The Clockwork Universe

by Edward Dolnick

  The headphones that would let everyone hear that music do exist, but they can only be built one pair at a time, by the person who intends to wear them, and the process takes years. Few people take the trouble. In the centuries that followed the scientific revolution, as the new worldview grew ever more dominant, poets would howl in outrage that scientists had stripped the landscape bare. “Do not all charms fly / At the mere touch of cold philosophy?” Keats demanded. Walt Whitman, and many others, would zero in even tighter. “When I heard the learn’d astronomer,” wrote Whitman, the talk of figures, charts, and diagrams made him “tired and sick.”

  Mankind had long taken its place at the center of the cosmos for granted. The world was a play performed for our benefit. No longer. In the new picture, man is not the pinnacle of creation but an afterthought. The universe would carry on almost exactly the same without us. The planets trace out patterns in the sky, and those patterns would be identical whether or not humans had ever taken notice of them. Mankind’s role in the cosmic drama is that of a fly buzzing around a stately grandfather clock.

  The shift in thinking was seismic, and the way it came about had nothing in common with the textbook picture of progress in science. Change came not from finding new answers to old questions but from abandoning the old questions, unanswered, in favor of new, more fruitful ones. Aristotle had asked why. Why do rocks fall? Why do flames rise? Galileo asked how. How do rocks fall—faster and faster forever, or just until they reach cruising speed? How fast are they traveling when they hit the ground?

  Aristotle’s why explained the world, Galileo’s how described it. The new scientists began, that is, by dismissing the very question that all their predecessors had taken as fundamental. (Modern-day physicists often strike the same impatient tone. When someone asked Richard Feynman to help him make sense of the world as quantum mechanics imagines it, he supposedly snapped, “Shut up and calculate.”)

  Aristotle had an excellent answer to the question why do rocks fall when you drop them? Galileo proposed not a different answer or a better one, but no answer at all. People do not “know a thing until they have grasped the ‘why’ of it,” Aristotle insisted, but Galileo would have none of it. To ask why things happen, he declared, was “not a necessary part of the investigation.”

  And that change was only the beginning.

  Chapter Sixteen

  All in Pieces

  Galileo, Newton, and their fellow revolutionaries immediately turned their backs on yet another cherished idea. This time they banished common sense. Long acquaintance with the world had always been hailed as the surest safeguard against delusion. The new scientists rejected it as a trap. “It is not only the heavens that are not as they seem to be, and not only motion,” Descartes argued, in a modern historian’s paraphrase. “The whole universe is not as it seems to be. We see about us a world of qualities and of life. They are all mere appearances.”

  It was a Polish cleric and astronomer named Nicolaus Copernicus who had struck the first and hardest blow against common sense. Despite the evidence, plain to every child, that we live on solid ground and that the sun travels around us, Copernicus argued that everyone has it all wrong. The Earth travels around the sun, and it spins like a top as it travels. And no one feels a thing.

  This was ludicrous, as everyone who heard about the newfangled theory delighted in pointing out. For one thing, the notion of a sun-centered universe contradicted scripture. Had not Joshua ordered the sun (rather than the Earth) to stand still in the sky? This was a huge hurdle. In the 1630s, nearly a century after Copernicus’s death, Galileo would face the threat of torture and then die under house arrest for arguing in favor of a sun-centered universe.

  (Isaac Newton was born in the year that Galileo died. That was coincidence, but in hindsight it seemed to presage England’s rise to scientific preeminence and Italy’s long drift to mediocrity. What was not coincidence was that seventeenth-century England welcomed science, on the grounds that science supported religion, and thrived; and seventeenth-century Italy feared science, on the grounds that science undermined religion, and decayed.)

  Copernicus himself had hesitated for decades before publishing his only scientific work, On the Revolutions of the Celestial Spheres, perhaps because he knew it would stir religious fury as well as scientific opposition. Legend has it that he was handed the first copy of his masterpiece on his deathbed, on May 24, 1543, although by that point he may have been too weak to recognize it.

