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Tt is perfectly clear that students who will major in physics can wait until
theïr third year for quantum mechanics. Ôn the other hand, the argument was
made that many of the students in our course study physics as a background for
theïr primary interest in other fields. And the usual way of dealing with quantum
mnechanics makes that subJect almost unavailable for the great majJority of students
because they have to take so long to learn it. Yet, in i6s real applications——
especially in its more complex applications, such as in electrical engineering
and chemistry—the full machinery of the diferential equation approach is not
actually used. So ÏI tried to describe the prineiples of quantum mechanics In
a way which wouldnˆt require that one first know the mathematics of partial
diferential equations. Even for a physicist I think that is an interesting thing
to try to do—to present quantum mechanics in this reverse fashion——for several
reasons which may be apparent in the lectures themselves. However, I think that
the experiment in the quantum mechanies part was not completely successful——in
large part because I really did not have enough time at the end (I should, for
Instance, have had three or four more lectures in order to deal more completely
with such matters as energy bands and the spatial dependence of amplitudes).
Also, I had never presented the subject this way before, so the lack of feedback was
particularly serious. Ï now believe the quantum mechaniecs should be given at a
later time. Maybe lI have a chance to do it again someday. Then Ƒl] do it right.
The reason there are no lectures on how to solve problems 1s because there
were recitation sections. Although I did put in three lectures in the first year on
how to solve problems, they are not included here. Also there was a lecture on
inertial guidance which certainly belongs after the lecture on rotating systems,
--- Trang 18 ---
but which was, unfortunately, omitted. 'Phe fñifth and sixth lectures are actually
due to Matthew Sands, as Ï was out of town.
'The question, of course, is how well this experiment has succeeded. My own
point of view——which, however, does not seem to be shared by most of the people
who worked with the students——is pessimistic. I don't think I did very well by
the students. When I look at the way the majority of the students handled the
problems on the examinations, I think that the system is a failure. Of course,
my fiends point out to me that there were one or ÿ6wo dozen students who—very
surprisingly——understood almost everything in all of the lectures, and who were
quite active in working with the material and worrying about the many points
in an excited and interested way. Thhese people have now, l believe, a first-rate
background in physics—and they are, after all, the ones Ï was trying to get at.
But then, “The power of instruction is seldom of mụch efflcacy except in those
happy dispositions where it is almost superfuous.” (Gibbon)
Stil, I didn't want to leave any student completely behind, as perhaps I did.
T think one way we could help the students more would be by putting more hard
work into developing a set of problems which would elucidate some of the ideas
in the lectures. Problems give a good opportunity to fll out the material of the
lectures and make more realistic, more complete, and more settled in the mind
the ideas that have been exposed.
1 think, however, that there isnˆt any solution to this problem of education
other than to realize that the best teaching can be done only when there is a
direct individual relationship between a student and a good teacher—a situation
in which the student discusses the ideas, thinks about the things, and talks about
the things. It's impossible to learn very much by simply sitting in a lecture, or
even by simply doing problems that are assigned. But in our modern tỉmes we
have so many students to teach that we have to try to fnd some substitute for
the ideal. Perhaps my lectures can make some contribution. Perhaps in some
small place where there are individual teachers and students, they may get some
inspiration or some ideas from the lectures. Perhaps they will have fun thinking
them through——or goïng on to develop some of the ideas further.
RICHARD P. FEEYNMAN
Jưne, 1963
--- Trang 19 ---
orosror-‹l
This book is based upon a course of lectures in introductory physics given
by Prof. R. P. Feynman at the California Institute of Technology during the
academic year 1961-62; it covers the frst year of the Ewo-year introductory course
taken by all Caltech freshmen and sophomores, and was followed in 1962-63 by
a similar series covering the second year. The lectures constitute a major part of
a fundamental revision of the introductory course, carried out over a Íour-year
period.
'The need for a basic revision arose both from the rapid development of physics
in recent decades and from the fact that entering freshmen have shown a steady
increase in mathematical ability as a result of improvements in high school mathe-
matics course content. We hoped to take advantage of this improved mathematical
background, and also to introduce enough modern subject matter to make the
course challenging, interesting, and more representative of present-day physics.
In order to generate a variety of ideas on what material to include and how to
present it, a substantial number of the physics faculty were encouraged to offer
theïr ideas in the form of topical outlines for a revised course. Several of these were
presented and were thoroughly and critically discussed. It was agreed almost at
once that a basic revision of the course could not be accomplished either by merely
adopting a diferent textbook, or even by writing one øb ?m2fio, but that the new
course should be centered about a set of lectures, to be presented at the rate of
two or three per week; the appropriate text material would then be produeced as a
secondary operation as the course developed, and suitable laboratory experiments
would also be arranged to fit the lecture material. Accordinply, a rough outline of
--- Trang 20 ---
the course was established, but this was recognized as being incomplete, tentative,
and subject to considerable modification by whoever was to bear the responsibility
for actually preparing the lectures.
Concerning the mechanism by which the course would fnally be brought
to life, several plans were considered. “These plans were mostly rather similar,
involving a cooperative efort by Ñ staff members who would share the total
burden symmetrically and equally: each man would take responsibility for 1/N of
the material, deliver the lectures, and write text material for his part. However,
the unavailability of suficient staf, and the dificulty of maintaining a uniform
point of view because of diferences in personality and philosophy of individual
participants, made such plans seem unworkable.
The realization that we actually possessed the means to create not jusÈ a
new and diferent physics course, but possibly a unique one, came as a happy
inspiration to Professor Sands. He suggested that Professor R. P. Feynman pre-
pare and deliver the lectures, and that these be tape-recorded. When transcribed
and edited, they would then become the textbook for the new course. This is