Richard Feynman Lecture on Quantum Electrodynamics: QED. 6/8

Part 7:http://www.youtube.com/watch?v=dydiSZejrzA
Richard Feynman gives us a lecture on Quantum electrodynamcis, the theory of photons and electron interactions which incorporates his unique view of the fundamental processes that create it. one of the 3 winners of the 1965 Nobel prize in Physics for his work, Feynman is was an expert on quantum mechanics and developed the Path Integral formulation of Relativistic Quantum mechanics, used in Quantum Field Theory, interpreted the Born series of scattering amplitudes as vertices and Green's function propagators in his famous diagrams, the Feynman Diagrams, and also worked on the fundamental excitations in Liquid Helium leading to a correct model describing superfluidity using phonons, maxons and rotons to describe the various excitation curves.
other fields of work include the Feynman-Hellmann Theorem, which can relate the derivative of the total energy of any system to the expectation value of the derivative of the Hamiltonian under a single parameter, e.g volume.
he also worked on the Rogers Commission report during the investigation of the 1986 Space Shuttle Challenger disaster, where Feynman famously demonstrated how the Booster Rocket O-rings, which are elastic sealing joints, became less resilient and subject to seal failures at ice-cold temperatures by immersing a sample of the material in a glass of ice water- his high intelligence and independant way of looking at the world often made him "a real pain" in the eyes of other, less skilled, Commission members.
Feynman's own investigation reveals a disconnect between NASA's engineers and executives that was far more striking than he expected. His interviews of NASA's high-ranking managers revealed startling misunderstandings of elementary concepts, such as safety proceedures.
Although Feynman got plenty of media coverage due to him being on the Commission, he was often told to stay quiet about NASA's more sinister secrets and tactics in space exploration.

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• Feynman
• Quantum
• electrodynamics
• Field
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• photons
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• lectures
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[myrtlebox]

4:56

Makes me happy that even the great Feynman has to stop and think occasionally. He doesn't want to commit the time-honored factor of 2 error ;-)

[MuonRay]

@myrtlebox This is similar to a Fresnel Zone problem. As the axis of the aperture moves towards the aperture, the light field at the axis alternates between darkness & light. This is due to the interference between light travelling from different regions of the aperture (in this case circular) being either destructive or constructive due to the number of zones on the axis, where light is π radians (lambda/2) out of phase. even number=destructive interference,odd number=constructive interference.

[prasoonpandey2000]

hey guys!why only 12 likes??

just see any Feynman video & press like.that's the way to do it

[willzer808]

I love this guy. He's the first scientist i've seen whose manner is not that of a scientist. He is more rock and roll than science. Not that science isn't rock and roll. Oh Jesus. Anyway, legendary

[ienjoyapples]

im not going out tonight. this is gonna be my friday night.

[anand308]

Despite the fact that Feynman says terms for things aren't as important as their meaning, he's still has a remarkable way of using language to stimulate the imagination

[CamiloSanchez1979]

I love how energetic he is to explain it

[myrtlebox]

@MuonRay Muon! Thanks so much for uploading. Yes, I know the theory. I've read his book QED perhaps a dozen times. I was just laughing at his momentary concern whether it was lambda or (lambda/2) for the dark/light fringes.

I actually had the chance to meet and talk with him briefly in 1979. I was applying to Caltech, but eventually went to Berkeley.

[nikanj]

I wish I were alive to see him lecture in person.