Category Archives: Quantum Physics

Physicists have long been unable to crack the mystery of what happened in the moments when a vanishingly small seed ballooned into the universe. Now, one scientist thinks he knows why they can't come up with a physical description of this phenomenon called inflation: The universe won't let us.

Specifically, the scientist describes a new conjecture that states, regarding the young universe, "the observer should be shielded" from directly observing the smallest structures in the cosmos.

In other words, by definition physicists may never be able to build a model of inflation using the usual tools, and they will have to come up with a better way.

Related: From Big Bang to present: Snapshots of our universe through time

But why not? This new conjecture, which is an opinion or thought based on incomplete information, points the finger of blame at a particular feature of inflation models. These models take very, very small fluctuations in spacetime and make them bigger. But we don't have a complete physical theory of those small fluctuations, and so models of inflation that have that feature (which is almost all of them) will never work.

Enter string theory, which could be the key to elucidating the secrets of inflation.

Observations of the large-scale structure of the universe and the leftover light from the Big Bang have revealed that in the very early universe, our cosmos likely experienced a period of incredibly rapid expansion. This remarkable event, known as inflation, drove the universe to become trillions upon trillions of times larger in the tiniest fraction of a second.

In the process of getting huge, inflation also made our cosmos a little bit bumpy. As inflation unfolded, the tiniest random quantum fluctuations fluctuations built into the very fabric of space-time itself got much, much larger, meaning some regions were more densely packed with matter than others. Eventually, those sub-microscopic differences grew to become macroscopic and even bigger, in some cases stretching from one end of the universe to the other. Millions and billions of years later, those tiny differences in density grew to become the seeds of stars, galaxies and the largest structures in the cosmos.

Related: The 12 biggest objects in the universe

Astronomers strongly suspect that something like this inflation story happened in the early moments of the universe, when it was less than a second old; even so, they don't know what triggered inflation, what powered it, how long it lasted or what shut it off. In other words, physicists lack a complete physical description of this momentous event.

Adding to the mix of mysteries is that in most models of inflation, fluctuations at exceedingly tiny scales get inflated to become macroscopic differences. How tiny? Tinier than the Planck length, or roughly 1.6 x 10^minus 35 meters (the number 16 preceded by 34 zeroes and a decimal point). That's the scale where the strength of gravity rivals that of the other fundamental forces of nature. At that scale, we need a unified theory of physics in order to describe reality

We have no such theory.

So we have a problem. Most (if not all) models of inflation require the universe to grow so large that sub-Planckian differences become macroscopic. But we don't understand sub-Planckian physics. So how could we possibly build a theoretical model of inflation if we don't understand the underlying physics?

Maybe the answer is: We can't. Ever. This concept is called the trans-Planckian Censorship Conjecture, or TCC (in this name, "trans-Planckian" means anything reaching below the Planck length).

Robert Brandenberger, a Swiss-Canadian theoretical cosmologist and a professor at McGill University in Montreal, Canada, recently wrote a review of the TCC. According to Brandenberger, "The TCC is a new principle which constrains viable cosmologies." In his view the TCC implies that any observer in our large-scale world can never "see" what happens at the tiny trans-Planckian scale. Even if we had a theory of quantum gravity, the TCC states that anything living in the sub-Planckian regime will never "cross over" into the macroscopic world. As to what the TCC might mean for models of inflation, unfortunately it's not good news.

Most theories of inflation rely on a technique known as "effective field theory." Since we don't have a theory that unifies physics at high energy and small scales (a.k.a. conditions like inflation), physicists try to build lower-energy versions to make progress. But under the TCC, that kind of strategy doesn't work, because when we use it to build models of inflation, the process of inflation happens so rapidly that it "exposes" the sub-Planckian regime to macroscopic observation, Brandenberger said.

Related: What happened before the Big Bang?

In light of this issue, some physicists wonder if we should take a completely different approach to the early universe.

String gas cosmology is a possible approach to modeling the early universe under string theory, which is itself a hopeful candidate for a unified theory of physics that brings classic and quantum physics under the same roof. In the string gas model, the universe never undergoes a period of rapid inflation. Instead, the inflation period is much gentler and slower, and fluctuations below the Planck length never get "exposed" to the macroscopic universe. Physics below the Planck scale never grows up to become observable, and so the TCC is satisfied. However, string gas models don't yet have enough detail to test against the observable evidence of inflation in the universe.

Related: What is the smallest thing in the universe?

