# Feynman Definition and 25 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. ### I Six not so easy pieces (Richard Feynman)

In section 3.8, Feynman does a derivation of the Lorentz transformation for mass starting from $$\frac{d}{dt}E=F \cdot v \hspace{1cm}(1)$$ But is this a valid starting point if you are going to show mass changes with velocity? He says (1) comes from chapter 13 of his Lectures which he...
2. ### I Why is the speed of photons different?

Hi, I read the Feynman's book about the quantum electrodynamics and I realized, that he was talking about the different speed of photons. I know, that the light travel's "slower" in a material, but he is also talking about the different speed of photons. I read on the web, that some photons...
3. ### B What happens to the uncertainty principle if....

I just read the Feynman Lectures about the electron gun experiment with two holes in the middle wall. It demonstrates that if we don't look at the electrons while they travel toward the detector there is an interference pattern in the probability curve of the electrons similarly to what happens...
4. ### Intro Physics Feynman Lectures on Physics Photos posted online

Hello, Everyone. I'm happy to announce that the entire collection of (3043) photos taken of Richard Feynman giving his famous 1961-64 introductory physics lectures at Caltech (including his blackboards - original source material for the book, The Feynman Lectures on Physics [FLP]) have been...
5. ### A Does Feynman's path integral ignore alternative histories?

Summary: Does Richard Feynman's multiple histories ignore alternative histories? Did Richard Feynman's multiple histories (https://en.wikipedia.org/wiki/Multiple_histories) ignore the existence of other alternarive histories or paths? I ask this referring to this comment from this page...
6. ### Intro Physics Feynman's Notes for The Feynman Lectures on Physics

611 pages of notes Richard Feynman made in 1961-64 to plan and prepare lectures for Caltech's two-year introductory physics course, later known as The Feynman Lectures on Physics, have been posted in deep-zoomable format at The Feynman Lecture Website. Photos of Feynman giving his...
7. ### Intro Physics Suggested outline/syllabus for Feynman lectures?

I just finished the intro physics sequence at my college, and I wanted to work through the Feyman lecture Vol.1, with the workbook, over the summer. Does anyone know of any sample curriculum used for this book? Or perhaps, knows a good way to work through the book?
8. ### I Exploring Feynman's Theory on Reflection of Light from Glass Surfaces

I recently started reading Feynmans book QED. There are a couple of questions I have regarding his theory on the percentage of light that is reflected of two surfaces of glass. My question is as follows, A piece of glass in fact has four surfaces. The front of the glass the back side of...
9. ### How to prove that electric field propagates like a wave?

I was studying Feynman Lectures on Physics Volume 1 chapter 29. In there he proves that electric field propagates like a wave. Here is my attempt (in image), please tell me my mistake. Thank you
10. ### Compare and contrast Bohr and Feynman?

While doing research on Feynman and Bohr, I came across how Bohr never warmed up to Feynman even though he frequently sought him out for discussions in Los Alamos - which lead me to this question. Reasons were given for why he may not have, but that still leaves me wondering if there was...
11. ### Mechanics II: Feynman Paradox

I am currently going through a friend's Mechanics II notes and homework before I take the course at a different university next semester. I have a few problems that I am having trouble understanding and am posting here for help. 1. Homework Statement 1. A solenoid is on, Flux is Φ. 2. The...
12. ### B The Conscious Observer

How exactly does the mere act of observing collapse the wave function of, say, photons? I don't quite understand that one. And Richard Feynman's question related to Young's double slit experiment and the fact the electron went through both slits, as well as neither, and just one slit, and just...
13. ### I Feynman's Thesis, 3 Principles

Hi, I've just started studying Feynman's thesis and am in need of some discussion regarding the three principles he put forward on the development of his 'Principle of least action in quantum mechanics'. The three principles are 1) The acceleration of a point charge is due to the sum of its...
14. A

### Calculus Feynman's High School Calculus Book

Hi everybody. I enjoy looking at other people's handwritten notebooks, as well as what textbooks they learned math and physics from. This evening I came across this article about how Feynman learned calculus in high school by studying Calculus for the Practical Man by Thompson. He kept very...
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### Intro Physics Why are the Feynman lectures not good for beginners?

Is it because it is more rigorous than books like Halliday and Resnick? Or maybe you need to digest those books as a prerequisite for the feynman lectures? Or maybe people don't believe a regular person could digest the feynman lectures as a introductory level physics book? If someone is a...
16. ### Feynman explanation of gravitational energy

Hello! I hope this is the proper forum for my question(s). English is not my native language, so I apologize in advance for language mistakes. In Feynman Lectures on Physics, there is a chapter about the conservation of energy. The first part, which deals with the definition of energy, I...
17. ### If Feynman was a Geologist by Jun Cowan

I have found this article on the net, which is fun to read. At least to all who are interested in Feynman's habits and attitudes. In the end it is about the "current state of geology", but it can be read as a reminder on how to do science in general...
18. ### The principle of least Action proof of minimum

Homework Statement Reading Feynman The Principle of Least Action out of The Feynman Lectures on Physics, Vol 2. Link to text http://www.feynmanlectures.caltech.edu/II_19.html So I'm having a problem proving that, section 19-2 5th paragraf, that "Now the mean square of something that deviates...
19. ### Intro Physics The Final Verdict on the Feynman Lectures?

Hello guys. I've seen a lot of differing opinions on this site. I'm a middle schooler with a decent understanding of basic calculus, trig, and algebra. I want to learn physics, and am wondering if The Feynman Lectures supplemented with problems from Irodov and some of Walter Lewin's lectures...
20. ### Feynman & Tidal Forces

I used to think I understood this - big mistake! I've just watched a great classic Feynman lecture posted by another PF user (a superb way to spend 50 mins of you can spare the time) https://www.physicsforums.com/threads/i-found-the-best-teacher-of-physics.855335/ In that lecture, Feynman...
21. ### How to prepare for the Calculus BC and Physics C Exam?

Firstly, let me talk about my BC exam situation first and then the Physics C exam secondly. I just recently downloaded a PDF full of released BC exams from 1969 to 1998. Is there any PDF for a fully released BC exam from last year(2015)? What is the best textbook that is oriented towards this...
22. ### Antiparticles are regular particles going backward in time?

First I would like to say that I'm sorry if this question has been asked before- I'm new here. I was reading QED by Richard Feynman, and he mentioned that any given antiparticle is just it's regular particle counterpart moving backwards in time. How is this possible? I thought that it was only...
23. ### Zero cross section

Homework Statement I am making an old exam of a particle physics course, and i know how to calculate the cross section for example for bhabha or moller scattering. now one of the questions on the old exam is: Explain why e-+ e+ -> γ is zero, but i am not sure why this is, can someone explain...
24. ### How can I show that the amplitude of a reflected wave?

In Feynman Lectures on Physics (you can find it online), chapter 33 of volume 1, the author derives Fresnel's formulas for the coefficient of reflection in an unusual way by making considerations about the different possible polarization of light. In this way he derives the squares of the...
25. ### Action corresponding to photon emission

Hi I am trying to write the probability of photon emission due to transition of electron in feynman's path integral formulation. I am stuck trying to figure out the action corresponding to the photon emission. Would anyone shed some light on this? Thanks