Re: textbook touchstones

[Leigh Palmer <palmer@SFU.CA>]

> Let's imagine an introductory textbook which has eliminated any
> idealization/simplification to which someone has strenuously objected.   It
> would eliminate all of the 'errors' (as perceived by any faction of
> physicists).  It would deal 'realistically' with friction, capacitors,
> entropy, etc., etc.  I suspect it would read like a Bowman post--very
> detailed and correct in the current understanding of physics.  It could be
> liberally footnoted like a Hake post.  We would then universally require
> this text to be used in all introductory physics courses.  In the third year
> of such use, we could then count up the students voluntarily taking the
> course.  Would we even have to take off our shoes and socks to finish the
> count?  ;-)
>
> Rick
>
> {It seems to me that much of the nit-picking done on this list IS of
> moderate importance in the teaching of future physicists, but very little is
> all that critical in other courses, the courses that comprise the bulk of
> our teaching loads.  We need to digest and discuss these points, but each of
> us, as educators, need to make decisions on the pedagogical value of any
> suggested change in method or content in the context of our classes and our
> students.}

Lighten up, Rick. We're not the fascists you suggest we are here.
When I listed my touchstones I didn't mean to suggest that they were
absolute requirements. For example, in the introductory astronomy
textbook I've used for the last two years Bradley isn't mentioned. I
put him into the lectures, of course, and I hope the author on that
textbook (who is a listmember) will take the suggestion. Almost all
introductory textbooks make a fatuous statement about entropy being
a measure of the disorder of a system. It is a common sin, but I can
correct it in my lectures, and I do.

The nit-picking done here is frequently of importance to physics
taught at all levels. The item I mentioned, telling the student that
entropy is a measure of the disorder of a system, only has meaning
and rational content when disorder is defined quantitatively. It has
negative value (it is counterproductive) when taught to nonscience
students who, given no further guidance, will think they understand
what disorder is. Taught to introductory level science students the
introduction of "disorder" only confuses them. It in no way helps
them to calculate the entropy of a system.

I graduated from UC Berkeley in 1957. There were *two sections* of
the upper division E&M course taught in rooms 2 and 3 Leconte Hall,
large lecture rooms, in my last semester, a two semester course
taken only by physics majors. There were, I estimate, about 150 of
us then. Textbooks were more rigorous then. Few, if any, had color
pictures. Sears and Zemansky, the introductory text, had a very good
treatment of thermodynamics, including the demonstration of the
equivalence of thermodynamic and ideal gas temperatures using the
Carnot cycle, but without introducing the concept of entropy at all.
Both these authors produced good thermodynamics texts at a higher
level, so they certainly understood the concept of entropy. They
recognized, however, that at the introductory level it is unnecessary
to introduce the concept. Indeed in today's introductory textbooks
entropy is a dead end! If one masters the concept as given, one can
then calculate entropy changes - and nothing more. Never does a
modern author explain why one would want to calculate an entropy
change in the first place. (Sorry, but looking at this old textbook
induced reverie and digression.)

Today we have sexier textbooks. I don't know what text is used at UCB
now, but I'll bet the number of students in Physics 110A and 110B is
smaller today than it was in 1956-57, and I bet they don't even have
two sections any more. (I would appreciate modern statistics if any
UCB physics major has the time to read this list.) Rick is very
interested in courses for nonscience students. Edward Teller taught
Physics 10 at UCB to classes exceeding 1,000 nonscience students. The
overflow from Wheeler Auditorium watched him on CCTV in other rooms
in Wheeler Hall.

I would suggest that the current trend to sexier texts with weaker
attempts at rigor and fewer references to other sources (not URLs,
books and journals) and, of course, often augmented by completely
redundant CDROMs, has not led to an increase in market share for the
physics major. I do not wish to commit the error of saying that the
sexier texts have led to a decrease in the number of students called
to physics (yes, physics is a vocation to some of us), but I believe
that we ought to return at least part way to the older forms.

Leigh

(I wouldn't want to get along without Bowman and Hake, either.)