because of its biases. Whenever we exclude whole peoples, we not only disallow their questions we disavow their knowledge. The field squanders other cultures' perceptions of time. And as Prescod-Weinstein notes, physicists may even misinterpret the wave-particle duality and confuse the rotating identities of neutrinos because they are too oriented toward binaries.

"The Disordered Cosmos" is not perfect. There are phrases that Prescod-Weinstein might have heated longer or squeezed harder until they crystalized. There are intervals when the pressure of having to cite so many ideas make matters too dense. But these are quibbles. Besides, the defects of an otherwise ideal crystal can render it more colorful and electric.

Prescod-Weinstein aspires to loftier matters. The book's frontispiece is a sketch of two women who remind her that "even in the worst conditions, Black women have looked up at the night sky and wondered." These women were slaves, who not only navigated the stars to freedom but also wondered at that black expanse. They are "as much my intellectual ancestors as Isaac Newton is."

Prescod-Weinstein's most vital work, in the end, is the emancipation of Black and brown children who still cannot see their futures in the stars. She distills this labor in a series of questions: "What are the conditions we need so that a 13-year-old Black kid and their single mom can go look at a dark night sky, away from artificial lights, and know what they are seeing? What health care structures, what food and housing security are needed?"

Prescod-Weinstein teaches that all humans are made of luminous matter. And she knows just how radiant people can be, despite the obstacles in their way. She understands, intimately, that "Black people hunger for a connection to scientific thought and will overcome the barriers placed in front of them in order to learn more."

* * *

Joshua Roebke is finishing a book on the social and cultural history of particle physics, titled "The Invisible World." He won a Whiting Foundation Creative Nonfiction Grant and teaches literature and writing at the University of Texas at Austin.

This article was originally published on Undark. Read the original article.

The featured photo for this story was updated at 4/20/2021 at 16:30 ET.

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A cosmologist throws light on a universe of bias - Salon

The Fermilab Muon g-2 equipment is used to measure the magnetic properties of muons.

On April 7, 2021, the worlds scientific community watched with rapt attention as scientists based at Fermi National Accelerator Laboratory presented a research result that the science media reported heavily.A new measurement disagreed in a very significant way with predictions.This disagreement could have been strong evidence that scientists would have to rethink their theory.Thats an exciting prospect, if its true.However, a theoretical paper was released the same day as the experimental result that puts the entire situation in turmoil.

The new experimental measurement involved the magnetic properties of subatomic particles called muons.Muons are essentially heavy cousins of the electron.Like the electron, the muon has both electric charge, and it spins.And any spinning electric charge creates a magnet.It is the strength of the magnet that researchers measured.

It is possible for scientists to calculate the relationship between the strength of the magnet and the quantity describing the amount of spin.Ignoring some constants, the ratio of magnetic strength to amount of spin is called g.Using the quantum theory of the 1930s, it is easy to show that for electrons (and muons) that g is exactly equal to two (g = 2).

History

Measurements in 1947 found that this prediction wasnt quite right.The measured value of g was closer to 2.00238, or about 0.1% higher.This discrepancy could have been simply a measurement error, but it turned out that the difference was real.Shortly after measurement, a physicist by the name of Julian Schwinger used a more advanced form of quantum mechanics and found that the earlier prediction was incomplete and the correct value for g was indeed 2.00238.Schwinger shared the 1965 Nobel Prize in physics with Richard Feynman and Sin-Itiro Tomonaga, for developing this more advanced form of quantum mechanics.

This more advanced form of quantum mechanics considered the effect of a charged particle on the space surrounding it.As one gets close to a charged particle, the electric field gets stronger and stronger.This strengthened field is accompanied by energy.According to Einsteins theory of relativity, energy and mass are equivalent, so what happens is that the energy of the electric field can temporarily convert into a pair of particles, one matter and one antimatter.These two particles quickly convert back to energy, and the process repeats itself.In fact, there is so much energy involved in the electric field near, for example, an electron, that at any time there are many pairs of matter and antimatter particles at the same time.

A principle called the Heisenberg Uncertainty Principle applies here.This quantum principle says that pairs of matter and antimatter particles can appear, but only for a short time.Furthermore, the more massive the particles are, the harder it is for them to appear, and they live for a shorter amount of time.

Because the electron is the lightest of the charged subatomic particles, they appear most often (along with their antimatter counterpart, called the positron).Thus, surrounding every electron is a cloud of energy from the electric field, and a second cloud of electrons and positrons flickering in and out of existence.

