QED
Using everyday language, spatial concepts, visualizations and his renowned "Feynman diagrams," the author clearly and humorously communicates the substance and spirit of QED (quantum electodynamics).
Stats for nerds
60recommend
118mentions
77people
2008–2026years
74% recommend25% neutral1% critical
Mentions per year
What Hacker News says
- I loved the book QED: The Strange Theory of Light and Matter by Feynman as a child. Funny enough I always saw QM from a path integral PoV, a decade before I got to learn the formalism
- I became fascinated with quantum after reading Feynman's QED. Interested in learning more, the internet pointed me to Mike & Ike's textbook on quantum computing, which I highly recommend. But I find that personally the unstructured and untested nature of it makes it hard to self learn without a large amount of discipline. So I put together a free to use website for anyone else who might be in a similar spot: https://ketsandgates.com/ It has lessons spanning early ideas in quantum computing with refresher material on an as needed basis. It also will actively test your understanding as you go. I was using it offline but assumed there might be others who would benefit from a similar structure so posted it for free.
- Feynman's QED is an excellent read. It covers the topic in-depth in a descriptive, rather than mathematical way, covering many of the real-world effects that result from the way QED works.
https://en.wikipedia.org/wiki/QED:_The_Strange_Theory_of_Lig...
- In case anyone is curious about _why_ light bends when it enters a lens:
First, light apparently slows down in some materials because the photons are constantly interacting with electrons, and these interactions create secondary waves that are slightly out of phase with the original light. The end result is a modified wave that effectively travels more slowly. So light going in a straight line through air travels more quickly than light going through a lens.
Second, getting more into quantum physics, light typically follows the shortest path from one point to another because that path tends to provide the most constructive interference between different possible routes. (The "why" of this is more involved; Feynman's book QED gives a good intro.)
Third, if you imagine a lifeguard running to rescue someone in the ocean, then they will take the fastest path, which is not directly toward the person in the ocean. Rather, they will run a bit more on the beach in order to have to swim less because travel through the water is slower. The end result is piecewise linear = two straight lines of travel, with a bend at the water line.
To summarize, you can ask "_why_ does light bend going into and out of lenses?" and the answer involves seeing light no longer as a particle but as a wave function (the quantum perspective), and then taking advantage of that wave function's tendency to prefer fastest-travel paths, and then noticing that the apparent bend is in fact the path of fastest travel.
- I want to like Collier, but she has a patronizing, gatekeeping edge to some of her videos that I don't like. She also spends nearly as much time talking about science communication as she does actually communicating science.
Like for example, her QCD video was about how explaining QCD to laypersons is impossible. She dunked on Feynman diagrams, first as not being real math, then because its antimatter notation makes laypeople think antimatter is time-reversed matter. ...which it is, iiuc, as far as the calculations of quantum field theory are concerned. Also that QCD is misleading because color charge isn't actual colors, as if viewers are doomed to take the color-wheel analogy literally.
But this is a cynically pessimistic view to have as a science communicator. PBS Spacetime has covered QCD. Feynman's QED book teaches the layperson how diffraction, lensing, magnetic repulsion etc. work in terms of Feynman diagrams he shows you how to work through!
Why not teach science, rather than spread snark? Why not bring the audience up to you, rather than talking down to them?
- If you'd like something more technical, these two are fun (especially if you read them in order):
The first book is a nice way to get started with reversible computation and quantum computing.• Feynman Lectures On Computation • QED: The Strange Theory of Light and Matter
Related
Quantum electrodynamics
5 recommend · 6
Lectures on physics
14 recommend · 36
The Feynman Lectures on Physics
69 recommend · 156
Feynman's Thesis
1 recommend · 2
A modern approach to quantum mechanics
3 recommend · 4
Feynman lectures on computation
17 recommend · 29
