What is Feynman: Definition and 646 Discussions

Richard Phillips Feynman (; May 11, 1918 – February 15, 1988) was an American theoretical physicist, known for his work in the path integral formulation of quantum mechanics, the theory of quantum electrodynamics, the physics of the superfluidity of supercooled liquid helium, as well as his work in particle physics for which he proposed the parton model. For contributions to the development of quantum electrodynamics, Feynman received the Nobel Prize in Physics in 1965 jointly with Julian Schwinger and Shin'ichirō Tomonaga.
Feynman developed a widely used pictorial representation scheme for the mathematical expressions describing the behavior of subatomic particles, which later became known as Feynman diagrams. During his lifetime, Feynman became one of the best-known scientists in the world. In a 1999 poll of 130 leading physicists worldwide by the British journal Physics World, he was ranked the seventh greatest physicist of all time.He assisted in the development of the atomic bomb during World War II and became known to a wide public in the 1980s as a member of the Rogers Commission, the panel that investigated the Space Shuttle Challenger disaster. Along with his work in theoretical physics, Feynman has been credited with pioneering the field of quantum computing and introducing the concept of nanotechnology. He held the Richard C. Tolman professorship in theoretical physics at the California Institute of Technology.
Feynman was a keen popularizer of physics through both books and lectures, including a 1959 talk on top-down nanotechnology called There's Plenty of Room at the Bottom and the three-volume publication of his undergraduate lectures, The Feynman Lectures on Physics. Feynman also became known through his semi-autobiographical books Surely You're Joking, Mr. Feynman! and What Do You Care What Other People Think?, and books written about him such as Tuva or Bust! by Ralph Leighton and the biography Genius: The Life and Science of Richard Feynman by James Gleick.

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  1. D

    How Does the Higgs Field Affect Particle Speeds in Feynman Diagrams?

    I need help - Higgs for idiots: So, how a particle which have no mass without higgs (so it travels at c, and on feynman diagram we would draw its worldline at 45deg) can slow down or even be at rest when Higgs is switched on? Could anyone draw a feynman diagram?
  2. S

    Discussion on Feynman lecture - E / B Field

    Greetings, In Feynman's lectures - vol. 2 either chap 19, 21 or 23 - I think 23 (I'm at work and don't have the lectures here), Feynman shows in a capacitor that a changing E-Field induces a B-field, then he shows that the B-field induces a new E-Field (he calculates the E-field) and then...
  3. G

    Please point me to more info about these Feynman statements

    I'm watching a youtube video () of an interview with Feynman. He says, "...there are a number of paradoxes with this quark picture...we've done some experiments at very high energy, hitting a proton with an electron...that can only be interpreted by supposing that the number of particles inside...
  4. J

    Feynman QED, Permanent Magnets, and Virtual Photons

    I'm not making any statements here, only asking questions. When I take two permanent magnets and I feel the repulsive force between them, Feynman QED says it is the momentum of the virtual photons "pushing" the magnets apart? Experiments have been done, forcing some of these virtual...
  5. Hepth

    Feynman Diagram Question, Antiparticle

    Lets say we have a process where: Particle B(P) -> v(p2) + k some particle effectively goes to an antifermion and a photon, with momentums P, p2, and k. And the diagram is just straightforward, in arrow to vertex, out photon and out antifermion from vertex. Now the arrow on the...
  6. R

    Question on irreducible versus reducible Feynman graphs

    Consider the functional: (1) \mbox{ }e^{iW[J]} = \int d \hat{\phi} \mbox{ }e^{i\int d^4x \mbox{ } \mathcal L(\hat{\phi})+J\hat{\phi}} Define a Legendre transformation to get a functional in \phi(x) instead of J(x): (2) \mbox{ }\Gamma[\phi]=W[J(\phi)]- \int d^4x \mbox{ } J(\phi) \phi...
  7. Oddbio

    Most popular (best?) Feynman lectures.

    I hear a lot about "the feynman lectures", but is there any set of lectures that most people have in mind when they hear "the Feynman Lectures"? Or does that phrase really not point to a specific set of really good/popular lectures? I'm trying to find some to watch, but it seems like there...
  8. D

    What would Richard Feynman say about Global warming?