Those clouds are the reason that the g factor for electrons or muons isnt exactly 2.The electron or muon interacts with the cloud and this enhances the particles magnetic properties.

So thats the big idea.In the following decades, scientists tried to measure the magnetic properties of both electrons and muons more accurately.Some researchers have focused on measuring the magnetic properties of muons.The first experiment attempting to do this was performed in 1959 at the CERN laboratory in Europe.Because researchers were more interested in the new quantum corrections than they were with the 1930s prediction, they subtracted off the 2 from the 1930s, and only looked at the excess.Hence this form of experiment is now called the g 2 experiment.

The early experiment measuring the magnetic properties of the muon was not terribly precise, but the situation has improved over the years.In 2006, researchers at the Brookhaven National Laboratory on Long Island, New York, measured an extremely precise value for the magnetic properties of the muon.They measured exactly 2.0023318418, with an uncertainty of 0.0000000012.This is an impressive measurement by any standards.(The measurement numbers can be found at this URL (page 715).)

The theoretical calculation for the magnetic properties of the muon is similarly impressive.A commonly accepted value for the calculation is 2.00233183620, with an uncertainty of 0.00000000086.The data and prediction agree, digit for digit for nine places.

Two measurements (red and blue) of the magnetic properties of the muon can be statistically combined ... [+] into an experimental measurement (pink). This can be compared to a theoretical prediction (green), and prediction and measurement don't agree.

Implications

Such good agreement should be applauded, but the interesting feature is in a slight remaining disagreement.Scientists strip off all of the numbers that agree and remake the comparison.In this case, the theoretical number is 362.0 8.6 and the experimental number is 418 12.The two disagree by 56 with an uncertainty of 14.8.

When one compares two independently generated numbers, one expects disagreement, but the agreement should be about the same size as the uncertainty.Here, the disagreement is 3.8 times the uncertainty.Thats weird and it could mean that a discovery has been made.Or it could mean that one of the two measurements is simply wrong.Which is it?

To test the experimental result, another measurement was made.In April of 2021, researchers at Fermilab, Americas flagship particle physics laboratory, repeated the Brookhaven measurement.They reported a number that agreed with the Brookhaven measurement.When they combine their data and the Brookhaven data, they find a result of 2.00233184122 0.00000000082.Stripped of the numbers that agree between data and theory, the current state of the art is:

Theoretical prediction: 362.0 8.6

Experimental measurement: 412.2 8.2

This disagreement is substantial, and many have reported that this is good evidence that current theory will need to be revised to accommodate the measurement.

However, this conclusion might be premature.On the same day that the experimental result was released, another theoretical estimate was published that disagrees with the earlier one.Furthermore, the new theoretical estimate is in agreement with the experimental prediction.

Two theoretical calculations are compared to a measurement (pink). The old calculation disagrees ... [+] with the measurement, but the new lattice QCD calculation agrees rather well. The difference between the two predictions means any claims for a discovery are premature.

How the theory is done

Theoretical particle physics calculations are difficult to do.In fact, scientists dont have the mathematical tools required to solve many problems exactly.Instead, they replace the actual problem with an approximation and solve the approximation.

The way this is done for the magnetic properties of the muon is they look at the cloud of particles surrounding the muon and ask which of them is responsible for the largest effect.They calculate the contribution of those particles.Then they move to the next most important contributors and repeat the process.Some of the contributions are relatively easy, but some are not.

While the particles surrounding the muon are often electrons and their antimatter electrons, some of the particles in the cloud are quarks, which are particles normally found inside protons and neutrons.Quarks are heavier than electrons, and they also interact with the strong nuclear charge.This strong interaction means that the quarks not only interact with the muon, the quarks interact with other quarks in the cloud.This makes it difficult to calculate their effect on the magnetic properties of the muon.

So historically, scientists have used other data measurements to get an estimate of the quarks contribution to the muons magnetism.With this technique, they came up with the discrepancy between the prediction and measurement.

However, a new technique has been employed which predicts the contribution caused by quarks.This new technique is called lattice QCD, where QCD is the conventional theory of strong nuclear force interactions.Lattice QCD is an interesting technique, where scientists set up a three dimensional grid and calculate the effect of the strong force on that grid.Lattice QCD is a brute force method and it has been successful in the past.But this is the first full attempt to employ the technique for the magnetic properties of muons.

This new lattice QCD calculation differs from the earlier theoretical prediction.Indeed, it is much closer to the experimental result.

