The Day We Found the Universe (13 page)

Despite the lack of support for his creative hypothesis, Curtis was still gaining appreciable momentum on his endeavor, at least until World War I intervened. Just months after the United States officially joined the fight in 1917, Curtis went first to San Diego and then to Berkeley to teach officer recruits navigation. Afterward, he proceeded to Washington, D.C., to work for the Bureau of Standards on the design and development of military optical devices. Before taking his leave, though, Curtis made sure to compile a master list of the spiral nebulae he had photographed with the Crossley, by now more than five hundred. And as before, each of his photographs revealed ever more nebulae, pale and murky, surrounding the more consequential spirals that he officially cataloged. On one plate alone he counted 304 additional spirals. Keeler had estimated that 120,000 spiral nebulae were within observational range of the Crossley. Another Lick astronomer later upped that number to 500,000. Now Curtis was raising the figure even higher. “The great numbers of small spirals found on nearly all my plates of regions distant from the Milky Way, long since led me to the belief that [an earlier] estimate of half a million was likely to be under, rather than in excess of, the truth,” he reported. “[I] believe that the total number accessible with the Crossley Reflector with rapid plates and exposures of from two to three hours may well exceed 1,000,000.” This was an astounding hike in the spiral estimate.

While still in the U.S. capital wrapping up his work after the 1918 armistice, Curtis was invited to deliver a semipopular lecture on the spiral nebulae before the Washington Academy of Sciences and the Philosophical Society of Washington. His expertise on the topic was getting noticed. “Get up a collection of about 40 classy slides and send to me at once,” he wrote Campbell at Lick in great excitement. Curtis was thrilled at the opportunity, his first actually, to lay out before an influential scientific conclave all his hard-won evidence in support of the island-universe theory. He planned to use a lantern slide—the early-twentieth-century version of PowerPoint—to display the various types of spirals he had come across, to point out the dark lanes running through them, and to reveal the many fainter nebulae lurking in the background of his photographs of the spirals.

On the appointed day—March 15, 1919—a large audience gathered to hear Curtis in the new lecture room at Washington's prestigious Cosmos Club (then located at Lafayette Square), the traditional meeting place for the city's intelligentsia. Curtis opened with a tip of the hat to William Herschel. “The history of scientific discovery affords many instances where men with some strange gift of intuition have looked ahead from meager data, and have glimpsed or guessed truths which have been fully verified only after the lapse of decades or centuries,” he said. “We have now, as far as the spiral nebulae are concerned, come back to the standpoint of Herschel's fortunate, though not fully warranted deduction…that these beautiful objects are separate galaxies, or ‘island universes,’ to employ the expressive and appropriate phrase coined by Humboldt.” With these words, Curtis became the most outspoken and identifiable advocate of the island-universe theory.

Curtis at the time estimated that our stellar home was some 30,000 lightyears wide and contained about a billion stars, with the Sun nicely situated right near the center. He was wrong about that: The Milky Way's dimensions were even then being revised upward, and the Sun was losing its front-row seat on galactic affairs. But Curtis was right about the spiral nebulae being far-off galaxies.

Over the course of that March evening, Curtis laid out his arguments point by point. First, there was the peculiar distribution of the spiral nebulae. If they are stars in the making, he asked, why are there no spirals in the very place where stars are most numerous, the Milky Way? “Occulting matter,” he answered, was masking our view, making it only appear as if the spirals were avoiding the plane of the Milky Way. And then there was the very light of a spiral to consider: The spectrum of a spiral revealed that its light was emanating from a massive assembly of stars, not just a cloud of gas.

His logic was impeccable. Going through the historical records, Curtis determined that nearly thirty “new stars” had made an appearance within the Milky Way over the last three hundred years, each suddenly rising to great luminosity and then sinking back into obscurity once again. But half that number had already been sighted in spiral nebulae in just a few years, making it all the more likely that the “spirals are themselves galaxies composed of hundreds of millions of stars.” Moreover, with the novae being so faint, they had to be situated millions of lightyears away. “This is an enormous distance,” admitted Curtis, “but, if these objects are galaxies like our own stellar system, this is about the order of distance at which we should expect them to be placed.”

Curtis was fully aware of the magnitude and complexity of the new cosmic scheme he was proposing. “We know that the relative space in this, our galaxy, occupied by…our solar system … is about the same order as that occupied by a single drop of water in Chesapeake Bay,” he told his audience. “To go still beyond such a concept, the island universe theory forces us to consider a still mightier whole, a space containing hundreds of thousands of stellar universes like our own, each containing millions upon millions of suns… Awe-inspiring as are the concepts of astronomy, this newer concept surpasses them all; it staggers the imagination.” Curtis was plainly carried away by the allure of this astounding idea. His audience was enthralled as well. At the end they applauded with great enthusiasm and kept him long afterward for further discussion.

At the close of the war, officials at the Bureau of Standards had hoped that Curtis would stay with the agency, but he refused. “As to my staying here permanently, I have no idea whatever of doing that,” he assured Campbell. “[I'm] anxious to get back to my hill and the Crossley, and
stay
there…. I am more than ever of the opinion that men like you [and] Hale…get all the hard knocks, and not half the fun out of life that those of us lower down get.” An observer at heart, he was eager to return to his nebulae. By May 1919, he was back on Mount Hamilton gathering more evidence in support of distant galaxies.

