Today, we wonder: How big is big? How small is
small? 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.
The extent of our universe
is some 15 billion light years. It's about
10-to-the-nineteenth times bigger than earth. Earth
in turn is about 10-to-the-nineteenth times bigger
than an electron. As far as size goes, we're
curiously placed right in the middle. Things reach
just as far inward as they do outward.
The universe, expanding at the speed of light, is
one light year larger each year. That's around ten
trillion miles. It seems like a lot, but the
universe is already so big that it expands by only
a ten trillionth of a percent in a year.
These enormities do funny things. When I say we
breathe 10-to-the-22 molecules in each breath,
that's just a number. But see it another way:
Consider the first breath you exhaled when you got
off the plane in -- say -- London, 15 years ago.
That breath diffused into the air. It blew off into
the trade winds. It has circled the earth, mixed
into hurricanes and blizzards. Over the years it's
been stirred into the air over every land and every
sea. Right now, as you listen to my voice, no
matter where you are, you take in one molecule of
that single 15-year-old breath that you spent in
another land -- every time you inhale. That's what
the number 10-to-the-22 means.
And we're centered in all this magnitude. Our
ability to comprehend is also centered. We can
understand distances up to about 1000 times our
length. We can see lengths down to about 1/1000th
of our length. Beyond that, we fly on instruments.
If we look at a germ under a microscope, the
experience of seeing becomes synthetic. We can gaze
at the moon and stars, but we have no idea whether
they lie one mile or a billion miles away. To find
out, we have to use analysis and instruments. We
resort to synthetic experience.
So we play the delicious magnitude game. The earth
is as much larger than you, as you are larger than
the cells that make up your body. We're oddly
centered in a world that's both too large and too
small to comprehend. We could be no smaller than we
are and still own that great computer called a
brain. And our immense universe is as small as it
could be and yet be old enough to have spawned us.
It took 15 billion years for the expanding stars
and planets to ripen -- for earth to cool until it
could sustain carbon-based life.
So we dwell in the right place at the right time.
It's a huge and ancient place made to our measure.
It's large enough to contain a free people. And
it's small enough that we can either spoil it or
shape it into a fit dwelling.
I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds
Barrow, J.D. and Tipler, F., The Anthropic
Cosmological Principle. New York: Oxford
University Press, 1988.
Tien, C-l. and Lienhard, J.H., Statistical
Thermodynamics. New York: Hemisphere Pub.
Corp., 1979 (See especially Example 2.2.)
Schrödinger, E., What is Life? & Other
Scientific Essays. New York: Doubleday Anchor
The Engines of Our Ingenuity is
Copyright © 1988-1997 by John H.
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