Feynman's Lost Lecture: The Motion of Planets
Around the Sun is a book based on a lecture
by Richard Feynman.
Restoration of the lecture notes and conversion
into book form was undertaken by Caltech physicist
David L. Goodstein and archivist Judith R.
Goodstein.
Feynman had given the lecture on the motion
of bodies at Caltech on March 13, 1964, but
the notes and pictures were lost for a number
of years and consequently not included in
The Feynman Lectures on Physics series.
The lecture notes were later found, but unfortunately
without the photographs of his illustrative
chalkboard drawings.
One of the editors, David L. Goodstein, stated
that at first without the photographs, it
was very hard to figure out what diagrams
he was referring to in the audiotapes, but
a later finding of his own private lecture
notes made it possible to understand completely
the logical framework with which Feynman delivered
the lecture.
== Overview ==
You can explain to people who don't know much
of the physics, the early history...
how Newton discovered...
Kepler's Laws, and equal areas, and that means
it's toward the sun, and all this stuff.
And then the key - they always ask then, "Well,
how do you see that it's an ellipse if it's
the inverse square?"
Well, it's God damned hard, there's no question
of that.
But I tried to find the simplest one I could.
In a non-course lecture delivered to a freshman
physics audience, Feynman undertakes to present
an elementary, geometric demonstration of
Newton's discovery of the fact that Kepler's
first observation, that the planets travel
in elliptical orbits, is a necessary consequence
of Kepler's other two observations.
The structure of Feynman's lecture:
A historical introduction to the material
An overview of some geometric properties of
an ellipse
Newton's demonstration that equal areas in
equal times is equivalent to forces toward
the sun
Feynman's demonstration that equal changes
in velocity occur in equal angles in the orbit
Feynman's demonstration, using techniques
of Ugo Fano, that these velocity changes imply
that the orbit is elliptical
Discussion of Rutherford's experiments with
scattering of alpha particles, and the discovery
of the atomic nucleusThe audio recording of
the lectures also includes twenty minutes
of informal Q&A at the blackboard with students
who had attended the lecture.
== See also ==
Isaac Newton's work: Philosophiae Naturalis
Principia Mathematica