  Religion aside, the scientific objections were enormous. If Copernicus was right, the Earth was speeding along a gigantic racetrack at tens of thousands of miles an hour, and none of the passengers suffered so much as a mussed hair. The fastest that any traveler had ever moved was roughly twenty miles an hour, on horseback.

  These arguments came from the most esteemed scholars, not from yokels. They knew, on both scientific and philosophical grounds, that the Earth does not move. (Aristotle had argued that the Earth rests in place because it occupies its natural home, the center of the universe, just as an ordinary object on the ground stays in its place unless something comes along and dislodges it.) Scholars pointed to countless observations that all led to the same conclusion. We can be sure the Earth stands still, one eminent philosopher explained, “for at the slightest jar of the Earth, we would see cities and fortresses, towns and mountains thrown down.”

  But we don’t see cities toppled, the skeptics noted, nor do we see any other evidence that we live on a hurtling platform. If we’re racing along, why can we pour a drink into a glass without worrying that the glass will have moved hundreds of yards out of range by the time the drink reaches it? If we climb to the roof and drop a coin, why does it land directly below where we let it go and not miles away?

  But Copernicus’s new doctrine inspired fear as well as ridicule and confusion, because it led almost at once to questions that transcended science. If the Earth was only one planet among many, were those other worlds inhabited, too? By what sort of creatures? Had Christ died for their sins? Did they have their own Adam and Eve, and what did that say about evil and original sin? “Worst of all,” in the words of the historian of science Thomas Kuhn, “if the universe is infinite, as many of the later Copernicans thought, where can God’s Throne be located? In an infinite universe, how is man to find God or God man?”

  Copernicus could not disarm such fears by pointing to new discoveries or new observations. He never looked through a telescope—Galileo would be one of the first to turn telescopes to the heavens, some seven decades after Copernicus’s death—and in any case telescopes could not show the Earth moving but only provided evidence that let one deduce its motion.

  On the contrary, everything that Copernicus could see and feel spoke in favor of the old theories and against his own. “Sense pleads for Ptolemy,” said Henry More, a colleague of Newton at Cambridge and a distinguished English philosopher. But common sense lost out. The old, Earth-centered theory that Ptolemy had devised was a mathematical jumble, and that marked it for death. The old system worked perfectly well, but it was a hodgepodge.

  The great challenge to pre-Copernican astronomy had to do with sorting out the motions of the planets, which do not trace a simple course through the sky but at some point interrupt their journey and loop back in the direction they’ve just come from. (The stars present no such mystery. Each night Greek astronomers watched them rotating smoothly through the sky, turning in a circle with the North Star at its center. Each constellation moved around the center, like a group of horses on a merry-go-round, but the stars within a constellation never rearranged themselves.)

  The path of Saturn as seen from Earth, as depicted by Ptolemy in 132–33 A.D. From March through June, Saturn appears to reverse course.

  Accounting for the planets’ strange course changes would have been enough to give classical astronomers fits. Making the challenge all the harder, classical doctrine decreed that planets must travel in circular orbits (since planets are h
eavenly objects and circles are the only perfect shape). But circular orbits didn’t fit the data. The solution was a complicated mathematical dodge in which the planets traveled not in circles but in the next best thing—in circles attached to circles, like revolving seats on a Ferris wheel, or even in circles attached to circles attached to circles.

  Copernicus tossed out the whole complicated system. The planets weren’t really moving sometimes in one direction and sometimes in the other, he argued, but simply orbiting the sun. The reason those orbits look so complicated is that we’re watching from the Earth, a moving platform that is itself circling the sun. When we pass other planets (or they pass us), it looks as if they’ve changed course. If we could look down on the solar system from a vantage point above the sun, all the mystery would vanish.