The TCC is related to another sticking point between inflation and theories of unified physics like string theory. String theory predicts an enormous number of potential universes, of which our particular cosmos (with its set of forces and particles and the rest of physics) represents only one. It seems as if most (if not all) models of inflation are incompatible with string theory at a basic level. Instead, they belong to what string theorists called the "swampland" the region of possible universes that simply aren't physically realistic.

The TCC could be an expression of the swampland rejection of inflation.

It may still be possible to build a traditional model of inflation that satisfies the TCC (and lives outside string theory's swampland); but if the TCC is true, this severely limits the kinds of models that physicists can build. If inflation manages to proceed for a short enough period of time (imagine blowing up a balloon slowly and stopping before it pops), while still planting the seeds that will someday grow up to be massive structures, inflation theory might work.

Right now, the TCC is unproven it's just a conjecture. It lines up with other lines of thinking of string theory, but string theory is itself also unproven (in fact, the theory isn't complete and isn't even able to make predictions yet). But still, ideas like this are useful, because physicists fundamentally don't understand inflation, and anything that can help sharpen that thinking is welcome.

Originally published on Live Science.

See the original post here:

Will we ever know exactly how the universe ballooned into existence? - Livescience.com

Chanda Prescod-Weinstein is an award-winning physicist, feminist, activist and the first Black woman to earn a PhD in the field of theoretical cosmology. Photo: Chanda Prescod-Weinstein

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 PhD in the subject.

Prescod-Weinsteinis an assistant professor of physics and astronomy, and a core faculty member in the department of womens 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 girls 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 realise 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 realised, 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 worlds 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 colour, 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. Its 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 events 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 coloured physics, more commonly known as quantum chromodynamics, which she describes as a theory that uses colour as an analogy for physical properties that have nothing to do with colour. 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: Its 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.

Also read: Astronomers May Not Like It but Astronomy and Colonialism Have a Shared History

Studying the physical world requires confronting the social world, Prescod-Weinstein writes. It means changing institutionalised 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 crystallised. 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 colourful and electric.

Prescod-Weinstein aspires to loftier matters. The books 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-Weinsteins 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.

Read more from the original source:

'The Disordered Cosmos', A Contemplation of the Exclusionary Culture of Physics - The Wire Science

Albert Einstein is the genius we all know and love. He was a German theoretical physicist. He is known as one of the greatest physicists of all time and for developing the theory of relativity.

He also made important contributions to the development of the theory of quantum mechanics. He received the 1921 Nobel Prize in Physics for his services to theoretical physics and especially for his discovery of the law of photoelectric effect which was a pivotal step in the development of quantum theory.

April 18 is the death anniversary of this great man.

How did Albert Einstein die?

World-renowned physicist Albert Einstein passed away in Princeton Hospital in New Jersey on 18 April, 1955. The cause of his death was the rupture of an aneurysm, which had already been reinforced by surgery in 1948.

He refused to undergo further surgery saying, "I want to go when I want. It is tasteless to prolong life artificially. I have done my share, it is time to go. I will do it elegantly." He kept working almost to the very end, leaving the Generalized Theory of Gravitation unsolved.

He was 76 years old at the time of his death. However, his last words will forever remain unknown as they were uttered in his native German. On his deathbed, he muttered a few last words in that language and the only witness was his nurse but, unfortunately, she didn't speak the language.

Famous Quotes of Albert Einstein:

1. Imagination is more important than knowledge.

2. If you can't explain it simply, you don't understand it well enough.

3. Life is like riding a bicycle. To keep your balance you must keep moving.

4. Imagination is everything. It is the preview of life's coming attractions.

5. No problem can be solved from the same level of consciousness that created it.

Read the original:

Albert Einstein Death Anniversary: How did the greatest physicists of all time die? - Free Press Journal

Author Krista Foss with her new novel, Half Life.

Fehn Foss/Handout

At the Milwaukee high school where she teaches physics, Elin, the protagonist of Krista Fosss new novel, Half Life (M&S), often uses unorthodox methods to explain principles like nuclear fission and chain reactions to her students. Far more complex, and at times less explicable, however, are the reactions occurring in Elins own family in the wake of the sudden death of her father, a revered Danish-born furniture designer.

Foss has twice been a finalist for the Journey Prize for her short fiction. Her previous novel, Smoke River (2014), won the Hamilton Literary Award. She lives in Hamilton.

This novel is a notable departure from your previous one, at least in terms of subject matter. How did it come to you?

