Quoting from Alan Lightman's, "A Modern Day Yankee In A Connecticut Court
and other essays on Science".
Conversations with Papa Joe
The First Evening
"An extraordinary thing happened one night last winter. I was
relaxing in my study after a long day at the university. As I sat
reading, drawing on my great-grandfather's pipe, the old gentleman
himself materialized in the curling gray smoke and seated himself in the
comfortable wingback across from me. He seemed much less surprised than
I and immediately occupied himself with dusting off his suit, as if he'd
been on a long journey.
I should explain that I know little of Papa Joe. He came to this country
from Hungary about 1880, in his early teens, and started a construction
company in Nashville. According to my older relatives, he was not
formally educated, but a capable man, with a good head on his shoulders
and a strong curiosity about the world. His pipe, a fine old England
briar with a solid bowl and a beautiful straight grain, had been tucked
away in a drawer for years when my father found it and gave it to me.
This was only the second time I had lit it.
After introducing ourselves, we settled into conversation. "I've been
looking for that pipe," the old gentleman said, taking a deep whiff of
the aromas filling the room.
"It's a wonderful pipe," I agreed. "It's always made me wonder what you
were like."
Papa Joe was eager, of course, to learn what had happened in the last
sixty years and began asking questions. We talked of how his various
descendants had got on in life, the Great Depression, the Second World
War, the landing of men on the moon.
All of a sudden, I realized I hadn't offered Papa Joe his own pipe. I
wiped off the stem and held it out to him. He reached for it
immediately, but then hesitated, and finally pulled back his hand.
"What's been has been," he said with a sigh, then walked over to the
large window behind my desk and stood looking out. It was one of those
crystal nights, with cold, clear skies. Even from my chair near the
fire, I could easily make out Orion, with Betelgeuse at the hunter's
shoulder and Rigel marking his left foot. Taurus the Bull was close by,
glistening through the branches of my maple tree.
"I love the sky at night," said Papa Joe. "Never new much about the
stars, but I always wanted to." He paused, in thought. "I used to tell
your father that each star was a firefly."
"I suppose the nights you remember were clearer than this," I said. "Our
streetlamps and city lights spoil a view a bit."
He nodded. "But you're not bad off here, on this little street. Not bad
off at all. My pipe's found a good home." Just as the old gentleman
uttered those words, he started to fade.
"Wait! Wait!" I cried out to him. "I can tell you some things about the
sky, if you're interested. I'm actually an astronomer."
At that, my great-grandfather's figure grew firm once again. "I reckon
I'll stay awhile then," he said, and returned his gaze to the window. "I
trust the sky. Clothes and men change with the styles, but not the
stars."
"If you don't look too long, or too far," I said.
"What do you mean?" he asked, turning back toward me.
"You can be pretty sure that each of those stars up there will
eventually dim to a cinder or blow itself apart. It's only a matter of
time." Papa Joe had a stricken look on his face, like a man who'd
suddenly lost an old friend. I felt a wave of embarrassment. I tried to
change the subject, but he wouldn't let me. Instead, he pressed me to
explain my remark. I didn't know exactly where to begin, so I put
another log on the fire. Papa Joe returned to his chair.
"One thing I have to tell you about modern science," I finally said, "is
that it has galloped off into territories far beyond where we can follow
with our bodies. What we experience directly with our human senses is
only a small fraction of the world around us. But we very badly want to
see what our eyes cannot see, and hear what our ears cannot hear. We
want to know about places beyond the stars and about happenings before
the earth was formed. So we've built enormous machines that dissect the
insides of atoms. We've built telescopes that peer out to unimaginable
distances and instruments that record colors invisible to the human eye.
Our theorists have worked out equations to describe the beginning of
time".
"A lot of what we now believe about the world has come to us only by
looking at the readings of our instruments and trusting the logic of our
calculations. Of all people today, I think scientists have the deepest
faith in the unseen world. The greater the scientist, the deeper his
faith."
"That's a turn of events," exclaimed my great-grandfather. "I always
thought of scientists as fellows who wouldn't forecast rain until they
were drenched. This is pleasant news."
"It's a special brand of faith," I continued. "You might say that the
scientist sees God as a mathematician. and with some justification, as
far as I can tell. As our artificial eyes and ears have revealed each
new patch of the invisible tapestry, it looks more and more precise. And
our abstract equations and scribblings work remarkably well as
predicting the patterns."
"You've whetted my appetite, young man. But please mind, I'm not much
with philosophy. I like to have solid proof for what I believe."
"Do you believe the Earth spins on its axis, Papa Joe?"
"Yes."
"What solid proof do you have?" said I. "Do you feel yourself whipped
around through space at several hundred miles per hour?" Papa Joe
started to speak, twisted his thick moustache uneasily, and said
nothing.
"If you set swinging a long heavy pendulum and watched it carefully, the
way Monsieur Foucault first did in the last century, you'd notice that
its plane of motion very slowly rotates. That plus some principles of
physics prove that the Earth turns on its axis. But you'd never catch
the tiny effect with your own senses."
The old gentleman chuckled. "All right, I get your point. I'm all ears
to what you've learned with your modern devices, if ears are of use
anymore. Now tell me about the heavens, misbehaving behind our backs."
