Today, we look at the world through a narrow slit.
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.
I was trying to swat a fly
the other day when it struck me how fast and
elusive that fly was. It takes an eternity for a creature
of my great size to perceive the fly, process the
information, send a signal to my muscles, then move
my hand. The fly is a micromachine with short
neural paths and tiny parts to activate. It must
watch me as though I were moving in slow motion. It
struck me that the fly has a world-view that's
incomprehensible to me. Our whole sense of time is
molded to our limited range of responses.
And that's just motion. Try vision. The
electromagnetic spectrum runs from gamma and cosmic
rays in the neighborhood of a billionth of an inch
long, up to radio waves, which might be miles in
length. Within that range, the wavelengths you and
I see as light occupy an almost inconsequential
range of ten to twenty millionths of an inch. We
look at the world through a tiny slit.
Our hearing likewise responds to a miniscule range
of pressure waves in air. We hear from maybe 40 to
20,000 cycles per second when we're young. Consider
that ultrasound runs to frequencies in the millions
-- that weather might vary in cycles per day or
week -- and you have an idea of what you're missing.
Imagine, if you dare, a creature capable of
listening to the weather.
I recently saw a 3-D I-MAX movie about 3-D vision
-- about how our eyes create 3-D images in our
heads. The movie included a very surprising trick.
It showed stereopticon
movies shot with the two cameras placed very far apart.
The results showed how the world would look, seen
through the eyes of a giant.
Our eyes are only two-and-a-half inches apart. They
give us a good sense of the three-dimensionality of
nearby objects. For long distances, it's as though
we're looking at a flat picture. These images from
widespread cameras provide immense depth of field
as we view people on a long beach, or cars a block
away. We're suddenly giants looking into a doll's
I could go on. Our senses of taste and smell are
restricted by our chemical receptors. You and I can
feel temperature changes in a range of only about a
hundred degrees Fahrenheit -- sixty degrees
Celsius. Beyond that our nerves either freeze or
For four centuries now, we've been honing
instruments to show us the world beyond that narrow
slit of our perceptions. We've come very far. Yet,
in the end, we read our meters and computer outputs
from behind that slit. We seem forever forced to
view the larger world that science shows us through
a glass darkly. That's a pretty humbling
limitation. It leaves me wondering how far the
universe will prove to reach beyond the bunker of
my own body.
Perhaps even time itself is part of our
body-imposed limitations. So, until time tells, I
shall have to content myself with asking the cat
what she sees that I cannot -- what
she knows about life that I never
I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds