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  • richardmitnick 9:45 am on April 14, 2019 Permalink | Reply
    Tags: "The Day Feynman Worked Out Black-Hole Radiation on My Blackboard", , , , , , , Richard Feynman   

    From Nautilus: “The Day Feynman Worked Out Black-Hole Radiation on My Blackboard” 

    Nautilus

    From Nautilus

    Apr 11, 2019

    The amazing image of a black hole unveiled Wednesday, along with data from the Event Horizon Telescope, may not substantiate Stephen Hawking’s famous theory that radiation, an example of spontaneous emission at the quantum level, is emitted by a black hole.

    The first image of a black hole, Messier 87 Credit Event Horizon Telescope Collaboration, via NSF 4.10.19

    But the news did remind us of a story that physicist and writer Alan Lightman told Nautilus: Richard Feynman came up with the idea for spontaneous emission before Hawking. Here is Lightman in his own words:

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    After a few minutes, Richard Feynman had worked out the process of spontaneous emission, which is what Stephen Hawking became famous for a year later.Wikicommons

    “One day at lunch in the Caltech cafeteria, I was with two graduate students, Bill Press and Saul Teukolsky, and Feynman. Bill and Saul were talking about a calculation they had just done. It was a theoretical calculation, purely mathematical, where they looked at what happens if you shine light on a rotating black hole. If you shine it at the right angle, the light will bounce off the black hole with more energy than it came in with. The classical analogue is a spinning top. If you throw a marble at the top at the right angle, the marble will bounce off the top with more velocity than it came in with. The top slows down and the energy, the increased energy of the marble, comes from the spin of the top. As Bill and Saul were talking, Feynman was listening.

    We got up from the table and began walking back through the campus. Feynman said, ‘You know that process you’ve described? It sounds very much like stimulated emission.’ That’s a quantum process in atomic physics where you have an electron orbiting an atom, and a light particle, a photon, comes in. The two particles are emitted and the electron goes to a lower energy state, so the light is amplified by the electron. The electron decreases energy and gives up that extra energy to sending out two photons. Feynman said, ‘What you’ve just described sounds like stimulated emission. According to Einstein, there’s a well-known relationship between stimulated emission and spontaneous emission.’

    Spontaneous emission is when you have an electron orbiting an atom and it just emits a photon all by itself, without any light coming in, and goes to a lower energy state. Einstein had worked out this relationship between stimulated and spontaneous emission. Whenever you have one, you have the other, at the atomic level. That’s well known to graduate students of physics. Feynman said that what Bill and Saul were describing sounded like simulated emission, and so there should be a spontaneous emission process analogous to it.

    We’d been wandering through the campus. We ended up in my office, a tiny little room, Bill, Saul, me, and Feynman. Feynman went to the blackboard and began working out the equations for spontaneous emission from black holes. Up to this point in history, it had been thought that all black holes were completely black, that a black hole could never emit on its own any kind of energy. But Feynman had postulated, after listening to Bill and Saul talk at lunch, that if a spinning black hole can emit with light coming in, it can also emit energy with nothing coming in, if you take into account quantum mechanics.

    After a few minutes, Feynman had worked out the process of spontaneous emission, which is what Stephen Hawking became famous for a year later. Feynman had it all on my blackboard. He wasn’t interested in copying down what he’d written. He just wanted to know how nature worked, and he had just learned that isolated black holes are capable of emitting energy when you take into account quantum effects. After he finished working it out, he brushed his hands together to get the chalk dust off them, and walked out of the office.

    After Feynman left, Bill and Saul and I were looking at the blackboard. We were thinking it was probably important, not knowing how important. Bill and Saul had to go off to some appointment, and so they left the office. A little bit later, I left. But that night I realized this was a major thing that Feynman had done and I needed to hurry back to my office and copy down the equations. But when I got back to my office in the morning, the cleaning lady had wiped the blackboard clean.”

    See the full article here .

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    Welcome to Nautilus. We are delighted you joined us. We are here to tell you about science and its endless connections to our lives. Each month we choose a single topic. And each Thursday we publish a new chapter on that topic online. Each issue combines the sciences, culture and philosophy into a single story told by the world’s leading thinkers and writers. We follow the story wherever it leads us. Read our essays, investigative reports, and blogs. Fiction, too. Take in our games, videos, and graphic stories. Stop in for a minute, or an hour. Nautilus lets science spill over its usual borders. We are science, connected.