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I spent four years writing something else an entirely different book that I would have kept expanding and retooling had not my daughter, whose judgment I trust implicitly, found the courage to tell me it wasnt working and wasnt likely to either. As far as moments go, that was a devastating one. And not an easy message for her to deliver. At a gut level, I knew she was right as she was when she pointed to this other story, sniffing around the edges of the unsalvageable manuscript, suggesting I dig into that. It scared the bejeezus out of me. But my other option was to get depressed over having noodled away for four years with nothing to show for it.

So, Half Life was written in a swoon of fear, with equal parts humiliation and humility, but also a lot of love for mothers, daughters, the complexities of family. And those really brave moments when someone has to say something thats both true and devastating.

The grace note was the first draft came out quickly; it seemed to have been there all along. And because Half Life is a close character study, told with a singular voice, it feels wholly different from my first novel, which had 12 points of view. I got to stretch myself in a new way.

The specificity of its setting and characters is one of the most interesting things about Half Life. Why did you set it in Milwaukee?

Milwaukee was the whim that became the premeditated choice. I wanted Elin to live in a mid-sized city, that for her feels midway to somewhere else, namely the bigger cities her more accomplished siblings left Milwaukee for.

I also mistakenly thought Milwaukee had a large Danish-American population, so when I landed there during a January snowstorm, I thought Id be tripping over Scandinavians. But the more I discovered about Milwaukee the more it felt kindred to me, an inveterate Hamiltonian: its ugliness and its beauty and other troubling contradictions. Its the largest city in the U.S. to have elected socialist mayors. Yet, it remains racially segregated, divided by money, full of industrial pride, yet abandoned by many industries.

And then I discovered the curious, not-so-well-known role Milwaukee played in The Manhattan Project, and it worked so perfectly with the novel, I started to believe Id chosen the city on purpose, rather than acting on a gut feeling that led to productive serendipities.

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The patriarch in the novel, Tig, is a famous Danish mid-century furniture designer. How much did you know about such things before you began writing?

My childhood home was originally filled with Scandinavian mid-century modern furniture, but it didnt hold up under assault from me and my siblings: five very large, unruly children born in quick succession. It was replaced with rough-hewn pine benches and homemade durable sofas. Still, I never shook the impression of the earlier furnitures angles and curves, the low-lustre teak, the dark-striped boucle, all of it registering as birdlike, weird and beautiful.

So, my knowledge of Danish mid-century modern design begins with an old emotion supplemented by some later book-learning, BBC documentaries and hours spent staring at the offerings of online auction houses. Also, if a chair is unadorned physics it has to hold itself up under the forces of gravity, and then it has to hold you the Danish made it look cool to my eyes.

For much of my life, that was about my working level of physics that, and a disastrous first year of university engineering.

And yet physics and physicists also play a major role in the novel, so Im assuming you had to do a lot of research in that realm as well?

I backed into theoretical physics for this book through recreational reading on whats called the hard problem of consciousness and stumbling on how neurology, philosophy, computer science and physics have all staked out turf in this debate (and turfs inside turfs). Its vociferous, and sometimes veers toward the polemical. And in going down that rabbit hole, I read more about theoretical physics than I expected to. At the simplest level, I became intrigued by how much we do in this world that breezes over underlying paradox: science works even when its practitioners dont fully understand or agree on how or why. The consciousness question didnt show up in my book, but the physics did.

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Eventually, research has a showdown with hubris. I couldnt become an expert on subjects others have dedicated their lives to mastering. In an early draft, my main character had long conversations with Niels Bohr on the epistemological questions arising from quantum mechanics. Thats not great fiction or at least not the way I wrote it. And it taught me another lesson: resist using most of your research.

Ultimately, I needed to understand as much of the physics that interested my character and that she would use in the context of her story arc. That allowed me to approach the subject with more wonder. What does she contemplate walking through busy halls holding a full cup of coffee? How does Schrodingers cat show up in her dreams? Who are the physicists she wishes she knew?

So did you emerge from it with a favourite physicist, or theorem?

Physicists fascinate me how often messy lives produce brilliant, elegant science. But it was the female physicists in the period straddling the foundations of quantum mechanics and the beginnings of nuclear physics who left the deepest impressions, because other than Marie Curie and her daughter, they were largely shut out of recognition and rewards a reality thats only recently shifting with the 2018 and 2020 Nobel Prizes in Physics. Among them was Lise Meitner, exiled from her beloved Berlin, tromping off in the snow with her nephew to sit down in a Swedish forest and scribble calculations on the back of stationery that confirmed nuclear fission. For the man whod betray her. She had that trifecta of emotional complexity, deep humanity and utter brilliance.

People like to say things dont matter, and yet objects in this novel have a weight and a power. Can you talk about that?

