The Perfect Machine (12 page)

The generous funding and the prestigious names of Millikan, Hale, and Noyes soon attracted a faculty of first-rate appointments. Before the decade was out, Caltech achieved the impossible, vaulting into competition with eastern universities that had spent centuries building their faculties, facilities, and prestige.

For George Hale the special appeal of the California Institute was that it would provide laboratories and faculty in physics and astrophysics as a resource for the Mount Wilson Observatory. Hale had predicted, years before, when he established the
Journal of Astrophysics,
that new research and theory in astronomy would draw heavily from developments in physics, from Einstein’s work on gravity to the theoretical work on particles and waves in Europe. At the same time physicists and mathematicians with no formal training in astronomy were drawn to the problems of cosmology and astrophysics. As astronomers began to explore the basic processes at work in stars and other celestial objects, physicists saw a grand laboratory in which they could explore the most basic phenomena of nature. Between the new faculty and laboratories at Caltech, and the facilities of the Mount Wilson Observatory, George Hale was in the midst of exciting developments. The 1920s were heady days for astronomy.

Not long after the great debate in Washington, and after Henry Norris Russell turned down the position, Harlow Shapley was
appointed director of the Harvard College Observatory. For years Harvard, with its southern station in Peru and its voluminous records of observations recorded by generations of “computers,” had been the leading institution in American astronomy. Shapley would miss the access to the powerful telescopes at Mount Wilson, but his ambition had clashed often enough with others at the observatory that there was little love lost at his departure. One astronomer recalled, “I have never seen a quicker mind, a more agile sense of humor, or a more complete absence of what usually passes for humility.” Walter Adams, who had been virtually in charge during Hale’s frequent absences for illness or other commitments, thought that Shapley’s methods with Cepheids were “not new and that he has never given the credit where it belongs.”

At Harvard, Shapley had enough to keep him busy without worrying about what his former colleagues thought. The famed Harvard College Observatory was equipped with ancient telescopes and instrumentation, much of it located where urban growth had made serious observation impossible. The famed computers and their accumulations of ledgers were no substitute for state-of-the-art observation facilities. Shapley engaged Fecker & Co. of Ohio to explore the design of a large modern telescope for Harvard, while Shapley familiarized himself with the foundations. He soon became a regular visitor to the Rockefeller Foundation, willing to talk astronomy or to give his views on proposals from other observatories. The prestige of his position at Harvard, along with his experience at Mount Wilson, his fame after the great debate in Washington, and his ready access to reporters, made him a force to be reckoned with in American astronomy. Others were ready to take his place at Mount Wilson.

Edwin Hubble, like Harlow Shapley, was born in rural Missouri. He attended the University of Chicago on a scholarship and distinguished himself as a student of math and astronomy and a letterman in track and basketball. It is tricky to sort fact from myth in Hubble’s early life. He liked to give the impression that he had been a good-enough boxer to fight an exhibition with George’s Carpentier, then the reigning light-heavyweight champion, and that promoters had asked him to fight as a “white hope” against Jack Johnson, the black heavyweight champion, but there is no record that he ever fought professionally. He did accept a Rhodes scholarship to Oxford, where he read law at Queen’s College. He returned to the United States in 1913. He liked to tell people that he had passed the Kentucky bar and practiced law, but the only records have him teaching and coaching basketball at a high school in Indiana, just across the Kentucky line. Teaching bored him. According to a friend, the astronomer Nicholas Mayall, Hubble “chucked the law for astronomy” because “astronomy mattered.”

Hubble reenrolled in the University of Chicago in 1914, and went
to Yerkes to get his Ph.D. in astronomy. Service in the infantry in France interrupted his studies, but by 1919 he had arrived at Mount Wilson, sporting a newly acquired English accent, a tweed jacket, and a pipe. He was eager to use the famous one-hundred-inch telescope.