     
  • richardmitnick 12:09 pm on November 25, 2017 Permalink | Reply
    Tags: , , Max Planck, Paul Halpern’s "The Quantum Labyrinth", , Richard Feynman   

    From Ethan Siegel: “Richard Feynman And John Wheeler Revolutionized Time, Reality, And Our Quantum Universe” 

    Ethan Siegel
    Nov 24. 2017

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    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. Our understanding of the quantum Universe continues to evolve over time, and Feynman and Wheeler were two of the players who pushed the needle forward as never before. Image credit: Derek A. Leinweber.

    A new look at the intertwined lives of two of the 20th century’s greatest minds.

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    Paul Halpern’s The Quantum Labyrinth explores the lives and physics contributions of Wheeler and Feynman as never before. Image credit: Basic Books.

    In the years prior to World War II, physics was in an odd, post-revolutionary state. Quantum mechanics and Einstein’s General Relativity had turned our picture of a classical, deterministic Universe upside down. It was replaced with indeterminate states, wavefunctions instead of particles, and a fabric of spacetime that could be bent, distorted, and could even have holes poked in it. Yet there were many open questions that didn’t have sensible answers. Meeting at Princeton in the late 1930s, graduate student Richard Feynman and his young advisor, John Wheeler, would begin a working relationship that would bring forth some of the greatest ideas in modern physics, along with a friendship that would last a lifetime. In his new book, The Quantum Labyrinth, Paul Halpern brings the full story of these men to life in a brilliant way unlike any I’ve ever seen before.

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    A Feynman diagram representing electron-electron scattering, which requires summing over all the possible histories of the particle-particle interactions. The idea that a positron is an electron moving backwards in time grew out of the collaboration between Feynman and Wheeler. Image credit: Dmitri Fedorov.

    Over the course of their respective careers, Feynman and Wheeler brought forth some of the most incredible ideas modern physics has ever seen. Feynman’s contributions to the development of quantum field theory, including his Nobel Prize-winning development of quantum electrodynamics (Q.E.D.) and his intuitive Feynman diagrams, his contributions to teaching, the Manhattan project, gravitational wave physics, the Challenger disaster and much more are not only covered, they’re explained in gloriously in-depth and simultaneously comprehensible fashion.

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    Theoretical calculations predict an event horizon to all black holes, obscuring the central region in accordance with General Relativity. Wheeler not only worked on these ultra-dense objects, he coined the term ‘black hole’ and brought about a renaissance of interest in General Relativity from a non-cosmological perspective. Image credit: Ute Kraus, Physics education group Kraus, Universität Hildesheim; Axel Mellinger (background).

    Wheeler, although less renowned among the general public, brought about contributions to General Relativity, from black holes and parallel Universes to quantum gravity, wormholes, and information theory. While Halpern has a gift for breaking down these complex concepts to make them accessible to a non-specialist, perhaps the most spectacular and unique part of this book is his ability to get inside their minds. Feynman was insecure, conservative in his ideas, careful in his calculations, and skeptical of any notion that was too far afield. Wheeler, to the contrary, was full of wild ideas, from there only being one electron in the Universe to viewing antimatter as normal matter traveling backwards in time to the idea that there were no particles, only information.

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    Richard Feynman and his family with their custom-painted van in Altadena, California. While Wheeler would never present himself publicly like this, when it came to ideas, he was the wild one. Image credit: Symmetry Magazine.

    Yet at their core, these two were practically tailor-made to collaborate with one another. Wheeler’s wild ideas always contained components that were spectacularly wrong and unworkable, but often contained a kernel of deep truth that would pave the road to an understanding that was otherwise unachievable. The idea of a path integral, the essential tool used to calculate physical observables in quantum field theory, came about from Wheeler’s insistence on a sum over histories, but it was Feynman who worked out the details correctly, and applied them properly to our physical Universe.

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    A few terms contributing to the zero-point energy in quantum electrodynamics. The development of this theory, due to Feynman, Schwinger, and Tomonaga, led to a Nobel Prize for all three. Image credit: R. L. Jaffe, from https://arxiv.org/pdf/hep-th/0503158.pdf.

    Feynman’s ability to connect the wild ideas to the physical Universe, never far afield from what could be measured, was the perfect complement to Wheeler’s imagination. Together and separately, they took on gravitation, the quantum nature of reality, and even space and time itself. And as much as any physicist ever did, they not only took these ideas on; they won.