  This new system was conceptually tidier than the old one, but it didn’t yield new or better predictions. For any practical question—predicting the timing of eclipses and other happenings in the solar system—the old system was fully as accurate as the new. No wonder Copernicus kept his ideas to himself for so long. And yet think of the astonishing leap this wary thinker finally nerved himself to make. With no other rationale but replacing a cumbersome theory with one that was mathematically more elegant, he dared to set the Earth in motion.

  A few intellectuals might have been won over by a revolutionary argument with nothing in its favor but aesthetics. Most people wanted more. How did the new theory deal with the most basic questions? “If the moon, the planets and comets were of the same nature as bodies on earth,” wrote Arthur Koestler, “then they too must have ‘weight’; but what exactly does ‘the weight’ of a planet mean, what does it press against or where does it tend to fall? And if the reason why a stone falls to Earth is not the Earth’s position in the center of the universe, then just why does the stone fall?”

  Copernicus did not have answers, nor did he have anything to say about what keeps the planets in their orbits or what holds the stars in place. The Greeks had provided such answers, and the answers had stood for millennia. (Each planet occupied a spot on an immense, transparent sphere. The spheres were nested, one inside the other, and centered on the Earth. The stars occupied the biggest, most distant sphere of all. As the spheres turned, they carried the planets and the stars with them.)

  No one could yet answer the new questions about the stars and planets. No one knew why objects on Earth obey one set of laws and bodies in the heavens another. No one even knew where to look for answers. John Donne, poet and cleric, spoke for many of his perplexed, frustrated contemporaries. “The Sun is lost, and th’ earth, and no man’s wit / Can well direct him where to look for it,” he lamented, in a poem written a year after Galileo first looked through his telescope.

  “The new Philosophy calls all in doubt,” Donne wrote in another verse. “ ’Tis all in pieces, all coherence gone.”

  Part Two: Hope and Monsters

  Chapter Seventeen

  Never Seen Until This Moment

  Virginia Woolf famously remarked that “on or about December 1910 human character changed.” She might have picked a different date, almost precisely three centuries earlier. On January 7, 1610, Galileo turned a telescope to the night sky. Human nature—or at least humankind’s picture of the universe and our own place within it—changed forever.

  Three months later Galileo told the world what he had seen, in a book called The Starry Messenger. On the day the book reached Venice, the English ambassador, Sir Henry Wotton, sent a startled letter home. “I send herewith unto his Majesty the strangest piece of news (as I may justly call it) that he hath ever yet received from any part of the world.” Sir Henry’s emphasis on the word news was fitting. What he was about to pass on was not merely “news” in the modern, journalistic sense but “news” in the truest sense—a report of something that until that moment had never been seen or even imagined.

  What was this astonishing news? “The Mathematical Professor at Padua . . . hath discovered four new planets rolling about the sphere of Jupiter”—four new planets in the unchanging heavens—and that was only part of the story. Galileo had also uncovered the secret of the Milky Way; he had learned, for the first time, the true nature of the moon, with all its pockmarked imperfections; he had found that the supposedly pristine sun was marred with black spots. In short, Wotton reported in slack-jawed astonishment, “he hath . . . overthrown all former astronomy.”

  Four decades before, the Danish astronomer Tycho Brahe had startled the world with a discovery of his own. In 1572 Tycho saw what he took to be a new star in the constellation Cassiopeia.23 The last of the great naked-eye astronomers, Tycho was a meticulous observer with an unsurpassed knowledge of the sky. He had known “all the stars in the sky” from boyhood, he boasted, but even casual stargazers knew Cassiopeia, with its striking W shape. The supposed star shone so brightly that it could be seen during the day. It stayed in view for well over a year, which meant that it couldn’t be a comet. It never changed its position against the backdrop of other stars, which meant that it had to be immensely far away. Nothing but a star had those properties. It was undeniable, and it was impossible.

  Today every promising actor or athlete is a “new star,” and the cliché has lost its force, but the appearance of the first new star in the immutable heavens was shocking. Tycho proclaimed it “the greatest wonder that has ever shown itself in the whole of nature since the beginning of the world, or in any case as great as when the Sun was stopped by Joshua’s prayers.”