    I wonder... Would it be something like that?
  9. G

    Feynman Lectures Audio - Find Where to Listen

    Hi, Does anyone know where I can find the audio version of the "Feynman Lectures"?? I know not all of them are taped, but most are, I can't seem to find them anywhere. Help! Thanks.
  10. nomadreid

    Links between Everett, Feynman, Kripke?

    As I state my questions, there are likely to be errors that I would appreciate being corrected. Beyond that, however, if the gist of the questions can be salvaged after correcting these errors, I would also like answers to your version of the questions. Both Feynman's summation over histories...
  11. R

    Feynman Looking for A Particle Version of QFT

    Feynman Looking for A "Particle Version" of QFT Hey, I think I read somewhere (though can't find it now) that Feynman was looking for a 'particle' version of quantum field theory which he didn't find but this instead led to the path integral approach of quantum mechanics. Can anyone shed any...
  12. B

    Feynman diagrams - neutrino interactions

    I have some well ordered feyman diagrams which have an incoming neutrino interacting at a vertex with a w boson and emitting an electron. since a neutrino can pass through some 18 light years of led without interacting, I'm wandering how a single neutrino interacts at this vertex?
  13. P

    Wick's Theorm to Feynman Diagrams?

    Is this right? To calculate a scattering amplitude for a certain scattering event, you take the term in the wick's expansion of the S-Matrix that suits your situation best. Then you draw a Feynman Diagram that corresponds to the term in the wick's expansion, then just use the Feynman Rules to...
  14. B

    Carl Sagan and Richard Feynman Singing a Song

    https://www.youtube.com/watch?v=http://www.youtube.com/watch?v=QMRGYkfzgs0
  15. L

    Original Audio recordings of Surely You're Joking Mr. Feynman

    I've been in a very history of physics mood lately and have been rediscovering Feynman. I was watching the Nova special from after his death and SJMF was typed out from audiotapes of Feynman telling the stories. Does anyone know if there is anyway to get a hand on the original version as read by...
  16. nicksauce

    Proving Feynman Slash Identity: 2a\cdot b

    Homework Statement I am trying to prove that \displaystyle{\not} a \displaystyle{\not} b + \displaystyle{\not} b \displaystyle{\not} a = 2a\cdot b using the relation \{\gamma^{\mu},\gamma^{\nu}\} = 2g^{\mu\nu} Homework Equations The Attempt at a Solution If I work backwards...
  17. D

    Calc Feynman Amp Q: Chi+ Chi- -> Chi+ Chi-

    I'm having a problem calculating the Feynman amplitude for the scalar scattering process \chi^+ \chi^- \to \chi^+ \chi^- for an interaction Lagrangian which is: \mathcal{L} = - g \chi^\dagger \chi \Phi - \frac{\lambda}{4} (\chi^\dagger \chi)^2 So far I have the 2 Feynman Diagrams for...
  18. O

    Feynman rules for scalar qed

    Homework Statement Hello all, thanks for reading... I was assigned to calculate feynman rules for the scalar QED theory via functional methods. The fields are a scalar complex field \phi, \phi^* and gauge field A_\mu, and the lagrangean is \mathfrak{L} = (D_\mu \phi)^* (D^\mu \phi) - m^2...
  19. W

    Have you experienced the enlightening Feynman Lectures on Physics?

    Has anyone read the Feynman Lectures of Physics*? I've heard about them and they seem pretty nice. I'm thinking of looking into them but wanted some feedback from someone who has already read them. I already know some of the basics and so I mainly wanted these to better my understanding of...
  20. B

    Short question: Spontaneous emission from Feynman diagrams?

