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