    Their personal lives are also recounted as never before, not even by Feynman himself in his autobiographical writings. On the surface, Feynman and Wheeler couldn’t have been more different. Feynman was outrageous, extroverted, casual, loud, and seemed willing to try absolutely anything, just to know what the experience was like. Wheeler was the opposite: soft-spoken, buttoned-up, and never without a jacket and tie. You never would guess, from their outward appearances, which one would embrace the most wildly outrageous imaginings concerning the Universe, and which one was inextricably bound to measurables and calculable, real-world observables.

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    The idea of parallel Universes, as applied to the Schrödinger’s cat thought experiment. Hugh Everett, a student of Wheeler’s is credited with the invention of the many-worlds interpretation of quantum mechanics, spurred on by Wheeler himself. Image credit: Christian Schirm.

    Yet their shared love of teaching, exploration, possibilities, and taking on new challenges comes through in this intensely personal account of both men’s lives. Throughout the tale, an innumerable set of titans in the field of physics appear, from Hugh Everett (of the many-world interpretation) to Kip Thorne (of black hole and LIGO fame) to Ken Ford (codiscoverer of dark matter in galaxies) to Oppenheimer, DeWitt, Schwinger, Dyson, Dirac, Pauli, Bohr (Wheeler’s mentor), Einstein and many more. Some were elder statesmen; some were contemporaries; some were young, eager students. When you reach the end, you might be shocked to realize how many famous physicists in how many different fields were mentored by Wheeler himself! (All told, Wheeler was the advisor of 46 different PhDs!)

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    By mapping the distance coordinate outside the event horizon, R, with an inverse coordinate inside the event horizon, r = 1/R, you find a unique 1-to-1 mapping of space. However, connecting two distinct locations in either space or time via a wormhole remains a theoretical idea only, one which Wheeler explored at length. Image credit: Wikimedia Commons user Kes47.

    Throughout the book, there are stories that give an insight into each of Feynman and Wheeler’s world views. Both dealt with significant loss and grief early on: Feynman losing his first wife, Arline, and Wheeler losing his brother, Joe, in World War II. Both struggled with their losses throughout the rest of their lives, with it affecting their work and personal life decisions for decades thereafter. In the world of physics, both were the equivalent of rock stars; in their personal lives, both faced the same struggles common to much of humanity. Feynman died relatively young after a decade-long battle with cancer; Wheeler lived almost to 100. But both remained active in physics and problem-solving until the very end of their lives. In fact, Feynman commented that although Wheeler appears as a crazy old man now, you must realize that he’s always been crazy.

    Halpern’s writing style is incredibly approachable. The book is filled with countless anecdotes that tell of moments and events in their lives and those whose lives they touched, and it paints a wholly human portrait of each. Halpern never passes judgment on the actions of either one, instead portraying them as generously as possible, reminding us of their struggles in their personal lives. He doesn’t excuse Feynman’s decades of womanizing or Wheeler’s extensive weapons development work, but rather puts them in the context of the rest of their lives. He leaves it for the reader to judge. Paul’s use of a gentle hand in a world where heavy-handed judgments are the norm is so refreshing that it comes as a welcome surprise.

    If you’re a fan of physics, history, and the development of quantum physics and astrophysics, you’ll definitely want a copy of The Quantum Labyrinth: How Richard Feynman and John Wheeler Revolutionized Time and Reality. Paul Halpern’s well-researched, well-written, and highly accessible explainer on these two physicists, their work, their lives, and their impact on the world around them is unique, and a must-have for science aficionados (or junkies) anywhere. If you’ve know of someone like that in your life, you’ll be hard-pressed to find a better present for the upcoming holiday season!

    See the full article here .

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    “Starts With A Bang! is a blog/video blog about cosmology, physics, astronomy, and anything else I find interesting enough to write about. I am a firm believer that the highest good in life is learning, and the greatest evil is willful ignorance. The goal of everything on this site is to help inform you about our world, how we came to be here, and to understand how it all works. As I write these pages for you, I hope to not only explain to you what we know, think, and believe, but how we know it, and why we draw the conclusions we do. It is my hope that you find this interesting, informative, and accessible,” says Ethan

     
  • richardmitnick 8:24 am on October 9, 2017 Permalink | Reply
    Tags: Evernote, Identify the subject - Teach it to a child. If you can teach a concept to a child, If Einstein created the ‘beautiful equation’ then Feynman brought an unparalleled sense of beauty and romanticism previously absent in the world of scientific research, Learning From the Feynman Technique, Richard Feynman, They called Feynman the “Great Explainer.”, you’re way ahead of the game   

    From Evernote: “Learning From the Feynman Technique” 

    1

    Evernote

    1
    Posted by Taylor Pipes on 21 Jul 2017

    They called Feynman the “Great Explainer.”