Curtis already had a few converts to his cause. Astronomer Andrew Crommelin of the Royal Observatory in Greenwich favored the island-universe theory as well, but voiced caution: “The hypothesis of external galaxies is certainly a sublime and magnificent one,” he said. “[But] our conclusions in Science must be based on evidence, and not on sentiment.” His fellow astronomers were setting the bar high. Curtis had to provide more than logical arguments to win his case. He needed concrete evidence. Additional clues had been arriving, but they did not originate with Curtis. They instead turned up at the Lowell Observatory, Lick Observatory's long-standing competitor located in northern Arizona.

My Regards to the Squashes

R
oman god. Bringer of War. Fourth planet from the Sun. Astronomers eager to solve the spiral nebulae dilemma had Mars, strangely enough, to thank for a further step toward an answer—at least in a roundabout way.

The red planet, with its vivid ruby luster, has fascinated stargazers for millennia, but interest grew even more intense after the invention of the telescope. With the extra magnification astronomers could at last discern markings on the surface of Mars. Bright patches around its poles, similar in appearance to our own planet's arctic and antarctic regions, were seen to wax and wane with the Martian seasons. So Earthlike was this behavior that by 1784 William Herschel was reporting that Mars “is not without a considerable atmosphere … so that its inhabitants probably enjoy a situation in many respects similar to ours.”

Scrutiny of Mars was particularly favorable in the fall of 1877, when Earth and Mars were at their closest, approaching in their orbits to within thirty-five million miles of each other. The superb viewing conditions allowed the Italian astronomer Giovanni Schiaparelli to catch sight of numerous dark streaks crossing Mars's reddish ochre regions, then known as “continents.” In his native language, he called these thin shadowy bands
canali
, or “channels,” which many figured arose from natural geographical processes.

But Schiaparelli's term was translated inaccurately, a gaffe that encouraged many fanciful conjectures. The most controversial, by far, was the assumption that the “canals” were irrigation works built by advanced beings, who were directing scarce resources over the surface of their planet for cultivation. “Considerable variations observed in the network of waterways,” wrote French astronomer Camille Flammarion in 1892, “testify that this planet is the seat of an energetic vitality… There might at the same moment be thunderstorms, volcanoes, tempests, social upheavals and all kinds of struggle for life.” No one championed this idea more avidly than Percival Lowell, a wealthy businessman whose crusade generated a Mars mania among the public, so much so that the
Wall Street Journal
in 1907 reported that evidence for the existence of Martian folk surpassed that year's financial panic as the news story of the year.

Percival Lowell
(Lowell Observatory Archives)

Lowell, the oldest of five children, came from a well-established New England family. He was one of the Boston Brahmins, upper-crust Bostonians who had made their fortunes creating the American cotton industry. A few years after graduating from Harvard in 1876, Lowell began to travel extensively, especially to the Far East, which led to his writing several well-received books on the region and its religions. By the 1890s, though, restless and searching for individual expression, he renewed a childhood interest in astronomy. “After lying dormant for many years,” recalled his brother, “it blazed forth again as the dominant one in his life.” Independently wealthy, Lowell decided to establish a private observatory atop a pine-forested mesa nestled against the small village of Flagstaff, Arizona (then still a territory of the United States). His initial aim was to observe the particularly close approaches of Mars occurring in 1894 and 1896. Later, the entire solar system became his celestial playground. He was taking to heart his family's motto—
occasionem cognosce
, “seize your opportunity.” It was a daring venture for an amateur astronomer with no professional experience, especially since he found himself competing with the new and larger astronomical outposts then being built by universities and research institutions. But in this rivalry, Lowell became the outsider, dedicating his observatory to the pursuit of questions that interested him and him alone. Given his obsession with the red planet, the high perch on which the observatory rested, 7,250 feet above sea level, was soon dubbed Mars Hill.

Lowell devoted the rest of his life to this infatuation. A rugged individualist and showman, he once listed his address as “cosmos” in a friend's guestbook. Though often charming when necessary, the patrician Bostonian could easily become enraged if either his opinions or scientific credentials were challenged. He eventually fired one charter member of his observing staff for continually insisting that the canals on Mars might be illusory after all.

Lowell installed a 24-inch refractor on Mars Hill. Though a modest-sized telescope (by then several others in the world had lens widths of thirty inches or more), it was still perched more than three thousand feet higher than the giant scope at the venerable Lick Observatory, and Lowell sought to outdo his competitor at every turn. Sometimes he tried too hard. Lowell and his staff occasionally reported on sightings—certain elusive stars or markings on planets—that simply weren't there. Lick staffers rolled their eyes in exasperation at the dubious announcements coming out of Flagstaff and hinted that there were defects in Lowell's scope (or with his eyesight). Before long a battle of the observatories ensued—California's top instrument versus Arizona's best. One newspaper headlined the unceasing skirmish as “The Strife of the Telescopes.”

In 1900 Lowell upped the stakes when he ordered a custom-built spectrograph that was an improved version of the one already in use at the Lick Observatory. He directed its manufacturer to make it “as efficient as could be constructed.” To operate it, Lowell hired a recent graduate of the Indiana University astronomy program, Vesto Melvin Slipher, who was grateful to be posted at one of the few observatories in the United States with a large telescope, along with high altitude, clear air, and good “seeing,” minimal blurring from atmospheric activity.