Things matter in this novel insofar as they are matter. Which is Elins central dilemma. Her memory is analogous to quantum physics: she cant produce visible tangible evidence. It is dogged by uncertainty. And yet, it is an underlying reality.

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The other reality is material, the realm of classical physics dealing with the insults of time to her body and home, seeing her daughter bruised, a branch falling in her path. Even the bombs that fell in the past have macroscopic footprints.

So, the objects in the book a beautiful chair or dining set, a collection of smoky Danish glass mirror the dilemma. They have their own classical reality, the substances they are made of and their tactile aesthetics. But these are overlaid with strata of narrative: who designed them, how they are made and where the wear and tear came from. And finally, that invisible encoding of memory: the laughter, meals, song, comfort and wounds they hold. The secrets.

The paradoxes we cant see joy co-existing with pain along those we can aesthetic delight simultaneous with ugliness, with stain can all be the reality of something as utilitarian, yet intimate, as a chair or a table or a drinking glass.

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Continued here:

Half Life traces family complexities for a Milwaukee physics teacher - The Globe and Mail

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.

BOOK REVIEW The Disordered Cosmos: A Journey into Dark Matter, Spacetime, & Dreams Deferred, by Chanda Prescod-Weinstein (Bold Type Books, 336 pages).

Prescod-Weinsteinis an assistant professor of physics and astronomy, and a core faculty member in the department of womens 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 girls 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 worlds 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. Its a brilliant sprint, and the prize for finishers is some of her finest writing about race and science.

I promised myself that I would make more room in my life for my dreams of being a physicist, Prescod-Weinstein wrote. But not like this.

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 events 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: Its 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.

Learning about the mathematics of the universe could never be an escape from the earthly phenomena of racism and sexism.

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 books 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-Weinsteins 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.

Read more from the original source:

Book Review: A Cosmologist Throws Light on a Universe of Bias - Undark Magazine

Scott Aaronson is therecipient of the 2020 ACM Prize in Computing for his "groundbreaking contributions to quantum computing." Aaronson, who is Professor of Computer Science at the University of Texas, Austin, has also made fundamental contributions to classical complexity theory.

The award, which was established in 2007 to recognize "early to mid-career fundamental innovative contributions in computing" carries a prize of $250,000, with its financial support provided by Infosys Ltd.

In today's announcement,Pravin Rao, COO of Infosys states:

Infosys is proud to fund the ACM Prize in Computing and we congratulate Scott Aaronson on being this years recipient. When the effort to build quantum computation devices was first seriously explored in the 1990s, some labeled it as science fiction. While the realization of a fully functional quantum computer may still be in the future, this is certainly not science fiction. The successful quantum hardware experiments by Google and others have been a marvel to many who are following these developments. Scott Aaronson has been a leading figure in this area of research and his contributions will continue to focus and guide the field as it reaches its remarkable potential.

Explaining that the goal of quantum computing is:

"to harness the laws of quantum physics to build devices that can solve problems that classical computers either cannot solve, or not solve in any reasonable amount of time"

the ACM notes that Aaronson showed how results from computational complexity theory can provide new insights into the laws of quantum physics, and brought clarity to what quantum computers will, and will not, be able to do.

Aaronson helped develop the concept of quantum supremacy, something that would be achieved when a quantum device can solve a problem that no classical computer can solve in a reasonable amount of time and established many of the theoretical foundations of quantum supremacy experiments. He has also explored how quantum supremacy experiments could deliver a key application of quantum computing, namely the generation of cryptographically random bits.

Among his notable contribution are the 2011 paper The Computational Complexity of Linear Optics, in which, with co-author Alex Arkhipov, he put forward evidence that rudimentary quantum computers built entirely out of linear-optical elements cannot be efficiently simulated by classical computers.

Earlier, in his 2002 paper Quantum lower bound for the collision problem, Aaronson proved the quantum lower bound for the collision problem, which had been for years a major open problem. This work bounds the minimum time for a quantum computer to find collisions in many-to-one functions, giving evidence that a basic building block of cryptography will remain secure for quantum computers.

Aaronson is known for hiswork on algebrization, a technique he invented with Avi Wigderson to understand the limits of algebraic techniques for separating and collapsing complexity classes. Beyond his technical contributions, Aaronson is also credited with making quantum computing understandable to a wide audience, through his popular blog,Shtetl Optimized, where he explains timely and exciting topics in quantum computing in a simple and effective way, TED Talks to dispel misconceptions and provide the public with a more accurate overview of the field and his bookQuantum Computing Since Democritus, see side panel.