    Hey all, I am just wondering if one can directly calculate the Einstein coefficient in spontaneous emission of, say, two-level atoms through feynman diagrams? I searched for sources in google but could not find anything. Thanks a lot for an answer! Wit best regards, blue2script
  21. W

    When Feynman describes scatterers

    I was reading the Feynman lectures, on the parts that deal with optics, and he explains diffraction in a very interesting way. He imagines a diffraction grating to be made up of a long line of infinitesimal dipole oscillators, all oscillating in phase. What I don't understand is, in which...
  22. C

    Did Feynman Smoke Cigarettes? - Answers Here

    Not looking for much of a discussion, just a simple answer. Did Feynman smoke cigarettes?
  23. D

    Feynman diagram: incoming and outgoing particles

    I always wanted to ask (but was afraid to) about the borders on the famous Feynman diagrams. As I understand, Feynman diagrams have the same age as Copenhagen Interpretation. So at that time it looked very logical: quantum behavior inside, but classical world outside. Outgoing particles are the...
  24. S

    About Feynman rules for an external field

    Hi everybody, I'm new. I'm approaching to QFT in these months and I have a couple of questions about Feynman rules. The most of the books I have read (or tried to) explain feynman rules telling what you have to do when you have an internal or external line in a graph, and when you have a...
  25. robphy

    Feynman Messenger Lectures (via Microsoft)

    http://research.microsoft.com/apps/tools/tuva/index.html" has a transcript, timeline, and other interesting features. (Silverlight required.) I learned this from Slashdot: http://science.slashdot.org/story/09/07/15/1635245/Bill-Gates-Puts-Classic-Feynman-Lectures-Online?art_pos=4"
  26. D

    Divergent tree level Feynman diagrams?

    Hi everybody! I'm a new Physics Forums user and hope someone could help me out with my minor dilemma. I'm a PhD student in mathematical/theoretical physics and I' working on the Boltzmann equation in QFT. Up to now, there was no major emphasis on Feynamn diagrams - the approach was rather more...
  27. W

    How good Feynman Lectures are ?

    how good Feynman Lectures are ? and if learn basic physics what mathematical physics book should i learn to learn core course physics ? Is Mathematical methods for physicists good enough ?
  28. W

    Learning Physics Basics: Feynman vs Serway

    Is Feynman lectures on physics suitable for beginning physics (learn basics of physics) OR physics for scientists and engineers (Serway) ? i want to learn basics most powerful thx
  29. M

    Feynman diagram for sigma+ -> n + pi+

    Homework Statement Hello, I am trying to draw a Feynman Diagram at quark level for the decay sigma+ -> neutron + pi+.Homework Equations sigma+ -> neutron + pi+ uus -> udd + udbarThe Attempt at a Solution Well, the attachment is what I came up with. I have no idea if it's right to be honest...
  30. thrill3rnit3

    Halliday physics vs. Feynman lectures

    which is the better series one can learn physics from? I've personally read feynman's but I haven't tried halliday's.
  31. W

    So where can I get The Feynman lectures ?

    My library only had the first volume, I would love to read them all. Is it worth to buy them?. Its just that the shipping will be quite expensive to my country.
  32. Spinnor

    Let us assume Feynman was wrong.

    After summing up the rudiments of quantum mechanics Feynman tries to answer a question that readers might have at this point of his book, The Feynman Lectures on Physics, Vol. III, page 1-10.1. He writes, "One might still like to ask: "How does it work? What is the machinery behind the law?"...
  33. W

    Feynman on visualizaing the electromagnetic field

    There was a question several days ago related to visualizing the electro-magnetic field. I reminded me of a great passage from the Feynman Lectures on Physics. I won't quote the whole thing, but it is in section 20-3, "Scientific Imagination" (unfortunately I don't think the lectures are...
  34. I

    Alternative Feynman Diagram Calculation of Axial Anomaly

    Homework Statement I'm working my way through Quantum Field Theory in a Nutshell by A. Zee. I'm religiously doing the exercises but since I'm doing it on my own (I'm not in school) I have no one to ask when I get stuck. Any hints would be appreciated. The problem is IV.7.5, on page 253 of...
  35. K

    Gluon radiation Feynman diagram

    can someone please explain the attached picture to me? if the electron and positron are just annihilating each other shouldn't the positron be going the other way? and shouldn't the antiquark be going the other way too? and what's up w/ the ->t thing at the bottom?
  36. malawi_glenn

    Exponent of disconnected Feynman diagrams

    hello, I am trying to follow the arguments in Peskin pages 96-97 where the exponentiation of disconnected diagrams are performed. I think the 'proof' is too 'not detailed' and was wondering if there exists a better explanation elsewhere? My biggest question is the sentence on page 97 "The sum...
  37. S