From the beginning Hubble’s interest was the nongalactic nebulae, including the spirals, those wispy pinwheels in the heavens that had formed the basis of Heber Curtis’s arguments in the “great debate.” In his Ph.D. dissertation Hubble argued that even if the current data were inconclusive, astronomers should proceed on the assumption that the “white” nebulae are galaxies or island universes—Heber Curtis’s position at the debate—because the assumption that they are within our stellar system leads to a full stop in research. At first Hubble was careful not to take a formal position on the Shapley-Curtis debate. “There appears to be a fundamental distinction between galactic and nongalactic nebulae,” he wrote. “This does not mean that the latter class must be considered as ‘outside’ our galaxy.”

In 1917 Ritchey had identified a nova—an exploding star—in an old photograph of a spiral nebula in the constellation Cygnus. Heber Curtis, at the Lick Observatory, then found plates from the Lick archives that showed novas in other spiral nebulae. These newly discovered novas were so much dimmer than novas in the Milky Way—the relative luminosity was as if a one-hundred-watt bulb were viewed at a distance of miles instead of inches—that if they had the same intrinsic luminosity they would have had to be very distant indeed. The novas were a powerful argument for island universes.

Hubble began a program of searching for novas in distant nebulae, counting nebulae for their space distribution, and photographing a wide range of nebulae to derive a morphology. He began his work at Mount Wilson with the sixty-inch telescope. His first night of observing was marked by seeing that the Mount Wilson astronomers rated as extremely poor. Hubble, used to the conditions at Yerkes, came back from the darkroom jubilant. “If this is a sample of poor seeing conditions,” he said, “I shall always be able to get usable photographs with the Mount Wilson instruments.”

Night after night he exposed plates on the big reflector. Day after day he studied the plates. The telescope drive turned the telescope on its polar axis to compensate for the rotation of the earth, but to make a successful plate, the observer had to track a guide star within the field of the exposure, using electrical hand controls to make tiny movements in the position of the telescope that would compensate for atmospheric effects, the flexure of the telescope tube and mount, and the slight quirks of the telescope-guiding mechanism. As the telescope slewed to different portions of the sky, Hubble had to contort his body on a precarious perch to keep the guide star in the crosshairs of the eyepiece. The winter nights were cold enough to freeze his tears to the eyepiece. The exposures were long enough to test his bladder control.
By morning his body would be a bundle of cricks. Lack of sleep and hours staring at the glass plates gave him headaches.

In 1923 Hubble began using the one-hundred-inch telescope to search for novas in the spiral nebula M33 in Triangulum and M31, the Andromeda Nebula. These are the only spiral nebulae visible to the naked eye, and he assumed that they were the closest to the earth. Lacking a wide-view camera to survey the entire nebulae for likely targets, he selected what he hoped would be promising areas of the two nebulae and photographed them repeatedly with the narrow field of view of the one-hundred-inch telescope. The relative luxury of the many nights of time he was allowed on the telescope meant that Hubble could take plates on the darkest nights with the best seeing, hoping the combination of perfect conditions would reveal the faint images he sought.

Each plate covered only a small region of sky, but the light-grasp of the big telescope, and the long exposures, revealed thousands of stars. “Critical tests made with the 100-inch reflector,” he wrote, “… show no difference between the photographic images of the so-called condensations in Messier 33 and the images of ordinary galactic stars.” The images he was resolving were fainter than photographic magnitude eighteen, dim enough to require long exposures on the regions of the nebulae where the stars were far enough apart from one another that they could be resolved. The resulting plates had to be scrutinized star by star in the search for images that had not appeared in the same place or at the same brightness on a previous plate of the same region. After months of exposures Hubble shifted to a more sensitive photographic emulsion and finally began to find novas. In all he studied more than 350 plates of the Andromeda Nebula.

On a plate from the night of October 5–6, 1923, Hubble marked off three apparent novas in M31 (Andromeda). On later examination he concluded that one of the three was not a nova at all but a Cepheid variable star. He extrapolated its luminosity and period from the formula and tables Shapley had used and concluded that the star had to be at an extreme distance from the Milky Way. He had found evidence that the Andromeda spiral was indeed an “island universe,” a separate galaxy like our own Milky Way. It was a staggering discovery: If the Milky Way was one of many galaxies, the universe was immense, bigger than even Shapley had imagined.