In his latest blog post, Aaronson recounts how he was toled about winning the prize and writes:

I dont know if Im worthy of such a prizebut I know that if I am, then its mainly for work I did between roughly 2001 and 2012. This honor inspires me to want to be more like I was back then, when I was driven, non-jaded, and obsessed with figuring out the contours of BQP and efficient computation in the physical universe. It makes me want to justify the ACMs faith in me.

ACM Prize Awarded to Pioneer in Quantum Computing

Dr. Scott J Aaronson

The ACM Prize thing

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David Silver Awarded 2019 ACM Prize In Computing

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Computer Graphics Pioneers Win 2019 Turing Award

2021 Abel Prize Shared By Math and Computer Science

Knuth Prize 2019 Awarded For Contributions To Complexity Theory

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Scott Aaronson Winner of 2020 ACM Prize In Computing - iProgrammer

A minimal Weyl semimetal

Many compounds have now been identified as Weyl semimetals, materials with an unusual electronic band structure characterized by the so-called Weyl points. Weyl points always appear in pairs, but the solid-state materials studied so far have at least four. Wang et al. engineered a Weyl semimetallic state with the minimum number of Weyl points (two) in a gas of ultracold atoms trapped in an optical lattice (see the Perspective by Goldman and Yefsah). To do that, the researchers had to create three-dimensional spin-orbit coupling in this system. The relative simplicity of the resulting band structure will make it easier to observe the unusual effects associated with this state.

Science, this issue p. 271; see also p. 234

Weyl semimetals are three-dimensional (3D) gapless topological phases with Weyl cones in the bulk band. According to lattice theory, Weyl cones must come in pairs, with the minimum number of cones being two. A semimetal with only two Weyl cones is an ideal Weyl semimetal (IWSM). Here we report the experimental realization of an IWSM band by engineering 3D spin-orbit coupling for ultracold atoms. The topological Weyl points are clearly measured via the virtual slicing imaging technique in equilibrium and are further resolved in the quench dynamics. The realization of an IWSM band opens an avenue to investigate various exotic phenomena that are difficult to access in solids.

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Realization of an ideal Weyl semimetal band in a quantum gas with 3D spin-orbit coupling - Science Magazine

A powerful new idea about how the laws of physics work could bring breakthroughs on everything from quantum gravity to consciousness, says researcher Chiara Marletto

By Chiara Marletto

Manshen Lo

QUANTUM supremacy is a phrase that has been in the news a lot lately. Several labs worldwide have already claimed to have reached this milestone, at which computers exploiting the wondrous features of the quantum world solve a problem faster than a conventional classical computer feasibly could. Although we arent quite there yet, a general-purpose universal quantum computer seems closer than ever a revolutionary development for how we communicate and encrypt data, for virtual reality, artificial intelligence and much more.

These prospects excite me as a theoretical physicist too, but my colleagues and I are captivated by an even bigger picture. The quantum theory of computation originated as a way to deepen our understanding of quantum theory, our fundamental theory of physical reality. By applying the principles we have learned more broadly, we think we are beginning to see the outline of a radical new way to construct laws of nature.

It means abandoning the idea of physics as the science of whats actually happening, and embracing it as the science of what might or might not happen. This science of can and cant could help us tackle some of the big questions that conventional physics has tried and failed to get to grips with, from delivering an exact, unifying theory of thermodynamics and information to getting round conceptual barriers that stop us merging quantum theory with general relativity, Einsteins theory of gravity. It might go even further and help us to understand how intelligent thought works, and kick-start a technological revolution that would make quantum supremacy look modest by comparison.

Since the dawn of modern physics in

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Quantum computers are revealing an unexpected new theory of reality - New Scientist

Pablo Bonilla Ataides (left) with co-author Dr Ben Brown from the School of Physics. Photo: Louise Cooper

What started out as a second-year physics project is making its way into Amazon Web Services (AWS) quantum computing program.

University of Sydney science undergraduate Pablo Bonilla Ataides has tweaked some computing code to effectively double its capacity to correct errors in the quantum machines being designed in the emerging technology sector.

The simple but ingenious change to quantum error correcting code has grabbed the attention of quantum researchers at the AWS Center for Quantum Computing in Pasadena, California, and the quantum technology programs at Yale University and Duke University in the United States.

Quantum technology is in its infancy, partly because we havent been able to overcome the inherent instability in the machines that produce so many errors, 21-year-old Mr Bonilla said.

In second-year physics I was asked to look at some commonly used error correcting code to see if we could improve it. By flipping half of the quantum switches, or qubits, in our design, we found we could effectively double our ability to suppress errors.