    Feynman rules & diagram for phi^3 theory

    I'm reading a course in Introduction to QFT and I'm stuck at a problem. I'm hoping someone here could point me in the right direction or say if my assumptions are incorrect. Homework Statement Derive the Feynman rules and all diagrams at tree-level for \lambda \phi^3 theory using Wick's...
  38. C

    Feynman diagram interpretation - 2 electrons in and 2 electrons out

    Homework Statement Hello :smile: The question is from "Advanced Physics" by Adams and Allday. It is from section 9 "The Physics of Particles", "Practice Exam Questions". It is question 11, part c. The level of this study is between school and University. Figure 9.5 represents a simple...
  39. T

    What are some recommended Feynman diagram calculators?

    Can anyone recommend a good Feynman diagram calculator ?
  40. K

    What are the key concepts in Srednicki's explanation of Feynman diagrams in QFT?

    I'm trying to learn Feynman diagrams from Srednicki's QFT book! Could someone retell and summarize in his or her own words what Srednicki is saying in the three paragraphs after equation 9.11? (I don't understand what the (2P)!/(2P-3V)! different combinations are, how Feynman diagrams are...
  41. W

    Feynman rules for vector bosons

    I'm learning QFT by reading Lewis Ryder's book, so my question in short is: how he arrives at Eq 7.57 and Eq 7.58? If you don't have the book, the question is: why are there Minkowski metric terms in the Feynman rules for a gauge field coupling to itself? If the answer is complicated, simply...
  42. I

    How to study the Feynman lectures?

    I got my final pick of books as extra readings/studying to supplement my rather deficient Physics C class. It's the Feynman lectures on Physics and Irodov problem book (and when my calculus is ready, I'll tackle Introduction to Mechanics by Kleppner and Kolenkow) How do you think should I...
  43. A

    Evaluating Feynman diagram in QFT without external fermion lines

    ...like in Photon-Photon-scattering. I know this doesn't make sense physically but the value for the diagram should still be computeable. If I want to put the expression for the matrix element together, I get a matrix, but it should be a scalar, right? Since the spinor bi-product is missing...
  44. I

    [QFT] Feynman rules for self-interacting scalar field with source terms

    I'm not sure if this is the right place to post a graduate level course material, but I have a question about perturbative expansion of the 2n-point function of a scalar field theory. Homework Statement First, the question: In which space (position or momentum) is the topological distinctness...
  45. G01

    Have You Seen Richard Feynman Playing the Bongos?

    A friend introduced me to this very strange, very funny video of Richard Feynman. Has anyone seen it? What a guy...:rofl:
  46. I

    Drawing the Feynman Diagram for e⁻ + p → n + νe

    Homework Statement Draw the Feynman diagram for: e^{-} + p \rightarrow n + \upsilon_{e} Sorry, I don't know how to make everything even but you should get the gist. Homework Equations The Attempt at a Solution Well, what I have is the electron and proton annihilating(and this...
  47. D

    Particle - Feynman Diagram

    Homework Statement Q) Neutral pion decays into 2 photons which then decay into electron-positron pairs. What would the feynman diagram look like? :confused:
  48. S

    Finding a Criterion for Allowed Reactions in ABC Toy Theory

    Homework Statement In an ABC toy theory, the only allowed vertex is one that couples A, B and C. Thus there are no AAA, ABB, ACC...ect vertices allowed. My question is suppose a diagram has na external A lines, nb external B lines, and nc external C lines. Develop a simple criterion for...
  49. CarlB

    PI talk on Feynman Checkerboard Model and the wave function

    The Perimeter Institute has a talk on the Feynman chessboard / checkerboard model scheduled for a few days from now. This will be recorded and you can play it back, sometime after November 18th. Links: Speaker(s): Garnet Ord - Ryerson University Ord's website...
  50. J

    Symmetry factors for Feynman diagrams

    Hello I have to calculate symmetry factors for the following feynman diagrams for my qft class, and would be hugely grateful if anyone could point out any mistakes (I'm sure there are lots!) that I've made. http://picasaweb.google.com/jessicagreerstanley/Physics#5259179071440262450"...
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