Hubble did not publish his findings immediately. His earlier study of law had made him cautious about evidence. He went back and reexamined earlier plates to confirm his results. He switched from Andromeda to a cluster of stars named NGC6822 in the rich star clouds of Sagittarius. A British veteran of the Lick Observatory named Charles Perrine had studied the cluster from Argentina and concluded
that it was
not
part of the Milky Way. Hubble identified fifty Cepheid variables in NGC6822. If Shapley’s Cepheid yardstick was correct, the cluster was deep in the cosmos, clearly an “island universe,” distinct from the Milky Way. “The principle of the uniformity of nature,” Hubble wrote, “seems to rule undisturbed in this remote region of space.” He leaked his findings to a few astronomers but waited to present them in a formal paper.

The perfect opportunity arose at the 1924 joint meeting of the American Astronomical Society (AAS) and the American Association for the Advancement of Science (AAAS), in Washington, where a prize of one thousand dollars, approximately six months’ salary for Hubble, was being offered for the best scientific paper. Henry Norris Russell, who knew of Hubble’s findings, arrived late at the conference and found that Hubble not only wasn’t there but hadn’t submitted a paper.

“Well,” said Russell, “he is an ass.”

Russell and a small group decided to draft a telegram to Hubble, urging that he send his new results so Russell and Shapley could draft them into a paper. Russell and Joel Stebbins, secretary of the AAS, were on their way to the telegraph desk when they spotted a large envelope from Hubble, addressed to Russell. They returned to the group, holding up the paper and joking that they had gotten a very quick reply to their telegram.

The next day, New Year’s Day 1925, Russell read Hubble’s paper, announcing the discovery of Cepheid variable stars in the Andromeda galaxy. By then Hubble had also discovered Cepheid variables in M33. By Shapley’s yardstick, which mapped the extent of the Milky Way at one hundred thousand parsecs,
^*
these two spiral nebulae were so distant that they were clearly outside our galaxy. Hubble and the one-hundred-inch telescope had settled the celebrated question of the great debate. Astronomy would never be the same.

Success begets ambition. Hubble’s discovery of Cepheid variables in the Andromeda galaxy, like Shapley’s earlier work, and Hale’s early work on magnetic fields in sunspots, had certified Mount Wilson as the leader in astronomical research. While other observatories were playing catch-up, searching for funds to upgrade existing facilities, in
the offices and library on Santa Barbara Street in Pasadena, and at the dining table in the Monastery on Mount Wilson,
^*
the astronomers had begun to talk of the possibilities of an even bigger telescope, powerful enough to penetrate to the depths of the universes that had been revealed by the one-hundred-inch telescope. George Hale was a regular at the talks: Big telescopes were a topic he couldn’t resist.

At Hale’s request, in 1921 Francis Pease prepared a preliminary drawing of a three-hundred-inch telescope. By 1925, after many revisions to his sketches, Pease had built a wooden model of his tentative design. Rumors of the plans leaked out, and Lester Markel of the
New York Times
fired off telegrams asking for details of the design and confirmation of a tentative price tag of $12 million. Bethlehem Shipbuilding, which had done some of the fabrication work on the one-hundred-inch, wrote to offer its facilities to build the new telescope. Harlow Shapley, eager to know what was in the works, wrote a friendly query from Harvard.

All the telegrams and letters were answered with evasions and denials. Pease’s drawings and model weren’t a working plan. They were a blown-up derivation of the sixty-inch telescope on Mount Wilson, with rudimentary concessions to the problems of a larger machine.

There were two problems with any plan for a bigger telescope. The first was that there were no funds available to build it and no prospect to raise those funds. And even if at some later date Yerkes or Hooker had miraculously come forward with the funds needed for a new telescope, it wasn’t clear that the technology existed to build such a machine. As a machine gets bigger, the engineering demands grow exponentially. The volume and mass of a machine increase not in linear proportion to the increase in linear dimensions, but by the
cube
of the increase. A three-hundred-inch telescope wouldn’t be 5 times as massive as a sixty-inch, but closer to 125 times. Pease’s early drawing shows the domes of the sixty- and one-hundred-inch telescopes superimposed on the dome of the new instrument. They look like toys in the corner.