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Re: Capilary tubes.

As this is a popular book, it is written for the general public (not the
engineering/physics major) as it should be. Nevertheless, I believe that
these excerpts substantially answer the original questions posed - that
capillary action is not how trees pump water and that the tubes in a tree
are not 0.5 microns in diameter. For further details, books such as this
have many references at the end for the interested reader to pursue.
In general, I have found popular books are often much better at providing
conceptually useful understanding than technical books. For example, I
learned more about the interaction of light and matter by reading Craig
Bohren's book "Clouds in a Glass of Beer" than from my optics books. And I
am currently involved in multilayer thin film optical design and
fabrication at my company . For detailed calculations and mathetical
understanding, the technical books, papers and review articles are great,
but the popular books written by experts have great utility (often
underappreciated) for scientists both during and after their formal
schooling. Feynman's QED and Greene's The Elegant Universe are other nice
examples.


At 10:27 AM -0700 12/15/00, Larry Woolf, you wrote about Re: Capilary tubes.:


This point is discussed in "Life's Matrix: A Biography of Water" by Philip
Ball ( an editor at Nature) on p. 239-240. I'll provide some quotes from
these pages. its pressure
falls to less than zero - less than that of a vacuum! Yet there is nothing
particularly outlandish about the concept of a negative pressure: it is
simply a tension, an outward pull.

One of Giancoli's texts mentioned this example of 'negative
pressure'. I think that MANY of his examples are chosen to appeal to
to an audience beyond the typical engineering/physics major undergrad.

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Dr. Lawrence D. Woolf
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