    Richard Feynman (1918-1988), an author, graphic novel hero, intellectual, philosopher, physicist, and No Ordinary Genius is considered to be one of the most important physicists of all time.

    He pioneered an entire field: quantum electrodynamics (QED).
    In the 1940s, his invention of the Feynman Diagram helped bring much-needed visual clarification to the enigmatic behavior of subatomic particles.
    His work helping scientists understand the interaction of light and matter earned him a share of a Nobel Prize in 1965.
    His work has directly influenced the fields of nanotechnology, quantum computing, and particle physics.
    In 1986, his research and explanations were critical in helping to understand the cause of the space shuttle Challenger disaster.

    In addition to his groundbreaking research, Feynman was brilliant, eloquent, and an exquisitely passionate thinker. In the world of science, he stands unequivocally for his ability to synthesize and explain complex scientific knowledge. His lectures are the stuff of legend —Albert Einstein attended Feynman’s first talk as a graduate student, and Bill Gates was so inspired by his pedagogy that he called Feynman, “the greatest teacher I never had.” Gates purchased the rights to his lectures and made them publicly available on a video portal nicknamed “Tuva” in honor of Feynman’s famous failed quest to reach the Russian region later in his life.

    “I do think that making science cool to people when they’re young and therefore getting more people to go into it in an in-depth way, I think that’s very important right now,” Gates said, when announcing the purchase.

    Feynman’s lectures, many of which were delivered during his time at California Institute of Technology, were aimed at students who had no previous knowledge of particle physics or deep science. Taking the mystery out of complex scientific principles was Feynman’s forte. His lectures were underscored by a conviction and passion for science.

    If Einstein created the ‘beautiful equation,’ then Feynman brought an unparalleled sense of beauty and romanticism previously absent in the world of scientific research. A vast majority of Feynman’s life was as vividly eccentric and illustrious as the unpredictable movements of the atomic particles that defined his life’s work. When he wasn’t in the throes of researching particle physics, he spent significant time dabbling in the arts, sketching, and even playing the bongo.
    The Feynman Technique

    Have you ever had a coworker who used business-speak, or had a teacher explain something with language that was difficult to understand?

    You’re not alone. The Feynman technique for teaching and communication is a mental model (a breakdown of his personal thought process) to convey information using concise thoughts and simple language. This technique is derived from Feynman’s studying methods when he was a student at Princeton.

    At Princeton, Feynman started to record and connect the things he did know with those he did not. In the end, Feynman had a comprehensive notebook of subjects that had been disassembled, translated, and recorded.

    In James Gleick’s biography of Feynman, Genius: The Life and Science of Richard Feynman, he recalled his subject’s technique. “He opened a fresh notebook. On the title page he wrote: NOTEBOOK OF THINGS I DON’T KNOW ABOUT. For the first but not last time he reorganized his knowledge. He worked for weeks at disassembling each branch of physics, oiling the parts, and putting them back together, looking all the while for the raw edges and inconsistencies. He tried to find the essential kernels of each subject,” Gleick wrote.

    You can use this model to quickly learn new concepts, shore up knowledge gaps you have (known as targeted learning), recall ideas you don’t want to forget, or to study more efficiently. Taking that concept further, you can use this technique to grapple with tough subject matter, which is one of the great barriers to learning.

    Feynman’s technique is also useful for those who find writing a challenge. Feynman had an interesting relationship with writing. Instead of committing his knowledge to paper like many other scientific figures, he chose to use speech as the foundation for many of his published works. He dictated most of his books and memoirs, and his scientific papers were transcribed from his lectures.

    “In order to talk to each other, we have to have words, and that’s all right. It’s a good idea to try to see the difference, and it’s a good idea to know when we are teaching the tools of science, such as words, and when we are teaching science itself,” Feynman said.

    Feynman relied heavily on verbal and spoken communication, and when he turned to his cartoonish diagrams of highly scientific principles, for example, he could tap into ideas with shapes, squiggly lines, and drawings. It stripped away clunky language and allowed the power of verbal storytelling to take root.

    Explaining the essentials of particle physics is extremely difficult. Before Feynman’s diagrams that earned him a Nobel Prize, there wasn’t a clear way to explain their meaning.

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    Attribution for Feynman diagram: By JabberWok at the English language Wikipedia, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=1601027
    This is the first-ever published diagram by Feynman helped scientists track particle movements in illustrations and visual equations rather than verbose explanations. What seemed almost improbable at the time is now one of the greatest explanations of particle physics — the squiggly lines, diagrams, arrows, quarks, and cartoonish figures are now the established nomenclature and visual story that students, scientists, and readers will see when they learn about this field of science.