So where does this leave us?When the Fermilab results were released, it appeared that the measurement and prediction disagreed substantially, suggesting that perhaps we needed to modify our theory to make it agree with data.However, now we have the unsettling situation that perhaps the theory wasnt right.Maybe the new lattice QCD calculation is correct.In that case, there is no discrepancy between data and prediction.

I think that the bottom line is that the entire situation is uncertain and it is too soon to draw any conclusion.The lattice QCD calculation is certainly interesting, but its new and also not all lattice QCD calculations agree.And the Fermilab version of the experiment measuring the magnetic properties of the muon is just getting started.They have reported a mere 6% of the total data they expect to eventually record and analyze.

Precision measurements of the magnetic properties of muons have the potential to rewrite physics.But thats only true if the measurement and predictions are both accurate and precise, and were not really ready to conclude that either are complete.It appears that the experimental measurement is pretty solid, although researchers are constantly looking for overlooked flaws.And the theory side is still a bit murky, with a lot of work required to understand the details of the lattice QCD calculation.

I think its safe to say that we are still many years from resolving this question.This is, without a doubt, an unsatisfying state of affairs, but thats science on the frontier of knowledge for you.We waited nearly two decades to get an improved measurement of the magnetic properties of muons.We can wait a few more years while scientists work hard to figure it all out.

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Recent Reports Of Overturned Scientific Theory Are Premature - Forbes

An illustration showing quantum vortex tubes undergoing apparent superdiffusion. The white dots represent trapped particle that the researchers tracked to visualize and track the motion of the tubes, and the red lines represent the random patterns that the particles traveled. Credit: Courtesy of Wei Guo

Nobel laureate in physics Richard Feynman once described turbulence as the most important unsolved problem of classical physics.

Understanding turbulence in classical fluids like water and air is difficult partly because of the challenge in identifying the vortices swirling within those fluids. Locating vortex tubes and tracking their motion could greatly simplify the modeling of turbulence.

But that challenge is easier in quantum fluids, which exist at low enough temperatures that quantum mechanics which deals with physics on the scale of atoms or subatomic particles govern their behavior.

In a new study published in Proceedings of the National Academy of Sciences, Florida State University researchers managed to visualize the vortex tubes in a quantum fluid, findings that could help researchers better understand turbulence in quantum fluids and beyond.

Our study is important not only because it broadens our understanding of turbulence in general, but also because it could benefit the studies of various physical systems that also involve vortex tubes, such as superconductors and even neutron stars, said Wei Guo, an associate professor of mechanical engineering at the FAMU-FSU College of Engineering and the studys principal investigator.

From left, Wei Guo, an associate professor of mechanical engineering at the FAMU-FSU College of Engineering, and Yuan Tang, a postdoctoral researcher at the National High Magnetic Field Laboratory, in front of the experimental setup. Credit: Courtesy of Wei Guo

The research team studied superfluid helium-4, a quantum fluid that exists at extremely low temperatures and can flow forever down a narrow space without apparent friction.

Guos team examined tracer particles trapped in the vortices and observed for the first time that as vortex tubes appeared, they moved in a random pattern and, on average, rapidly moved away from their starting point. The displacement of these trapped tracers appeared to increase with time much faster than that in regular molecular diffusion a process known as superdiffusion.

Analyzing what happened led them to uncover how the vortex velocities changed over time, which is important information for statistical modeling of quantum-fluid turbulence.

Superdiffusion has been observed in many systems such as the cellular transport in biological systems and the search patterns of human hunter-gatherers, Guo said. An established explanation of superdiffusion for things moving randomly is that they occasionally have exceptionally long displacements, which are known as Lvy flights.

But after analyzing their data, Guos team concluded that the superdiffusion of the tracers in their experiment was not actually caused by Lvy flights. Something else was happening.

We finally figured out that the superdiffusion we observed was caused by the relationship between the vortex velocities at different times, said Yuan Tang, a postdoctoral researcher at the National High Magnetic Field Laboratory and a paper author. The motion of every vortex segment initially appeared to be random, but actually, the velocity of a segment at one time was positively correlated to its velocity at the next time instance. This observation has allowed us to uncover some hidden generic statistical properties of a chaotic random vortex tangle, which could be useful in multiple branches of physics.

Unlike in classical fluids, vortex tubes in superfluid helium-4 are stable and well-defined objects.

They are essentially tiny tornadoes swirling in a chaotic storm but with extremely thin hollow cores, Tang said. You cant see them with the naked eye, not even with the strongest microscope.

To solve this, we conducted our experiments in the cryogenics lab, where we added tracer particles in helium to visualize them, added Shiran Bao, a postdoctoral researcher at the National High Magnetic Field Laboratory and a paper author.