The research is published today in Nature Communications.

The results of the study, co-authored by Dr Steve Flammia who has recently moved from the University of Sydney to AWSs quantum computing effort, are to featurein the tech companys arsenal of error correction techniques as it develops its quantum hardware.

Dr Earl Campbell is a senior quantum research scientist at AWS. He said: We have considerable work ahead of us as an industry before anyone sees real, practical benefits from quantum computers.

This research surprised me.I was amazed that such a slight change to a quantum error correction code could lead to such a big impact in predicted performance.

The AWS Center for Quantum Computing team looks forward to collaborating further as we explore other promising alternatives to bring new, more powerful computing technologies one step closer to reality.

Errors are extremely rare in the digital transistors, or switches, that classical computers use to run our phones, laptops and even the fastest supercomputers.

However, the switches in quantum computers, known as qubits, are particularly sensitive to interference, or noise, from the external environment.

In order to make quantum machines work, scientists need to produce a large number of high-quality qubits. This can be done by improving the machines so they are less noisy and by using some capacity of the machines to suppress qubit errors below a certain threshold in order for them to be useful.

That is where quantum error correction comes in.

Assistant Professor Shruti Puri from the quantum research program at Yale University said her team is interested in using the new code for its work.

What amazes me about this new code is its sheer elegance. Its remarkable error-correcting properties are coming from a simple modification to a code that has been studied extensively for almost two decades, Assistant Professor Puri said.

It is extremely relevant for a new generation of quantum technology being developed at Yale and elsewhere. With this new code, I believe, we have considerably shortened the timeline to achieve scalable quantum computation.

Co-author Dr David Tuckett from the School of Physics said: Its a bit like playing battleships with a quantum opponent. Theoretically, they could place their pieces anywhere on the board. But after playing millions of games, we know that certain moves are more likely.

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Student's physics homework picked up by Amazon quantum researchers - News - The University of Sydney

The Muon g-2 electromagnet at Fermilab, ready to receive a beam of muon particles. This experiment ... [+] began in 2017 and will take data for a total of 3 years, reducing the uncertainties significantly. While a total of 5-sigma significance may be reached, the theoretical calculations must account for every effect and interaction of matter that's possible in order to ensure we're measuring a robust difference between theory and experiment.

In early April, 2021, the experimental physics community announced an enormous victory: they had measured the muons magnetic moment to unprecedented precision. With the extraordinary precision achieved by the experimental Muon g-2 collaboration, they were able to measure the spin magnetic moment of the muon not only wasn't 2, as originally predicted by Dirac, but was more precisely 2.00116592040. There's an uncertainty in the final two digits of 54, but not larger. Therefore, if the theoretical prediction differs by this measured amount by too much, there must be new physics at play: a tantalizing possibility that has justifiably excited a great many physicists.

The best theoretical prediction that we have, in fact, is more like 2.0011659182, which is significantly below the experimental measurement. Given that the experimental result strongly confirms a much earlier measurement of the same g-2 quantity for the muon by the Brookhaven E821 experiment, theres every reason to believe that the experimental result will hold up with better data and reduced errors. But the theoretical result is very much in doubt, for reasons everyone should appreciate. Lets help everyone physicists and non-physicists alike understand why.

The first Muon g-2 results from Fermilab are consistent with prior experimental results. When ... [+] combined with the earlier Brookhaven data, they reveal a significantly larger value than the Standard Model predicts. However, although the experimental data is exquisite, this interpretation of the result is not the only viable one.

The Universe, as we know it, is fundamentally quantum in nature. Quantum, as we understand it, means that things can be broken down into fundamental components that obey probabilistic, rather than deterministic, rules. Deterministic is what happens for classical objects: macroscopic particles such as rocks. If you had two closely-spaced slits and threw a small rock at it, you could take one of two approaches, both of which would be valid.

But for quantum objects, you cant do either of those. You could only compute a probability distribution for the various outcomes that could have occurred. You can either compute the probabilities of where things would land, or the probability of various trajectories having occurred. Any additional measurement you attempt to make, with the goal of gathering extra information, would alter the outcome of the experiment.

Electrons exhibit wave properties as well as particle properties, and can be used to construct ... [+] images or probe particle sizes just as well as light can. This compilation shows an electron wave pattern, which cumulatively emerges after many electrons are passed through a double slit.

