Today, we think about thinking abstractly. 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.
bstraction is such an off-putting
word! An object-
oriented society turns it into a
bad word. It's good to be
down-to-earth; it's effete to be abstract. Yet
we live by abstractions
all the time. I can say a
scarf is green
without showing anyone the scarf.
You know the color
of leaves, or the backs of
dollar bills, or
moldy cheese. You've abstracted vegetation and
money to the point where you understand
green apart from any object.
We engineers would be hamstrung without
abstraction. We absolutely have to reduce real
machinery to frictionless pulleys, point masses,
and perfectly insulated bodies. If we didn't, we'd
drown in intractable detail. We'd never get around
to making anything.
Here's an example: Heat flows through a slab of
steel heated by boiling water on one side and
cooled by ice cubes on the other: The boiling water
agitates atoms on one side -- makes them jiggle
faster. Those atoms agitate the atoms next to them,
and so on. On the other side, the ice slows
the moving atoms and absorbs their energy. As you
move from hot to cold, each atom passes energy on
to the next one. Finally all that motion passes
into the ice. And the ice gradually melts away.
It's completely impractical to calculate heat flow
by describing such a complicated process, so we do
a strange thing. We go back to an 18th-century
abstraction. Before we had an atomic theory, we
imagined that an invisible substance called
caloric flowed from hot objects to cold
ones. There is no such material, but no matter. You
can describe heat flow just fine by
imagining caloric. Our mathematical theory
of heat flow still comes to rest on an 18th-century
abstraction.
Hardly anyone remembers that invisible and mystical
essence, caloric. Yet we still use the idea. We
abstract reality in a way that's unrealistic. When
would-be realists catch on to that, they shrink
back, even though we'd flounder without it.
So realists with good sense do set up abstract
parallel universes. When an invented world truly
runs parallel to the messy world around us, then a
problem solved in the imagination is also a problem
solved in the real world. The public, uncomfortable
with the ways of science, fights that kind of
down-home good sense.
A person might chance thousand-to-one odds
of having a car accident on vacation, yet be
terrified by million-to-one odds of getting
cancer from Alar. But then statistics is one more
abstraction of human experience that we use to make
sense of reality -- one more locus of discomfort if
we need things cast in concrete. Shaping worthwhile
abstractions means extracting the essence of
reality from the clutter of sense data. It is,
quite literally, a matter of seeing more -- by
knowing how to see less.
I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds
work.
(Theme music)
