Today, let's talk about technology, revolution, and
tsunamis. 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.
Here's a thought for you.
It's about technological revolution -- about any
revolution, for that matter. It is a tidal wave
analogy. Somewhere, under the ocean, the plate
tectonics shift slightly. We suffer an undersea
earthquake. It launches a wave.
The wave is only a few feet high, but it's hundreds
of miles long -- much longer than the ocean is
deep. It moves like a wave in a water-filled cookie
sheet. It travels hundreds of miles an hour and
carries enormous energy in complete quiet and
repose.
The wave takes an hour to pass a ship at sea. You
don't even know it's been there. You take an hour
to rise a few feet, then be let back down. The
tidal wave is quite invisible to you.
Only when it reaches the sloping coastal shore does
it pile up into a great crashing wall of water.
Only then is its energy released. It was a long
time coming. Now it uncoils in seconds.
So it is with technological revolutions. The
Medieval Church moved the earth in the 12th century
when her scholars started the first universities --
when they aggressively started asking questions
about the nature of things.
That set off a new craving for written material.
For 300 years inventors worked on the problem of
mass-producing books. They worked out the
technologies of copying, organizing text, binding,
paper and ink-making, and block printing. Finally
Gutenberg put the pieces together and perfected the
printed book.
People who lived through those years couldn't have
known a tidal wave was passing. But now the wave
reached shore. In the next 40 years we printed 20
million new books. Life on Earth was changed.
Suddenly we knew a tsunami had broken over our
heads.
Try another tsunami wave; Around 1880 we could buy
a telephone. That was the first real medium of
interactive electronic communication. When I used a
phone in the 1930s, I had little sense that the
whole fabric of human concourse was being rewoven.
Actually two plate tectonics shifted in 1880. The
first commercial hand-cranked calculators also came
on the market about then. Those two technologies,
computers and electronic communication, finally
married in the mid 1980s.
Now the tidal wave is just breaking on the shore.
People are either buying into the new electronic
networks or shrinking from them in horror. Now, at
last, we see the cresting wave, and it is far
larger than anything we were prepared for.
I've said before that our machines rise out of our
animal nature and ride beyond our conscious
control. So the tidal waves of human ingenuity
gather energy invisibly and finally break upon us
-- suddenly, irrevocably, and magnificently, as
well.
I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds
work.
(Theme music)
Bascom, W., Waves and Beaches. New York:
Anchor Books, 1980.
For more on the print revolution see Episodes
696, 736, 753,
and 756. For more on the
electronic revolution see Episodes 680, 685,
708, 725, and more. This idea was the
central theme of a joint lecture series developed
for a sophomore design class by John Lienhard, Pat
Bozeman, and Nancy Buchanan (the latter two from
the UH Library.)
Students of fluid mechanics identify a tidal waves
as a type of "shallow wave." That means the wave is
much longer than the depth of fluid in which it
moves. Consider a typical tidal wave:
The surface of the ocean might be sinusoidal with a
wavelength of 400 miles and an amplitude of 3 feet.
The local depth of the ocean, h, might be around
12,000 feet. This wave is 176 times as long as the
depth of the ocean. Let us calculate the speed of
the wave under those circumstances.
The "phase velocity," c, of a shallow wave is given
by:
c = SQRT(gh)
where g is the acceleration of gravity, and where the
phase velocity is the speed that shape of the wave
travels. The actual liquid only moves slowly up and
down as the horizontal shape moves horizontally. In
the example at hand,
c = SQRT[(32.2 ft/sec/sec)*12,000 ft)]
= 622 ft/sec
= 424 mi/hr
This is over half the speed of sound at normal
atmospheric conditions. That is an extremely high
velocity, yet at this speed the wave still takes
400/424 hr, or 57 minutes, to pass.
The tidal wave presents us with a problem of
perceiving relative scale. The wave on a cookie
sheet is understandable to us. When we scale that
up to oceanic dimensions, it surprises us in many
ways.
And so, of course, do technological
revolutions.
The Engines of Our Ingenuity is
Copyright © 1988-1997 by John H.
Lienhard.
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