Thats the quantum weirdness were used to: quantum mechanics. Generalizing the laws of quantum mechanics to obey Einsteins laws of special relativity led to Diracs original prediction for the muons spin magnetic moment: that there would be a quantum mechanical multiplicative factor applied to the classical prediction, g, and that g would exactly equal 2. But, as we all now know, g doesnt exactly equal 2, but a value slightly higher than 2. In other words, when we measure the physical quantity g-2, were measuring the cumulative effects of everything that Dirac missed.

So, what did he miss?

He missed the fact that its not just the individual particles that make up the Universe that are quantum in nature, but also the fields that permeate the space between those particles must also be quantum. This enormous leap from quantum mechanics to quantum field theory enabled us to calculate deeper truths that arent illuminated by quantum mechanics at all.

Magnetic field lines, as illustrated by a bar magnet: a magnetic dipole, with a north and south pole ... [+] bound together. These permanent magnets remain magnetized even after any external magnetic fields are taken away. If you 'snap' a bar magnet in two, it won't create an isolated north and south pole, but rather two new magnets, each with their own north and south poles. Mesons 'snap' in a similar manner.

The idea of quantum field theory is simple. Yes, you still have particles that are charged in some variety:

but they dont just create fields around them based on things like their position and momentum like they did under either Newtons/Einsteins gravity or Maxwells electromagnetism.

If things like the position and momentum of each particle have an inherent quantum uncertainty associated with them, then what does that mean for the fields associated with them? It means we need a new way to think about fields: a quantum formulation. Although it took decades to get it right, a number of physicists independently figured out a successful method of performing the necessary calculations.

A visualization of QCD illustrates how particle/antiparticle pairs pop out of the quantum vacuum for ... [+] very small amounts of time as a consequence of Heisenberg uncertainty. If you have a large uncertainty in energy (E), the lifetime (t) of the particle(s) created must be very short.

What many people expected to happen although it doesnt quite work this way is that wed be able to simply to fold all the necessary quantum uncertainties into the charged particles that generate these quantum fields, and that would allow us to compute the field behavior. But that misses a crucial contribution: the fact that these quantum fields exist, and in fact permeate all of space, even where there are no charged particles giving rise to the corresponding field.

Electromagnetic fields exist even in the absence of charged particles, for instance. You can imagine waves of all different wavelengths permeating all of space, even when no other particles are present. Thats fine from a theoretical perspective, but wed want experimental proof that this description was correct. We already have it in a couple of forms.

As electromagnetic waves propagate away from a source that's surrounded by a strong magnetic field, ... [+] the polarization direction will be affected due to the magnetic field's effect on the vacuum of empty space: vacuum birefringence. By measuring the wavelength-dependent effects of polarization around neutron stars with the right properties, we can confirm the predictions of virtual particles in the quantum vacuum.

In fact, the experimental effects of quantum fields have been felt since 1947, when the Lamb-Retherford experiment demonstrated their reality. The debate is no longer over whether:

But what we do have to recognize is as in the case with many mathematical equations that we know how to write down that we cannot compute everything with the same straightforward, brute-force approach.

The way we perform these calculations in quantum electrodynamics (QED), for example, is we do whats called a perturbative expansion. We imagine what it would be like for two particles to interact like an electron and and electron, a muon and a photon, a quark and another quark, etc. and then we imagine every possible quantum field interaction that could happen atop that basic interaction.

Today, Feynman diagrams are used in calculating every fundamental interaction spanning the strong, ... [+] weak, and electromagnetic forces, including in high-energy and low-temperature/condensed conditions. The electromagnetic interactions, shown here, are all governed by a single force-carrying particle: the photon.

This is the idea of quantum field theory thats normally encapsulated by their most commonly-seen tool to represent calculational steps that must be taken: Feynman diagrams, as above. In the theory of quantum electrodynamics where charged particles interact via the exchange of photons, and those photons can then couple through any other charged particles we perform these calculations by:

Quantum electrodynamics is one of the many field theories we can write down where this approach, as we go to progressively higher loop orders in our calculations, gets more and more accurate the more we calculate. The processes at play in the muons (or electrons, or taus) spin magnetic moment have been calculated beyond five-loop order recently, and theres very little uncertainty there.

Through a herculean effort of the part of theoretical physicists, the muon magnetic moment has been ... [+] calculated up to five-loop order. The theoretical uncertainties are now at the level of just one part in two billion. This is a tremendous achievement that can only be made in the context of quantum field theory, and is heavily reliant on the fine structure constant and its applications.

The reason this strategy works so well is because electromagnetism has two important properties to it.

The combination of these factors guarantees that we can calculate the strength of any electromagnetic interaction between any two particles in the Universe more and more accurately by adding more terms to our quantum field theory calculations: by going to higher and higher loop-orders.

