Today, we try to see what we're looking at. The
University of Houston's College of Engineering presents
this series about the machines that make our civilization
run, and the people whose ingenuity created them.
How we turn things to the light
makes all the difference. We look at the external world
and don't always see the same thing. Try a personal
example: Years ago, I studied heat removal from
cylindrical heaters in water. That's important where
intense heating occurs in, say, nuclear reactors,
quenching, or solar furnaces.
As we release more energy from a heater, the water boils,
and heat escapes by spurting away in jets of vapor. We
can remove as much as a megawatt of energy per square
meter of the heater's surface. But, after that, the jets
abruptly become unstable and collapse. The cooling path
is lost, and the heater suffers a meltdown.
I was trying to write a theory for the way diameter
affected that breakdown. So I stared at heaters lit by a
blinking strobe light. The smaller the heater, the more
erratic and unpredictable the breakdown became. I kept
refining experiments, trying to make sense of them. But
the data were always inconsistent.
Now I also happened to be studying surface tension. I
began to see how surface tension dominates small systems.
I should've quit thinking about jets and started looking
at how beads of dew behave on spider webs. The penny
finally dropped. Surface tension was clamping the
jet-like escape paths shut on small heaters.
I'd been seeing jets because I expected to see jets. What
I was really seeing were beads of vapor. I'd been chasing
vapor in more ways than one. Heat was being carried away,
not by jets, but by randomly flickering vapor blobs. When
I finally saw what I was looking at, I was no longer
looking at the same thing.
That's the perennial story of invention. I bring you this
variant only because of something that happened last
week. An angry web-surfer found a program I'd done on
racism. He wrote to say that the intellectual superiority
of the white race was obvious. My denial of it was
cowardly political correctness.
This is another place where we've stared at data shaped
by our own expectations. We've measured skulls and thrown
out data that didn't look right. We've written
IQ tests based on the knowledge in our own heads. We've
measured relative educational levels of people who were,
for centuries, kept out of schools, and so forth.
The closer we look, the more our very definitions of race
vaporize into differences we've created in our minds.
Remove our a priori expectations and the very
concept of race evaporates. You cannot consistently
define it by genetics, anatomy, color, or the shape of
features. We look at a person and see jets instead of
bubbles only because we expect to see them.
This is an old and sad story: We discover only
when we see through the vapor and open ourselves to
surprise. The very word prejudice means
determining an outcome before we let the facts
surprise us. That's what Louis Pasteur meant when he
warned us that,
In the field of observation,
chance favors the prepared mind.
I'm John Lienhard, at the University of Houston, where
we're interested in the way inventive minds work.
(Theme music)
You may find a textbook discussion of the boiling "burnout"
problem in Chapter 9 of A Heat Transfer Textbook
(available free of charge online at:
http://web.mit.edu/lienhard/www/ahtt.html
).
For a major review article about burnout on cylindrical
heaters, see: Lienhard, J. H., Burnout on Cylinders.
Journal of Heat Transfer, Vol. 11, No. 4(B),
(50th Anniversary Issue) Nov. 1988, pp.1271-86.
Stephen J. Gould provides excellent background on the
issue of racism. See, e.g., Gould, S.J., The
Mismeasure of Man. New York: W.W. Norton & Co.,
1981, and Gould, S.J., The Flamingo's Smile:
Reflections in Natural History. New York: W.W. Norton
& Co., 1985.
Sun and Lienhard,
Int. J. Ht. Mass Tr., Vol. 12,
1970, pp. 1425-1439
The Engines of Our Ingenuity is Copyright
© 1988-2001 by John H. Lienhard.
