Today, a closer look at scientific knowledge. 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.
"We hold these truths to be
self-evident," said our founding fathers. They were
speaking of human rights and liberties. But they
were tying into 18th-century scientific thinking.
In that rationalist world, Euclid's geometrical
axioms were models of the self-evident truths from
which all other knowledge derives.
By now, many of Euclid's self-evident axioms have
come under question. And we realize that
self-evident scientific truth is only scientific
misdirection. All science comes to rest on what we
call concepts. A concept is a building block we
Take the word energy. My dictionary
says energy is the capacity for doing work. So I
look up work, and find it defined as a transfer of
energy. The definitions just take us in a big
circle. So what is energy?
The answer's simple, really. But we find it outside
science. Energy's something we've all experienced
and know in our gut. Energy's what it takes to get
us to the mountaintop, or just out of bed in the
morning. Energy's what we have to contribute to
cold water to make it boil. Energy is what gasoline
releases to make our automobiles run. Energy is an
essential human experience.
If we look closely at physics books, we'll find
that they don't define energy at all. They give
examples of its various forms. They show how to
calculate work-energy. They show how to translate
that into other forms of energy. But they never,
never address the question, "What is energy?"
The trouble with most physics texts is that they
seldom tell students that energy remains undefined.
They create the illusion of a definition to give
students confidence. Who wants to say that science
comes to rest on the human gut, or in the human
The same is true of other essential quantities. I
dare you to define distance, time, or force. Or to
prove Newton's laws, for that matter! Any real
physical law is simply a statement of human
experience in dealing with conceptual quantities.
Science is a strange pursuit. It is far and away
the most careful and accurate attempt we make at
understanding the world around us. It's loaded with
safeguards against imposing what we want to be
true. It gives to engineers a vast toolkit for
getting things done.
It's just because science is such a formidable tool
that we try to take it all the way to absolute
truth. But absolute truth is God's province, not
ours. In the meantime, this highly-honed,
still-imperfect mode of inquiry takes us to Mars
and lets us do surgery on our own DNA. For me, the
most spectacular thing about the scientific process
is that is gives us means for doing so much -- when
we can't even define the elementary tools of the
I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds