

Richard Feynman on Physics: 4-part lecture series (videos) - chaosmachine
http://vega.org.uk/video/subseries/8

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mixmax
I've read the Feynman lectures on physics, but I had no idea there was
actually a series of videos as well.

Great find.

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pkrumins
I have collected some Feynman lectures as well. See this:

[http://freescienceonline.blogspot.com/2008/12/richard-
feynma...](http://freescienceonline.blogspot.com/2008/12/richard-feynman-
physics-video-lectures.html)

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b-man
Just a question, does anyone know how to download these videos to watch
offline?

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itistoday
I just finished watching the first lecture, it was very enjoyable as is
typical of Feynman lectures, but what I'm confused about is the metaphor that
he chose to give as an explanation for the reason the probabilities are the
way they are.

Isn't another interpretation of that experiment (what I thought was the
current default interpretation), that as you increase the distance between the
two surfaces you have light rays reflecting back, and because of the distance
(not the time it takes an arrow to spin as in the video), the two light rays
become out-of-phase, and therefore you get constructive and destructive
interference?

Secondly, I was also confused as to his insistence that "light is a particle",
hasn't it be established that light has properties of both particles and
waves? Certainly Feynman doesn't deny that, so why would he make that
statement so insistently? The _wave_ -length of the light "particle" is very
important in calculations, and while this characteristic of light wasn't
denied in the lecture, it certainly seemed to be ignored amidst the talk of
"little spinning arrows"...

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graphene
To address your second concern, all quantum particles (this includes photons)
have wavelike properties (including wavelength), and thus can show wavelike
effects, such as interference. For example, a ray of light contains a huge
number of photons and obeys certain wave equations, but if the intensity is
decreased enough, the light is found to impinge in discrete units, which have
been named photons.

When Feynman says light is particles, he means that it comes in discrete
units, not that it behaves as a stream of tiny billiard balls with classical
behavior.

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itistoday
I'm aware of this, but this is the exact sort of caveat that he failed to
mention in his lecture, despite promising his audience that he would tell them
exactly his understanding of the situation.