The researchers injected a mixture of deuterium gas and helium gas into the cold superfluid helium. Upon injection, the deuterium gas solidified and formed tiny ice particles, which the researchers used as the tracers in the fluid.

Just like tornadoes in air can suck in nearby leaves, our tracers can also get trapped on the vortex tubes in helium when they are close to the tubes, Guo said.

This visualization technique is not new and has been used by scientists in research labs worldwide, but the breakthrough these researchers made was to develop a new algorithm that allowed them to distinguish the tracers trapped on vortices from those that were not trapped.

Reference: Superdiffusion of quantized vortices uncovering scaling laws in quantum turbulence by Yuan Tang, Shiran Bao and Wei Guo, 9 February 2021, Proceedings of the National Academy of Sciences.DOI: 10.1073/pnas.2021957118

Their research was supported by the National Science Foundation and the U.S. Department of Energy. The experiment was conducted at the National High Magnetic Field Laboratory at Florida State University.

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Researchers Visualize the Motion of Vortices in Quantum Superfluid Turbulence - SciTechDaily

We're delighted to present an extract from Helgoland, the new book from Carlo Rovelli, the acclaimed author of Seven Brief Lessons on Physics and There Are Places in the World Where Rules Are Less Important Than Kindness.

In June 1925, twenty-three-year-old Werner Heisenberg, suffering from hay fever, retreated to a treeless, wind-battered island in the North Sea called Helgoland. It was there that he came up with the key insight behind quantum mechanics. A century later, this theory has given us modern technology and nuclear energy but remains disconcerting, enigmatic and fiercely debated.

Helgoland is the story of quantum physics and its bright young founders who were to become some of the most famous Nobel winners.

aslav and I are sitting on the sand a few steps from the shore. We have been talking intensely for hours. We came to the island of Lamma, across from Hong Kong, during the afternoon break of a conference. aslav is a world-renowned expert on quantum mechanics. At the conference, he presented an analysis of a complex thought experiment. We discussed and re-discussed the experiment on the path through the coastal jungle leading to the shore, and then here, by the sea. We have ended up basically agreeing. On the beach there is a long silence. We watch the sea. 'It's really incredible, aslav whispers. Can we believe this? Its as if reality . . . didnt exist . . .

This is the stage we are at with quanta. After a century of resounding triumphs, having gifted us contemporary technology and the very basis for twentieth-century physics, the theory that is one of the greatest ever achievements of science fills us with astonishment, confusion and disbelief.

There was a moment when the grammar of the world seemed clear: at the root of the variegated forms of reality, just particles of matter guided by a few forces. Humankind could think that it had raised the Veil of Maya, seen the basis of the real. It didnt last. Many facts did not fit. Until, in the summer of 1925, a twenty-three-year-old German spent days of anxious solitude on a windswept island in the North Sea: Helgoland in English also Heligoland the Sacred Island. There, on the island, he found the idea that made it possible to account for all recalcitrant facts, to build the mathematical structure of quantum mechanics, quantum theory. Perhaps the most impressive scientific revolution of all time. The name of the young man was Werner Heisenberg, and the story told in this book begins with him.

Quantum theory has clarified the foundations of chemistry, the functioning of atoms, of solids, of plasmas, of the colour of the sky, the dynamics of the stars, the origins of galaxies . . . a thousand aspects of the world. It forms the basis of our latest technologies: from computers to nuclear power. Engineers, astrophysicists, cosmologists, chemists and biologists all use it daily; the rudiments of the theory are included in high-school curricula. It has never been wrong. It is the beating heart of todays science. Yet it remains profoundly mysterious, subtly disturbing.

It has destroyed the image of reality as made up of particles that move along defined trajectories without, however, clarifying how we should think of the world instead. Its mathematics does not describe reality. Distant objects seem magically connected. Matter is replaced by ghostly waves of probability.

Whoever stops to ask themselves what quantum theory has to say about the actual world remains perplexed. Einstein, even though he had anticipated ideas that put Heisenberg on the right track, could never digest it himself. Richard Feynman, the great theoretical physicist of the second half of the twentieth century, wrote that nobody understands quanta.

But this is what science is all about: exploring new ways of conceptualizing the world. At times, radically new. It is the capacity to constantly call our concepts into question. The visionary force of a rebellious, critical spirit, capable of modifying its own conceptual basis, capable of redesigning our world from scratch.

Helgoland by Carlo Rovelli (published by Allen Lane) is out now.

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Helgoland by Carlo Rovelli - read an exclusive extract - RTE.ie