    Essentially, the Feynman Technique is this:

    Identify the subject

    Write down everything you know about the topic. Each time you run into new sources of information, add them to the note.

    Teach it to a child

    If you can teach a concept to a child, you’re way ahead of the game.

    Start with a blank note and write the topic or subject you want to teach. Then, below that topic, write everything you know about it. But, the trick is to write it plainly and simply —so that a child can understand what you’re talking about.

    Doing this takes into consideration a few things:

    Speaking in plain terms: Children don’t understand jargon or a lexicon of dense vocabulary. Science is full of complex terminology, which is the reason Feynman’s diagrams became so valuable. His charts illustrated things that other scientists delivered marathon lectures about.

    When we speak without jargon, it frees us from hiding behind knowledge we don’t have. Big words and fluffy “business speak” cripples us from getting to the point and passing knowledge to others.

    Brevity: The attention span of a child requires you to deliver concepts as if you were pitching a business idea during one short elevator ride. You better get the concept out before those doors open. Children also don’t have the ability — or mental capacity, to understand anything longer than that.

    If you had difficulty putting thoughts into your note, that shows you have room to improve. This is also where the power of creativity can help you reach new heights in learning.

    For Feynman, much of the pleasure in science was in this first step —unraveling his levels of understanding.

    Identify your knowledge gaps

    This is the point where the real learning happens. What are you missing? What don’t you know?

    Highlighting knowledge gaps will help you when you collect and organize your notes into a cohesive story (which is the next step.) Now you can call upon your source material (lecture notes, ideas, etc.) when you run into questions about how much you do know about your topic.

    If you don’t know something, hit the books. Go back to the source material and compile information that will help you fill in the cracks.

    Organize + simplify + Tell a story

    Start to tell your story. Piece together your notes and begin to spin a tale using concise explanations. Bring the most vital pieces of your knowledge about the topic together.

    Practice reading your story out loud. Pretend to tell the story to a classroom of students. That way, you’ll hear where language stops being simple. Stumbles could indicate incomplete thoughts.

    Use analogies and simple sentences to strengthen your understanding of the story.

    This sentence, written by Feynman, encapsulates the power of this technique. What started as a question about our existence has been translated into a single sentence that can be understood by a middle school student.

    “All things are made of atoms—little particles that move around in perpetual motion, attracting each other when they are a little distance apart, but repelling upon being squeezed into one another.”

    Basically, Feynman says that if you know nothing about physics, the most essential scientific knowledge to understand is that everything is made up of atoms. In one simple sentence, Feynman conveys the foundational existence of our universe. It’s a master class not just for scientists, but for writers of any stripe. Get to the hypothesis in as few words as possible. Avoid clunky, verbose language.

    Drawing on passions

    Feynman was a believer in a multi-disciplinary approach to learning and found connections to his work in creative outlets like drawing and music. He never stopped asking questions—who, what, and why?

    Einstein had his violin. Werner Heisenberg played the piano. Richard Feynman had bongos. And a passion for art. He was able to eloquently communicate, but he could also see the beauty in art, and the stories that art tells. It was as much a distraction as much as it was an unending source of inspiration he could connect to his work in particle physics.

    “I wanted very much to learn to draw, for a reason that I kept to myself: I wanted to convey an emotion I have about the beauty of the world. It’s difficult to describe because it’s an emotion. … It’s a feeling of awe — of scientific awe — which I felt could be communicated through a drawing to someone who had also had that emotion. I could remind him, for a moment, of this feeling about the glories of the universe.” — Feynman discussing the intersection of art and science.”

    Making things stick forever

    The next time you stare at an empty notebook page, think about turning that page into an opportunity.

    As Feynman illustrates in his mental model, learning can be a lifelong pursuit. This technique is designed to help you study for exams and learn new subjects, but it can be easily adapted to pursue deep work. Dedicating a notebook to a place where your knowledge can grow and evolve your ideas and provide inspiration to continue following a path of ongoing learning critical to the fundamentals of deeper, meaningful work.

    Today, researchers are still parsing through Thomas Edison’s notebooks and are constantly learning about how he cataloged his ideas and innovations. For Feynman, after he was done cataloging his knowledge with his technique, he had a comprehensive record of his knowledge that became a notebook he was incredibly proud of.

    Armed with the Feynman technique and Evernote, anything is possible. How could you use this technique in your work? Share your story in the comments.

    See the full article here.

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