Electromagnetism, of course, isnt the only force that matters when it comes to Standard Model particles. Theres also the weak nuclear force, which is mediated by three force-carrying particles: the W-and-Z bosons. This is a very short-range force, but fortunately, the strength of the weak coupling is still small and the weak interactions are suppressed by large masses possessed by the W-and-Z bosons. Even though its a little more complicated, the same method of expanding to higher-order loop diagrams works for computing the weak interactions, too. (The Higgs is also similar.)

At high energies (corresponding to small distances), the strong force's interaction strength drops ... [+] to zero. At large distances, it increases rapidly. This idea is known as 'asymptotic freedom,' which has been experimentally confirmed to great precision.

But the strong nuclear force is different. Unlike all of the other Standard Model interactions, the strong force gets weaker at short distances rather than stronger: it acts like a spring rather than like gravity. We call this property asymptotic freedom: where the attractive or repulsive force between charged particles approaches zero as they approach zero distance from one another. This, coupled with the large coupling strength of the strong interaction, makes this common loop-order method wildly inappropriate for the strong interaction. The more diagrams you calculate, the less accurate you get.

This doesnt mean we have no recourse at all in making predictions for the strong interactions, but it means we have to take a different approach to our normal one. Either we can try to calculate the contributions of the particles and fields under the strong interaction non-perturbatively such as via the methods of Lattice QCD (where QCD stands for quantum chromodynamics, or the quantum field theory governing the strong force) or you can try and use the results from other experiments to estimate the strength of the strong interactions under a different scenario.

As computational power and Lattice QCD techniques have improved over time, so has the accuracy to ... [+] which various quantities about the proton, such as its component spin contribtuions, can be computed.

If what we were able to measure, from other experiments, was exactly the thing we dont know in the Muon g-2 calculation, there would be no need for theoretical uncertainties; we could just measure the unknown directly. If we didnt know a cross-section, a scattering amplitude, or a particular decay property, those are things that particle physics experiments are exquisite at determining. But for the needed strong force contributions to the spin magnetic moment of the muon, these are properties that are indirectly inferred from our measurements, not directly measured. Theres always a big danger that a systematic error is causing the mismatch between theory and observation from our current theoretical methods.

On the other hand, the Lattice QCD method is brilliant: it imagines space as a grid-like lattice in three dimensions. You put the two particles down on your lattice so that they're separated by a certain distance, and then they use a set of computational techniques to add up the contribution from all the quantum fields and particles that we have. If we could make the lattice infinitely large, and the spacing between the points on the lattice infinitely small, we'd get the exact answer for the contributions of the strong force. Of course, we only have finite computational power, so the lattice spacing can't go below a certain distance, and the size of the lattice doesn't go beyond a certain range.

There comes a point where our lattice gets large enough and the spacing gets small enough, however, that well get the right answer. Certain calculations have already yielded to Lattice QCD that havent yielded to other methods, such as the calculations of the masses of the light mesons and baryons, including the proton and neutron. After many attempts at predicting what the strong forces contributions to the g-2 measurement of the muon ought to be over the past few years, the uncertainties are finally dropping to become competitive with the experimental ones. If the latest group to perform that calculation has finally gotten it right, there is no longer a tension with the experimental results.

The R-ratio method (red) for calculating the muon's magnetic moment has led many to note the ... [+] mismatch with experiment (the 'no new physics' range). But recent improvements in Lattice QCD (green points, and particularly the top, solid green point) not only have reduced the uncertainties substantially, but favor an agreement with experiment and a disagreement with the R-ratio method.

Assuming that the experimental results from the Muon g-2 collaboration hold up and theres every reason to believe they will, including the solid agreement with the earlier Brookhaven results all eyes will turn towards the theorists. We have two different ways of calculating the expected value of the muons spin magnetic moment, where one agrees with the experimental values (within the errors) and the other does not.

Will the Lattice QCD groups all converge on the same answer, and demonstrate that not only do they know what theyre doing, but that theres no anomaly after all? Or will Lattice QCD methods reveal a disagreement with the experimental values, the same way that they presently disagree with the other theoretical method we have that presently disagrees so significantly with the experimental values we have: of using experimental inputs instead of theoretical calculations?

Its far too early to say, but until we have a resolution to this important theoretical issue, we wont know what it is thats broken: the Standard Model, or the way were presently calculating the same quantities were measuring to unparalleled precisions.

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The Big Theoretical Physics Problem At The Center Of The 'Muon g-2' Puzzle - Forbes