  Unable to sort out its meaning, most observers labeled this aberration “Tycho’s star” and did their best to put it out of their minds. But in 1604, still another new star appeared, this one perhaps even brighter than its predecessor. Galileo, caught up in the excitement, delivered a public lecture on the new star to a standing-room-only crowd. The discovery of two new stars within three decades shocked the learned world. Stargazers knew the appearance of the night sky as intimately as coast dwellers know the sea. We miss the point if we downplay their astonishment. How could a star appear where no star could be? All Europe was as stunned as another group, on the other side of the Atlantic, at almost the same moment.

  On the morning of September 3, 1609, a band of Indians fishing from dugout canoes just off present-day Manhattan saw something odd in the distance. At first, it was only clear that the strange object was “something remarkably large swimming or floating on the water, and such as they had never seen before.” These first witnesses raced to shore and recruited reinforcements. The object drew closer. The guesswork grew frenzied, “some [of the Indians] concluding it either to be an uncommon large fish or other animal, while others were of opinion it must be some very large house.” The mysterious object drew closer still and then halted, its huge white wings billowing. In fear and fascination, the Indians on shore and the sailors on the deck of Henry Hudson’s Half Moon stood staring at one another.

  What was it like to see what no one had ever seen before?

  In that same year of 1609, perhaps in May, Galileo heard talk of a Dutch invention, a lens maker’s device with the power to bring far-off objects into close view. By this time, reading glasses to compensate for farsightedness were centuries old. Glasses to help with nearsightedness were more recent but widely available, too. Lenses for farsightedness were convex, thick in the middle and thin at the edges (lentil-shaped, hence the word lens); lenses for nearsightedness were concave, thinner in the middle than at the edges. The breakthrough that made the telescope possible was to combine a convex lens with a concave one. Everything hinged on the proportion between the strengths of the two lenses, which called for difficult feats of grinding and polishing.

  By the end of August, Galileo had built one of the sorcerer’s tubes for himself. It didn’t look like much—a skinny tube about a yard long made mostly from paper and wood, it resembled a tightly rolled poster—and it took a bit of fiddling to get the hang of seeing through it. Galileo unveiled it to a group of high-r
anking Venetians. They took turns peering through his telescope and responded with “infinite amazement,” in Galileo’s proud words.

  “Many of the nobles and senators, although of a great age, mounted more than once to the top of the highest church tower in Venice,” Galileo reported, “in order to see sails and shipping that were so far off that it was two hours before they were seen, without my spy-glass, steering full sail into the harbor.” The military advantages of such an invention were plain, but Galileo made sure that no one could miss them. The telescope, he pointed out, allows its users “to discover at a much greater distance than usual the hulls and sails of the enemy, so that for two hours and more we can detect him before he detects us.”

  Galileo rocketed to fame. Thrilled by what they had seen, the senators immediately doubled his salary and awarded him a lifetime contract at Padua. (Galileo had helped his own cause by presenting the senators an elaborate telescope as a gift, this one no drab tube but an ornate instrument in red and brown leather decorated, like an elegant book, in gold filigree.)

  Galileo’s decision to highlight the telescope’s value for warfare and commerce was cagey, but it was necessary, too. Galileo had grand ambitions. He knew from the start that the real discoveries would come from looking up to the stars, not out to sea. Which meant that the world had to be cajoled into believing that it could trust the sights revealed by this new, mysterious invention. In Rome, in 1611, he pointed his telescope at a palace far in the distance, and “we readily counted its each and every window, even the smallest.” With the telescope trained on a distant wooden sign, “we distinguished even the periods carved between the letters.”

  So the telescope provided honest information. It revealed true features of faraway objects; it didn’t somehow, through trickery or strange properties of light and lenses, conjure up mirages. If Galileo had simply aimed his telescope at the heavens, without preliminaries, skeptics might have dismissed the wonders he claimed to see. (Even so, some people refused to look, as today some might shy away from a purported ESP machine.)