"First," I said, "we need to get some idea of the distances. But that's
not easy. The prickliest problems in astronomy has been finding the
distances to the stars. When we look into the sky, we perceive length
and width, but not depth. From our vantage, stars are just white dots on
the night sky, like distant ships on the night sea, visible only by
their running lights. Some are certainly closer than others, but which
ones? How can we measure the size and shape of space itself, stretching
all around us? Astronomers puzzled over this problem for thousands of
years, knowing that it held the answer to so many other celestial
mysteries."
"I'm surprised you can't figure depths with your telescopes."
"Look at any star thorough the most powerful telescope," I said, "and
it will appear as a mere point of light. How do you gauge something like
that? And all you've got for reference are other points of light."
"I guess that must mean that the stars are very small, or else very far
away," said Papa Joe.
"They're not small, " I replied, "but you're right about the distance.
If the stars were nearby, then we'd see their locations shift back and
forth as the Earth moves from one side of the Sun to the other, changing
our angle of view. In fact, we do see a slight yearly shift in the
closest stars and can measure their distances by the amount of the
shift. The nearest star is several thousand times farther away than
Pluto. But the great majority of stars are so distant that they appear
fixed while we go back and forth around the Sun."
"Surely," spoke the old gentleman, "the nearer ships must look brighter
and the old ones farther away must look dimmer. Couldn't their distances
be judged in such a way?"
"Aha," I answered, "you're on the right track. But you're assuming that
all of the ships carry the same lights on board. Some of the ships, the
grander ones, will have stronger beacons, so at a great distance they
will appear just as bright as the closer but less luminous ones."
"I should have guessed that the stars, like everything else, would have
their own privates and captains," said Papa Joe. "I reckon the first
step might be to group the stars by kind somehow, although I can't see
how to do it. Then the dimness and brightness trick could be used on
stars of the same kind." Papa Joe smiled faintly, as if pleased with his
comments.
"That's in fact very close to what Professor Shapley did several decades
ago," I said. "Astronomers had noticed that certain stars change
brightness in a rhythmic and regular fashion, with some running through
their light cycles rapidly and others more slowly. Shapley put these
pulsating stars into groups, according to the length of their cycles.
Then he used the assumption that every star in the same group was
identical, with the same luminosity. For example, every star with a
light cycle between ten hours and eleven hours would be in one group;
every star with a cycle between eleven and twelve hours would be in
another, and so on. With this clever way of identifying what kind of
star he was looking at, Shapley could then use the dimness and
brightness method to figure its distance. So the pulsating stars became
points of reference, at known distances. Find a pulsating star lodged
within a group of other stars and you know the distance to them too.
Little by little, Shapley began mapping out the heavens and placing many
of the points of light at their proper depths, with better accuracy than
anyone had managed before. it was immensely tedious work, requiring the
scrutiny of thousands of telescopic photographs over time, in order to
see which stars changed brightness and how quickly."
"I'm pleased to hear," said Papa Joe, "that you Professor Shapley had
put in some hard work at his job. That makes me believe him all the
more. From what you said before, I had the notion that modern scientists
simply had to turn on their machines and lie back while new knowledge
was cranked out and charted. If you'll pardon me, it sometimes seems
that progress breeds laziness. For years, I had a fellow running my
stone quarry outside Nashville. Once the telephone lines came in, he
started calling me up with every damn fleabite, instead of thinking them
out like he used to do. But I've carried us off the point. What did
Shapley's labors turn up?"
"For one thing," I answered, "the heavens extend much farther than
astronomers previously thought. For another, we're not at the center,
and more than our planet is at the center of our solar system. Our sun
seems to be casually dropped at the outskirts of an enormous,
disk-shaped gathering of stars, called a galaxy, containing every star
our eyes can see and a hundred billion more. Before Shapley, astronomers
thought our sun was at the center of this galaxy. But the center is far
off, in the direction of Sagittarius. The dimensions of the whole this
are fantastic. If our solar system were the size of a dime, then the
galaxy would be the size of Tennessee."
My great-grandfather let out a whistle. "I can't imagine anything that
large. But being off center could have its advantages," he offered. "It
might keep us from getting too stuffed with ourselves. And what's out
past the galaxy?"
"Other galaxies, with a lot of mostly empty space in between. As far as
our telescopes can see, there are galaxies. Picture yourself gliding
through the depths of the universe. You come to a flotilla of stars, all
huddled together. That's a galaxy. After you've left the first galaxy
far behind, so it's a tiny white patch of fuzz in the dark, you come to
another huddling of stars. That's another galaxy. You pass one galaxy
after another, some shaped like pinwheels, some like spheres, some like
nothing in particular. Then you come to your own galaxy, the Milky Way.
you quickly search for your own sun and can hardly find it, a single
speck lost in the billions of other specks. The Earth is invisible. Then
you are gone and your galaxy dwindles behind you, becomes nothing. More
galaxies come and go, come and go."
Papa Joe had walked to the window and was looking out at the sky again.
He stood there a long while. "And Professor Shapley," he said softly,
"worked it out in a office somewhere, with his photographs and his good
head. He sure was small compared to what he was thinking about. That's
powerful faith. powerful faith."
As Papa Joe whispered these last words, his figure grew misty and began
to dissolve. I noticed my pipe had gone out. "Don't go," I called out.
"There's much more I haven't told you."
"All right. I'll be back tomorrow night," came a wisp of a voice.
"Tomorrow night," I repeated, and then he was gone.
To Be Continued